First Report of Powdery Mildew Caused by Podosphaera xanthii on Sphagneticola trilobata in Hainan Province, China

Sphagneticola trilobata (L.) Pruski is a perennial creeping herb of the Asteraceae family, which is native to South America. It was introduced into Southern China as a groundcover in the 1970s (Zhang et al. 2023). Now it is mainly used for folk medicine to treat various kinds of inflammatory, incuding joint pain, rheumatic diseases, arthritis, in addition to treating persistent wounds, ulcers, and edemas (Gonçalves et al. 2022). In February and November 2023, powdery mildew symptoms were observed on 60% of S. trilobata plants on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 74 to 161 × 10 to 14 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 27 to 56 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 17 to 30 ×14 to 28 µm (length/width ratio = 1.1 to 1.9), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMST-23. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 577-bp sequence was deposited in GenBank (accession no. OR784549). A BLASTn search in GenBank of this sequence showed 100% similarity with the ITS sequences of P. xanthii isolates from China (MT260063, MN203658, OP765400, and MT739423), Thailand (LC270780), and Vietnam (KM260731, KM260730, and KR779870). Additionally, the 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O´Donnell 1993; accession no. OR784550). This region shared 100% similarity with P. xanthii isolates (LC371334, LC270782, AB936277, and OP765401) as well. Powdery mildew from Hainan sample belonged to the P. xanthii group with strong bootstrap values support 99% in maximum likelihood phylogenetic tree based on ITS and 28S gene sequences. To confirm pathogenicity, five healthy potted plants of S. trilobata were inoculated by gently pressing a powdery mildew-infected leaf onto 15 young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. In different countries and regions, P. xanthii has been previously reported on S. trilobata in Taiwan (Yeh et al. 2021). To our knowledge, this is the first record of P. xanthii infecting S. trilobata in Hainan Province, China. S. trilobata is often planted as an ornamental plant on both sides of the road, and we are concerned that it may serve as a new host, spreading this pathogen to other economic crops.

Molecular-Phylogenetic Characterization of Xanthomonas hortorum pv. pelargonii Strains Causing Leaf Spot of Geraniums in Iran

Bacterial blight and leaf spot of geraniums is a destructive disease of cultivated Pelargonium species around the world. During 2020-2021, surveys were conducted in seven geranium-growing provinces of Iran to monitor the status of bacterial blight and leaf spot disease. The disease was observed in six surveyed provinces varying in the extent of occurrence and severity. Twenty-two Gram-negative pale-yellow bacterial strains resembling members of Xanthomonas were isolated from symptomatic leaves and stems. Pathogenicity and host range assays showed that the bacterial strains were pathogenic on Pelargonium grandiflorum, P. graveolens, P. peltatum, and P. zonale. All strains were positive for PCR test using the primer pair XcpM1/XcpM2 which is specific for Xanthomonas hortorum pv. pelargonii. Phylogenetic analysis using the sequences of gyrB and lepA genes showed that the 22 strains clustered in a clade among the sequences of X. hortorum pv. pelargonii strains retrieved from the GenBank, while distinct from the other pathovars of X. hortorum. BOX-PCR-based fingerprinting using BOX-A1R primer revealed that the strains isolated in this study were grouped into two clusters while no distinct correlation was observed between the host/area of isolation and BOX-PCR fingerprinting. None of the strains obtained in this study nor reference strain of the pathogen did produce bacteriocin against each other. Results obtained in this study shed light on the geographic distribution, taxonomic status and host range of the bacterial blight and leaf spot pathogen of geraniums in Iran, paving the path of further research on disease management.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Acalypha indica in China

Acalypha indica L. is an annual erect herb of the Euphorbiaceae family. This plant is found widely in the tropics and parts of Africa and Asia (Chakraborty et al. 2023). In China, A. indica is a vegetable and also used as a folk medicine due to its antipyretic and hemostatic, antibacterial and anti-inflammatory properties. In February 2022 and 2023, powdery mildew symptoms were observed on 70% of A. indica plants on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 66 to 150 × 10 to 15 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 31 to 59 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 20 to 33 ×12 to 20 µm (length/width ratio = 1.3 to 2.4), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMAI-23. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 575-bp sequence was deposited in GenBank (accession no. OR775733). A BLASTn search in GenBank of this sequence showed 99% similarity with the ITS sequences of P. xanthii on plants of Fabaceae, Malvaceae and Cucurbitaceae family from China (MH143485, MT242593, MK439611 and MH143483), Thailand (LC270779 and LC270778), Korea (MG754404), Vietnam (KM260704), and Puerto Rico (OP882310). Additionally, the 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O´Donnell 1993; accession no. OR784547). This region shared 99% similarity with P. xanthii isolates (LC371333, LC270780, AB936277, and OP765401) as well. To confirm pathogenicity, five healthy potted plants of A. indica were inoculated by gently pressing a powdery mildew-infected leaf onto 15 young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. In different countries and regions, P. xanthii has been previously reported on A. indica from Sudan and India (Amano 1986). To our knowledge, this is the first record of P. xanthii infecting A. indica in China. We are concerned that the pathogen could become a threat to the widespread planting of A. indica in the future.

First report of leaf blight caused by Stemphylium lycopersici on Salvia splendens in China

Salvia splendens is a popular ornamental plant in China with extensive potentials, including value in traditional Chinese medicine and in environmental restoration function (Li et al. 2008). In September 2019, leaf blight disease was observed on road side plants of S. splendens in Bayi park, Nanchang city, Jiangxi province, China. The typical symptoms appeared as irregular necrotic spots or leaf blight, accompanied by extensive scorch necrosis or ultimately defoliation. Small segments cut from diseased leaves were surface sterilized in a 2% sodium hypochlorite solution for 2 min and rinsed three times with sterile distilled water. Then, the samples were placed on potato dextrose agar (PDA) plates incubated at 25°C in darkness. Pure cultures were obtained by the hyphal tip method. Morphologically, all 11 colonies were identical to each other on PDA. Two strains, YZU 191468 and YZU 191481, were selected for further study and deposited in the Fungal Herbarium of Yangtze University (YZU), Jingzhou, Hubei, China. The 7-day-old colonies were circular, 53 to 56 mm in diameter, and consisted of white mycelium with a buff margin, and were cinnamon colored in the center of the reverse side. To examine conidial morphology, the mycelium was transferred onto potato carrot agar (PCA) and incubated at 23°C with a period of 8 h light/16 h dark for 7 days. Conidia were normally solitary or two in a chain, ellipsoid or long ellipsoid, beakless, 10 to 23×30 to 60 µm in size (n=50). Based on morphology, the isolates were consistent with Stemphylium lycopersici (Yamamoto 1960). To confirm the identification, genomic DNA was extracted from both isolates and used to amplify the internal transcribed spacer rDNA region (ITS), glyceraldehydes-3-phosphate dehydrogenase (GAPDH) and calmodulin (CAL) genes with primer pairs ITS5/ITS4, gpd1/gpd2, and CALDF1/CALDR2, respectively (Woudenberg et al. 2017). Sequences were deposited in GenBank with accession numbers OP564983 and OP564984 (ITS), OP892529 and OP892530 (GAPDH), OP584970 and OP584971 (CAL). A neighbor-joining tree was constructed with Mega 7.0 based on the combined dataset with 1,000 bootstrap replicates. The resulting phylogenetic tree showed that the strains from S. splendens clustered with S. lycopersici (CBS 122639 and CBS 124980) supported with 100% bootstrap values. The molecular analyses confirmed that the species causing leaf blight symptoms was S. lycopersici. To test pathogenicity, healthy leaves of S. splendens were surface sterilized and inoculated by mycelium blocks (6 mm in diameter) and spore suspension (1×106 spore/mL) of representative strains YZU 191468 and YZU 191481, respectively. Controls were inoculated with blocks of PDA and sterile water. Each strain was inoculated on three leaves of a plant. One clean plant was used as control. The test was replicated three times. After inoculation, the plants were covered with plastic bags and incubated in a greenhouse (25℃, 80 % relative humidity, 8 h light/16 h dark). After 5 days, the inoculated leaves exhibited dark brown spots with white mycelium, followed by withering of necrotic tissues. There were no symptoms observed on the controls. The fungal isolates inoculated leaves had the same morphological characteristics as the strains used for inoculation. S. lycopersici has been found on eggplant and Zinnia elegans in China (He et al. 2019; Yang et al. 2017). To the best of our knowledge, this is the first report of S. lycopersici causing leaf blight on S. splendens in China. This finding offers a new reference for the management and control of S. splendens leaf diseases in China.

First Report of Anthracnose on Euonymus japonicus Thunb. Caused by a Provisionally Novel Species of Colletotrichum in the Magnum Complex in South Korea

Euonymus japonicus Thunb., also known as the evergreen spindle tree, is an evergreen tree, which is widely planted as a hedge plant along streets in South Korea. In April 2022, severe anthracnose symptoms were observed on the leaves of this tree in Jangsu in the Jeonbuk Province of the country (35°43'49.44″N, 127°34'53.7″E). About 80% of the leaves of each affected tree within a 0.03-ha area showed incidence of the disease on approximately 30 trees were planted along the roadside (~30 m). These symptoms typically included circular or irregularly shaped whitish-gray lesions with a diameter of 2.0 to 3.0 cm. In cases where some leaves were severely affected, larger blotches formed. To isolate the pathogen, about ten leaves showing anthracnose symptoms on each tree were randomly selected and brought to the laboratory. Fungal isolations were made from acervuli filled with conidial masses on infected evergreen tissues, followed by plating onto 2% potato dextrose agar (PDA) as well as incubated at 25℃. On the PDA, colonies were circular, raised, green-grey or dark grey, and had a distinct white margin. The conidia were single-celled, transparent, cylindrical with rounded ends, had smooth walls, with a length ranging from 12 μm to 16.7 μm and a width raging from 4 μm to 6.5 μm (av. = 14.1 X 5.0 μm, n=40). Of those that were successfully recovered with approximately 90% frequency, two monoconidial isolates were deposited to the culture collection at Chungnam National University in South Korea (Accession number: CDH059-060). To ensure the identity of the fungus, genomic DNAs were extracted from the selected isolates, CDH059-060, and were sequenced. This was achieved based on partial sequences of the internal transcribed spacer (ITS), actin and beta-tubulin (TUB2) gene regions which were amplified using ITS1F / ITS4 (Gardes and Bruns 1993; White et al. 1990), ACT-512F / ACT-783R (Carbone and Kohn 1999), and T1 / Bt2b (O'Donnell and Cigelnik 1997; Glass and Donaldson 1995) primer pairs, respectively. The resulting sequences were deposited to GenBank (OR984424-425) for ITS, (OR996289-290) for actin, and (OR996291-292) for TUB2. For a phylogenetic analysis, sequences from different gene regions (ITS, actin and TUB2) retrieved from GenBank were aligned, concatenated, and analyzed as a single dataset based on a maximum likelihood analysis. The phylogenetic result revealed that the fungus isolated in this study was positioned in a clearly distinct lineage, provisionally representing an undetermined species of Colletotrichum, which is most closely related to Colletotrichum liaoningense (Y.Z. Diao, C. Zhang, L. Cai & X.L. Liu, CGMCC3.17616 (KP890104 for ITS, KP890097 for actin, and KP890111 for TUB, Diao et al. 2017). Sequence comparisons revealed that this pathogen differed from C. liaoningense at 20 of 494 characters (∼4.0%) in the ITS and 2 of 251 (∼1.0%) in the actin sequences. For pathogenicity tests, three seedlings of E. japonicus were used. The leaves for each tree were treated with 10 ml of a conidial suspension by spraying (1x10⁶ conidia ml-1 of the isolate, CDH059), while the three seedlings were treated with distilled water as control. After sprayed, the treated areas were sealed with plastic bags for a day to maintain humidity. Anthracnose symptoms identical to those observed in the field appeared seven days after inoculations, while no symptoms were observed in the control. Re-isolations were successfully achieved from the treatments, fulfilling Koch's postulates. Anthracnose associated with the provisionally novel species of Colletotrichum sp. on E. japonicus has not been recorded elsewhere, and in this regard, this is the first report of anthracnose caused by Colletotrichum sp. on E. japonicus in Korea. To effectively control the disease, more attention should be paid to the host range of the pathogen and other regions where the disease caused by the pathogen might occur in the country.

First report of Pseudomonas cichorii causing bacterial leaf blight of pocketbook plant (Calceolaria hybrida) in Taiwan

Pocketbook plants (Calceolaria spp.) are flowering ornamentals often grown as potted plants (Poesch 1937). In December 2022, leaf blight symptoms were observed on 2-mo-old plants of C. hybrida F1 'Dainty'. The disease was found in a nursery in Ren'ai Township, Nantou, and about 20% of the plants exhibited symptoms. Symptomatic plants had brown or gray necrotic lesions of different sizes and shapes, mostly around leaf margins. Lower leaf wilting was also observed (Fig. S1, A and B). Three plants were sampled. Leaf lesions were surface-disinfected with 75% ethanol and cut into smaller pieces in 10 mM MgCl2. After observing bacterial streaming under a microscope, the bacteria were streaked onto nutrient agar (NA). Following 2 days at 28°C, a type of round, creamy white colony predominated on all the plates. Three strains (Calc-A, Calc-B, and Calc-C) were obtained, one from each plant. The strains produced fluorescent pigments on King's B medium and were tested Gram-negative. The strains were characterized with the LOPAT scheme (Schaad et al. 2001). They did not exhibit activities of pectic enzymes, arginine dihydrolase and levan sucrase, but produced oxidase and induced the hypersensitive response in tobacco. DNA was extracted from the strains for PCR amplification of the 16S rDNA with primer pair 27f/1492r as described by Lane (1991). The 16S rDNA sequences were compared with entries in the GenBank database. The sequences obtained (GenBank accession no. OR824302) matched that of Pseudomonas cichorii MAFF 301158 (accession no. AB724288; 1,403/1,403 bp) and were 99% identical to that of DSM 50259T (accession no. CP074349; 1,391/1,405 bp). The strains were also tested with the species-specific primers hrp1a and hrp2a (Cottyn et al. 2011). The amplicons were sequenced and a BLASTn search showed that the sequences (accession no. OR827305) shared the highest identity (99.3%) with that of P. cichorii strain 83-1 (accession no. DQ168848; 848/854 bp) and were 97.3% identical to the sequence of DSM 50259T (accession no. CP074349; 831/854 bp). Calc-A was selected as a representative strain and deposited in the Bioresource Collection and Research Center, Taiwan (reference no. BCRC 81432). Koch's postulates were fulfilled by spray-inoculating a suspension of Calc-A on three 2-mo-old C. hybrida F1 'Dainty' plants. The inoculum was prepared by suspending NA-grown cells in 10 mM MgCl2 including 0.02% Silwet L-77 (OD600 = 0.3; 1.5 x 108 CFU/ml). For the controls, three plants were sprayed with bacteria-free solution. The plants were bagged throughout the experiment and kept in a growth chamber (14/10 h light/dark; 26/24°C day/night). Leaf blight and wilting symptoms developed on all leaves of the inoculated plants after 30 h, but not the controls (Fig. S1, C and D). The pathogen was reisolated from the treatment group, and colony PCR with hrp1a/hrp2a showed that the reisolated strain shared the same sequence with Calc-A to Calc-C. Repeating the inoculation assay produced consistent results. This is the first report of P. cichorii affecting Calceolaria in Taiwan. The bacterium has been reported infecting diverse crops in Taiwan, such as tomato and lettuce (Tsai et al. 2014). Expanding the understanding of the pathogen's potential hosts could help prevent its spread across important crops.

First Report of White Mold Caused by Sclerotinia sclerotiorum on Echeveria gigantea in Mexico

Echeveria gigantea, native of Mexico (Reyes et al. 2011), holds economic importance as it is marketed as a potted plant and cut flower due to its drought-tolerant capabilities and aesthetic appeal. In September 2023, a field sampling was conducted at the Research Center in Horticulture and Native Plants (18°55'56.6" N, 98°24'01.5" W) of UPAEP University. Echeveria gigantea cv. Quilpalli plants with white mold symptoms were found in an area of 0.5 ha, with an incidence of 40% and severity of 50% on severely affected stems. The symptoms included chlorosis of older foliage, necrosis at the base of the stem, and soft rot with abundant white to gray mycelium and abundant production of irregular sclerotia resulting in wilted plants. The fungus was isolated from 30 symptomatic plants. Sclerotia were collected, sterilized in 3% NaOCl, rinsed with sterile distilled water (SDW), and plated on Potato Dextrose Agar (PDA) with sterile forceps. Subsequently, a dissecting needle was used to place fragments of mycelium directly on PDA. Plates were incubated at 23 °C in darkness. A total of 30 isolates were obtained using the hyphal-tip method, one from each diseased plant (15 isolates from sclerotia and 15 from mycelium). After 6 days, colonies had fast-growing, dense, cottony-white aerial mycelium forming irregular sclerotia of 3.67 ± 1.13 mm (n=100). Each Petri dish produced 32.47 ± 7.5 sclerotia (n=30), after 12 days. The sclerotia were initially white and gradually turned black. The isolates were tentatively identified as Sclerotinia sclerotiorum based on morphological characteristics (Saharan and Mehta 2008). Two isolates were selected for molecular identification. Genomic DNA was extracted using the CTAB protocol. The ITS region and the glyceraldehyde 3-phosphate dehydrogenase (G3PDH) gene were sequenced for two randomly selected isolates (White et al. 1990; Staats et al. 2005). The ITS and G3PDH sequences of the SsEg9 isolate were deposited in GenBank (ITS-OR816006; G3PDH-OR879212). BLAST analysis of the partial ITS (510 bp) and G3PDH (915 bp) sequences showed 100% and 99.78% similarity to S. sclerotiorum isolates (GenBank: MT101751 and MW082601). Pathogenicity was confirmed by inoculating 30 120-day-old E. gigantea cv. Quilpalli plants grown in pots with sterile soil. Ten sclerotia were deposited at the base of the stem, 10 mm below the soil surface. As control treatment, SDW was applied to 10 plants. The plants were placed in a greenhouse at 23 °C and 90% relative humidity. After 16 days, all inoculated plants displayed symptoms similar to those observed in the field. Control plants did not display any symptoms. The fungus was reisolated from the inoculated stems, fulfilling Koch's postulates. The pathogenicity tests were repeated three times. Recently S. sclerotiorum has been reported causing white mold on cabbage in the state of Puebla, Mexico (Terrones-Salgado et al. 2023). To the best of our knowledge, this is the first report of S. sclerotiorum causing white mold on E. gigantea in Mexico. Information about diseases affecting this plant is very limited, so this research is crucial for designing integrated management strategies and preventing spread to other production areas.

First Report of Stem and Foliage Blight of Chrysanthemum morifolium cv. Fubaiju Caused by Stagonosporopsis chrysanthemi in China

Chrysanthemum (Chrysanthemum morifolium cv. Fubaiju) is used as medicinal herb (Chen et al. 2020). In October 2021, a leaf spot disease was observed on leaves of C. morifolium in Huanggang, Hubei province. Disease incidence was approximately 40%. Leaf lesions manifested as necrotic spots, coalesced, and expanded to form brown-black spots, leading to wilting of the leaves. On stems, the lesions manifested as dark brown necrotic spots. To identify the pathogen, 29 pieces (5 × 5 mm) from lesion margins were surface sterilized in 1% NaOCl and rinsed three times with sterile water. The pieces were transferred onto potato dextrose agar (PDA) for incubation at 25℃ for 3 d in the dark. Fifteen fungal colonies were successfully isolated. The colony morphology with flat wavy edge, sparse aerial mycelia, and surface olivaceous black were observed at 7 days post incubation. Subglobular pycnidia were brown with a short beak, and pycnidia diameters were thick (212 to 265 × 189 to 363 µm, n = 20). Ovoid conidia were aseptate and hyaline, conidia diameters were thick (4.0 to 9.8 × 1.8 to 4.7 µm, n = 100). The morphological characters of these isolates were consistent with those of Stagonosporopsis chrysanthemi (Zhao et al. 2021). Pure culture of representative HGNU2021-18 isolated from the diseased leaves subjected to molecular identification. Sequences of the rDNA internal transcribed spacer (ITS) region, 28S large subunit ribosomal RNA (LSU), β-tubulin (TUB2), actin (ACT), and partial RNA polymerase II largest subunit (RPB2) genes were amplified from genomic DNA of isolate HGNU2021-18 using the following primer pairs: ITS1/ITS4 (White et al. 1990), LR0R/LR5 (Rehner et al. 1994), Btub2Fd/Btub4Rd (Woudenberg et al. 2009), ACT512F/ACT783R (Carbone et al.1999), and RPB2-5F2 (Sung et al. 2007)/fRPB2-7cR (Liu et al. 1999), respectively. The PCR products were purified and then sequenced by Sangon Biotech (China). Nucleotide sequences of ITS (544 bp, OM346748), LSU (905 bp, OM758418), TUB2 (563 bp, OM945724), ACT (294 bp, OM793715), and RPB2 (957 bp, OM793716) amplified from the isolate HGNU2021-18 were subjected to BLASTn analysis. The results showed that ITS, LSU, TUB2, ACT, and RPB2 shared 100.00%, 99.45%, 99.20%, 100.00%, and 100.00% sequence identity to the five published sequences (MW810272.1, MH869953.1, MW815129.1, JN251973.1, and MT018012.1, respectively) of the S. chrysanthemi isolate CBS 500.63. Phylogenetic analysis of the multilocus sequences of ITS, LSU, RPB2, ACT, and TUB2 belonging to different Stagonosporopsis species was performed in MEGA 7.0 (Chen et al. 2015). Isolate HGNU2021-18 was placed in a clade with S. chrysanthemi with 99% bootstrap support. Thus, the results of morphological and molecular analyses indicated that the disease symptoms on chrysanthemum plants were caused by S. chrysanthemi. Under conditions of 25°C and 85% relative humidity, pathogenicity test was performed on 2-month-old healthy plants using isolate HGNU2021-18. The leaves were inoculated with 5 mm diameter mycelial plugs or with sterile agar plugs (control). Six plants were used in each treatment. Disease symptoms were observed on treated plants at 2 weeks post inoculation which were those previously observed in the field, while the control plants remained symptomless. The pathogen was re-isolated from the diseased plants, and S. chrysanthemi was confirmed as the causal pathogen. This is the first report of S. chrysanthemi causing stem and foliage blight of chrysanthemum in China.

Transversotrema hafniensis n. sp. infection in Poecilia reticulata by cercariae released from Melanoides tuberculata in Denmark

BACKGROUND

Exotic and ornamental fish are highly popular companion animals resulting in a significant transcontinental trade of fish, invertebrates and aquatic plants. A major issue is the diseases associated with these organisms, as they have a major impact on health of the fish in both public and private household aquaria. A secondary issue is the trade with these products, which potentially may expand the distribution area and spread a range of diseases to new habitats.

RESULTS

We here describe how Poecilia reticulata (guppy), produced in a private household aquarium, were invaded by cercariae of an exotic trematode released by imported Melanoides tuberculata snails. The fish presented with severe clinical signs (tremor, flashing, scraping of body against objects). A standard parasitological examination and morphometric identification showed scale pocket infections with a digenean trematode species within the genus Transversotrema. Molecular identification by PCR, sequencing and phylogenetic analyses of a 2646 bp sequence encoding ribosomal RNA (partial 18 S, ITS1, 5.8 S, ITS2, partial 28 S) was performed. The 1107 bp sequence of mitochondrial DNA (cox1) showed that the parasite differed from previously described Transversotrema species in M. tuberculata. Morphometrics of adult and larval specimens of this isolate also differed from previously described freshwater species within the genus. The new species was described and is named after Copenhagen, for its geographic origin.

CONCLUSIONS

The genus Transversotrema comprises a range of species, adapted to a microhabitat in scalepockets of teleosts. A combination of morphological and molecular characterization techniques has been shown to provide a good differentiation between species. The fish were not purchased from a pet shop but produced in the home aquarium. This indicated that an infection pressure existed in the aquarium, where the source of infection was found to be exotic intermediate host snails M. tuberculata, which originally were imported and purchased from a pet shop. The potential spread of fish diseases associated with trade of fish and snails to new geographic regions, where climate conditions are favourable, is discussed.

Southern blight of water lily: The first host record of Agroathelia rolfsii on Nelumbo nucifera discovered in Florida, USA

Nelumbo nucifera Gaertn. (Nelumbonaceae, Eudicots), also known as water lily or sacred lotus, is a nonnative and invasive plant commonly found in artificial ponds and natural lakes throughout Florida (UF-IFAS 2023; Wunderlin et al. 2023). In August 2020, a single sample of water lily plants showing large leaf spots were collected at a residence in Dunnellon, Marion County, Florida (80% disease prevalence with 40% leaf coverage). Symptoms and signs of the disease were necrotized adaxial leaf spots only, bordered by whitish mycelia and hyphae with clamp connections, and whitish to light brown sclerotia formed in the center (<0.7 mm diameter). Symptomatic tissue was plated on acid potato dextrose agar (APDA) amended with chloramphenicol (100 mg/L) and ampicillin (30mg/L), and incubated at 20 °C for one week. Data supporting the molecular identification of this putative pathogen were gathered by PCR amplification and Sanger sequencing of the complete internal transcribed spacer (ITS) and a fragment of the large subunit (LSU) of the rRNA gene (~1.5 kb) using primers ITS1F and LR5 (FDACS-DPI PPST 2020-105211, GenBank OR492009) (White et al. 1990). The identification of the host was confirmed by Sanger sequencing of three plant barcode fragments: ITS2 (ITS2-S2F/ITS4, OR492008), ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) (rbcLa-F/rbcLa-R, GenBank OR502388), and Maturase K (matK) (matK-KIM1R/matK-KIM3F, GenBank OR502389) (Fazekas et al. 2012). MegaBLAST queries of the ITS/LSU sequence obtained here recovered a 99.61% match to the fungal pathogen Agroathelia (=Athelia) rolfsii (Sacc.) Redhead & Mullineux. (Redhead and Mullineux 2023) (Amylocorticiaceae, Agaricomycotina) strain GP3 (GenBank JABRWF010000005) (Yan et al. 2021). MegaBLAST queries of three host plant DNA barcodes recovered matches of greater than 99.62% similarity to N. nucifera sequences. After diagnosis, symptomatic dried leaf samples were deposited at Plant Industry Herbarium Gainesville (PIHG 17807) and an axenic culture was deposited at the Agricultural Research Services Culture Collection (NRRL 66964). Koch's postulates were fulfilled by the inoculation of sclerotia (as in Terrones-Salgado et al. 2022) on adaxial leaf surface of four-week- old water lily transplants obtained from an artificial pond on campus (two plants with five leaves each). One additional transplant was not inoculated and served as a control; this plant remained asymptomatic during the experimentation period. Each transplant was kept in a 27-gallon plastic container (21W × 30L × 14H in) filled with tap water containing one tablespoon of 20-20-20 all-purpose-water-soluble plant fertilizer (VPG, TX, USA) in a plant biosafety level 2 greenhouse (23 °C, >50% relative humidity, and a 12-h/12-h photoperiod). All inoculated leaves showed necrotized areas after one week and new sclerotia were observed floating on the water surface after three weeks. Fungal pathogen was reisolated and reidentified subsequently. Agroathelia rolfsii is the causal agent of southern blight, also known as grey rot, and is reported from at least in 260 plant genera, including specialty crops such as citrus, cucumber, pepper, peanuts, pumpkin, and strawberry (Farr and Rossman 2018). Agroathelia rolfsii usually causes lower stem, crown, and root rots; consequently, leaf spots are a noteworthy presentation of symptoms for this fungus.

First Report of the Rust Fungus Melampsora ferrinii on Salix babylonica in China and a New Spermogonial and Aecial Host, Corydalis bungeana

The occurrence of rust fungi on Corydalis bungeana Turcz. and Salix babylonica L. were found in same area of Hebei Province, China from 2022 to 2023. The life cycle connection of these rust fungi was suspected because Peng et al. (2022) reported the life cycle of Melampsora ferrinii Toome & Aime by inoculations, producing spermogonia and aecia on Corydalis species, and uredinia on S. babylonica. The morphology of the uredinial and telial stages on S. babylonica collected in the field was identical with the description of M. ferrinii by Toome and Aime (2015), and its identity was confirmed by phylogenetic analyses using the method of Ji et al. (2020) (LSU-PP087777, ITS-PP091274; Similarity with M. ferrinii: LSU-100%, ITS-99.85%). To confirm the life cycle of this rust fungus, inoculations were conducted on C. bungeana with basidiospores obtained from the teliospores on fallen leaves of Salix babylonica. The fallen leaves producing basidiospores were cut into small pieces (ca. 5 mm2) and placed on healthy leaves of C. bungeana. The inoculated plants were kept in a moist plastic box in darkness at 15-20℃ for 2 days and then transferred to the floor near windows at about 15-20℃ for observations. Ten days after inoculations small yellow spots of spermogonia appeared on the upper surface of the leaves of C. bungeana. About 7 days later, pale yellow aecia with aeciospores were produced mainly on the under surface of the leaves and petioles. The morphology of rust fungus on C. bungeana collected from the fields and obtained by inoculations was identical with the description by Peng et al. (2022). Phylogenetic analyses also showed that a specimen on C. bungeana collected from the field (LSU-OR607838, ITS-OR612063) were included into the same clade of M. ferrinii (Similarity: LSU-100 %, ITS-99.85). Based on morphology, inoculations and DNA sequence analyses, the rust fungi on C. bungeana and S. babylonica are identified as different stages of life cycle of M. ferrinii. This rust fungus has been reported to produce spermogonia and aecia on C. acuminata Franch., C. edulis Maxim. and C. racemosa (Thunb.) Pers. in China (Peng et al. 2022), and uredinia and telia on S. babylonica in USA, Argentina and Iran (Toome and Aime 2015, Abbasi et al. 2024), and on Salix sp. in Chile (Zapata 2016). Therefore, C. bungeana is a new host for M. ferrinii, and its field occurrence on S. babylonica is reported for the first time in China although Peng et al. (2022) reported successful results in its inoculations to S. babylonica in China. This report contributes to the control of rust diseases caused by this species. Specimens used in this experiment were deposited in the Fungal Herbarium of the Jilin Agricultural University, Changchun, China (HMJAU) and sequences newly analyzed were deposited in GenBank.

First report of Ralstonia pseudosolanacearum causing bacterial wilt on Rosa sp. in Greece

In March 2021, a sample of nine-month-old, non-grafted, diseased rose (Rosa sp.) plants was sent by a grower to the Benaki Phytopathological Institute for examination. The plants exhibited symptoms of dieback with black necrosis of pruned shoots, brown discoloration of shoot and root vascular tissues, and whitish slime exudation on cutting wounds of the shoots. The symptoms resembled those caused by Ralstonia pseudosolanacearum (Tjou-Tam-Sin et al. 2016). According to the sample's information sheet, the sample had been collected in a commercial greenhouse rose crop for cut flowers with a 10% disease incidence in the area of Troizinia-Methana (Regional Unit of Islands, Greece). Microscopic examination of symptomatic shoot and root vascular tissues revealed masses of bacterial cells streaming out of them. Sections of symptomatic tissues were suspended in water and in the resulting suspension, bacteria of the R. solanacearum species complex (RSSC) were detected by an indirect immunofluorescence (IF) assay using polyclonal antibodies (Plant Research International, the Netherlands) and a qPCR assay (RS-I-F/RS-II-R primers, RSP-55T probe) (Vreeburg et al. 2016). Furthermore, colonies with typical characteristics of RSSC were isolated from vascular tissues of shoots and roots on non-selective (NA) and semi-selective (mSMSA) media (EPPO 2022), and their identification as RSSC was confirmed by the above-mentioned IF and qPCR assays. Also, the isolates were assigned to: i) biovar 3, based on their ability to metabolize three disaccharides (maltose, lactose, D(+) cellobiose) and three hexose alcohols (mannitol, sorbitol, dulcitol) producing acid (EU 2006) and ii) phylotype I, by multiplex conventional PCR (Opina et al. 1997; Fegan and Prior 2005). A representative isolate was selected for sequencing part of the genes: 16S rDNA (1464bp), mutS (729bp) and egl (795bp) with GenBank Accession Nos. OR102443, OR683617 and OR702781, respectively. Blast analysis of these sequences showed 100% identity with those of various RSSC strains (e.g. GenBank Ac. Nos. CP025741.1, CP021762.1, MF141029.1, respectively). The obtained egl sequence conforms with the characteristics of phylotype I based on the DNA barcoding tool (EPPO 2021) and is 100% identical to that of the Dutch strain PD7216 (MF141029.1) reported to be sequevar I-33 (Bergsma-Vlami et al. 2018). The pathogenicity of two isolates was tested by inoculating: i) tomato seedlings (cv. 'Belladona') at their stem between the cotyledons and the first true leaf (EU 2006) and b) rose plants (cv. 'Aqua' and 'Papa Meilland') at their shoot base (Tjou-Tam-Sin et al. 2016), with bacterial suspensions in water (108 cfu/ml). The inoculated plants were maintained at a day/night temperature about 28/20°C with tomato plants exhibiting leaf wilting (7-17 dpi) and rose plants exhibiting chlorosis and necrosis of leaves (17 dpi). The pathogen was re-isolated on mSMSA from both artificially infected plant species and identified by the IF assay described above, thus fulfilling Koch's postulates. This is the first diagnosis in Greece of: i) rose plants infected by a Ralstonia species and ii) a crop infected by R. solanacearum phylotype I that corresponds to the R. pseudosolanacearum species (EPPO 2022). Official phytosanitary measures imposed in the affected area include an annual survey of rose crops for the presence of this pathogen, aiming at an early detection and prevention of its spread in such a highly valued ornamental crop.

First report of Dactylonectria pauciseptata causing root rot on Eucalyptus cinerea in China

Eucalyptus cinerea is an evergreen tree in the Myrtaceae. It is native to southern and eastern New South Wales and northern and eastern Victoria, Australia. It was introduced into China in the 1980s (Silva et al. 2011). Because of its unique shape, flexible stems, and rapid growth characteristics, it is widely used in the pulp industry and in decorative materials such as flower bouquets. In July 2022, 5- to 10-year-old E. cinerea showing symptoms of dehydration, withering and yellowing leaves, were found in forests and nurseries in Kunming and Songming, China. More than 37% of the trees showed these symptoms at each location, and disease severity was about 30%. Sixty symptomatic plants were collected from five tree nurseries. Diseased roots with 2-cm-long lesions were soaked in 75% ethanol for 15 s, 0.1% mercuric chloride for 2 min, rinsed with sterilized water, and placed on potato dextrose agar (PDA) at 25℃ for 3 days. Thirty samples were plated, and 21 isolates (YJLGF01 to YJLGF21) obtained, 11 strains with similar colony morphology (including representative strains YJLGF03 to YJLGF05). Three isolates (YJLGF03 to YJLGF05) were obtained by single-spore purification. On PDA, the colonies were circular with fluffy white to light yellow mycelium; the underside was yellowish brown. Conidiophores were bifurcated, with macroconidia borne terminally. The macroconidia were cylindrical with rounded, blunt ends, yellow to transparent, 1 to 3 septate (22.5 to 47.6 × 4.5 to 7.1 µm); microconidia were 0 to 1 septate (12.5 to 19.6 × 4.7 to 6.4 µm). Chlamydospores were spherical, rosary-like, and light yellow. Morphological characteristics were consistent with published descriptions of Dactylonectria pauciseptata (Piperkova et al. 2017). For molecular identification, the internal transcribed spacer (ITS), translation elongation factor 1- alpha (ef1-α) gene, and the beta-tubulin 2 (β-tub2) gene were amplified and sequenced (ITS accessions OR735053, OR735054, OR735055; β-tub2 accessios OR757447, OR757448, OR757449; ef1-α accessions OR757450, OR757451, OR757451) using published primers (White et al. 1990; Carbone et al. 1999). A phylogenetic tree was developed by Maximum Parsimony (MP) and Maximum Likelihood (ML) methods. These three isolates fell into the D. pauciseptata clade and were distinguished clearly from other species. Pathogenicity tests were performed using the same three isolates. Each isolate was cultured on PDA, and then subcultured in V8 juice broth on an orbital shaker at 180 RPM for 5 days. Conidia were collected by centrifugation at 6,000 RPM for 5 min, and then resuspended in sterilized distilled water (1×106 conidia/ml). Injured roots of one-year-old E. cinerea were soaked in the spore suspension for 1 h before being transplanted in sterile vermiculite. The plants were incubated at 25℃ with a 12 h photoperiod and 90% humidity. Five plants were inoculated as a group for each treatment and the entire experiment was completed three times. Among the inoculated plants, the incidence of disease development was 100%. A small sot appeared after 4 days, with a water-soaked lesion appearing and gradually expanding during days 5 to 7. After 10 days symptoms of root necrosis were similar to the those observed in the nursery, and aboveground plant parts had yellow, withering leaves and defoliation after 10 to 15 days. Control plants treated with sterile water showed no disease symptoms. The three strains were successfully reisolated from inoculated seedlings and confirmed them using DNA sequencing. No isolates were obtained from the control plants, thus fulfilling Koch's postulates. Dactylonectria pauciseptata was first reported from necrotic tissue of infected grape roots (Schroers et al. 2008). So far, it has been reported in Turkey, Canada, Brazil, Italy, and other countries (Erper et al. 2013; Úrbez-Torres et al. 2014; Santos et al. 2014). Based on our results, E. cinerea is a new host plant of D. pauciseptata in China. This disease is a threat to the nursery production of E. cinerea, potentially leading to a reduction in yields and economic losses.

First Report of Root Rot Caused by Fusarium incarnatum on Mongolian Snake gourd in China

Mongolian snake gourd (Trichosanthes kirilowii Maxim) is a precious traditional Chinese herbal medicine and perennial liana plant in the family Cucurbitaceae, and the root, fruit, seed and peel all possess the medicinal value (Zhang et al. 2016). During 2021-2022, the root rot was observed in a 20-ha commercial farm and became a major disease limiting Mongolian snake gourd production in Zhenjiang City, Jiangsu Province, China (119°27'E, 32°12'N). Field investigations showed that disease incidence was estimated at approximately 70% and resulted in up to a 50% decrease in total production. Symptoms on snake gourd initially appeared as yellow mottling produced on the surface of the infected new leaves and systemic wilting on the upper leaves. With the development of the infection, the base of the stem began to brown and die, and has lots of filamentous hyphae attached to it. As the lesions coalesced, the whole plant gradually wilted and died. In order to explore the cause of the disease, six infected plants were randomly collected from the commercial farm. The roots of the plants were rinsed in sterile water to remove soil debris, and symptomatic roots were surface sterilized using 75% ethanol for 60s, rinsed three times in sterile water, then plated onto the potato dextrose agar (PDA), and incubated at 25°C for 3 days in the dark. White fungal colonies grew from the tissue pieces, then hyphal tips were transferred to PDA to obtain pure cultures. A total of six isolates with similar morphological characteristics were obtained from six of the infected plants. One representative isolate GL21091501 was chosen for further analysis. At 5 days after inoculation, the colonies on PDA began to grow as white, and with the incubated time was extended, the hyphae turned yellowish-brown with a yellowish-brown center on the reverse side. Observations under a light microscope showed conidia that were falculate, slender and slightly curved, and the cells at both ends were sharp. Macroconidia had four to five septa, measuring 22.4 ~ 33.5 μm. Microconidia without septa, elliptical, measuring 4.36 ~ 9.88 μm. On the tip of aerial hyphae can form conidiophore, and produce macroconidia (Wonglom et al. 2020; Lin et al 2018). The pathogen was typical Fusarium spp. by morphological characteristics. To identify the species level, the mycelia of the representative isolate GL21091501 was used for genomic DNA extraction (Tiangen, China). The internal transcribed spacer (ITS) region and partial translational elongation factor subunit 1-α (TEF-1α) of the cultures were amplified and sequenced using the primer pairs EF1/EF2 and ITS1/ITS4 respectively (White et al. 1990; O'Donnell et al. 1998). The obtained sequences were deposited in GenBank under the accesion numbers OP311409 and OP311410. BLAST searches of the deposited sequences showed 100% identity with the existing TEF sequences (MT563420.1) and ITS sequences (MN539094.1) of Fusarium incarnatum isolates in GenBank. In addition, BLASTn analysis of these in FUSARIUM-ID database showed 99.62% and 100% similarity with F. incarnatum-equiseti species complex (FIESC) NRRL13379 [ITS] and NRRL34004 [TEF-1α]), respectively. Phylogenetic analysis was conducted with the neighbor-joining (NJ) method using MEGA6.0 (Tamura et al. 2007). Combined phylogenetic analysis revealed that the isolate shared a common clade with the reference sequence of F. incarnatum in the F. incarnatum-equiseti species complex. Therefore, according to morphological and molecular characteristics confirming the identity of the isolated pathogen as F. incarnatum. In order to fulfill Koch's postulates, fresh isolate GL21091501 hyphae were cut into 3 × 3 mm agar plugs from a 7 cm PDA plate and inoculated in 200 mL the Potato Dextrose (PD) liquid medium on a shaker at 170 rpm, 25°C for 5 days. Spores were filtered through four layers of gauze, adjusted to 1 × 106 spores/ml with sterilized water. Then Mongolian snake gourd seedlings at the two true leaves stage were transplanted in (15-cm-diameter) pots (1 plants/pot) filled with mixture of sterilized soil: vermiculite: pearlite (2:1:1, v/v). The pathogenicity test was conducted on seedlings plants by root irrigation method (50 ml/plant, 1×106 conidia/mL), control plants were irrigation with sterilized water (50 ml/plant). Each treatment was repeated three times. After 15 days, all inoculated plants showed the same symptoms observed on the original diseased plants in the field, whereas, the control plants remained symptomless. The same pathogen was successfully re-isolated from the inoculated plants, and identical to those of the originals based on morphological and sequence data. To our knowledge, this is the first report of F. incarnatum causing root rot on Mongolian snake gourd in China. F. incarnatum has been reported to cause root and stem rot in many plants worldwide, including muskmelon (Wonglom et al. 2020), Cucurbita pepo (Thomas et al. 2019) and Bambusa multiplex (Lin et al. 2018). This discovery is of great importance for Mongolian snake gourd planters because the fungus is accurately identified in a certain geographic area and effective field management strategies are necessary to control this disease.

Lavender harbours more viruses than previously thought: First report of Raspberry ringspot virus and Phlox virus M in Lavandula x intermedia

Plants of the genus Lavandula are thought to be rarely infected by viruses. To date, only alfalfa mosaic virus, cucumber mosaic virus, tobacco mosaic virus, and tomato spotted wilt virus have been reported in this host. In this study, we identified for the first time raspberry ringspot virus (RpRSV) and phlox virus M (PhlVM) in lavender, using herbaceous indexing, enzyme-linked immunosorbent assay, and high-throughput sequencing. Nearly complete genome sequences for both viruses were determined. Phylogenetic and serological characterisations suggest that the obtained RpRSV isolate is a raspberry strain. A preliminary survey of 166 samples indicates RpRSV was spread only in the lavender cultivar 'Grosso' while PhlVM was detected in multiple lavender cultivars. Although RpRSV raspberry strain may have spread throughout Auckland and nearby areas in New Zealand, it is very likely restricted to the genus Lavandula or even to the cultivar 'Grosso', due to the absence or limited occurrence of the nematode vector. Interestingly, all infected lavender plants, regardless of their infection status (by RpRSV or PhlVM or both) were asymptomatic. RpRSV is an important virus that infects horticultural crops including grapevine, cherry, berry fruits and rose. It remains on the list of regulated pests in New Zealand. RpRSV testing is mandatory for imported Fragaria, Prunus, Ribes, Rosa, Rubus, and Vitis nursery stock or seeds for sowing while this is not required for Lavandula importation. Our study revealed that lavender could play a role not only as a reservoir but also as an uncontrolled import pathway of viruses that pose threat to New Zealand's primary industries.

Occurrence of Fusarium fujikuroi Causing Fusarium Wilt on Carthusian Pink in China

Carthusian pink (Dianthus carthusianorum) is native to Europe and is widely grown in China for landscaping. In September 2022, wilting symptoms of carthusian pink were found in Xixia City (33°18'31″ N, 111°29'45″ E), Henan Province, China, with a disease incidence of 65%. Approximately 100 plants were surveyed on the landscaping lawns of the park. Initial symptoms were yellow to brown lesions on the base of stems and leaves. Later, the lesions spread throughout the plants, turning leaves yellow, and leading to root and leaf rot. Eventually, the plants shriveled and died (Figure S1a). Thirty diseased tissues isolated from the roots and leaves were cut into 5×5 mm pieces, which were surface sterilized with 75% ethanol solution for 30 seconds and 1% NaClO solution for 1 minute, rinsed three times in sterilized water, placed on potato dextrose agar (PDA) plates supplemented with 50 μg ml-1 streptomycin, and incubated at 28°C for five days. A total of 25 purified fungal strains with similar phenotypic features were obtained. Three representative strains named OSZ-P1, OSZ-P2, and OSZ-P3 were selected for identification. Fungal colonies developed an abundant aerial mycelium, initially white, which subsequently developed red to purple pigments (Figure S1b). Macroconidia were slender, straight, and measured 12.74 to 49.39 × 2.07 to 4.39 μm (n=50), with two to five septa. Microconidia were clavate and measured 6.31 to 11.61 × 2.15 to 4.02 μm (n=50) (Figure S1c). These morphological characteristics were consistent with Fusarium spp.. The rDNA internal transcribed spacer (ITS), β-tubulin gene (tub2), translation elongation factor 1-alpha gene (tef1), calmodulin (cmdA), RNA polymerase largest subunit (rpb1), and RNA polymerase II second largest subunit (rpb2) were amplified with primers ITS1/ITS4, BT-2a/BT-2b, EF1/EF2, CL1/CL2A, Fa/G2R, and 5F2/7Cr, respectively, for further identification (Yilmaz et al. 2021, O'Donnell et al. 2022). ITS (OQ726389, OQ726390, OQ726391), tub2 (OQ730191, OQ789645, OQ789646), tef1 (OR088904, OR088905, OR088906), cmdA (OR133730, OR133731, OR133732), rpb1 (OR088907, OR088908, OR133729), and rpb2 (OR133733, OR133734, OR133735) nucleotide sequences of the strains OSZ-P1, OSZ-P2, and OSZ-P3 were submitted to GenBank. BLASTn analysis of OSZ-P1 sequences exhibited 99 to 100% similarity with Fusarium fujikuroi sequences (strains Augusto2, I1.3, and CSV1) CP023096, CP023108, CP023084 of cmdA, CP023089, CP023077 of rpb1, and CP023093, CP023105, CP023081 of rpb2. A Phylogenetic tree was constructed of combined genes (tub2, tef1, cmdA, rpb1, rpb2) of sequences, alongside the sequences of the type strains by the neighbor-joining method. The three strains formed a clade with the type strains CBS257.52 and Augusto2 of F. fujikuroi in phylogenetic trees, being clearly separated from other Fusarium spp. (Figure S2). The morphological features and molecular analyses supported the strains as members of F. fujikuroi. To verify the pathogenicity, aboveground parts of the plants of five healthy six-month-old potted plants were sprayed with 100 µl of conidial suspension per pot (106 conidia ml-1), and five similar plants were sprayed with sterilized water as a control. All plants were placed in a climate incubator at 28°C and 90% relative humidity. Seven days after inoculation, withered and yellowed lesions were observed, similar to the natural lesions (Figure S1e). No symptoms were observed on the control plants. The whole pathogenicity tests were performed thrice. Reisolation resulted in cultures that were morphologically and molecularly identical to the original isolates, fulfilling Koch's postulates. Fusarium wilt disease has been reported on other plants of the genus Dianthus. Vascular wilt on Dianthus caryophyllus (carnation) caused by Fusarium oxysporum is the most destructive disease of carnation crops worldwide (Ardila et al. 2014). Fusarium acuminatum causing Dianthus chinensis root rot and foliage blight has recently been reported in Nanjing, China (Xu et al. 2022). To our knowledge, this is the first report of F. fujikuroi causing Fusarium wilt on carthusian pink worldwide. The host range of F. fujikuroi still needs to be clarified for accurate disease management in the selection of plant species for landscape.

First Report of rattail cactus necrosis-associated virus Infecting Prickly pear (Opuntia macrocentra) in the United States

Black-spined prickly pear (Opuntia macrocentra Engelmann; Cactaceae) is a cactus native to Arizona, New Mexico, Texas, and northwest Mexico. The plant is often grown for ornamental purposes in the United States. In February 2023, virus-like symptoms such as concentric ringspots and chlorotic spots were observed on O. macrocentra plants grown at the vicinity of Maricopa County Cooperative extension, University of Arizona, Phoenix, AZ (33°24'24.6"N, 111°59'15.3"W). Total RNA was extracted from two samples (YPHC-60-A and YPHC-60-B), following the protocol by Tzanetakis et al. (2007). Reverse transcription polymerase chain reaction (RT-PCR) was performed with degenerate tobamovirus, TobamodF/TobamodR (Li et al. 2018) and potexvirus, 1RC, Potex 2RC, and Potex 5 (van der Vlugt and Berendsen 2002) primers. An expected amplicon of ~880 bp was obtained from both samples using TobamodF/TobamodR primers, while no amplification was observed with potexvirus primers. Further, RT-PCR was carried out using species-specific primers to detect cacti related tobamoviruses: cactus mild mottle virus (CMMoV), rattail cactus necrosis-associated virus (RCNaV) (Park et al. 2018) and Opuntia virus 2 (Salgado-Ortiz et al. 2020). Amplicons of ~540 bp were amplified from both samples using RCNaV specific primers, whereas no amplification was obtained using CMMoV and Opuntia virus 2 specific primers. Then, the amplicons from both YPHC-60 (A-B) isolates (~540 bp) were Sanger sequenced and shared 99.22% nucleotide identity to each other. A BLAST search revealed 93% nucleotide identity with RCNaV CP sequences (KY581586.1, JF729471, and MT130378.1). The sequences were submitted in the GenBank (accessions no. OQ914798 and OR828526). Furthermore, complete RCNaV- RNA dependent RNA polymerase (RdRP) gene was amplified using primers 3490-s-5'GTAGGTGGTACCGCATAGCA-3'; 3490as 5'AAACGCAAGTCMRYGACYGA-3' (designed in this study from accession no. JF729471.1, position 3490-3509 and 4905-4925). The expected amplicons of ~1,500 bp were obtained from both YPHC-60 (A-B) samples and sequenced (GenBank: OQ914799 and OR823954) showing 87.5 % identity with RCNaV sequences (JF729471.1 and NC_016442.1). The maximum-likelihood phylogenetic tree clustered YPHC-60 (A-B) isolates in a single clade with other RCNaV isolates. RCNaV virus particles were isolated from YPHC-60 (A-B) and submitted for RNA extraction, testing positive for RCNaV by RT-PCR. Sap extract of YPHC-60 (A-B) prepared in 0.01 M phosphate buffer (pH =7.0) was used to mechanically inoculate 3 indicator plant species (n=10): Phaseolus vulgaris, Medicago sativa, and Cucumis melo. Also, infected tissue was used to graft Opuntia sp. plants. Symptoms such as local lesions were observed on M. sativa and vein thickening on P. vulgaris 14 days post-inoculation, while Opuntia sp. showed chlorosis 30 days after grafting. RCNaV infection in mechanically inoculated P. vulgaris, M. sativa, and Opuntia sp. was also confirmed through RT-PCR. C. melo and non-inoculated control plants did not show any symptoms, nor tested positive through RT-PCR. RCNaV has been reported earlier to infect cactus species in South Korea (Park et al. 2018) and O. albicarpa in Mexico (De La Torre-Almaráz et al. 2016), where it was found in several orchards. To the best of our knowledge, this is the first report of RCNaV infecting O. macrocentra in the United States. This study highlights that RCNaV is easily transmitted mechanically or by grafting, which could impact the nursery industry as most cacti are clonally propagated.

First report of a 'Candidatus Phytoplasma australasiaticum'-related phytoplasma strain associated with shoot proliferation disease of variegated croton in Taiwan

Codiaeum variegatum (family Euphorbiaceae) is a leaf ornamental commonly known as variegated croton, which is often found in gardens or grown as indoor plants. In December of 2022, two cutting-propagated variegated croton plants exhibiting abnormal shoot proliferation and little leaf symptoms (Fig. S1) were found in a nursery owned by a private breeder in Wanluan Township, Pingtung County, Taiwan. The plants were propagated from a single stock plant, which died during transplanting from a commercial nursery in Changzhi Township, Pingtung County. To determine the potential cause of such symptoms, leaf tissues were collected from the center of the two symptomatic plants. Their DNA were extracted with a Synergy 2.0 Plant DNA Extraction Kit (OPS Diagnostics, Lebanon, NJ) and used for further testing. As controls, two symptomless stock plants were collected from the commercial nursery in Changzhi Township and used to produce cutting-propagated plants; leaf DNA was extracted from each plant as described above. The DNA samples were subjected to PCR testing using the phytoplasma-specific primer pair P1/P7 (Schneider et al. 1995), and only DNA from the symptomatic plants produced the expected 1.8-kb amplicon. The two phytoplasma isolates detected in the plants were designated as CvaA and CvaB. After sequencing and analyzing the data using the iPhyClassifier program (Zhao et al. 2009), both CvaA and CvaB were classified to subgroup 16SrII-A (GenBank accession no. L33765) with a similarity coefficient of 1.0. The near-full-length 16S rDNA fragments of the detected isolates (GenBank accession no. OR794242) were also identical (1,463/1,463 bp) to that of NCHU2014 (GenBank accession no. CP040925, bp 537768-539230), a reference 'Ca. Phytoplasma australasiaticum'-related strain (16SrII-A) found in Taiwan (Chang et al. 2015; Rodrigues Jardim et al. 2023). To validate the results, the DNA samples were also tested with 16SrII group-specific semi-nested PCR targeting the elongation factor Tu gene. The outer and inner primer pairs used were TUF-II-F1/TUF-II-R1 and TUF-II-F2/TUF-II-R1, respectively (Al-Subhi et al. 2017). An expected amplicon was detected in the symptomatic samples but not in the symptomless counterparts. The amplified fragments' sequences (GenBank accession no. OR634931) were identical to that of the elongation factor Tu gene of the 'Ca. Phytoplasma australasiaticum'-related strain NCHU2014 (989/989 bp; GenBank accession no. CP040925, bp 139344-140332). The protein translocase gene secY of the detected phytoplasma was also amplified and sequenced using semi-nested primers SecYF1(II), SecYF2(II) and SecYR1(II) (Lee et al. 2010). Again, the sequences of the detected isolates (GenBank accession no. OR862773) were identical to that of NCHU2014 (1,263/1,263; GenBank accession no. CP040925, bp 192846-194108). The quality of the DNA samples was confirmed by PCR targeting the plant host's 28S rDNA using primer pair 28KJ/28C (Cullings 1992) and all symptomatic and symptomless samples produced the target amplicon (0.7 kb). 16SrII phytoplasmas have been detected in different host plants in Taiwan (Chang et al. 2015). To our knowledge, this is the first record of this group of pathogens infecting variegated croton in Taiwan. Branch-inducing phytoplasma has been used to improve the ornamental values of poinsettias, another Euphorbiaceae species (Lee et al. 1997). Further testing is needed to determine whether the phytoplasma detected in this work could be used for similar purposes.

First report of Streptocarpus flower break virus in Streptocarpus hybrids in Aotearoa New Zealand

Streptocarpus (Cape primrose, family Gesneriaceae) is a genus of plants native to Southern Africa commonly grown indoors for their foliage and trumpet-shaped flowers. In Aoteroa New Zealand (NZ) to date, no viruses have been reported to infect plants of the Gesneriaceae (Veerakone et al. 2015). In September 2022, a plant of Streptocarpus hybrid exhibiting necrotic rings was observed in a hobbyist's greenhouse in Auckland, NZ. High-Throughput Sequencing (HTS) using MinIONTM (Oxford Nanopore Technologies), was applied as a first screen (Liefting et al. 2021). Phylogenetic analysis was performed using Geneious Prime 2021 (Biomatters Ltd, NZ). A BLASTn search with 622,847 obtained reads resulted in 3,260 and 4,340 matches to the sequences of Streptocarpus flower break tobamovirus (SFBV) and Impatiens necrotic spot orthotospovirus (INSV), respectively. A near-complete (98.5%) genome sequence of SFBV was obtained (GenBank accession No. OQ970154), which shared 99.52% nucleotide identity to a SFBV type isolate from Germany (GenBank accession No. NC_008365). A phylogenetic tree was also generated (e-Xtra). To confirm the presence of both viruses, leaf tissue was rub inoculated onto herbaceous indicator plants as described by Tang et al. (2013). Chenopodium amaranticolor and C. quinoa plants developed local lesions while Nicotiana occidentalis plants showed local necrosis followed by systemic leaf puckering by 14 days post inoculation (dpi). Nicotiana benthamiana and N. clevelandii plants showed systemic chlorosis but N. tabacum plants did not exhibit any symptoms by 28 dpi. Samples from indicators and Streptocarpus were tested by RT-PCR (SFBV) or RT-qPCR (INSV), using in-house designed primers: SFBV-forward (5'-GTCATCAGCCGGAGAGGTTC-3'), SFBV-reverse (5'-AGGGCGAGTCTCTTCCTCTG-3'), INSV-forward (5'-CAATCAGAGGGTGACTTGGAA-3'), INSV-reverse (5'-GACTTTCCGAAGACTTGATGC-3') and INSV-probe (5'-CCATTGTCCTTTATCATTCCAACAAG-3'). RT-PCR products (across MP and CP regions) of the expected size (357 bp) were amplified from the Streptocarpus sample and symptomatic indicators. All amplicons were sequenced in both directions and found to be identical to the obtained HTS sequence. The presence of INSV was confirmed in all Streptocarpus and inoculated indicators except N. tabacum by INSV-specific RT-qPCR. A further 77 Streptocarpus plants were collected from a greenhouse in Auckland that holds a collection of multiple Streptocarpus cultivars from across NZ and overseas. Twenty-five plants, either displaying flower colour-break (only one plant) or asymptomatic (24 plants), tested positive for SFBV by RT-PCR. All amplicons were sequenced and found to be identical. SFBV was first described from naturally infected Streptocarpus plants in 1995 in the Netherlands (Verhoeven et al. 1995), and then in Germany (Heinze et al. 2006) and the United States (Pappu & Druffel 2007). While INSV has been found in NZ in several plant genera (Veerakone et al., 2015), to our knowledge, this is the first report of SFBV in NZ. SFBV was thought to be associated with colour breaking of Streptocarpus flowers (Verhoeven et al. 1995) but the virus was detected in asymptomatic Streptocarpus plants in this study and in California (Pappu & Druffel 2007). Given SFBV-infected plants were purchased from several sources, and leaf cuttings for propagation are shared among hobbyists, SFBV is likely to have spread throughout NZ. How this will affect production is unclear at this stage.

First report of Hibiscus soymovirus in Hibiscus rosa-sinensis in Colombia in mixed infection

Hibiscus is native to southeast Asia but well suited to Colombia's arid soil and dry climates from the coast to the mountains of Bogotá. Viruses infecting hibiscus in Colombia are largely unexplored, with four viruses previously known: hibiscus chlorotic ringspot virus (HCRSV), hibiscus latent Fort Pierce virus (HLFPV), hibiscus latent Singapore virus (HLSV), and citrus leprosis virus C2 (CiLV-C2) (Padmanabhan et al., 2023). Mixed infections between these viruses were frequently detected. A recent virome analysis of a single hibiscus plant from Colombia revealed multiple viruses in mixed infection; : HCRSV, HLFPV, passion fruit green spot virus (PFGSV), a strain of physalis vein necrosis nepovirus, four novel carlavirus, one new potexvirus and a mitovirus. In addition, few smaller contigs of blunervirus and soymovirus were also identified in the high throughput sequencing (HTS) data, but their presence in the mixed infection could not be validated (A. Roy et al. 2023unpublish data). During Brevipalpus-transmitted virus (BTV) surveys, two asymptomatic and 15 hibiscus foliar samples showing green ringspots with central chlorotic spots in senescing areas, mosaic, and black or chlorotic spots were collected from six departments (states) in three geographical regions of Colombia: Tolima (n=4) and Cauca Valley (n=2) (Andean region), Meta (n=6) and Casanare (n=1) (Orinoquia region), and Quindío (n=1) and Risaralda (n=1) (coffee growing region). About 100 mg of 17 hibiscus leaf samples were separately processed for RNA isolation without DNase I treatment and tested for known BTVs, and for newly discovered hibiscus soymovirus (HSV; genus Soymovirus family Caulimoviridae) using PCR assays (Padmanabhan et al. 2023, Wang et al. 2023). To identify potential HSV infection in the samples, published SVF1/SVR1 and newly designed primer pairs (HSV-REP-F/-R and HSV-CPG-F/-R) were used to amplify the 430 nt transactivation (ORF-VI), 631 nt replicase (REP) and 401 nt coat protein gene (CPG), respectively (Supplementary 1). Of 17 samples tested, three from Tolima and one each from Meta and Quindío yielded all three expected size amplicons. Bi-directional sequencing followed by BLASTn analysis revealed 95-98% nt identity with the CPG, REP, and ORF-VI genes of HSV (OP757659). Ribo-depleted libraries were prepared using the RNA extracts of five HSV PCR positive samples. HTS yielded 11.6 to 50.3 million raw reads per sample library. Adapters were trimmed and filtered from the raw reads with Trimmomatic v0.39 and then assembled using SPAdes v3.15.5 (Padmanabhan et al., 2023). Contigs were blasted against the Arabidopsis proteome and a RefSeq-based viral protein database. Potential viral sequences were then blasted against the complete NCBI nr database. Assembled soymo contigs covered 99-100% of the HSV genome, with per-nucleotide read depths of 23.8 to 393. Contigs from the Tolima (Accessions; OR621030- OR621032 and Quindío samples (OR621033) covered 99-100% of the HSV genome and had >96-98% nt identity to Hawaiian isolate (OP757659) whereas the Meta sample contigs covered 78% of the genome with 9495% nt identity. HTS contigs shared >98-99% nt identities with their PCR amplicons. Along with HSV, other virus sequences (HCRSV, HLFPV, PFGSV, CiLV-C2, and mycoviruses) were variously detected from all five libraries. Due to mixed infection no symptom similarity was noticed among these 5 samples. The findings in hibiscus in Tolima, Meta and Quindío represent the first confirmed report of HSV infection in hibiscus in Colombia. The widespread distribution suggests the possibility of HSV dispersion via movement of planting material, and potential further spread to another hibiscus growing region.

First report of saffron latent virus in Crocus sativus from Hungary

In early April of 2018 we sampled asymptomatic autumn flowering Crocus plants (Fig. S1.) in a private collection in Hajdú-Bihar county, Hungary. From each species (Cr. kotschyanus subsp. kotschyanus, Cr. sativus, Cr. speciosus) 200 mg leaf sample was collected from 5 neighboring shoot, which were treated as one sample. ELISA tests were carried out in duplicates using potyvirus-specific MAb PTY1 antibodies (Jordan and Hammond 1991) on the samples (Agdia, Elkhart, IN, USA). A sample was considered positive if the absorbance was at least three times greater than that of the negative control. Only one sample tested positive; the absorbance values of Cr. sativus leaves were 0.013 and 0.014, while the negative controls were 0.002 and 0.003, respectively. The samples were further tested by RT-PCR for potyviruses (Salamon and Palkovics 2005), tomato spotted wilt virus (TSWV) (Nemes and Salánki 2020) and nepovirus subgroup A (Digiaro et al. 2007). Total nucleic acid was extracted with the phenol-chloroform method of White and Kaper (1989), and reverse transcription was carried out with Maxima H Minus First Strand cDNA Synthesis Kit (Thermo Fisher Scientific Baltics UAB, Vilnius, Lithuania) using random hexamer primer. The samples were negative for TSWV and nepovirus subgroup A, but a single PCR product of ~ 1700 nucleotide (nt) was amplified with potyvirus specific primers and cloned into pGEM®-T Easy vector (Promega, Madison, WI, USA). The 1726 nt long insert sequence, including the complete coat protein region was determined and deposited in the NCBI GenBank database (Accession No: OR425160). Digestion of the original PCR products with restriction enzyme SacI yielded only the predicted restriction fragments (364 / 1362 bp), indicating the presence of only a single potyvirus in the infected sample. BLASTn analysis of the CP cistron revealed the highest nt identities to saffron latent virus (SaLV) Iranian isolates (GenBank AccNo.: MN990394 - 85.44%, MN990415 - 85.39% and RefSeq: NC_036802 - 84.05%). For phylogenetic analyses MEGA11 (Tamura et al. 2021) was used. The resulting Maximum Likelihood tree (Fig. S2) showed that all Iranian SaLV isolates grouped together, while the Hungarian isolate is on an adjacent branch, separate from other virus species, and supported with 100% bootstrap values. From these results, it appears that the Hungarian isolate has been separated from the Iranian clade, and has evolved separately as a distinct lineage. We were unable to fulfill Koch's postulates as all available Crocus sativus plants were infected with SaLV. Latent potyvirus infection of Crocus species, by bean yellow mosaic virus (BYMV), iris mild mosaic virus (IMMV), iris severe mosaic virus (ISMV) and turnip mosaic virus (TuMV) has been reported by Grilli Caiola and Faoro (2011). SaLV was first reported from Iran (Parizad et al. 2017), but to our knowledge has never been reported from Europe or from any current EPPO member state. Since Crocus species can be asymptomatic virus reservoirs, it is important that any certification scheme for production should require laboratory tests to prove the health of the plants; or advise growers to keep possible high value susceptible crops such as breeding material and nuclear stocks at a distance from crocuses to mitigate virus transmission between stocks. It is also advisable to grow infected lots far from healthy stocks and protected wild hosts. To our knowledge, this is the first report of SaLV from Hungary and from Europe.

First report of powdery mildew caused by Podosphaera fusca on Coreopsis tinctoria in China

Coreopsis tinctoria is an annual herb and commonly cultivated in gardens due to its attractive flowers, its capitula also have been used as a traditional medicine in China, Asia, North America and Europe (Shen et al. 2021). In June 2023, severe powdery mildew infection was observed on C. tinctoria in a hillside near headwork of the middle route of the South to North Water Diversion Project (32°40'55''N, 111°41'59''E). Abundant irregular white spots were found on adaxial surface of the leaves and tender stems. Approximately 75% of the observed C. tinctoria plants showed these signs and symptoms. Generative hyphae were thin-walled, smooth or almost so, and 5 to 9 μm wide. Conidiophores were unbranched, straight, 80.5 to 162.5 × 9.3 to 12.9 μm (n=25), and produced one to three immature conidia. Foot-cells of conidiophores were cylindrical, 38.5 to 62.3 μm (n=20) long. Conidia were ellipsoid to ovoid, 25.1 to 31.9 × 15.2 to 19.5 μm (n=30). The morphological characteristics of asexual structures corresponded to Podosphaera sp. (Braun and Cook 2012). For further identification, genomic DNA was extracted directly from the mycelia and conidia using Chelex 100 (Sigma Aldrich, Shanghai, China). The internal transcribed spacer (ITS) regions and 28S large subunit (LSU) of ribosomal DNA from the specimen (CT2302) were amplified using the primers ITS1/ITS4 (expected amplicon size 566 bp) (White et al. 1990) and NL1/NL4 (expected amplicon size 618 bp) (Baten et al. 2014), respectively. The sequences of ITS (GenBank accession no. OR649304) and LSU (GenBank accession no. OR649305) showed 99.63% and 100% identity values to the Podosphaera fusca isolate HMNWAFU-CF2012074 in the NCBI database (KR048109 for ITS and KR048178 for LSU), respectively. Phylogenetic analyses based on the combined ITS and LSU sequences using MEGA 7.0 software indicated that CT2302 formed a monophyletic clade together with isolates of P. fusca. Therefore, this fungus was identified as P. fusca based on the morphological and molecular characteristics. Pathogenicity tests were performed by gently pressing the infected leaves onto 15 young leaves of five healthy plants and three noninoculated plants were used as controls. All plants were maintained in a greenhouse (25℃ and 70% relative humidity). Powdery mildew symptoms similar to those of originally diseased plants were observed on all inoculated leaves after 12 days, whereas no symptoms were observed on the control leaves. Powdery mildew caused by P. fusca (previously Sphaerotheca fusca) on C. tinctoria has been reported in Russia, Poland, Korea, Romania and Ukraine (Cho and Shin 2004; Rusanov and Bulgakow 2008). To our knowledge, this is the first report of P. fusca on C. tinctoria in China. The identification of P. fusca as the causal agent on C. tinctoria is critical to the prevention and control of this disease in the future.

First Report of Clover yellow vein virus Infecting Senna septemtrionalis (Arsenic bush)

Clover yellow vein virus (ClYVV) is a member of the genus Potyvirus, family Potyviridae and was reported to infect many plant species, such as Ammi majus L., Phaseolus vulgaris L., Vicia faba L., Lens culinaris L., Borago officinalis L., Cicer arietinum L., Gladiolous gandavensis L., Glycine max L., Trifolium repens L., and Dendrobium sp. (Irey et al. 2006; Ortiz et al. 2009; Park et al. 2014; Yoon et al. 2022). Senna septemtrionalis (Viv.) H.S.Irwin & Barneby (arsenic bush), a species in the subfamily Caesalpinioideae, is widely distributed in tropical and subtropical regions (Datiles et al. 2022). In June 2021, virus-like symptoms of mosaic, chlorosis, and leaf-curling were observed in arsenic bush in Kunming, Yunnan province, China. Symptomatic leaves were collected from four arsenic bush (SS1-4), and asymptomatic leaves were collected from 3 additional arsenic bush plants (SS5-7) (eXtra S1). To identify the putative causal virus, sap of symptomatic leaves (SS1) was stained with 1 % phosphotungstic acid and observed under a transmission electron microscope (TEM). Potyvirus-like particles (about 750-800 nm  13 nm) were observed from the sample (eXtra S1). Total RNA was extracted from sample SS1 using TRIzol Reagent (Invitrogen, USA) and subjected to the Illumina NovaSeq platform for RNA-Seq. After trimming and quality control of raw data, 24,125,963 high-quality clean reads were assembled into 72,835 Unigenes using Trinity software. BLAST searches indicated that the nucleotide sequence of Unigene c29731 (10,893 nt) and its deduced amino acid sequence shared 82.62% to 96.45% and 92.60% to 99.19% identity with several ClYVV isolates, respectively. Unigene c29731 had the highest coverage ratio (88%) and the highest nucleotide sequence identity (96.45%) with ClYVV isolate IA-2016 (GenBank accession No. MK292120.1). The complete genome of ClYVV SS1 isolate (ClYVV-SS, GenBank accession No. OP868578) was determined using RT-PCR and 5' and 3' rapid amplification of cDNA ends (RACE) (Chen et al. 2001). A total of 224,936 out of 24,125,963 reads were mapped to the ClYVV-SS1 genome, yielding an average depth of coverage of 3,056.823 (min=1, max=7,859) at nucleotides from 1 to 9,324 of ClYVV genome (eXtra S2). BLASTN results indicated that the complete genome of ClYVV-SS1 shared 96.45% nucleotide sequence identity and 99% coverage ratio with ClYVV isolate IA-2016 genome. Phylogenetic analysis showed that ClYVV-SS1 and other ClYVV isolates clustered together (eXtra S2). RT-PCR was performed on samples (SS2-7) using a pair of primers of the coat protein gene (5'- TCCGACAAAGATAAGTTGAATGCTGGTG-3' and 5'-GAATCGTGCTCCAGCAATGTGA-3') designed from multiple sequences alignment (MSA). Using SS1 sample as positive control, amplicons of ~813 bp were obtained from three symptomatic samples (SS2-4) but not the asymptomatic ones (SS5-7). A total of 17 of 20 arsenic bushes developed symptoms of mosaic and leaf-curling approximately two weeks after mechanical inoculation with arsenic bush (SS1) sap, with 10 uninoculated plants used as control (eXtra S1). RT-PCR was performed for all tested plants. 17 symptomatic arsenic bushes tested positive for ClYVV, while all other samples tested negative. This confirmed that the symptomatic arsenic bushes were infected with ClYVV. To our knowledge, this is the first report of ClYVV infecting arsenic bush.

First Report of Leaf Spot Caused by Corynespora cassiicola on Jasminum sambac in Pakistan

Jasminum sambac L. is a species of jasmine native to a small region in the eastern Himalayas and is cultivated worldwide as an ornamental plant (USDA-ARS 2016). In Pakistan, it is cultivated for ornamental purposes throughout the country. The flowers of this plant are traditionally used in the preparation of essential oils and for making jasmine tea. The flowers and leaves also have been used in folk medicine to treat breast cancer, epilepsy, ulcers and promote wound healing (Al-Snafi 2018). In December, 2017, almost 10 leaves of 3 plants of J. sambac growing plant nursery of Gehlan, Pattoki, Punjab a province of Pakistan were observed with leaf spot disease. Infected leaves exhibited circular to sub-circular spots with indistinct margins and grey papery centers delimited by dark brown rims. For further microscopic study, the infected leaves were examined under a stereomicroscope. For the isolation and cultural studies of infecting fungus, infected parts of leaves were surface sterilized in 1% NaOCl for about 10 seconds, washed twice in sterilized distilled water, plated on potato dextrose agar (PDA) medium and incubated at 25°C for 4 days. Pure cultures were obtained having colonies of light to dark brown color. Conidia (n=20) were light brown to pale olivaceous brown, smooth, obclavate to cylindrical in shape, 99.5-118.5 μm in length and 12.5-15.0 μm in width, with mostly 3 to 14 pseudosepta. Conidiophores (n=20) were straight to slightly curved, unbranched, and pale to light brown in color. Based on the morphological characteristics of the colonies and conidiophores and conidia, the pathogen was identified as Corynespora cassiicola (Berk and M.A. Curtis) C.T. Wei. (Berkeley & Curtis 1968; Lu et al. 2021; Wei 1950). Genomic DNA was extracted following using modified CTAB method (Gardes and Bruns 1993) and internal transcribed spacer (ITS) region was amplified with ITS1 and ITS4 primers (White et al. 1990). The ITS sequence generated of about 553 bp and deposited in GenBank (accession no. MN954556), was found more than 99% similar to previously deposited sequences of C. cassiicola (GenBank accession nos. MN339671, EU364535, FJ852574, MK139711, EU131374) as verified through BLASTn and phylogenetic tree construction. A pathogenicity test was performed for fulfilling Koch'spostulates. Conidial suspension (105 conidia/ml) of the recovered isolate was sprayed on the 5 healthy leaves of 2-month-old seedling of J. sambac. Mock inoculated plants sprayed sterile distilled water were used as a control. The seedlings were covered with plastic bags to maintain high humidity at 24 to 28°C for a week. Identical disease symptoms to those observed in nursery plants were observed on the leaves of the inoculated plants in 7 days but not mock inoculated plants and results were reconfirmed. The reoccurred fungus was isolated from the diseased spots of the inoculated leaves to complete Koch's postulates and identified microscopically. A representative sample of leaves with lesions was deposited in the LAH herbarium, Department of Botany University of the Punjab, Pakistan (LAH35691). Previously, C. cassicola has been found infecting Jasminum mesnyi in China and Jasminum sp. in Florida (Alfieri et al. 1984; Zhang et al. 2018). The best of our knowledge, this is the first report of leaf spot caused by C. cassiicola on J. sambac in Pakistan. It will establish a foundation for future studies of management strategies for this plant disease caused by C. cassiicola.

The first USA continental record of coffee leaf rust (Hemileia vastatrix) on coffee (Coffea arabica) in southwest Florida, USA

Coffee leaf rust (CLR), caused by Hemileia vastatrix Berk. & Broome (Zaghouaniaceae) is considered the most significant fungal disease of Coffea arabica L. (Rubiaceae), from which berries are harvested and processed to obtain coffee beverage (Talhinhas et al. 2017). In Florida, coffee plants are mainly used as ornamentals due to their fragrant flowers; however, there are ongoing field trials evaluating the adaptability of plants for coffee production to climate conditions in the state (Crane et al. 2005). In November 2021, young seedlings of C. arabica var. caturra from a residence in Naples (Collier County) in southwest Florida were discovered with signs of rust fungus. Minute, yellow, suprastomatal sori 53-81 µm in diam were formed on the abaxial leaf surface, forming blotches. Light-yellow urediniospores measured 29-31 × 20-29 µm, with a reniform or "hunchbacked" shape, had thick walls measuring 1.5-2.5 µm in height, and were dorsally echinulate, the individual spikes measuring 2.5-3.3 µm in height. Spikes were scattered over most of the dorsal surface and form a dense ridge separating the dorsal from the smooth ventral side. (e-Xtra Fig. 1). Symptoms and signs are consistent with published descriptions of CLR produced by H. vastatrix (Ritschel 2005). To confirm the identification, DNA sequencing of the large subunit (LSU) of the ribosomal repeat was done following the protocols of Aime (2006) (GenBank accession number OR296753-OR296754). The Florida specimen shares 100% sequence identity (887/728 bp) with other accessions of H. vastatrix in congruence with maximum likelihood phylogenetic analysis performed in RAxMLv8.0.0 (Stamatakis 2014) (e-Xtra Fig. 2). In addition to CLR, Hemileia coffeicola Maubl. & Roger, causal agent of powdery rust of coffee, produces similar leaf spots on coffee but has a restricted geographical distribution. This agent is found only above 500 m a.s.l. in central Africa (Silva et al. 2006) and produces larger urediniospores (34-40 × 20-28 µm) (Maublanc & Roger 1934) in sori are scattered in abaxial leaf surface giving a powdery appearance. Hemileia vastatrix has been reported from almost every major coffee growing country of the world as well as Hawaii and Puerto Rico (Keith et al. 2022, Ramirez-Camejo et al., 2022). This is the first report of CLR in the continental USA, however, CLR poses a limited threat to the USA agriculture in view of the fact coffee is not commercially grown within the continental USA. A voucher was made of dried symptomatic leaves and deposited at Plant Industry Gainesville Herbarium (PIHG 15712, 16332) and the Arthur Fungarium at Purdue University (PUR N23473). The remaining infested coffee seedlings were destroyed after phytopathological diagnosis, and the pathogen has been absent from all additional screenings since November 2021.

Susceptibility of centipede tongavine (Epipremnum pinnatum) commercially grown in nurseries in Florida to aroid leaf rust (Pseudocerradoa paullula)

Epipremnum pinnatum (L.) Engl., (Araceae, Monocots) known as dragon-tail plant or centipede tongavine, is the most cultivated aroid species worldwide (Boyce 2004). In 2022, symptomatic dragon-tail plants, collected from plant nurseries in south Florida (e-Xtra Fig.1). Symptoms included round leaf spots often with a yellow halo and erupting pustules mainly distributed in the underside of the leaves. Visits to the nurseries revealed a 60% incidence of approximability 50 mature plants, with some leaves showing up to 30% of tissue damage. The putative pathogen was identified morphologically as Pseudocerradoa paullula (Syd. & P. Syd.) M. Ebinghaus & Dianese (Pucciniaceae, Basidiomycota) (Ebinghaus et al. 2022), characterized by the production of pseudosuprastomatal uredinia with globose to subglobose urediniospores, light-brown, echinulate (1 µm height), 24-31 µm diam with thick walls, 1.5-2.5 µm in height (n=30). Identical morphological features reported by Urbina et al. (2023) (e-Xtra Fig. 1). PCR amplification followed by Sanger sequencing of the internal transcribed spacer (ITS) and large subunit (LSU) of the ribosomal RNA genes (Aime 2006) together with LSU internal species specific primer (Urbina et al. 2023) were used to confirm the identification of the pathogen (GenBank ON887194-ON887196). MegaBlast (Chen et al. 2015) searches resulted in a >99% sequence similarity to a P. paullula specimen collected in Florida (2019-101665, GenBank ON887197). Host identification was made by using the Ribulose-1,5-bisphosphate carboxylase-oxygenase (rbcL. GenBank ON887186, ON887187) and Maturase K (matK) loci (GenBank ON887190, ON887191) (Fazekas et al. 2012). Both barcodes resulted in >99.13% sequence similarity to voucher J.R. Abbott 24912 FLAS (GenBank GU135198 and GU135036, respectively). Symptomatic dried specimens were deposited in the Plant Industry Herbarium (PIHG 16229 - 16232). Koch's postulates were fulfilled using urediniospores collected from an infected E. pinnatum sample that was kept in darkness at 4°C for seven days until inoculation. Eight potted dragon-tail plants were inoculated by hand rubbing urediniospores against upper and lower leaf surfaces and three plants were used as controls. All plants were misted with sterile water and covered with plastic bags (23 °C, >90% RH, 12/12 h daylight). Bags were removed 48 h after inoculation, plants were set in a climate-controlled greenhouse (~30 °C, ~65% RH, 12/12 h light cycle) and monitored daily for symptoms. Chlorotic spots appeared after 10 days, and pustules after 25 days while the non-inoculated controls remained symptomless. Aroid leaf rust is known to infect several aroid species, including dragon-tail (Shaw 1995), which some varieties capable to outdoors in USDA 9a hardiness zones (Wunderlin et al. 2023), but the rust fungus has not been observed on any species of Epipremnum in the landscape yet, suggesting that its susceptibility could be driven by plant growth conditions that favor pathogen infection (e.g., excess of humidity and nutrients, dense planting, overhead irrigation, etc.). Here we encourage dragon-tail plant growers to be aware of its susceptibility to P. paullula and to stay vigilant of the culture conditions to avoid plants from getting infected with this airborne pathogen.

Molecular confirmation of Coleosporium plumeriae Causing Rust of Plumeria rubra in Mexico

Frangipani (Plumeria rubra L.; Apocynaceae.) is a deciduous ornamental shrub, native to tropical America and widely distributed in tropical and subtropical regions. In Mexico, P. rubra is also used in traditional medicine and religious ceremonies. In November 2018-2022, rust-diseased leaves of P. rubra were found in Yautepec (18°49'29"N; 99°05'46"W), Morelos, Mexico. Symptoms of the disease included small chlorotic spots on the adaxial surface of the infected leaves, which as the disease progressed turned into necrotic areas surrounded by a chlorotic halo. The chlorotic spots observed on the adaxial leaf surface coincided with numerous erumpent uredinia of bright orange color on the abaxial leaf surface. As a result of the infection, foliar necrosis and leaves abscission was observed. Of the 40 sampled trees, 95% showed symptoms of the disease. On microscopic examination of the fungus, bright orange, subepidermal uredinia were observed, which subsequently faded to white. Urediniospores were bright yellow-orange color. They were ellipsoid or globose, sometimes angular, echinulate, (21.5) 26.5 (33.0) × (16.0) 19.0 (23.0) μm in size. Morphological features of the fungus correspond with previous descriptions of Coleosporium plumeriae by Holcomb and Aime (2010) and Soares et al., (2019). A voucher specimen was deposited in the Herbarium of the Departmet of Plant-Insect Interactions at the Biotic Products Development Center of the National Polytechnic Institute under accession no. IPN 10.0113. Species identity was confirmed by amplifying the 5.8S subunit, the ITS 2 region, and part of the 28S region with rust-specific primer Rust2inv (Aime, 2006) and LR6 (Vilgalys and Hester 1990). The sequence was deposited in GenBank (OQ518406) and showed 100% sequence homology (1435/1477bp) with a reference sequence (MG907225) of C. plumeriae from Plumeria spp. (Aime et al. 2018). Pathogenicity was confirmed by spraying a urediniospores suspension of 2×104 spores ml-1 onto ten plants of P. rubra. Six plants were inoculated and sealed in plastic bags, while four noninoculated plants were applied with sterile distilled water. Plants were inoculated at 25°C and held for 48 h in a dew chamber, after this, the plants were transferred to greenhouse conditions (33/span>2°C). The experiment was performed twice. All inoculated plants developed rust symptoms after 14 days, whereas the non-inoculated plants remained symptomless. The recovered fungus was morphologically identical to that observed in the original diseased plants, thus fulfilling Koch's postulates. According to international databases (Crous 2004; Farr and Rossman 2023), C. plumeriae has not been officially reported in Mexico, despite being a prevalent disease. Diseased plants have been collected and deposited in herbaria, unfortunately, these reports lack important information such as geographic location of sampling, pathogenicity tests, or molecular evidence, which are essential for a comprehensive study of the disease in Mexico. To our knowledge, this is the molecular confirmation of Coleosporium plumeriae causing rust of Plumeria rubra in Mexico. Rust of P. rubra caused by C. plumeriae has been previously identified in India, Taiwan, Malaysia, and Indonesia by Baiswar et al. (2008), Chung et al. (2006), Holcomb and Aime (2010) and Soares et al., (2019). This disease causes important economic losses in nurseries, due to the defoliation of infected plants.

First report of Phytophthora ramorum on Cotoneaster sp. in the USA

Cotoneaster (Rosaceae) is a genus of woody plants native to the Palearctic region which includes popular ornamental plants; some are invasive in parts of the USA. In May 2022 symptomatic leaves were detected on Cotoneaster pannosus (Silverleaf Cotoneaster) in Marin County, California (37.89165, -122.56755 ), an area infested heavily by Phytophthora ramorum, causal agent of Sudden Oak Death. Symptoms consisted of dark brown necrotic spots mostly near the tips and sometimes on the margin of the leaves, covering less than half of the leaf surface; no die-back or symptoms on twigs were detected. Diseased leaves were surface-sterilized with 70% ethanol, washed twice with de-ionized water, and placed on PARPH(V8) media. Two Phytophthora ramorum like isolates (NORS058 and NORS059) were obtained from different leaf samples from the same tree and the internal transcribed spacer (ITS) region was sequenced. Both sequences were deposited in GenBank (OR224345 and OR224346). NORS058 and NORS059 showed 99.88% and 99.75% sequence identity to P. ramorum strain Ex-type CPHST BL 55G (MG865581.1). Detached leaves of C. pannosus and C. lacteus (Milkflower Cotoneaster) were inoculated with mycelial plugs of P. ramorum NORS058, and incubated at 20°C. Both species developed necrotic leaf spots seven days post inoculation (dpi). Sporulation of the pathogen was observed on symptomatic leaves of C. lacteus. P. ramorum was reisolated from the symptomatic leaf tissue from both Cotoneaster species. Pathogenicity tests were also performed on whole plants of C. dammeri (Bearberry Cotoneaster) using the strain NORS058. Five plants each were inoculated using three different methods: 1) a zoospore solution (concentration 2.5 x10E5 spores/mL) were sprayed on the plant surface until run off. Ten leaves per plant were wounded with a needle, the remaining leaves were not wounded; 2) 200 µL of the zoospore solution in a PCR tube were attached to 5 leaves of each plant; and 3) 10 mL of the zoospore solution was drenched into the potting mix of the five plants. Control plants were treated as above but with water instead of the zoospore solution. Leaf spots developed 7 dpi on plants sprayed with zoospores on wounded leaves; and 10 dpi on plants treated with zoospores in the tube. P. ramorum was reisolated from symptomatic leaves treated with the first two methods mentioned above. Plants treated with a soil drench did not develop symptoms on the aerial parts or on roots that were sampled 50 dpi. Tests using AGDIA- immunostrips of the roots were negative. Control plants showed no aerial or root symptoms. To our knowledge, this is the first report of P. ramorum occurring on Cotoneaster in the USA. Previously, inoculation of detached leaves of C. dammeri and C. horizontalis with P. ramorum in Serbia resulted in symptom expression (Bulajić et al. 2010). P. ramorum was reported from a Cotoneaster sp. in the UK in 2010, but no further information were presented (FERA 2015). The tree sampled in 2022 showed symptoms again in spring 2023 and official regulatory samples were taken by the CDFA (California Department of Food and Agriculture) and confirmed by the USDA. During a survey in 2023, more symptomatic Cotoneaster plants were detected in Marin County, California, indicating Cotoneaster might play a role in the epidemiology of the disease. References: FERA 2015. https://planthealthportal.defra.gov.uk/pests-and-diseases/high-profile-pests-and-diseases/phytophthora/ Bulajić et al. 2010. Plant Dis. 94(6): 703.

First Report of Root Rot Caused by Pythium dissotocum on Tobacco in China

Tobacco (Nicotiana tabacum L.) is an important economic crop that is widely grown around the world. Its annual production in China is estimated at 2.2 million tons (Berbeć and Matyka 2020). Since 2022, a root rot disease was sporadically observed on tobacco seedlings on cultivar Yunyan 87 in cultivated tobacco fields in the Hunan province of China. A disease incidence of about 10% occurred across 48 ha of tobacco fields. The affected tobacco plants had slow and stunted growth with yellowing leaves. The roots turned grayish brown, decayed, and died. Diseased roots were collected from six fields and cut into small pieces (5 mm ×5 mm) from the edge of the rotted portions, and then sterilized with 70% ethanol for 10 s, 0.1% HgCl2 for 1 min, and washed in sterilized water three times. All the sterilized tissue were placed on potato dextrose agar (PDA) medium and cultured at 26 ℃ in the dark. About 3 days later, colonies with similar morphology were removed and sub-cultured on fresh PDA. A total of six strains were obtained from six tobacco samples. Strains were white and had radial growth on PDA. Hyphae were aseptate and the sporangia were filamentous. The oogonia were subglobose, smooth, 16.04 ± 0.25 µm (n=50) in diameter, and developed on unbranched stalks. The antheridia were barrel shaped and clavate. Oospores were globose, aplerotic or nearly plerotic, measuring 6.62 ± 0.33 µm (n=50). These morphological characteristics were consistent with the description of Pythium spp. (van der Plaats-Niterink 1981). For molecular identification, the internal transcribed spacer (ITS) region of rDNA and cytochrome c oxidase subunit I (Cox I) of a representative isolate, GF-3, were amplified and sequenced (GenBank accession nos. OR228424 for ITS and OR237556 for Cox I) using universal primers ITS1/ITS4 (White et al. 1990) and FM58/FM66, respectively (Villa et al. 2006). BLASTn analysis revealed that the ITS and Cox I sequences were 99.76 % (838/840 bp) and 99.85% (671/672 bp) identical to the corresponding sequences of P. dissotocum strain CBS 166.68 (AY598634.2) and UM982 (MT981147.1), respectively. A neighbor-joining phylogenetic tree based on the Cox I sequence showed that GF-3 grouped in the P. dissotocum branch. Based on morphological and molecular characteristics, GF-3 was identified to be P. dissotocum. For pathogenicity testing, four- to five-leaf-old healthy potted tobacco seedlings of the Yunyan 87 cultivar were inoculated with a zoospore suspension (1 × 105 zoospores/ml), which was induced on V8-juice medium. The zoospore suspension was introduced into the soil around plant roots and 10 mL of inoculum was used for each plant. In the control group, plants were inoculated with sterilized water. All of the treated plants were kept in humid chambers at 26°C under a 12 h/12 h photoperiod. The pathogenicity assays were performed twice, with each treatment having three replicated plants. After 5 days, tobacco seedlings inoculated with P. dissotocum showed symptoms resembling that observed in the field. However, the control plants remained healthy. Pythium dissotocum was re-isolated from the infected plants and identified by morphological and molecular methods, thus confirming Koch's postulates. Pythium dissotocum has been reported causing root rot in other plants, including hydroponic lettuce (McGehee et al. 2018) and spinach (Huo et al. 2020). Also, many Pythium species have recently been recovered from float-bed tobacco transplant production greenhouses (Zhang et al. 2022). However, to our knowledge, this is the first report of root rot on tobacco caused by P. dissotocum in China. Since this disease could greatly affect tobacco seedling establishment in the field, appropriate management strategies need to be developed to reduce further losses in tobacco planting fields.

First report of bacterial leaf spot caused by Pseudomonas cichorii on Monstera adansonii in Hawai'i, USA

Monstera adansonii is a popular ornamental house plant prized for its small size and unique leaf fenestrations. In Hawai'i, it is also sold as cut foliage (combined value ~$21K; USDA NASS 2019). In January 2022, yellow chlorotic lesions that progressed to greyish-black and, finally, to brown necrotic lesions were observed primarily along the margins of fenestrations on M. adansonii foliage at a plant nursery in Hilo, HI. All 100 variegated specimens in 4-inch pots were infected, exhibiting symptoms along the lighter yellowish-white margins. The green, unvariegated variety planted along a fence for cut foliage exhibited an infection rate of 10%. Symptomatic leaf tissue was disinfected for 1 minute in a 10% bleach solution. Tissue from the margins of leaf spots was subsequently dissected, soaked in sterile distilled water for 1 hour, and plated on Luria-Bertani (LB) agar. Plates contained nearly pure cream-colored bacterial colonies with undulate margins. Isolates were established from single colonies. One isolate (BCB001) was transferred to King's medium B (KMB) and culture fluorescence was observed under 365 nm UV light. Isolate BCB001, which was gram-negative, was identified as Pseudomonas cichorii based on the LOPAT scheme (Schaad et al. 2001). A partial 16S rRNA gene product (495 bp) using primers Y1/Y3 (Cruz et al. 2001) was sequenced and compared in GenBank (accession no. OQ875210) and was 100% identical to multiple accessions of P. cichorii in the NCBI database. Bacterial identity was further confirmed using the P. cichorii-specific primers Hrp1a/Hrp2a (Cottyn et al. 2011) to amplify and sequence a 790 bp fragment (accession no. OQ850761), which was identical to accession no. MH396007, a P. cichorii isolate recovered from Thai basil in Hawai'i. To prove pathogenicity, strain BCB001 was grown on LB agar for 48 h at 27°C and suspended in sterile water at 107-108 CFU/ml. Four healthy, 2-month-old unvariegated M. adansonii plants produced from cuttings were syringe inoculated following the protocol of Wang et al. (2022). Leaves were injected with sterile water using the same methods and acted as negative controls. Plants were placed in clear plastic bags and held at 24°C with 12 h light for 48 hours in a growth chamber, after which time the plants were removed from the bags and incubated under the same conditions for the remainder of the experiment. Leaf spots were not present on any of the control leaves or on noninjected leaves of the plants after five days of incubation. Grey to black, water-soaked leaf spots 0.84 - 15.24 mm in diameter were present on all injected leaves (96% of the injection sites) 2 days post-inoculation (DPI), which were identical to the original diseased samples. At 5 DPI, spots became dark brown to black with a yellow halo, and the affected tissue was completely collapsed. Bacterial colonies were consistently re-isolated from the lesion margins of inoculated plants and morphologically (LB and KMB) and molecularly (Hrp) identified as P. cichorii, thus fulfilling Koch's postulates. To the best of our knowledge, this is the first report of bacterial leaf spot caused by P. cichorii on M. adansonii in Hawai'i. Since M. adansonii is an ornamental plant that is prized for its leaves, leaf spots caused by P. cichorii can reduce the marketability of inventory. To avoid further spread, increasing plant spacing to improving airflow, decreasing the amount of watering, avoiding mist irrigation, and carefully removing and discarding diseased leaves are suggested.

First Report of Root Rot of Redbud Caused by Phytopythium vexans in Tennessee and the United States

The eastern redbud (Cercis canadensis L.) is an esthetically and economically important landscape tree with vibrant blossoms and attractive heart-shaped leaves. One-year-old eastern redbud seedlings grown in field condition in two commercial nurseries in Warren Co., Tennessee exhibited severe root rot in October 2021. Dark brown to black lesions and rot were observed in the affected roots (Fig. 1a). Disease severity was 50-75% of root area and disease incidence was approximately 30-40% of 10,000 plants. Surface sterilized (10% NaOCl; 1 min) symptomatic tissues were plated on V8-PARPH and incubated at 25°C. Whitish cottony mycelia with radiate and chrysanthemum flower-like growth patterns were observed within 4 days of incubation. Subglobose papillate sporangia (10.24 to 20.98 µm, n=50), filamentous to globose smooth oogonia, bell-shaped antheridia and spherical zoospores that are characteristic of Phytopythium vexans (de Cock et al. 2015) were observed in older cultures that were subjected to specific growth conditions as previously described by Ghimire & Baysal-Gurel (2023). Pathogen identification was confirmed by extracting total DNA using the DNeasy PowerLyzer Microbial Kit from 7-day-old cultures of isolates FBG0874, FBG1998, FBG2009 grown on V8-PARPH. P. vexans specific LAMP assay was conducted for the rapid molecular screening and confirmation of the isolates (Ghimire et al. 2023). Primer pairs ITS1/ITS4 (White et al. 1990), NL1/NL4 (Baten et al. 2014), Levup and Fm85mod (Robideau et al. 2011) were used to amplify and sequence the internal transcribed spacer (ITS), 28S large subunit (LSU) of ribosomal RNA and the cytochrome c oxidase subunit I (CoxI) of mitochondrial DNA genetic markers, respectively. The sequences (GenBank accession nos. OR204701, OR205212, OR205213: ITS; OR205214, OR205215, OR205216: LSU; OR220805, OR220806, OR220807: CoxI) were 100% similar to ITS, LSU, and CoxI genetic markers of P. vexans isolates in the NCBI database (MK011121: ITS, KX092469: LSU and KT692908: CoxI). Pathogenicity tests were performed on one-year-old eastern redbud seedlings grown in 1 gal containers to fulfill Koch's postulate. Eastern redbud seedlings were drench inoculated (150 ml/plant) with pathogen slurry (two plates of 7-day-old culture/liter) (Panth et al. 2021) of isolates FBG0874, FBG1998, and FBG2009 (five plants/isolate). Control plants were drenched with agar slurry without pathogen. The study was conducted in a greenhouse maintained at 21 to 23°C, 70%RH, with 16-h photoperiod and irrigated twice a day for 2 min using an overhead irrigation system. Fourteen days after inoculation dark brown to black lesions developed in the root of all inoculated plants that were identical to the symptoms observed in the original samples (Fig. 1b), while the roots of non-inoculated plants remained asymptomatic (Fig. 1c). Isolates resembling P. vexans morphological characteristics were recovered from inoculated plants, and their identity was confirmed as P. vexans using LAMP assay. P. vexans has been previously reported to cause root and crown rot in flowering cherry, ginkgo, and red maple in Tennessee (Baysal-Gurel et al. 2021, Panth et al. 2021). To our knowledge, this is the first report of P. vexans causing root rot of eastern redbud in Tennessee and the United States. Identification of this pathogen as the causal agent is important in designing and implementing effective management practices to mitigate this threat to redbud production.

Leaf Spot Caused by Didymella glomerata on Chaihu (Bupleurum falcatum L.) in China

Bupleurum falcatum is a Apiaceae family herbal medicinal plant, which has the functions of soothing liver, relieving depression, relieving fever, dispelling stagnation, and regulating menstruation. B. falcatum roots have been used in Chinese herbal formbulary for at least 2000 years (Ahmadimoghaddam et al. 2021). In June 2021, infected leaves of B. falcatum that had dark brown, circular, elliptical or irregular shaped lesions or severely withered were obtained in Yichang (30.75 ° N，111.24 ° E), Hubei, China. Disease incidence was approximately 40% in the 20 hm2 B. falcatum plantation base. Fifteen small pieces (3 mm) were cut from the junction between disease and health of surface sterilized (with 75% alcohol) leaves and then plated on potato dextrose agar (PDA). After 3 days incubation, eight isolates with the same colony morphology were sub-cultured and purified by hyphal tip isolation. Isolate CHYB1 cultured on potato dextrose agar (PDA) was selected for identification. The colony was initially white and later producing gray and brown. Pycnidia were dark, spherical or flat spherical, and 78.3 to 137.4 µm in diameter. Conidia were oval mostly, smooth, aseptate, and 18 the size was 3.7 to 5.1 × 1.6 to 2.5 µm. Following DNA extraction, PCR was performed using the TSINGKE 2×T5 Direct PCR Mix kit. Target areas of amplification were the internal transcribed spacer (ITS) and beta-tubulin gene (TUB2) using ITS1/4 (White et al. 1990) Btu-F-F01/Btu-F-R01 primers (Wang et al. 2014), respectively. BLAST analysis of the ITS sequence (MZ818334.1) had 99% similarity to a 498 bp portion of D. glomerata sequence in GenBank (KR709012.1) and TUB2 sequence (OL439060) had 100% similarity to a 323 bp portion of D. glomerata sequence in GenBank (LT592974.1). All isolates (CHYB1-8) were taken for a pathogenicity test in laboratory on surface-disinfested leaves of B. falcatum. Mycelial plugs (5 mm) were excised from the margin of colony cultured for 5 days, and placed on surface-disinfested leaves of potted B. falcatum which involved creating small wounds. The potted plants were placed in a closed bucket to keep 80% relative humidity. Controls were inoculated with non-colonized PDA plugs (5 mm). All treatments had three replicates. On the inoculated B. falcatum, the leaves of B. falcatum appeared brown spot and been covered with off-white hyphae 7 DPI. By comparision, the control leaves had no symptoms. The pathogen was reisolated from the inoculated leaves and exhibited same morphological characteristics and ITS sequence as those of D. glomerata. D. glomerata was reported to cause round leaf spot on Sophora tonkinensis Gagnep and black spot disease of Actinidia chinensis in China (Pan et al. 2018; Song et al. 2020). To our knowledge, this is the first report of leaf spot caused by D. glomerata on B. falcatum in China.

First Report of Xanthomonas campestris Causing Leaf Blight on Buttercup (Ranunculus asiaticus) in South Carolina, USA

Buttercup (Ranunculus asiaticus L.) is a popular and high value ornamental species grown in landscapes and gardens and as cut flowers. It is mostly cultivated in Europe, the Mediterranean, and the Americas (Beruto and Debergh, 2004). In January 2022, leaf blight was observed on approximately 24 of forty 4-month-old R. asiaticus plants grown in a high tunnel at a cut flower farm located in Anderson County, South Carolina, USA. Symptoms included irregular, vein-limited, and necrotic leaf lesions and yellowing. Some lesions had a chlorotic halo. Two diseased plants were submitted to the Clemson University Plant and Pest Diagnostic Clinic. Symptomatic leaves were surface sterilized with 10% bleach for 1 min and rinsed in sterile water. Small leaf portions (1 × 1 cm2) were excised from the margin of lesions. They were macerated in 500 µl of sterile water and incubated at room temperature for 10 min. A loopful of suspension was streaked on nutrient agar (NA). Slightly convex, yellowish-mucoid colonies appeared after incubation at 28°C for 48 h. Two isolates, 23A and 23B, from two plants were obtained by transferring single colonies to new NA plates. Both isolates were identified as X. campestris (probability values > 0.8) using a Biolog Microbial Identification System (GEN III Microplate; Identification Database v.2.8.0.15G). PCR amplification of these two isolates were performed for housekeeping genes gyrB, rpoD, and dnaK (Young et al. 2008). The amplicon sequences (GenBank accession nos.: OR101193 and OR101194 [dnaK]; OR101195 and OR101196 [gyrB]; OR101197 and OR101198 [rpoD]) were identical between the two isolates based on sequence alignment in MEGA11 (Tamura et al. 2021). Nucleotide BLAST of these three genes showed 94.6 to 98.9% identity (dnaK: 912 of 922 bp; gyrB: 827 of 839 bp; rpoD: 803 of 849 bp) with 100% coverage with the Xanthomonas campestris pv. campestris type strain (AE008922). A neighbor joining phylogenetic tree with the concatenated sequences of these three genes showed that 23A and 23B had the closest match with X. campestris pv. campestris. However, these two isolates tested negative in the probe-based qPCR assay specific for X. campestris pv. campestris with only the positive control amplified (Köhl et al. 2011), suggesting that they may belong to a new pathovar of X. campestris. To confirm the pathogenicity of these isolates, three healthy R. asiaticus plants each were spray inoculated with suspensions of 23A and 23B in sterile tap water until runoff (OD600 = 0.1, approx. 108 CFU/ml). The non-inoculated control plants received a sterile tap water spray. The experiment was conducted twice. All plants were maintained in a growth chamber at 24°C with 10-h photoperiod. Seven to 15 days after inoculation, necrotic lesions with chlorotic halo and leaf yellowing, similar to those observed in the field, were observed on inoculated plants, while the non-inoculated control plants remained symptomless. Koch's postulates were fulfilled by reisolating the bacteria from the symptomatic plants and confirming the bacterial identity with the sequence analysis described above. The disease was first reported in California in 1996 (Azad et al. 1996) but to the best of our knowledge has not been reported again in the United States. This is the first report of X. campestris causing bacterial leaf blight in R. asiaticus in South Carolina. Since more than 50% of the flower producers/farmers grow Ranunculus in South Carolina, further work is necessary to determine how widespread the disease is and its economic impact.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Vernonia cinerea in China

Vernonia cinerea (L.)Less. is an annual herbaceous plant of the Asteraceae family, which is widely distributed throughout Southeast Asia, India, and the tropical and subtropical regions of China. This herb is known to contain various bioactive compounds and is commonly used in traditional system of medicine in China and India (Singh et al. 2021). During the spring of 2022 and 2023, powdery mildew symptoms were observed on 70% of V. cinerea plants on the Hainan Medical University campus (19° 58' 53″ N; 110° 19' 47″ E) in Haikou, Hainan Province, China. Powdery mildew colonies covered the leaf surfaces and stems of affected plants, causing discoloration and defoliation. Mycelia were superficial and hyphal appressoria were nipple-shaped. Conidiophores (n =30) were unbranched, cylindrical, 104 to 188 × 11 to 15 µm, and produced three to five immature conidia in chains with a crenate outline. Foot cells (n =30) were cylindrical, straight or sometimes curved at the base, and 32 to 57 µm long. Conidia (n =100) were ellipsoid-ovoid to doliiform, 19 to 45 ×16 to 26 m (length/width ratio = 1.2 to 2.4), with well-developed fibrosin bodies, and produced germ tubes from the lateral position. Based on these morphological characteristics, the pathogen was provisionally identified as Podosphaera xanthii (Braun and Cook 2012). The teleomorph was not observed. A specimen was deposited in the Hainan Medical University Plant Pathology Herbarium as HMVC-22. To confirm the genus identification and ascertain a putative species, genomic DNA was extracted from mycelium, conidiophores, and conidia using a fungal DNA kit (Omega Bio-Tek, USA). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1/ITS4 (White et al. 1990) and sequenced directly. The resulting 577-bp sequence was deposited in GenBank (accession no. OP765400). A BLASTn search in GenBank of this sequence showed 100% similarity with the ITS sequences of P. xanthii isolates from China (MT260063, MT739423 and MT131253), Thailand (LC270780), and Vietnam (KM260731). Additionally, the 28S rDNA region was amplified using the primer pairs NL1 and NL4 (O´Donnell 1993; accession no. OP765401). This region shared 100% similarity with P. xanthii isolates (LC371333, LC270780, and AB936277) as well. Powdery mildew from Hainan sample belonged to the P. xanthii group with strong bootstrap values support 99% in maximum likelihood phylogenetic tree based on ITS and 28S gene sequences. To confirm pathogenicity, five healthy potted plants of V. cinerea were inoculated by gently pressing a powdery mildew-infected leaf onto 15 young leaves. Five non-inoculated plants served as controls. All plants were maintained in a greenhouse at 24 to 30°C, 70% relative humidity, with a 16-h photoperiod. After 7 days, inoculated leaves showed powdery mildew symptoms whereas no symptoms were observed on control plants. The fungal colonies observed on inoculated plants were morphologically identical to those found on the originally infected leaves collected from Hainan Province. Based on the morphological characteristics and molecular identification, the fungus was identified as P. xanthii. In different countries and regions, Erysiphe cichoracearum has been previously reported on some Vernonia species, including V. Galamensis from southern parts of Ethiopia (Hundesa and Mekonnen 2017). To our knowledge, this is the first record of P. xanthii infecting V. cinerea in China. We are concerned that the pathogen could become a threat to the widespread planting of V. cinerea in the future.

First report of powdery mildew on Euonymus japonicus caused by Erysiphe euonymicola in Taiwan

The Japanese spindle (Euonymus japonicus Thunb.) is commonly used as an ornamental hedge plant in Taiwan. In March 2020, a severe powdery mildew disease was observed on E. japonicus surrounding a city park spanning six hectares in Taichung city, Taiwan. Around 90% of the plants showed symptoms on the leaves and pedicels of young shoots. Similar symptoms were observed in other districts of Taichung city and Taipei city between March to June in subsequent years. Initial signs of infection manifest as circular chlorotic spots on the leaves, which are subsequently covered by white mycelia on either the upper or lower surfaces of the spots. In severe cases, both sides of the leaves become entirely covered by dense mycelia. Hyphal appressoria were solitary or in opposite paired, lobed to multilobed. Conidiophores grow erectly from the hyphae, consist of 2-3 cylindrical cells, 38.9 to 78.6 × 6.31 to 8.28 µm (n = 30). Foot cells are usually straight or slightly flexuous, 23.6 to 43.2 µm (n = 30), followed by 1 to 2 shorter cells. Ellipsoidal conidia are produced singly on the conidiophores, 24.1 to 36.3 × 10.6 to 14.97 µm (n = 30), without fibrosin bodies. Germ tubes are mostly subterminal, sometimes terminal, occasionally exhibiting a longitudinal pattern. Chasmothecia were not observed. These morphological characteristics correspond to the description of Erysiphe euonymicola U. Braun (Braun and Cook 2012), one of the Erysiphe species reported on E. japonicus. Genomic DNA was extracted from seven isolates obtained from different plants in the affected regions. The internal transcribed spacer (ITS) and 28S large subunit (LSU) of rDNA sequences (ITS accession nos.: OR073423-OR073429; LSU accession nos.: OR073448-OR073454) were amplified and sequenced using primer sets PMITS-1 / PMITS-2 (Cunnington et al. 2003) and NLP2 / PRM2 (Bradshaw and Tobin 2020), respectively. The resulting sequences exhibited identities ranging from 99.1 to 100% in ITS and 100% in LSU when compared to the corresponding sequences of E. euonymicola MUMH 133 (ITS: AB250228; LSU: AB250230) (Limkaisang et al. 2006). Phylogenetic analysis based on the concatenated sequences of ITS and LSU clustered the seven isolates within the same clade as three E. euonymicola isolates (MUMH 133, MUMH 6999 and MUMH 7012). Pathogenicity assays were conducted on one-meter tall E. japonicus plants by gently smearing infected leaves on all leaves of four healthy plants. Four uninoculated plants were used as control. All eight assayed plants were enclosed in plastic bags to maintain high humidity at 28 ± 2°C for 3 days. Chlorotic spots began to appear on leaves younger than one month old at 7 days post inoculation (dpi). By 28 dpi, all inoculated plants showed symptoms. Spots expanded or merged and formed a dense mycelial layer on leaves younger than three months, while mature dark green leaves were asymptomatic. No symptoms were observed on any leaves of the control plants. The morphological characteristics and sequences of ITS and LSU of the pathogen from the inoculated plants matched the above information. Based on these findings, E. euonymicola was identified as the causal agent of powdery mildew on E. japonicus, representing the first documented report of this disease in Taiwan. A voucher specimen TNM F0037001 (isolate EPM-1) was deposited in the National Museum of Natural Science, Taiwan. The pathogen has been frequently reported in recent years and significantly impacts the ornamental value of Euonymus spp. (Abbasi and Braun 2020; Lee et al. 2015; Li et al. 2011; Pei et al. 2022). This report also provides an evidence of an ongoing outbreak of the pathogen.

First report of a Herbaspirillum sp. causing leaf spots on Boston Fern (Nephrolepis exaltata) in Florida

Boston fern (Nephrolepis exaltata) samples were submitted by a nursery operation in Florida separately to the University of Florida Plant Diagnostic Center (UFPDC, Gainesville, FL) and to the North Carolina State University Plant and Pest Diagnostic Lab (NCSU PPDL, Raleigh, NC) in October 2021. Symptoms included tan spots on pinnules, some of which progressed into pinnule blight (Fig. S1). Bacterial streaming was noted from samples in both labs. Leaf spot margins were excised, macerated in sterile tap water, then streaked onto nutrient agar (NA) plates and incubated for 48 h at 27°C. Individual representative colonies that were opaque, creamy white, mucoid, and round with smooth margins were transferred and streaked onto additional NA plates. One strain from each lab (G21-1742, UFPDC and NC40101, NCSU PPDL) was selected for subsequent characterization. A suspension of each strain was adjusted to 108 CFU/mL and infiltrated into tobacco and tomato leaves, and confluent necrosis was observed 72 h after infiltration. The isolates were Gram-negative, oxidase-positive, HR-positive on tomato and tobacco, aerobic, not pectolytic, and nonfluorescent on King's Medium B. DNA was extracted from G21-1742 using Qiagen Stool kit (Qiagen cat#51604) and the 16S rRNA gene from strain G21-1742 was amplified using 16SrRNA universal primers UP1 (5'-TACGTGCCAGCAGCCGCGGTAATA-3') and UP2 (5'-AGTAAGGAGGGTATCCAACCGCA-3') (Kuppusamy et al. 2014). The amplicon was sequenced and submitted to NCBI (Genbank Accession No. OR004801). BLASTn analysis of 16S rRNA of G21-1742 resulted in 99.7% sequence identity to the type strain of Herbaspirillum huttiense subsp. huttiense ATCC 14670T (Genbank Accession NR_024698). The 16S rRNA sequence of NC40101 was identical to that of G21-1742. To determine if the G21-1742 strain was pathogenic, Boston fern plants were inoculated by suspending bacterial cells in tap water from a 24h culture grown on NA, adjusting the suspension to 108 CFU/mL and spraying the suspension on one three-week old frond from each of three healthy Boston fern plants. A second frond from each plant was sprayed with sterile tap water. Each treated frond was individually sealed in a clear plastic bag for 24h at approximately 25°C. Inoculated plants remained on the greenhouse bench after the plastic bags were removed. The inoculation experiment was repeated once. After 4 days, tan spots were observed on pinnules of inoculated plants that were identical to the original submitted samples, while no symptoms developed on water-inoculated plants. Bacterial strains were reisolated from symptomatic plants and were morphologically identical to G21-1742. The 16S rRNA sequence of the reisolated strain was identical to G21-1742. Additionally, we conducted MLSA analysis using 12 housekeeping genes (See Table S2 for housekeeping genes and accession numbers) from the fern strains and the corresponding housekeeping genes for the type strains of 13 Herbaspirillum species, which placed the fern strains most closely with H. huttiense (see Fig. S2). This is the first known report of a Herbaspirillum sp. on Boston fern, an important ornamental crop, that renders the plants aesthetically unsaleable. Previously, a Herbaspirillum sp. was reported in Florida to cause a leaf spot and blight on greenhouse grown tomato seedlings (Obradovic et al. 2007).

First report of Fig virus B in Ficus carica in New Zealand

Fig (Ficus carica) has been cultivated since ancient times, and is now grown worldwide, both for its fruit and as an ornamental plant. Several viruses and viroids are associated with Fig mosaic disease (FMD), a disease complex occurring worldwide (Preising et al. 2021). Fig mosaic virus (FMV), fig leaf mottle-associated virus 1 (FLMaV-1), fig mild mottle-associated virus (FMMaV), and fig badnavirus 1 (FBV-1) are known to infect fig in New Zealand (Minafra et al. 2012; Veerakone et al. 2015). In December 2020, leaf samples from a fig tree growing on the roadside at St Heliers, Auckland, showing dieback with foliar chlorotic mosaic symptoms, was received for virus testing. Total nucleic acid was extracted from the symptomatic leaves using a KingFisher™ mL Purification System (Thermofisher Scientific, Waltham, MA) with an InviMag Plant DNA Mini Kit (Invitek Molecular GmbH, Germany) and subjected to high-throughput sequencing on an Oxford Nanopore Technologies MinION device using the method described in Liefting et al. 2021. All sequence analysis was performed using Geneious Prime 2021.1.1 (https://www.geneious.com). A total of 355,858 reads that passed quality check were subjected to BLASTn search against the NCBI nt database as described in Liefting et al. 2021. The following viruses produced hits: FMV, FBV-1, FMMaV and a fig closterovirus. The presence of FMV, FBV-1 and FMMaV were confirmed by species specific RT-PCRs. To identify the closterovirus, reads were mapped to closteroviruses reported in fig including the recently identified tentative species fig virus A (FiVA; GenBank accession no MN817232) and fig virus B (FiVB; GenBank accession no. MN817233). Five viral contigs ranging from 939 to 2,340 nucleotides (nt) were obtained from mapping to FiVB. Subsequently, a 6.4 kb sequence (GenBank accession no. OQ968551) from the 3' region of the NZ isolate was amplified by overlapping RT-PCR using primers designed from the contig sequences. The sequence shared 79.5% nucleotide (nt) identity with FiVB The original sample and a further 25 symptomatic and 10 asymptomatic fig samples, collected from the Auckland area between 2016 and 2021, were tested using FiVB specific RT-PCR and Sanger sequencing using primers FiVB-F1 (5'-GAGGGAGAGATGTAGATGC-3') and FiVB-R2 (5'-TGTCGTCGATATCGTTGTGT-3'), designed to amplify a 725 nt fragment in the 70 kDa heat shock protein (HSP70) ORF. Products of the expected size were amplified from the original sample and three symptomatic samples and their sequences found to be identical. BLAST searches showed that the sequence (GenBank accession no. ON553403) shared 82.7% nt and 87.3% amino acid (aa) identity to an isolate of FiVB (GenBank accession no MN817233). These additional positive samples were collected from a small home nursery where the plants were propagated from cuttings and have been distributed locally, suggesting the virus is very likely to have a limited spread throughout the Auckland area. All three FiVB infected samples were also positive for FMV. However, the association of FiVB with FMD symptoms is unknown. FiVB was first identified from a latex sample exuded from a fig tree collected from Japan (Park et al. 2021) and is the only report of FiVB in the world to date. Although an identical sequence from Argentina, named fig closterovirus 1, was submitted to GenBank, the origin of this isolate is not known. To our knowledge, this is the first report of FiVB in New Zealand.

First Report of Stemphylium lycopersici Causing Leaf spot on Sedum plumbizincicola in Hunan Province of China

Sedum plumbizincicola is a perennial succulent herb that can hyperaccumulate high concentrations of cadmium and zinc (Liu et al. 2017). In October 2021, a leaf spot disease occurred on S. plumbizincicola seedlings in a nursery in Changsha (28°13' N; 112°56'E), the Hunan Province of China. Almost 30% of the nearly 1 million seedlings were infected. Symptoms initially appeared as small brown spots on the leaf surface or edges, gradually enlarged, becoming oval, and bearing chlorotic lesions with dark brown borders. Eventually, the center of the lesions became sunken and then fell off. Eight symptomatic plant samples were collected by five-point sampling method (Zheng et al. 2018). Small pieces of 5×5 mm were excised from the lesion margins, sterilized with 70% ethanol for 10 s, 0.1% HgCl2 for 40 s, rinsed with sterile distilled water three times, and then cultured on potato dextrose agar (PDA) at 26 °C for 5 days in the dark. Fungal colonies showing similar morphology were observed from all the isolated samples and, in total, eight fungal strains were obtained. On PDA, fungal colonies were initially white, and later become light gray. After cultured on V8 juice agar (V8A, each litre of medium contains 200 mL of V8 juice, 3 g of CaCO3 and 15 g of agarose) for 14 days (Hyowon et al. 2016), conidia of a representative isolate SY-1 were produced, which were oblong, muriform, with blunt ends and conical apex, pale to light brown, and constricted at the 1 to 3 major transverse septa, 38.34-46.68 μm×11.67-18.34 μm (n=50). These morphological characteristics were consistent with that of Stemphylium lycopersici (Nasehi et al. 2016). The internal transcribed spacer (ITS) region of rDNA and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene of representative isolates SY-1 to SY-3 were amplified and sequenced using the primer pairs ITS4/ITS5 and gpd1/gpd2 as described previously (Woudenberg et al. 2017). BLASTn analysis showed that ITS sequences of isolates SY-1, SY-2 and SY-3 (accession nos. OP317641, OQ852042 and OQ852043) had more than 99% identity with Stemphylium sp, while GAPDH sequences (OP331223, OQ858620 and OQ858621) had 100% identity with S. lycopersici KR911813 (Sun et al. 2016). A concatenated ITS-GAPDH phylogenetic tree grouped our isolates within the S. lycopersici clade. For the pathogenicity test, one-month-old potted S. plumbizincicola seedlings were inoculated with conidia suspension (105 conidia/ml), which was induced on V8A. Four sites of each leaf of the potted S. plumbizincicola plants were dropped with a conidia suspension of strain SY-1, with 10 μL per site. Leaves treated with sterile water were served as controls. All of the inoculated seedlings were placed in a growth chamber at 26°C with a photoperiod of 12 h. The pathogenicity tests were repeated twice, with each had three replicative plants. After 7 days, all the inoculated leaves developed brown spots resembling those observed in the nursery, whereas the control plants remained symptomless. Stemphylium lycopersici was specifically re-isolated and identified by morphological and molecular methods (accession nos. OQ852045 for ITS and OQ858622 for GAPDH, respectively), thus fulfilling Koch's postulates. To our knowledge, this is the first report of S. lycopersici causing leaf spot on S. plumbizincicola in China. Since S. plumbizincicola played an important role and widely planted for heavy metal pollution treatment (Jiang et al. 2010), and this disease might seriously influence the S. plumbizincicola seedling breeding, identification of the pathogen might provide a foundation for the diagnosis and control of the disease.

First report of Nerine yellow stripe virus infecting crinium lily (Crinium sp.) in Texas

Crinum sp. (family Amaryllidaceae) is an ornamental flower bulb that is commonly called crinum lily, cape lily, cemetery plant, spider lily, and swamp lily. In April 2023, two plants of Crinum sp. var. Maiden's Blush with yellow stripe symptoms (Fig. S1) were submitted to the Texas Plant Virus Diagnostic Laboratory, Weslaco, TX for virus diagnosis. Due to the resemblance of the observed symptoms to those described for potyviruses infecting ornamental flower bulbs (Pearson et al. 2009), total RNA extracts were made from each sample using the SpectrumTM Plant Total RNA Kit (Sigma-Aldrich, USA), according to the manufacturer's protocol. Complementary DNA (cDNA) was synthesized from 2 µg total RNA per sample with Oligo(dT) primers using the PrimeScript™ 1st strand cDNA Synthesis Kit (Takara Bio, USA) as recommended by the manufacturer. A 2µL aliquot of each cDNA template was initially subjected to PCR using the generic primer pair CIFor/CIRev (Ha et al., 2008) that targets a fragment of the cylindrical inclusion (CI) body of potyviruses. The expected ~700 bp DNA band was amplified from both samples using the Taq DNA polymerase, dNTPack kit (Sigma-Aldrich). The amplicons were cloned and sequenced (three recombinant clones per sample) as described by Hernandez et al. (2021) and the BLASTX analyses of the consensus sequence (GenBank acc. no. OR137018) returned significant hits only to nerine yellow stripe virus (NeYSV; Potyvirus, Potyviridae) at 100% query coverage. To further confirm the results, another pair of universal primers (Jordan et al. 2011) was used to amplify the expected ∼1,600 bp product specific to the partial nuclear inclusion body (NIb), coat protein (CP) cistron, and 3' untranslated region of potyviruses from the same samples. The amplicons were similarly cloned, and a consensus sequence obtained (OR137019). In pairwise comparisons, the partial CI sequence of NeYSV from Texas (NeYSV-TX; OR137018) shared 83% nucleotide (nt)/93% amino acids (aa) identities with the corresponding sequences of NeYSV isolate 63 (MT396083) from the United Kingdom. The partial (649 nt) NIb sequences of NeYSV-TX (OR137019) and the complete CP (OR137019) of NeYSV-TX shared 77-94%/88-94% and 83-99%/89-98% nt/aa identities with the corresponding sequences of global NeYSV isolates that were retrieved from GenBank. Phylogenetic analysis revealed a closer relationship between NeYSV-TX and the isolates Stenomesson (EU042758) and DC (MG012805) from the Netherlands and USA, respectively based on the partial NIb and CP cistrons (Fig. S2), suggesting that NeYSV-TX may have been introduced from foreign and/or domestic sources. NeYSV has been documented previously from the United Kingdom, the Netherlands, Australia, New Zealand, and India; its first report from the United States was a decade ago from Amaryllis belladonna in California (Guaragna et al. 2013). To the best of our knowledge, this is the first report of NeYSV in Texas, thus expanding the geographical range of the virus in the USA. Anecdotal information from the sample submitter implicated infected crinum lily bulbs as the likely source of NeYSV introduction into the property, with subsequent vegetative propagation of plants resulting in 100% incidence of symptomatic lilies (n>100) over time. Thus, the results underscore the importance of ensuring that only virus-free vegetative plant materials are distributed and propagated by florists to curtail virus spread.

First report of 'Candidatus Phytoplasma asteris' associated with witches'-broom disease of Pinus yunnanensis in China

Pinus yunnanensis is an evergreen tree belonging to Pinaceae. The species is distributed in the east of Tibet, southwest of Sichuan, southwest of Yunnan, southwest of Guizhou and northwest of Guangxi. It is an indigenous and pioneer tree species for barren mountain afforestation in southwest China. P. yunnanensis has important value to both the building and medicine industries (Liu et al. 2022). In May 2022, P. yunnanensis showing witches'-broom symptom were found in Panzhihua City, Sichuan Province, China. The symptomatic plants had yellow or red needle, and exhibited plexus bud and needle wither. The lateral buds of infected pines developed into twigs. Some lateral buds grew in clusters and a few sprouted needles (Fig.1). The disease was named the P. yunnanensis witches'-broom disease (PYWB) and was found in some areas of Miyi, Renhe, and Dongqu. More than 9% of the pines showed these symptoms in the three areas surveyed, and the disease was spreading. A total of 39 samples were collected from three areas, including 25 symptomatic plants and 14 asymptomatic plants, respectively. The lateral stem tissues of 18 samples were observed under a scanning electron microscope (Hitachi S-3000N). Spherical bodies were found in the phloem sieve cells of symptomatic pines (Fig.1). Total DNA was extracted from 18 plant samples using the CTAB method (Porebski et al. 1997) and subjected to nested-PCR testing. Double-distilled water and DNA extracted from asymptomatic plants were used as negative controls, and DNA extracted from Dodonaea viscosa affected by the D. viscosa witches'-broom disease was used as positive control. Nested PCR was employed to amplify the pathogen's 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993) and 1.2 kb segment were produced (GenBank accessions OP646619; OP646620; OP646621). PCR specific to the ribosomal protein (rp) gene yielded segment of approximately 1.2 kb (Lee et al. 2003)(GenBank accessions OP649589; OP649590; OP649591). The fragment size from 15 samples was consistent with the positive control, confirming the association of phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of P. yunnanensis witches'-broom phytoplasma showed that it shared 99.12% ~99.76% identity with that of Trema laevigata witches'-broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99.84%~99.92% identity with that of Cinnamomum camphora witches'-broom phytoplasma (GenBank accession OP649594). An analysis with iPhyClassifier (Zhao et. 2013) showed that the virtual RFLP pattern derived from OP646621 16S rDNA fragment of PYWB phytoplasma is identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (OY-M, GenBank accession AP006628). The phytoplasma is identified as a 'Candidatus Phytoplasma asteris'-related strain belonging to sub-group 16SrI-B. Interestingly, compared to AP006628, the virtual RFLP pattern derived from OP646619 and OP646620 fragments exhibit differences in three and one cleavage site, with a similarity coefficient of 0.92 and 0.97, respectively (Fig.2). These strains may represent a new subgroup within the 16Sr group I. The phylogenetic tree was reconstructed based on 16S rRNA and rp gene sequences using MEGA versio6.0 (Tamura et al. 2013). The analysis was conducted using the neighbor-joining (NJ) method with 1,000 replicates of bootstrap analysis. The results indicated that the PYWB phytoplasmas grouped into clades including phytoplasmas belonging to 16SrI-B and rpI-B, respectively (Fig.3). In addition, 2-year-old P. yunnanensis were used for grafting assays in nursery, and the twigs from infected pine under natural conditions were used as a scion, and the phytoplasma were detected using nested PCR after grafting for 40 d (Fig.4). In 2008-2014, P. sylvestris and P. mugo in Lituania had excessive branching symptoms that were attributed to 'Ca. Phtyoplasma Pini' (16SrXXI-A) or asteris' (16SrI-A) strains (Valiunas et al. 2015). In 2015, P. pungens with abnormal shoot branching in Maryland were found to be infected by 'Ca. Phytoplasma pini' strain (16SrXXI-B) (Costanzo et al. 2016). To the best of our knowledge, P. yunnanensis is a new host of 'Ca. Phytoplasma asteris'-related strain (16SrI-B) in China. The newly emerged disease is a threat to pines.

First report of Nalanthamala vermoesenii causing pink rot of Phoenix canariensis in Mexico

In Mexico City, the Canary Island date palm (Phoenix canariensis Chabaud) is an important plant forming part of its landscape identity. In February 2022, pink rot disease symptoms were observed on 16 P. canariensis plants in Mexico City (19°25'43.98"N, 99° 9'49.41"W). The incidence was 27%, while the severity 12%. External symptoms included necrotic lesions that advanced from the petiole towards the rachis. Internal symptoms were rotted, dark brown discoloration in bud, petiole, and rachis. Abundant conidial masses were developed on the infected tissues. Pieces of diseased tissues (5-mm cubes) were surface sterilized for 2 min in 3% sodium hypochlorite, rinsed with sterilized distilled water, plated onto potato dextrose agar (PDA), and incubated at 24°C and 12-h photoperiod, 20 pink fungal colonies were developed with sparse aerial mycelia on PDA. Conidiophores were hyaline, dimorphic, penicillate, and Acremonium-like. Conidia were dimorphic, typically with somewhat truncated ends, 4.5 to 5.7 × 1.9 to 2.3 μm (mean 4.99 × 2.15, n = 100), borne in long chains on penicillate conidiophores; on Acremonium-like conidiophores conidia were cylindrical, straight, and slightly curved, 4.55 to 10.1 × 1.2 to 2.35 μm (mean 8.2 × 1.7, n = 100). These morphological characteristics resembled those of Nalanthamala vermoesenii (Biourge) Schroers (Schroers et al. 2005). Genomic DNA was extracted from the mycelia of a representative isolate CP-SP53. The internal transcribed spacer (ITS) region and the large subunit of ribosomal ribonucleic acid (LSU) were amplified and sequenced. The sequences were deposited in GenBank with accession numbers OQ581472 (ITS) and OQ581465 (LSU). Phylogenetic trees based on ITS and LSU sequences of Nalanthamala species were reconstructed using maximum likelihood and Bayesian inference methods. Isolate CP-SP53 was placed in the clade of Nalanthamala vermoesenii. The pathogenicity test was carried out twice with isolate CP-SP53 on five 3-year-old P. canariensis plants. Four petioles per plant were surface disinfected with 75% ethanol, and wounded with a sterilized scalpel (shallow cuts 0.5 cm wide). A mycelial plug (5 mm in diam.) of a 1-week-old PDA culture was placed on each wounded site. Sterile PDA plugs were used for five non-inoculated control plants. All plants were maintained at 22 ± 2°C and a 12-h photoperiod. Twenty-five days after inoculation (dai), wounded petioles showed the same symptoms observed in the field, whereas control plants remained healthy. Forty-five dai, all inoculated plants died. Pink conidial masses developed on symptomatic tissues. To fulfill Koch's postulates, the pathogen was reisolated by placing the pink conidial masses onto PDA. The colony characteristics and morphometric measurements were identical to those of isolate CP-SP53. Nalanthamala vermoesenii has been reported on P. canariensis in Greece and United States (Feather et al. 1979; Ligoxigakis et al. 2013) and Syagrus romanzoffiana in Egypt (Mohamed et al. 2016). To our knowledge, this is the first report of Nalanthamala vermoesenii as the causal agent of pink rot on P. canariensis in Mexico. This plant is the most commonly planted ornamental palm in Mexico City. The spread of N. vermoesenii could be a threat for the estimated 15 thousand palms, therefore dramatically change the urban landscape.

First report of 'Candidatus Phytoplasma asteris' associated with witches'-broom and plexus bud disease of Cerasus serrula in China

Cherry blossoms (Cerasus serrula) are native to the temperate zone around the Himalayas in the northern hemisphere, mainly distributed in the west and southwest of China, including Yunnan, Sichuan and Tibet. Cherry has high ornamental, edible and medicinal value. In August 2022, we observed that Cherry trees exhibited witches' broom and plexus bud in Kunming City, Yunan Province, China. The symptoms consisted of many small branches with little leaves at the top of branches, stipule lobation, and clustered adventitious buds that are tumor-like on the branches that usually cannot sprout normally. As disease intensity increased, the branches dried up from the top to the bottom till the death of the whole plant. We named this disease C. serrula witches' broom disease (CsWB). We found CsWB in the areas of Panlong, Guandu, Xishan Districts in Kunming, where more than 17% of the plants we surveyed were infected. We collected 60 samples from across the three districts. These included 15 symptomatic and 5 asymptomatic plants per district. The lateral stem tissues were observed under a scanning electron microscope (Hitachi S-3000N). The nearly spherical bodies were found in the phloem cells of symptomatic plants. Total DNA extraction was conducted from 0.1 g tissue using the CTAB method (Porebski et al. 1997), ddH2O was used as the negative control, and Dodonaea viscose plants with witches' broom symptoms were used as the positive control. The nested PCR was used to amplify the 16S rRNA gene (Lee et al. 1993; Schneider et al. 1993) and PCR amplicon of 1.2 kb were amplified (GenBank accessions: OQ408098; OQ408099; OQ408100). The direct PCR specific to the ribosomal protein (rp) gene yielded amplicons of approximately 1.2 kb with primer pair rp(I)F1A and rp(I)R1A (Lee et a. 2003) (GenBank accessions: OQ410969; OQ410970; OQ410971). The fragment from 33 symptomatic samples was consistent with the positive control, and absent for asymptomatic samples, suggesting an association of phytoplasma with the disease. A BLAST analysis of the 16S rRNA sequences of CsWB phytoplasma showed that it has a 99.76% similarity with Trema laevigata witches' broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99.75% identity with Cinnamomum camphora witches' broom phytoplasma (GenBank accession OP649594). An analysis with iPhyClassifier showed that the virtual RFLP pattern derived from the 16S rDNA sequence shares 99.3% similarity with that of the 'Ca. Phytoplasma asteris' reference strain (GenBank accession: M30790), and the virtual RFLP pattern derived from the fragment is identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (GenBank accession: AP006628). Thus, CsWB phytoplasma is identified as 'Ca. Phytoplasma asteris'-related strain belonging to sub-group 16SrI-B. The phylogenetic tree was constructed based on 16S rRNA gene and rp gene sequences by using MEGA version 6.0 (Tamura et al. 2013) with neighbor-joining (NJ) method and bootstrap support was estimated with 1000 replicates. The result indicated that the CsWB phytoplasma formed a subclade in 16SrI-B and rpI-B respectively. In addition, the clean 1-year-old C. serrula were tested positive for the phytoplasma using the nested PCR 30 days after being grafted with naturally infected twigs with CsWB symptoms. To the best of our knowledge, Cherry blossoms is a new host of 'Ca. Phytoplasma asteris'-related strains in China. The newly emerged disease is a threat to the ornamental value of cherry blossoms and the production of wood quality.

Identification of Fusarium sacchari Causing Foliar Blight on Begonia semperflorens in China

Begonia semperflorens Link et Otto (Begoniaceae) is a flowering, ornamental plant widely cultivated in China. In April of 2020, a foliar blight disease on B. semperflorens was observed in plant nurseries (∼0.2 ha), with ~ 20% disease incidence (n = 150) in Nanning, Guangxi Province, China. Initial symptoms included irregular to circular, grayish white spots surrounded by a dark brown halo, mainly scattered on the edges the leaves. In severe infections, the spots frequently coalesced to form large, blighted areas, followed by defoliation. To isolate the pathogen, three representative plants exhibiting symptoms were collected from the nurseries. Leaf tissues (5 × 5 mm) were cut from the margin of necrotic lesions (n = 18), surface disinfected in 1% NaOCl for 2 min, then rinsed three times in sterile H2O. Then the tissues were plated on potato dextrose agar (PDA), and incubated at 28°C (12 h photoperiod) for 3 days. Hyphal tips from recently germinated spores were transferred to PDA to purify fungal isolates. A total of 11 isolates (85% isolation frequency) with similar morphological characteristics were obtained. Colonies on PDA plates were villose, had a dense growth of white aerial mycelia and appeared pale but becoming violet with age. On Spezieller Nährstoffarmer Agar (SNA), the macroconidia were slender, slight falcate, two to three septate, and 23.5 to 48.8 × 2.8 to 4.8 μm (n = 60), and the microconidia were abundant and formed in false heads on monophialides or polyphialides, slim, oval, zero to one septate, and 7.8 to 22.4 × 2.4 to 4.0 μm (n = 60). For molecular identification, the internal transcribed spacer (ITS) region of rDNA, and partial translation elongation factor-1 alpha (TEF-1α), and RNA polymerase second largest subunit (RPB2) genes of the representative isolate HT-2B were amplified and sequenced using primer pairs ITS1/ITS4 (White et al. 1990), EF-1/EF-2 (O'Donnell et al. 1998), and 5f2/11ar (Liu et al. 1999, Reeb et al. 2004), respectively. The obtained sequences were deposited in NCBI GenBank under the accession numbers OQ048268 (TIS), OP994260 (TEF-1α), OP994262 (RPB2) and showed 99.4%, 99.8%, and 99.4% similarity with the corresponding sequences (X94168，AF160278，and JX171580, respectively) of Fusarium sacchari from type material. In addition, a phylogenetic analysis showed that HT-2B was grouped with F. sacchari. Therefore, based on morphological (Leslie et al. 2005) and molecular characteristics, the isolates were identified as F. sacchari. To test pathogenicity, three healthy leaves on each of three B. semperflorens plants were stab-wounded with a sterile syringe and inoculated with a 10-μl droplet of a conidial suspension (106 spores/ml) of the isolate HT-2B. As a control, another three leaves were wound inoculated with sterilized dH2O. All plants were enclosed in transparent plastic bags and incubated in a greenhouse at 28°C (12 h photoperiod, ~ 80% relative humidity). Six days post-inoculation, symptoms appeared on the inoculated leaves. No symptoms were detected on control plants. Experiments were replicated three times with similar results. To fulfill Koch's postulates, the F. sacchari isolates were consistently re-isolated from symptomatic tissue and confirmed by morphology and sequencing, whereas no fungus was isolated from the control plants. To our knowledge, this is the first report of F. sacchari causing foliar blight on B. semperflorens in China. This result will help develop management strategies for this disease.

Agave attenuata and Agave amica, new hosts of Tuberose mild mosaic virus in Mexico

Agave attenuata is a Mexican wild plant originally from highlands in the central and occidental mountains of Mexico. This species, known as "swan´s neck agave", is used only as an ornamental plant in public and private gardens. No virus had previously been reported from A. attenuata before this study. In a survey conducted in a commercial greenhouse in Cuautla, Morelos, in 2018, several plants were observed with symptoms of green mosaic and streaks, consistent with a putative viral infection. Sap inoculation from symptomatic A. attenuata plants to herbaceous indicator plants (Nicotiana benthamiana and N. tabacum) failed to produce symptoms in the mechanically inoculated plants. ELISA specific test to CMV, TEV, AMV, TMV and Potyvirus Group (Agdia, Inc.), was positive only for the last one (Chen and Chang, 1998). To determine the identity of the potyvirus involved, total nucleic acid extracts from 100 mg of symptomatic leaves (Trizol reagent; Gibco BRL Life Technologies, England) were used as template in RT-PCR with genus-specific potyvirus primers POT1-POT2, which targeted the variable 5´ terminal half of the coat protein gene of potyviruses (Colinet et al. 1998). The expected 900 bp amplicon was consistently detected in 10 symptomatic A. attenuata plants whereas no PCR products were obtained from 15 asymptomatic A. attenuata plants collected from the "Agaves de México" section at the 'Botanic Garden' of the Instituto de Biología de la UNAM, México. The amplicons were sequenced by the Sanger´s method and the obtained nucleotide (nt) sequences (Acc. No KY190217.1; OP964597-598) and their derived amino acid (aa) sequences were 94.68% to 95.80% similar to an isolate of Tuberose mild mosaic virus (TuMMV; Potyvirus; (Acc. No ON116187.1) characterized from Agave amica in India (Raj et al. 2009). Interestingly, A. amica (formerly Poliantes tuberose) is also a wild Mexican plant that is geographically distributed in the central and south regions of Mexico and is currently being commercially cultivated as an ornamental plant. Plants of A. amica (n=10) showing yellow mild streak were collected from commercial greenhouse and tested positive for TuMMV by RT-PCR and Sanger sequencing (No Acc. OP964599-601 levels) described above. The derived TuMMV sequences from A. attenuata and A. amica were 99-100% similar to each other at the nt/aa level. To exclude the involvement of additional viral agents in the disease, high-throughput sequencing analysis was performed separately for each species of Agave on total RNA extracts from a composite sample of symptomatic leaf tissues using Illumina´s Next Seq 500 platform. Analysis of the obtained 13,260,700 reads (each 75 nt) by the Trinity software, with a total number of sequences of 22,793, resulted in the identification of a single viral contig of 9500 nt for A. attenuata (Acc. No OP964595). Similarly, for A. amica, 27,262,248 reads were obtained, with a total number of sequences of 23,269, resulting in the identification of a single viral contig of 8500 nt (ACC. No OP964602). These contigs showed an identity percentage of 96%/88% and 98%/96% for nucleotides and amino acids, respectively, compared to an isolate of TuMMV from India (Acc. OM293939). Mexico is a center of origin for numerous species of genus Agave which have high economic, social, and ecological impact. TuMMV could be a threat to these plants and potentially to other unknown susceptible crops. To our knowledge, this is the first report of TuMMV in A. attenuata and A. amica in Mexico. REFERENCE Chen, C. C., and Chang, C. A. 1998. Characterization of a potyvirus causing mild mosaic on tuberose. Plant Dis. 82:45-49. Colinet, D., Nguyen, M., Kummert, J., Lepoivre, P., and Xia, F. Z. 1998. Differentiation among potyviruses infecting sweet potato based on genus- and virus-specific reverse transcription polymerase chain reaction. Plant Dis. 82:223-229. Raj, S.K., Snehi, S.K., Kumar, S., Ram, T. and Goel, A.K. 2009. First report of Tuberose mild mosaic potyvirus from tuberose (Polianthes tuberosa L.) in India. Australasian Plant Dis. Notes 4, 93-95.

First Report of Colletotrichum fructicola Causing Anthracnose on Punica granatum in China

Punica granatum L. (Pomegranate), a deciduous shrub, is widely cultivated as a fruit tree and decorative plant in China. Its flowers, leaves, roots and fruit bark also has been widely used for the treatment of different types of human disease because of the high anti-inflammatory and antibacterial activitiy (Tehranifar et al. 2011). In October 2022, leaf spot symptoms were observed on P. granatum leaves in a landscaped area on the campus of Jiangxi Agricultural University (28.75°N, 115.83°E), Nanchang, Jiangxi Province, China. A survey of 40 P. granatum of 300 m2 found that up to 20% of the foliage was infected. Infection normally starts at the tip or edge of the leaves, with the initial symptoms of lesions usually being small dark brown spots (0.8 to 1.5 mm) that gradually expand into irregular spots with grayish white central parts, and brown margins (2.3 to 3.8 mm). Ten freshly infected leaves from three different plants were collected and cut into small slices, disinfected with 75% ethanol for 30 seconds followed by 5% NaClO for 1 minute, rinsed 3 times with sterile water, and then plated on potato dextrose agar (PDA) and incubated in the dark at 25°C. After 7 days, all incubated samples produced similar morphology of aerial mycelium pale grey, dense, and cottony. Conidia were hyaline, smooth-walled, cylindrical, aseptate and measuring 12.28 to 21.05 × 3.51 to 7.37 µm (n = 50). Morphological characteristics were consistent with those of Colletotrichum gloeosporioides species complex (Weir et al. 2012; Park et al. 2018). For molecular identification, we used two representative isolates (HJAUP CH005 and HJAUP CH006) for genomic DNA extraction and amplification, using primers for ITS4/ITS5 (White et al. 1990), Bt2a/Bt2b, GDF1/GDR1, ACT-512F/ACT-783R and CL1C /CL2C (Weir et al. 2012), respectively. The sequenced loci (GenBank accession nos. ITS: OQ625876, OQ625882; TUB2: OQ628072, OQ628073; GAPDH: OQ628076, OQ657985; ACT: OQ628070, OQ628071; CAL: OQ628074, OQ628075) exhibited 98 to 100% homology with corresponding sequences of C. fructicola strains (GenBank accession nos. OQ254737, MK514471, MZ133607, MZ463637, ON457800, respectively). A phylogenetic tree was constructed using the maximum-likelihood method in MEGA7.0 for the sequences of five concatenated genes (ITS-TUB2-GAPDH-ACT-CAL). Our two isolates clustered together with three strains of C. fructicola with 99% bootstrap support values in the bootstrap test (1000 replicates). The isolates were identified as C. fructicola based on morpho-molecular approach. The pathogenicity of HJAUP CH005 was tested indoors by inoculating the wounded leaves of four healthy P. granatum plants. Four leaves from each of two healthy plants were punctured with flamed needles and sprayed with a spore suspension (1 × 106 spores/ml), and four wounded leaves from each of other two plants were inoculated with mycelial plugs (5 × 5 mm3), respectively. Mock inoculations with sterile water and PDA plugs on four leaves each were used as controls. Treated plants were incubated in a greenhouse at high relative humidity, 25°C, and a photoperiod of 12 h. After 4 days, typical anthracnose symptoms similar to natural infection appeared on the inoculated leaves, whereas the control leaves remained asymptomatic. Based on morphological and molecular data, the fungus isolated from the inoculated and symptomatic leaves was identical to the original pathogen, confirming Koch's hypothesis. Anthracnose caused by C. fructicola has been reported to affect numerous plants worldwide, including cotton, coffee, grapes and citrus (Huang et al. 2021; Farr and Rossman 2023). This is the first report of C. fructicola causing anthracnose on P. granatum in China. This disease seriously affects the quality and yield of the fruit and should be of wide concern to us.

First report of Aloe root and stem rot caused by Phytophthora palmivora in Yunnan Province, China

Aloe genus plants are perennial evergreen herb belonging to Liliaceae family which is widely used in food, medicine, beauty, and health care (Kumar et al. 2019). In August 2021, symptoms of root and stem rot was observed in approximately 20% of Aloe vera plantings in Yuanjiang County, Yunnan Province, China (23° 64' 53" N, 101° 99' 84" E). The most typical symptoms were stem and root rot, browning and necrosis of vascular tissues, gradual greening, and reddish-browning of leaves from bottom to top, abscission, and eventual plant death (Fig. S1). Therefore, to isolate and identify the pathogen, the plants showing the above symptoms were collected. The plant tissues were cut from the edges of root and stem lesions, followed by disinfection with 75% ethanol for 1 min, rinsed three times with sterilized distilled water, and cut into 3 × 3 mm small squares after excision of marginal tissues. The tissues were transferred to the oomycetes selective medium (Liu et al. 2022) and incubated at 28 °C in the dark for 3~5 days, and suspected colonies were purified. The colonies were then inoculated onto potato dextrose agar (PDA), V8-juice agar (V8), and oatmeal agar (OA) medium plates for morphological characteristics. Finally, 18 isolates with the same colonial and morphological characteristics were obtained from 30 lesioned tissue and one of them was named as ARP1. On PDA, V8 and OA medium plates, the ARP1 colonies were white. On PDA plate, the mycelia were dense and the colonies were petal-like; on V8 plate, the mycelia were cashmere and the colonies were radial or star-like. Whereas, on OA plate, the mycelia were cotton-like and the colonies were fluffy and radial (Fig. S2 A~C). Mycelium did not have septum with high branching and swelling. Sporangia were abundant, semi-papillate, varying in shape from ovoid-ellipsoid to long-ellipsoid, 18-26 × 45-63 μm (average: 22 × 54 μm, n = 30), sporangia released numerous zoospores from the papillate after maturation. The chlamydospores were spherical, 20-35 μm in diameter (average: 27.5 μm, n = 30) (Fig. S2 D~F). These morphological features were like those of the pathogenic species of the oomycetes (Chen et al. 2022). For the molecular characterization, the genomic DNA of the isolate was extracted using the cetyl trimethyl ammonium bromide method, and the translation elongation factor 1α (tef-1α) (Stielow et al. 2015), β-tubulin (β-tub) (Kroon et al. 2004) and internal transcribed spacer (ITS) (White et al. 1990) of isolated strain ARP1 were amplified using primer pairs EF1-1018F/EF1-1620R, TUBUF2/TUBUR1 and ITS1/ITS4, respectively. The tef-1α, β-tub genes and ITS region of ARP1 were directly sequenced and their sequence information was deposited in GenBank under accession numbers OQ506129, OQ506127 and OQ449628. ARP1 was clustered on the same evolutionary branch with Phytophthora palmivora (Fig. S3). To confirm the pathogenicity of ARP1, the main root of A. vera was wounded to 1 cm long and 2 mm deep with a scalpel blade followed by inoculation with 50 ml suspension of ARP1 zoospores at a concentration of 1 × 106 spores / ml per potted plant, and an equal volume of water as control. All inoculated plants were placed in the greenhouse at 28°C, 12 h / 12 h light / dark. After 15 dpi, the inoculated plants showed typical symptoms of wilted and drooping leaves and stem and root rot, same as observed in the field condition (Fig. S4). After inoculation with ARP1, a strain with the same morphological and molecular characteristics as the original isolate was re-isolated, confirming Koch's postulates. To our knowledge, this is the first report of P. palmivora causing root and stem rot of A. vera in the study region. This disease could be a potential risk for aloe production and therefore appropriate management measures should be taken.

First report of Pseudocerradoa paullula causing aroid leaf rust on Swiss cheese plant Monstera deliciosa in South Carolina, USA

In February 2023, two Monstera deliciosa Liebm. (Araceae) plants with typical symptoms of leaf rust disease were detected at a grocery store in Oconee Co., South Carolina. Symptoms included chlorotic leaf spots and abundant brownish uredinia, mainly on the adaxial surface of more than 50% of leaves. The same disease was detected on 11 out of 481 M. deliciosa plants in a greenhouse at a plant nursery located in York Co., South Carolina, in March 2023. The first plant sample detected in February was used for morphological characterization, molecular identification, and pathogenicity confirmation of the rust fungus. Urediniospores were densely aggregated, globose, golden to golden brown in color, and measured 22.9 to 27.9 µm (aver. 26.0 ± 1.1 µm; n=50) in diameter with wall thickness at 1.3 to 2.6 µm (aver. 1.8 ± 0.3 µm; n=50). Telia were not observed. These morphological traits aligned with those of Pseudocerradoa paullula (basionym: Puccinia paullula; Ebinghaus et al. 2022; Sakamoto et al. 2023; Sydow and Sydow 1913; Urbina et al. 2023). Genomic DNA was extracted from urediniospores collected from the naturally infected plant sample and used for PCR amplification and DNA sequencing of the large subunit (LSU) genetic marker with primers LRust1R and LR3 (Vilgalys and Hester 1990; Beenken et al. 2012). The LSU sequence of the rust fungus in South Carolina (GenBank accession: OQ746460) is 99.9% identical to that of Ps. paullula voucher BPI 893085 (763/764 nt.; KY764151), 99.4% identical to that of voucher PIGH 17154 in Florida, USA (760/765 nt.; OQ275201), and 99% identical to that of voucher TNS-F-82075 in Japan (715/722 nt.; OK509071). Based on its morphological and molecular characteristics, the causal agent was identified as Ps. paullula. This pathogen identification was also corroborated by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Plant Pathogen Confirmatory Diagnostics Laboratory in Laurel, Maryland. To confirm the fungus's pathogenicity on M. deliciosa and M. adansonii Schott (Sakamoto et al. 2023), three plants of each Monstera species were inoculated by spraying with a suspension of urediniospores collected from the original plant sample (1 × 106 spores per ml; approx. 40 ml per plant). Three non-inoculated control plants of each host species were treated with deionized water in the same manner. Plants were placed in a plastic tray with wet paper towels to maintain moisture. The tray was placed at 22C for an 8-h photoperiod and covered for five days to facilitate infection. On 25 days after inoculation, abundant spots bearing urediniospores were produced on all leaves of inoculated M. deliciosa plants. A few uredinia were observed on two of the three inoculated M. adansonii plants. All non-inoculated control plants remained asymptomatic. Morphological features of urediniospores collected from inoculated plants matched those of Ps. paullula used as the inoculum. Aroid leaf rust on Monstera plants was officially reported in Australia, China, Japan, Malaysia, Philippines, and Florida, USA (Shaw 1991; Sakamoto et al. 2023; Urbina et al. 2023). This is the first report of Ps. paullula causing this disease on M. deliciosa in South Carolina, USA. Monstera species are popular indoor and landscape plants. Potential impact and regulatory responses regarding Ps. paullula, a newly introduced and rapidly spreading pathogen in the USA, warrant further evaluation and discussion.

First Report of Anthracnose Caused by Colletotrichum siamense on Hydrangea macrophylla in China

Hydrangea macrophylla (Thunb.) Ser. (Hydrangeaceae), a shrubby perennial plant, is widely used as an ornamental flowering plant because of its showy inflorescences and colorful sepals. In October 2022, leaf spot symptom was observed on H. macrophylla in Meiling Scenic Spot, which covers an area of about 143.58 km2 in Nanchang, Jiangxi Province, China (28.78°N, 115.83°E). An investigation was carried out in a 500 m2 mountain area with 60 H. macrophylla plants in a residential garden, the incidence of disease observed was 28~35%. The symptoms were visible as nearly round dark brown spots on the leaves in the early stages of infection. At later stages, the spots gradually developed grayish white center with dark brown margins. To isolate the pathogen, seven leaves randomly selected from 30 infected leaves were cut into 4-mm2 pieces, surface disinfected with 75% ethanol for 30s followed by 5% NaClO for 1 min, rinsed in sterile water three times, placed on potato dextrose agar (PDA), and cultured at 25 °C in the dark for 7 days, and four strains with similar morphological characteristics were obtained from 7 diseased samples. Conidia were aseptate, cylindrical, hyaline, obtuse at both ends, and measured 13.31 to 17.53 × 4.43 to 7.45 µm (15.47 ± 0.83 × 5.91 ± 0.62 µm, n = 60). Morphological characteristics matched Colletotrichum siamense (Weir et al. 2012; Sharma et al. 2013). For molecular identification, two representative isolates (HJAUP CH003 and HJAUP CH004) were used for genomic DNA extraction, and the internal transcribed spacer (ITS), partial sequences of actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB2) and partial calmodulin (CAL) were amplified, using primer pairs ITS4/ITS5 (White et al. 1990), ACT-512F/ACT-783R, GDF1/GDR1, Bt2a/Bt2b and CL1C/CL2C (Weir et al. 2012), respectively. The sequences were deposited in GenBank (accessions nos. ITS: OQ449415, OQ449416; ACT: OQ455197, OQ455198; GAPDH: OQ455203, OQ455204; TUB2: OQ455199, OQ455200; CAL: OQ455201, OQ455202). Concatenated sequences of the five genes were used to conduct phylogenetic analyses using the maximum-likelihood method in MEGA7.0 (Sudhir et al. 2016) and Bayesian inference analysis in MrBayes 3.2 (Ronquist et al. 2012). Our two isolates cluster together with four strains of C. siamense with 93%ML/1.00BI bootstrap support. The isolates were identified as C. siamense based on the morpho-molecular approach. Pathogenicity of HJAUP CH003 was tested indoors by inoculating detached wounded leaves of six healthy H. macrophylla plants. Three healthy plants with three leaves were punctured with flamed needles and sprayed with a 1 × 106 spores/ml spores suspension, and another three healthy plants were wounded inoculated with mycelial plugs (5 × 5 mm3). Mock inoculations were used as controls with sterile water and PDA plugs on three leaves each. Treated plant tissue were incubated in an artificial climate box at 25°C, 90% relative humidity and a photoperiod of 12 h. After 4 days, symptoms similar to those of natural infection were observed on all wounded inoculated leaves, while no symptoms appeared on mock-inoculated leaves. The fungus isolated from inoculated leaves was identical to the original pathogen based on morphological and molecular data, confirming Koch's hypothesis. It has been reported that C. siamense can cause anthracnose on numerous plants (Rong et al. 2021; Tang et al. 2021; Farr and Rossman 2023). This is the first report of C. siamense causing anthracnose on H. macrophylla in China. The disease is of major concern to the horticultural community as it seriously affects the aesthetic value of ornamentals.

First report of Fusarium equiseti causing bulb rot on lily (Lilium 'White planet' ) in China

Lily (Lilium spp.) is one of the main ornamental plants grown in the world. In addition, bulbs of lily have been extensively used as edible and medicinal herbs in northern and eastern Asia, especially in China (Yu et al. 2015; China Pharmacopoeia Committee 2020; Tang et al. 2021). In August of 2021, a disease of stem and leaf rot was observed on lily cultivar 'White planet' with approximately 25% disease incidence in the greenhouse and fields at the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences (Beijing, China). The bulbs of symptomatic plants were brown and rotten, with sunken lesions. Symptomatic plants showed short, discolored leaves, and eventually lead to stem wilt and death of the whole plants. Infected bulbs were surface sterilized in 75% ethanol for 30 s, then in 2% sodium hypochlorite for 5 min, and rinsed three times with sterile distilled water. A 0.5×0.5 cm2 tissue piece was then placed on potato dextrose agar (PDA) medium and incubated at 25±1℃. After 5 days, the isolate was purified by single spore isolation technique. The singled-spored fungal colony was characterized by fluffy white aerial mycelia, and produced orange pigments with age. After seven days on Spezieller Nahrstoffarmer agar (SNA), conidia produced from simple lateral phialides. Macroconidia have pronounced dorsiventral curvature typical, significantly enlarged in the middle, a tapered whip-liked pointed apical cell and characteristic foot-shaped basal cell, 3 to 6 septate, measuring 18.71 to 43.01×2.89 to 5.56 μm with an average size of 26.98×3.90 μm (n=30). Microconidia were not observed. Typical verrucose thick chlamydospore with rough walls were profuse in chains or clumps, ellipsoidal to subglobose. These morphological characteristics were consistent with Fusarium spp. (Leslie et al. 2006). For molecular identification, the internal transcribed spacer (ITS), translation elongation factor subunit 1-alpha (TEF1-α) and RNA polymeraseⅡsubunit 2 (RPB2) genes were amplified using primers ITS1/ITS4, EF1/EF2 and 5F2/7cR respectively and sequenced (White et al. 1990; Jiang et al. 2018; O'Donnell et al. 2007). Sequences were submitted to GenBank under accession numbers OM078499 (ITS), Accession OM638086 (TEF1-α) and OM638085 (RPB2). BLAST analysis showed that ITS, TEF1-α and RPB2 sequences shared 100%, 99.8%, 99.2% identity to F. equiseti (OM956073, KY081599, MW364892) in GenBank, respectively. In addition, ITS, TEF1-α and RPB2 sequences shared 100%, 99.53%, 100% identity with Fusarium lacertarum (LC7927, Fusarium incarnatum-equiseti species complex) in the Fusarium-ID database. Based on the morphological characteristics and molecular sequences, the isolates were identified as Fusarium equiseti. A pathogenicity test was performed on potted lily ('White planet') under greenhouse conditions (25±1℃ with a 16 h light and 8 h dark cycle). Three healthy lily bulbs were selected and one bulb was planted in each pot filled with sterilized soil. Each pot was inoculated with 5 mL of conidia suspension (1×107 conidia/mL) in te soil around bulbs with a stem length of 3 cm, with an equal amount of sterilized water as a control. This test had three replicates. After 15 days of inoculation, typical symptoms of bulb rotten, like those observed in the greenhouse and fields, developed on the inoculated plants but not on the controls. The same fungus was consistently reisolated from the diseased plants. To our knowledge, this is the first report that F. equiseti caused bulb rot on Lilium in China. Our result should help with future monitoring and control of lily wilt disease.

First Report of Powdery Mildew Caused by Golovinomyces bolayi on Veronica persica in Central China

Veronica persica, Persian speedwell, is a flowering plant belonging to the family Plantaginaceae. Due to its showy flowers, this plant is widely planted in many home gardens, city parks and universities in China. From April to June 2021, signs and symptoms of powdery mildew were found on leaves of V. persica growing on the campus of Henan Normal University, Henan Province, China. Signs initially appeared as thin white colonies and subsequently white powdery masses were abundant on the adaxial and abaxial surfaces of leaves and covered up to 99 % of the leaf area. The infected leaves showed chlorotic, deformed or senescence features. About 150 V. persica plants were monitored and more than 90 % of the plants showed these signs and symptoms. Conidiophores (n = 20) were 108 to 220 × 10 to 13 μm and composed of foot cells, followed by short cells and conidia. Conidia were hyaline, doliiform-subcylindrical shaped, 21 to 37 × 15 to 22 μm, and showed distinct fibrosin bodies. Conidial germ tubes were produced at the perihilar position. No chasmothecia were observed. The observed morphological characteristics were consistent with those of previously documented Golovinomyces bolayi (Braun and Cook 2012). To further confirm the powdery mildew fungus, structures of the pathogen were harvested and total genomic DNA was isolated using the method previously described by Zhu et al. (2019, 2021). Using the primers ITS1/ITS4, the internal transcribed spacer (ITS) region of rDNA was amplified (White et al. 1990) and the amplicon was sequenced. The resulting sequence was deposited into GenBank under Accession No. MZ343575 and was 100 % identical (592/592 bp) to G. bolayi on Kalanchoe blossfeldiana (LC417096) (Braun et al. 2019). The additional phylogenetic analysis clearly illustrated that the identified fungus and G. bolayi were clustered in the same branch (Zhu et al. 2022a; Zhu et al. 2022b). To test pathogenicity, healthy V. persica plants were collected from the campus of Henan Normal University and leaf surfaces of three plants were inoculated by dusting fungal conidia from mildew-infested leaves using pressurized air. Three plants without inoculation served as a control. The spore-treated and non-treated plants were separately placed in two growth chambers (temperature, 18℃; humidity, 60%; light/dark, 16h/8h). Seven- to eight-days post-inoculation, pathogen signs were noticeable on inoculated plants, whereas control plants remained healthy. Similar results were obtained by conducting the pathogenicity assays twice. Therefore, based on the analysis, G. bolayi was identified and confirmed as the causal agent of the powdery mildew. This pathogen has been reported on V. persica in Iran (Golmohammadi et al. 2019). However, to our best knowledge, there is no report concerning the powdery mildew caused by G. bolayi on V. persica in China. Recently, G. bolayi was segregated from species clades of G. orontii complex (Braun et al. 2019). Our record of the molecular characterization of G. bolayi will support the further phylogeny and taxonomy analysis of the G. orontii complex. The sudden outbreak of powdery mildew caused by G. bolayi on V. persica may detract from plant health and ornamental value. The identification and confirmation of this disease expands the understanding of this causal agent and will offer support for future powdery mildew control.