Fungal species associated with grapevine trunk diseases in Washington wine grapes and California table grapes, with novelties in the genera Cadophora, Cytospora, and Sporocadus

Kalmusia variispora (Didymosphaeriaceae, Dothideomycetes) Associated with the Grapevine Trunk Disease Complex in Cyprus

Grapevine trunk diseases (GTDs) are widespread worldwide, causing serious economic losses to the vitiviniculture industry. The etiology of the complex pathogenic mycobiome associated with this group of diseases is critical to implementing appropriate management strategies. Diseased grapevines exhibiting typical GTD symptoms were collected from vineyards in different provinces of Cyprus, resulting in 19 pycnidial isolates. A subsequent multilocus sequence analysis of six genetic loci (ITS, LSU, SSU, b-tub, tef1-a, and rpb2) identified them as Kalmusia variispora, and twelve representative isolates are included in the phylogenetic analyses. According to pathogenicity trials on two-year-old potted vines (cv. Mavro), all tested isolates were pathogenic, exhibiting light to dark brown discoloration and lesions of varying levels, ranging from 4 to 12.3 cm long. The capacity of K. variispora isolates to produce cell-wall-degrading exoenzymes was qualitatively estimated on solid media. Cellulase, pectinase, and laccase production were evident for all the tested isolates, except isolate CBS 151329, where the latter enzyme was undetected. The severity of the symptoms was consistent with the laccase-producing capacity. The present study confirmed the association of K. variispora with grapevines as a pathogen and represents the first description of this ascomycete as a GTD causal agent in Cyprus. This highly virulent species may play a significant role in the GTD complex, and its biological cycle and epidemiology should be further investigated.

Fatty acid methyl ester (FAME) profiling for species-specific characterization and detection of fungal pathogens that cause tree and grapevine trunk diseases

Fungal trunk diseases are of major concern for tree fruit, nut, and grape growers throughout the world. These diseases include Eutypa dieback of grape, caused by Eutypa lata, band canker of almond, caused by Neofusicoccum mediterraneum and Neofusicoccum parvum, and twig and branch dieback of walnut, caused by N. mediterraneum, Botryosphaeria dieback of grape, caused by Diplodia mutila, Diplodia seriata, N. mediterraneum, and N. parvum, and esca of grape, caused by Phaeomoniella chlamydospora and Phaeoacremonium minimum. Given the common occurrence of mixed infections, and the similar wood symptoms at the macroscopic level, species-specific detection tools are needed. Fatty acid methyl ester (FAME) profiling can be an effective and inexpensive diagnostic tool. FAME analyses were conducted on pure cultures of multiple isolates per species to characterize profiles and assess whether this technique could result in consistent identification. FAME profiles were dominated by oleic acid (18:1 ω9c) and palmitic acid (16:0), with less abundant FAMEs in different ratios for each species and isolates within species. Canonical discriminant analyses revealed which minor FAMEs were most variable, with a total of 20 different FAMEs that can explain 69.01% of profile variance in the first two canonicals. Using these analyses, samples were self-tested and correctly sorted 97.18% of the time. Within species, canonical discriminant analyses were able to separate isolates further, often by original geographic location or by host plant species. These results further suggest that potential novel species, subspecies, or races may be present among the isolates analyzed, demonstrating the capacity of FAME profiling to have a role in discovering cryptic species and accurately identifying fungal pathogens in conjunction with other molecular techniques and genomic analyses.

Sporocadaceae revisited

Sporocadaceae is a species-rich and cosmopolitan fungal family including species of plant pathogens, endophytes or saprobes, and parasites of humans and animals. The taxonomy of Sporocadaceae has recently been revised using a polyphasic approach. However, much remains unknown about the diversity of species and their host associations. A collection of 488 strains, mostly from China and associated with 129 host plant species, was studied based on morphological comparisons and multi-locus (LSU, ITS, tef-1α, tub2, and rpb2) phylogenies. Our results revealed that they belonged to 86 species, one new genus (Cavernicola gen. nov.) and seven known genera, including Discosia, Monochaetia, Neopestalotiopsis, Pestalotiopsis, Seimatosporium, Seiridium and Sporocadus. Of these, 43 new species and three new combinations (Dis. kaki, Mon. bulbophylli, and Neo. keteleeriae) are proposed in this paper. In addition, Neo. vaccinii, Pes. kaki and Pes. nanjingensis are synonymised under Neo. hispanica, Pes. menhaiensis and Pes. sichuanensis, respectively. We also corrected seven problematic sequences of type materials of previously published species, namely Neo. iranensis (tef-1α, ITS, tub2), Pes. jesteri (tef-1α), Pes. photinicola (ITS, tub2) and Pes. yunnanensis (ITS). Based on this study, Pestalotiopsis and Neopestalotiopsis are the most commonly detected genera within the Sporocadaceae family, associated with 84 and 70 plant species, respectively. Furthermore, considering the importance of Sporocadaceae and the fact that commonly used loci provide little valid information for species delimitation in this family, especially for Neopestalotiopsis and Pestalotiopsis, we initiated a phylogenomic project in this study. It will not only contribute to the knowledge of species boundaries but will also provide an important basis for evolutionary studies and research on secondary metabolites in Sporocadaceae. Taxonomic novelties: New genus: Cavernicola P. Razaghi, F. Liu & L. Cai. New species: Cavernicola guangxiensis P. Razaghi, F. Liu & L. Cai, Discosia ascidiata P. Razaghi, F. Liu & L. Cai, Discosia jiangxiensis P. Razaghi, F. Liu & L. Cai, Discosia navicularis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis ageratinae P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis castanopsidis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis celtidis P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis collariata P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis dimorphospora P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis dolichoconidiophora P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis fijiensis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis fimbriata P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis fuzhouensis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis guangxiensis P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis guizhouensis P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis jiangxiensis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis liquidambaris P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis machili P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis megabetaspora P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis moniliformis P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis nanningensis P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis phyllostachydis P. Razaghi, F. Liu, M. Raza & L. Cai, Neopestalotiopsis poae P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis smilacis P. Razaghi, F. Liu, M. Raza & L. Cai, Pestalotiopsis alloschemones P. Razaghi, F. Liu & L. Cai, Pestalotiopsis americana P. Razaghi, F. Liu & L. Cai, Pestalotiopsis biappendiculata P. Razaghi, F. Liu & L. Cai, Pestalotiopsis cratoxyli P. Razaghi, F. Liu, M. Raza & L. Cai, Pestalotiopsis exudata P. Razaghi, F. Liu & L. Cai, Pestalotiopsis fusiformis P. Razaghi, F. Liu & L. Cai, Pestalotiopsis ganzhouensis P. Razaghi, F. Liu & L. Cai, Pestalotiopsis leucospermi P. Razaghi, F. Liu & L. Cai, Pestalotiopsis lobata P. Razaghi, F. Liu & L. Cai, Pestalotiopsis machili P. Razaghi, F. Liu & L. Cai, Pestalotiopsis multiappendiculata P. Razaghi, F. Liu & L. Cai, Pestalotiopsis pruni P. Razaghi, F. Liu & L. Cai, Pestalotiopsis rubrae P. Razaghi, F. Liu, M. Raza & L. Cai, Pestalotiopsis wulichongensis P. Razaghi, F. Liu, M. Raza & L. Cai, Seimatosporium tibetense P. Razaghi, F. Liu & L. Cai, Seiridium rhododendri P. Razaghi, F. Liu & L. Cai, Sporocadus cavernicola P. Razaghi, F. Liu & L. Cai, Sporocadus hyperici P. Razaghi, F. Liu & L. Cai, Sporocadus tibetensis P. Razaghi, F. Liu & L. Cai. New combinations: Discosia kaki (Kaz. Tanaka et al.) P. Razaghi, F. Liu & L. Cai, Monochaetia bulbophylli (S.F. Ran & Yong Wang bis) P. Razaghi, F. Liu & L. Cai, Neopestalotiopsis keteleeriae (Y. Song et al.) P. Razaghi, F. Liu & L. Cai. Citation: Razaghi P, Raza M, Han SL, Ma ZY, Cai L, Zhao P, Chen Q, Phurbu D, Liu F (2024). Sporocadaceae revisited. Studies in Mycology 109: 155-272. doi: 10.3114/sim.2024.109.03.

Cytospora: an important genus of canker pathogens

Cytospora species have commonly been reported as important plant pathogenic fungi with wide host ranges and geographic distributions. With the increase in the number of cryptic species being described, a comprehensive global taxonomic revision of the genus Cytospora is required. The present study includes 399 isolates from 32 countries. These isolates were subjected to DNA sequence analysis for five genomic loci (ITS, act1, rpb2, tef1-α and tub2). Based on these data, it could be confirmed that Cytospora, Leucostoma, Valsa, Valsella and Valseutypella are congeneric. Furthermore, 111 species of Cytospora could also be reassessed, 44 species and four combinations newly introduced, and new typifications proposed for a further three species. Three asexual morphological groups (including 13 asexual morphological types) and three sexual morphological groups (including eight sexual morphological types) were designated. The present study explored the species diversity of Cytospora and re-evaluated the identity of all cultures in the Westerdijk Fungal Biodiversity Institute (Utrecht, The Netherlands) that were deposited as either Cytospora or as one of its related genera. This is the most comprehensive phylogenetic analysis thus far conducted on Cytospora and the results contribute to an increased understanding of the taxonomy of these important fungi. It is also hoped that the findings will lead to improved management strategies for diseases associated Cytospora species. Taxonomic novelties: New species: Cytospora acericola X.L. Fan & C.M. Tian, C. adamsii Jami, Crous & M.J. Wingf., C. beijingensis L. Lin & X.L. Fan, C. betulae Jami, Crous & M.J. Wingf., C. brabeji Jami, Crous & M.J. Wingf., C. castaneicola L. Lin & X.L. Fan, C. cerebriformis L. Lin & X.L. Fan, C. conceptaculata L. Lin & X.L. Fan, C. crataegina X.L. Fan & C.M. Tian, C. deqinensis L. Lin & X.L. Fan, C. diqingensis L. Lin & X.L. Fan, C. eastringensis L. Lin & X.L. Fan, C. elaeagnina L. Lin & X.L. Fan, C. fraxinea X.L. Fan & C.M. Tian, C. guyuanensis L. Lin & X.L. Fan, C. jiufengensis L. Lin & X.L. Fan, C. lauricola L. Lin & X.L. Fan, C. lhasaensis L. Lin & X.L. Fan, C. lijiangensis L. Lin & X.L. Fan, C. lvxinensis L. Lin & X.L. Fan, C. malvicolor X.L. Fan & C.M. Tian, C. multiseriata L. Lin & X.L. Fan, C. nanyangensis X.L. Fan & C.M. Tian, C. polyspora X.L. Fan & C.M. Tian, C. pseudochrysosperma L. Lin & X.L. Fan, C. qinghaiensis L. Lin & X.L. Fan, C. qingshuiensis L. Lin & X.L. Fan, C. sanbaensis L. Lin & X.L. Fan, C. shaanxiensis L. Lin & X.L. Fan, C. shangrilaensis L. Lin & X.L. Fan, C. sidaohensis L. Lin & X.L. Fan, C. sinensis L. Lin & X.L. Fan, C. songshanensis L. Lin & X.L. Fan, C. suecica Jami, Crous & M.J. Wingf., C. syringina L. Lin & X.L. Fan, C. tenebrica L. Lin & X.L. Fan, C. tetraspora L. Lin & X.L. Fan, C. tongzhouensis X.L. Fan & C.M. Tian, C. uniloculata L. Lin & X.L. Fan, C. washingtonensis Jami, Crous & M.J. Wingf., C. xiaolongmenensis L. Lin & X.L. Fan, C. yinchuanensis L. Lin & X.L. Fan, C. yuduensis L. Lin & X.L. Fan, C. yulinensis L. Lin & X.L. Fan. New combinations: Cytospora auerswaldii (Nitschke) L. Lin & X.L. Fan, C. multicollis (Checa et al.) L. Lin, X.L. Fan & Crous, C. tristicha (De Not.) L. Lin, X.L. Fan & Crous, C. weiriana (Petr.) X.L. Fan & Crous. New replacement names: Cytospora desmazieri L. Lin, X.L. Fan & Crous, C. fuckeliana L. Lin, X.L. Fan & Crous, C. hoffmannii L. Lin, X.L. Fan & Crous, C. massarii L. Lin, X.L. Fan & Crous, C. nitschkeana L. Lin, X.L. Fan & Crous, C. saccardoi L. Lin, X.L. Fan & Crous. New synonyms: Cytospora ampulliformis Norph., Bulgakov, T.C. Wen & K.D. Hyde, C. brevispora (G.C. Adams & Jol. Roux) G.C. Adams & Rossman, C. cenisia Sacc., C. ceratospermopsis C.M. Tian & X.L. Fan, C. cotini Norph., Bulgakov & K.D. Hyde, C. ershadii Zafari & Hanifeh, C. erumpens Norph., Bulgakov, T.C. Wen & K.D. Hyde, C. fraxinigena Senan., Camporesi & K.D. Hyde, C. galegicola Q.J. Shang, E. Camporesi & K.D. Hyde, C. granati D.P. Lawr., L.A. Holland & Trouillas, C. hippophaicola Spetik, Eichmeier, Gramaje, Stuskova & Berraf-Tebbal, C. massariana Sacc., C. nivea (Hoffm.) Sacc., C. parakantschavelii Norph., Bulgakov, T.C. Wen & K.D. Hyde, C. parasitica Norph., Bulgakov & K.D. Hyde, C. paratranslucens Norph., Bulgakov, T.C. Wen & K.D. Hyde, C. pini Desm., C. populicola D.P. Lawr., L.A. Holland & Trouillas, C. predappioensis Q.J. Shang, Norph., Camporesi & K.D. Hyde, C. quercicola Senan., Camporesi & K.D. Hyde, C. rosae Senan., Camporesi & K.D. Hyde, C. salicella Sacc., C. vinacea D.P. Lawr., Travadon & Pouzoulet, Valsa germanica Nitschke, V. massariana De Not., V. nivea (Hoffm.) Fr., Valsella salicis Fuckel, Sphaeria nivea Hoffm. Typification: Lecto- and epitypifications (basionyms): Sphaeria chrysosperma Pers., Valsa eucalypti Cooke & Harkn., Valsella salicis Fuckel. Citation: Lin L, Fan XL, Groenewald JZ, Jami F, Wingfield MJ, Voglmayr H, Jaklitsch W, Castlebury LA, Tian CM, Crous PW (2024). Cytospora: an important genus of canker pathogens. Studies in Mycology 109: 323-401. doi: 10.3114/sim.2024.109.05.

Evaluating Treatments for the Protection of Grapevine Pruning Wounds from Natural Infection by Trunk Disease Fungi

Infection of grapevines by fungal pathogens causing grapevine trunk diseases (GTDs) primarily arises from annual pruning wounds made during the dormant season. While various studies have showcased the efficacy of products in shielding pruning wounds against GTD infections, most of these investigations hinge on artificial pathogen inoculations, which may not faithfully mirror real field conditions. This study aimed to evaluate and compare the efficacy of various liquid formulation fungicides (pyraclostrobin + boscalid) and paste treatments, as well as biological control agents (BCA: Trichoderma atroviride SC1, T. atroviride I-1237, and T. asperellum ICC012 + T. gamsii ICC080), for their potential to prevent natural infection of grapevine pruning wounds by trunk disease fungi in two field trials located in Samaniego (Northern Spain) and Madiran (Southern France) over three growing seasons. Wound treatments were applied immediately after pruning in February. One year after pruning, canes were harvested from vines and brought to the laboratory for assessment of Trichoderma spp. and fungal trunk pathogens. More than 1,200 fungal isolates associated with five GTDs (esca, Botryosphaeria, Diaporthe and Eutypa diebacks, and Cytospora canker) were collected from the two vineyards each growing season. Our findings reveal that none of the products under investigation exhibited complete effectiveness against all the GTDs. The efficacy of these products was particularly influenced by the specific year of study. A notable exception was observed with the biocontrol agent T. atroviride I-1237, which consistently demonstrated effectiveness against Botryosphaeria dieback infections throughout each year of the study, irrespective of the location. The remaining products exhibited efficacy in specific years or locations against particular diseases, with the physical barrier (paste) showing the least overall effectiveness. The recovery rates of Trichoderma spp. in treated plants were highly variable, ranging from 17 to 100%, with both strains of T. atroviride yielding the highest isolation rates. This study underscores the importance of customizing treatments for specific diseases, taking into account the influence of environmental factors for BCA applications.

Lectotypification, epitypification, and molecular phylogenetic confirmation of Cytospora paulowniae comb. nov., a causal pathogen of Paulownia tree canker in Japan

Paulownia tree canker is a major disease of Paulowniae tomentosa in Japan. The pathogen was described as Valsa paulowniae in 1916 by Hemmi and Miyabe. However, its current taxonomic status and phylogenetic position are uncertain. In this study, we reviewed the protologue of this species and rediscovered the syntypes maintained at the Hokkaido University Museum (SAPA). From these specimens, a lectotype was selected. The molecular phylogenetic position of this species was examined with newly collected samples. Based on the result of phylogeny and morphology, an epitype of this species was designated and transferred to the genus Cytospora.

Morphology and phylogeny of Cytospora (Cytosporaceae, Diaporthales) species associated with plant cankers in Tibet, China

During our biodiversity investigations in Tibet, China, typical Cytospora canker symptoms were observed on branches of hosts Myricariapaniculate, Prunuscerasifera and Sibiraeaangustata. Samples were studied, based on morphological features coupled with multigene phylogenetic analyses of ITS, act, rpb2, tef1 and tub2 sequence data, which revealed two new species (Cytosporamyricicolasp. nov. and C.sibiraeicolasp. nov.) and a known species (C.populina). In addition, Cytosporapopulina is newly discovered on the host Prunuscerasifera and in Tibet.

Effects of Temperature on Spore Germination and Mycelial Growth of Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata Isolates Associated with Sweet Cherry Canker Diseases

Although fungal canker diseases constitute a limiting factor to orchard productivity and longevity, little is known about the effects of temperature on spore germination and mycelial growth of the fungal causal agents. Accordingly, the germination of spores and colony growth of Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata were evaluated after incubation on 2% water agar and 4% potato dextrose agar, respectively, at 5, 10, 15, 20, 25, 30, 35, and 40°C. Temperature optima for spore germination and mycelial growth were derived from nonlinear models fitted to germination rates and colony diameter data. The optimal temperatures for spore germination of Cal. pulchella were 28.5°C for ascospores and 29.2°C for conidia. The optimal temperatures for Cyt. sorbicola conidia and E. lata ascospore germination were 25.8 and 23.1°C, respectively. The germination of ascospores and conidia of Cal. pulchella at temperatures below 15°C required an incubation time of at least 72 h. Ascospores of E. lata and conidia of Cyt. sorbicola germinated at 10°C after 36 h. The optimal temperature for colony growth of Cal. pulchella was 24.6°C, whereas it was 21.7°C for both Cyt. sorbicola and E. lata. Our study indicates that temperature requirements for basic biological functions are higher for Cal. pulchella than for Cyt. sorbicola and E. lata. The overall higher temperatures of California relative to other cherry-producing regions in the United States or worldwide could explain the prevalence of Calosphaeria canker in the state. Conversely, Cyt. sorbicola and E. lata appear better adapted to cooler temperatures.