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Komondy L, Hoepting C, Fuchs M, Pethybridge SJ, Nault BA. Identifying Onion Fields at Risk of Iris Yellow Spot Virus in New York. PLANT DISEASE 2024; 108:1750-1754. [PMID: 38213120 DOI: 10.1094/pdis-10-23-2097-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Iris yellow spot virus (IYSV) poses a significant threat to dry bulb onion, Allium cepa L., production and can lead to substantial yield reductions. IYSV is transmitted by onion thrips, Thrips tabaci (Lindeman), but not via seed. Transplanted onion fields have been major early season sources of IYSV epidemics. As onion thrips tend to disperse short distances, seeded onion fields bordering transplanted onion fields may be at greater risk of IYSV infection than seeded fields isolated from transplanted ones. Additionally, seeded onion fields planted early may be at greater risk of IYSV infection than those seeded later. In a 2-year study in New York, we compared IYSV incidence and onion thrips populations in seeded onion fields relative to their proximity to transplanted onion fields. In a second study, we compared IYSV incidence in onion fields with either small or large plants during midseason. Results showed similar IYSV incidence and onion thrips populations in seeded onion fields regardless of their proximity to transplanted onion fields, while IYSV incidence was over four times greater in large onion plants than in small ones during midseason. These findings suggest a greater risk of onion thrips-mediated IYSV infection in onion fields with large plants compared with small ones during midseason and that proximity of seeded fields to transplanted ones is a poor indicator of IYSV risk. Our findings on IYSV spread dynamics provided valuable insights for developing integrated pest and disease management strategies for New York onion growers.
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Affiliation(s)
- Lidia Komondy
- Department of Entomology, Cornell University, Cornell AgriTech, Geneva, NY 14456
| | - Christy Hoepting
- Cornell Cooperative Extension Regional Vegetable Program, Cornell Cooperative Extension, Albion, NY 14411
| | - Marc Fuchs
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY 14456
| | - Sarah J Pethybridge
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY 14456
| | - Brian A Nault
- Department of Entomology, Cornell University, Cornell AgriTech, Geneva, NY 14456
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Komondy L, Hoepting C, Fuchs M, Pethybridge SJ, Nault BA. Spatiotemporal Patterns of Iris Yellow Spot Virus and Its Onion Thrips Vector, Thrips tabaci, in Transplanted and Seeded Onion Fields in New York. PLANT DISEASE 2024; 108:398-406. [PMID: 37622276 DOI: 10.1094/pdis-05-23-0930-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Onion thrips, Thrips tabaci (Lindeman), transmits iris yellow spot virus (IYSV) and is one of the most important pests of Allium crops. IYSV is a member of the species Tospovirus iridimaculaflavi in the genus Orthotospovirus of the family Tospoviridae. This virus typically reduces overall onion bulb quality and weight but can also prematurely kill onion plants. IYSV is neither seed nor mechanically transmitted. Onion fields are typically established via seeds and transplants. A decade ago, onion thrips tended to colonize transplanted fields before seeded fields because plants in transplanted fields were larger and more attractive to thrips than smaller onions in seeded fields. Therefore, we hypothesized that the incidence of IYSV in transplanted fields would be detected early in the season and be spatially aggregated, whereas IYSV would be absent from seeded fields early in the season and initial epidemic patterns would be spatially random. In 2021 and 2022, IYSV incidence and onion thrips populations were quantified in 12 onion fields (four transplanted fields and eight seeded fields) in New York. Fields were scouted four times throughout the growing season (n = 96 samples), and a geospatial and temporal analysis of aggregation and incidence was conducted to determine spatiotemporal patterns in each field type. Results indicated that spatial patterns of IYSV incidence and onion thrips populations were similar early in the season, indicating that transplanted onion fields are no longer the dominant early-season source of IYSV in New York. These findings suggest the need to identify other important early-season sources of IYSV that impact New York onion fields.
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Affiliation(s)
- Lidia Komondy
- Department of Entomology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Christy Hoepting
- Cornell Regional Vegetable Program, Cornell Cooperative Extension, Albion, NY 14411
| | - Marc Fuchs
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Sarah J Pethybridge
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Brian A Nault
- Department of Entomology, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Tayal M, Wilson C, Cieniewicz E. Bees and thrips carry virus-positive pollen in peach orchards in South Carolina, United States. JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:1091-1101. [PMID: 37402628 DOI: 10.1093/jee/toad125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/01/2023] [Accepted: 06/20/2023] [Indexed: 07/06/2023]
Abstract
Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne viruses of important stone fruit crops, including peaches, which can cause substantial yield loss. Although both horizontal and vertical (i.e., seed) transmission of both viruses occurs through pollen, the role of flower-visiting insects in their transmission is not well understood. Bees and thrips reportedly spread PNRSV and PDV in orchards and greenhouse studies; however, the field spread of PNRSV and PDV in peach orchards in the southeastern United States is not explored. We hypothesized that bees and thrips may facilitate virus spread by carrying virus-positive pollen. Our 2-yr survey results show that 75% of captured bees are carrying virus-positive pollen and moving across the orchard while a subsample of thrips were also found virus positive. Based on morphology, Bombus, Apis, Andrena, Eucera, and Habropoda are the predominant bee genera that were captured in peach orchards. Understanding the role of bees and thrips in the spread of PNRSV and PDV will enhance our understanding of pollen-borne virus ecology.
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Affiliation(s)
- Mandeep Tayal
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA
| | - Christopher Wilson
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA
| | - Elizabeth Cieniewicz
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA
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Hay F, Heck DW, Klein A, Sharma S, Hoepting C, Pethybridge SJ. Spatiotemporal Dynamics of Stemphylium Leaf Blight and Potential Inoculum Sources in New York Onion Fields. PLANT DISEASE 2022; 106:1381-1391. [PMID: 34798786 DOI: 10.1094/pdis-07-21-1587-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Stemphylium leaf blight (SLB) caused by Stemphylium vesicarium is the dominant foliar disease affecting large-scale onion production in New York. The disease is managed by fungicides, but control failures are prevalent and are attributed to fungicide resistance. Little is known of the relative role of inoculum sources in initiation and spread of SLB epidemics. Plate testing of 28 commercially available organic onion seedlots from 2016 and 2017 did not detect S. vesicarium. This finding suggests that although S. vesicarium has been reported as seed-transmitted, this is unlikely to be a significant inoculum source in commercially available organic seed lots and even less so in fungicide-treated seed used to establish conventional fields. The spatial and spatiotemporal dynamics of SLB epidemics in six onion fields were evaluated along linear transects in 2017 and 2018. Average SLB incidence increased from 0 to 100% throughout the cropping seasons with an average final lesion length of 28.3 cm. Disease progress was typical of a polycyclic epidemic and the logistic model provided the best fit to 83.3% of the datasets. Spatial patterns were better described by the beta-binomial than binomial distribution in half of the datasets (50%) and random patterns were more frequently observed by the index of dispersion (59%). Geostatistical analyses also found a low frequency of datasets with aggregation (60%). Spatiotemporal analysis of epidemics detected that the aggregation was influenced by disease incidence. However, diseased units were not frequently associated with the previous time period according to the spatiotemporal association function of spatial analyses by distance indices. Variable spatial patterns suggested mixed inoculum sources dependent upon location, and likely an external inoculum source at the sampling scale used in this study. A small-plot replicated trial was also conducted in each of 2 years to quantify the effect of S. vesicarium-infested onion residue on SLB epidemics in a field isolated from other onion fields. SLB incidence was significantly reduced in plots without residue compared with those in which residue remained on the soil surface. Burial of infested residue also significantly reduced epidemic progress in 1 year. The effect of infested onion residue on SLB epidemics in the subsequent onion crop suggests rotation or residue management may have a substantial effect on epidemics. However, the presence of an inoculum source external to fields in onion production regions, as indicated by a lack of spatial aggregation, may reduce the efficacy of in-field management techniques.
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Affiliation(s)
- Frank Hay
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Daniel W Heck
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Audrey Klein
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Sandeep Sharma
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Christy Hoepting
- Cornell Vegetable Program, Cornell Cooperative Extension, Albion, NY 14424
| | - Sarah J Pethybridge
- Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Hay F, Stricker S, Gossen BD, McDonald MR, Heck D, Hoepting C, Sharma S, Pethybridge S. Stemphylium Leaf Blight: A Re-Emerging Threat to Onion Production in Eastern North America. PLANT DISEASE 2021; 105:3780-3794. [PMID: 34546780 DOI: 10.1094/pdis-05-21-0903-fe] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Stemphylium leaf blight (SLB), caused by Stemphylium vesicarium, is a foliar disease of onion worldwide, and has recently become an important disease in the northeastern United States and Ontario, Canada. The symptoms begin as small, tan to brown lesions on the leaves that can progress to defoliate plants. Crop loss occurs through reduced photosynthetic area, resulting in smaller, lower-quality bulbs. Leaf necrosis caused by SLB also can compromise bulb storage, as green leaves are required for the uptake of sprout inhibitors applied prior to harvest. The pathogen can overwinter on infested onion residue and infected volunteer plants. Asymptomatic weedy hosts near onion fields may also be a source of inoculum. Production of ascospores of the teleomorph (Pleospora allii) peaks in early spring in northeastern North America, often before the crop is planted, and declines rapidly as daily mean air temperatures rise. Conidia are usually present throughout the growing season. Application of fungicides is a standard practice for management of the complex of fungi that can cause foliar diseases of onion in this region. Recent assessments have shown that populations of S. vesicarium in New York and Ontario are resistant to at least three single-site mode-of-action fungicides. Three disease prediction systems have been developed and evaluated that may enable growers to reduce the frequency and/or number of fungicide applications, but the loss of efficacious fungicides due to resistance development within S. vesicarium populations threatens sustainability. The lack of commercially acceptable onion cultivars with sufficient resistance to reduce the number of fungicides for SLB also limits the ability to manage SLB effectively. Integrated disease management strategies for SLB are essential to maintain profitable, sustainable onion production across eastern North America.
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Affiliation(s)
- Frank Hay
- Cornell AgriTech, Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
| | - Sara Stricker
- Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Bruce D Gossen
- Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2, Canada
| | - Mary Ruth McDonald
- Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Daniel Heck
- Cornell AgriTech, Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
| | - Christy Hoepting
- Cornell Cooperative Extension, Cornell Vegetable Program, Albion, NY 14411, U.S.A
| | - Sandeep Sharma
- Cornell AgriTech, Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
| | - Sarah Pethybridge
- Cornell AgriTech, Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Geneva, NY 14456, U.S.A
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Leach A, Fuchs M, Harding R, Nault BA. Iris Yellow Spot Virus Prolongs the Adult Lifespan of Its Primary Vector, Onion Thrips (Thrips tabaci) (Thysanoptera: Thripidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2019; 19:5492632. [PMID: 31127944 PMCID: PMC6534963 DOI: 10.1093/jisesa/iez041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Indexed: 05/20/2023]
Abstract
Iris yellow spot virus (IYSV) from the genus Tospovirus, family Peribunyaviridae, reduces yield in several crops, especially Allium spp. IYSV is primarily transmitted by onion thrips (Thrips tabaci), but little is known about how IYSV impacts the biology of its principal vector. In a controlled experiment, the effect of IYSV on the lifespan and fecundity of onion thrips was examined. Larvae were reared on IYSV-infected onions until pupation. Individual pupae were confined until adults eclosed, and the lifespan and total progeny produced per adult were monitored daily. Thrips were tested for the virus in reverse-transcriptase polymerase chain reaction using specific primers to confirm the presence of IYSV. Results indicated that 114 and 35 out of 149 eclosing adults tested positive (viruliferous) and negative (nonviruliferous) for IYSV, respectively. The viruliferous adults lived 1.1-6.1 d longer (average of 3.6 d) than nonviruliferous adults. Fecundity of viruliferous and nonviruliferous onion thrips was similar with 2.0 ± 0.1 and 2.3 ± 0.3 offspring produced per female per day, respectively. Fecundity for both viruliferous and nonviruliferous thrips also was significantly positively correlated with lifespan. These findings suggest that the longer lifespan of viruliferous onion thrips adults may allow this primary vector of IYSV to infect more plants, thereby exacerbating IYSV epidemics.
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Affiliation(s)
- Ashley Leach
- Department of Entomology, Cornell University, Cornell AgriTech, Geneva, NY
- Corresponding author, e-mail:
| | - Marc Fuchs
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY
| | - Riley Harding
- Department of Entomology, Cornell University, Cornell AgriTech, Geneva, NY
| | - Brian A Nault
- Department of Entomology, Cornell University, Cornell AgriTech, Geneva, NY
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