Managing the Most Significant Biotic Challenges for Organic Onion Production Across the Great Lakes Region

MANAGING THE MOST SIGNIFICANT BIOTIC CHALLENGES FOR ORGANIC ONION PRODUCTION ACROSS THE GREAT LAKES REGION

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

COMPLETE

Funding Source

OTHER GRANTS

Reporting Frequency

Annual

Accession No.

1013009

Grant No.

2017-51300-26816

Cumulative Award Amt.

$836,804.00

Proposal No.

2017-02467

Multistate No.

(N/A)

Project Start Date

Sep 1, 2017

Project End Date

Aug 31, 2022

Grant Year

2017

Program Code

[113.A]- Organic Agriculture Research & Extension Initiative

Recipient Organization
N Y AGRICULTURAL EXPT STATION
(N/A)
GENEVA,NY 14456

Performing Department
Entomology

Non Technical Summary
Organic onions are a highly valuable commodity in the Great Lakes region and their economic viability has been critically threatened by pests and pathogens that are difficult to manage. Stakeholders have identified onion thrips, Thrips tabaci, as the most serious insect pest and Stemphylium leaf blight (SLB), which is caused by Stemphylium vesicarium, as the most important foliar pathogen in this region. The long-term goal of this project is to develop and implement an effective IPM program for onion thrips and SLB that will ensure the sustainability and profitability of organic onion production in the Great Lakes. To meet this goal, the following objectives are proposed: 1) Evaluate OMRI-approved crop protectants in combination with thrips-resistant onions to manage thrips and SLB, 2) Implement and demonstrate an IPM strategy for thrips and SLB using resistant onions and OMRI-approved crop protectants in participating organic growers' fields, 3) Develop and release new early-maturing, multiple-pest-resistant onion cultivars for organic growers, and 4) Deliver project information and develop web-based resources for organic onion producers to implement our IPM program. Our project directly aligns with USDA-OREI program foci such as a) facilitating the development and improvement of organic agriculture production; b) conducting advanced on-farm research on organic farms that improves production; c) developing new and improved seed varieties that are particularly suited for organic agriculture. Moreover, two of these foci (a and c) directly align with the FY2017 USDA-OREI Program priorities.

Animal Health Component

80%

Research Effort Categories

Basic

10%

Applied

80%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
211	1451	1130	60%
212	1451	1102	40%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 211 - Insects, Mites, and Other Arthropods Affecting Plants;

Subject Of Investigation
1451 - Onion, garlic, leek, shallot;

Field Of Science
1130 - Entomology and acarology; 1102 - Mycology;

Keywords

ipm

onion

stemphylium leaf blight

host plant resistance

onion thrips

Goals / Objectives
Organic onion producers are challenged by insect pests and diseases that routinely cause serious losses and reduce profits. Onion thrips, Thrips tabaci, has been prioritized by stakeholders as the most serious pest in both conventional and organic onion production in the Great Lakes region. Thrips feeding damages onion foliage and significantly reduces the number of bulbs reaching marketable sizes. Onion thrips also transmits important pathogens such as Iris yellow spot virus (IYSV) and those that cause bacterial bulb rots. Thrips damage also may create additional entry points that facilitate infection by Stemphylium vesicarium, which causes Stemphylium leaf blight (SLB). SLB has recently emerged as the most serious foliar disease of onion in the Great Lakes region. SLB damages foliage that may reduce the size of marketable bulbs; SLB also may kill plants prematurely and can result in complete crop loss. Organic onion growers in the Great Lakes region urgently need an effective integrated pest management (IPM) program for onion thrips and SLB to avoid serious losses. We propose to develop and implement an IPM program that is based on a combination of host plant resistance and crop protectants that are approved by the Organic Materials Re-view Institute (OMRI).We have demonstrated that onions with unique cuticular-wax profiles ("semi-glossy" foliage) significantly reduce thrips damage and these selections may be less vulnerable to SLB. We also have identified some promising OMRI-approved crop protectants that may significantly reduce damage by onion thrips and SLB. The long-term goal of this research is to ensure the sustainability and profitability of organic onion production by developing and implementing an IPM program for thrips and SLB that will combine thrips-resistant cultivars and an OMRI-approved crop protectant program.There are four objectives that we have proposed to meet this long-term goal. The first objective is to evaluate OMRI-approved crop protectants with semi-glossy onions for onion thrips and Stemphylium leaf blight management. This will be accomplished by evaluating OMRI-approved crop protectants for thrips and SLB management on semi-glossy and standard waxy onions and evaluating co-applications of the best performing OMRI-approved crop protectants in a season-long thrips and SLB control program on semi-glossy and standard waxy onions towards the development of an IPM program.The second objective is to implement and assess the IPM strategy for onion thrips and Stemphylium leaf blight using resistant onions and OMRI-approved crop protectants in growers' fields. This will be accomplished by implementing this IPM strategy in organic growers' fields and compare levels of thrips damage, SLB damage and marketable yields of semi-glossy onions with those of a standard waxy onion managed following the growers' practices.The third objective is to develop and release new early-maturing, multiple-pest-resistant onion cultivars for organic growers. This will be done by releasing open-pollinated, semi-glossy, multiple-pest-resistant onion cultivars to stakeholders that minimize losses caused by onion thrips and SLB.The fourth objective is to deliver project information and develop web-based resources for organic onion producers to implement our IPM program for thrips and Stemphylium leaf blight. This will be accomplished by presenting organic onion IPM information at regional and national stakeholder meetings, developing web-based resources for researchers, extension educators, growers and consumers of organically produced onion, hosting field days to showcase onions produced via the IPM program, publishing research results in the scientific and lay press, and assessing the impact and knowledge gained about onion IPM by organic onion growers.

Project Methods
We will evaluate OMRI-approved crop protectants with semi-glossy onions for onion thrips and Stemphylium leaf blight (SLB) management. Field trials will be established at organic farm in New York to evaluate combinations of thrips-resistant cultivars and OMRI-approved pesticides. The proposed cultivars will include a semi-glossy onion phenotype with low amounts of wax, a semi-glossy phenotype with medium amounts of wax, and a waxy cultivar with high amounts of wax (= standard).Insecticides that have shown promise in preliminary field trials will be evaluated. The treatment design will be an onion selection by insecticide factorial with treatments established as a randomized complete block design and replicated four times. Onions will be transplanted in early May into raised beds covered with reflective silver plastic mulch and drip tape. Insecticides will be applied in mid-June when densities of onion thrips reach an action threshold of 1 per leaf. Additional applications will be made at 7-day intervals for approximately 6 weeks or until the crop has matured normally (leaves fall over). Efficacy of treatments will be evaluated by recording the number of onion thrips larvae and adults per plant from 15 randomly selected plants per plot approximately one week after each application. Data collection will be completed when the crop is nearly mature Damage ratings will be made every two weeks. Plots will be harvested and bulbs graded according to USDA standards (jumbo, standard and boiler) and weighed. Sub-samples of 50 bulbs will be inspected for fungal and bacterial rots.Fungicides that have shown promise in preliminary field trials also will be evaluated. The location of field trials, years that trials will be conducted, onion selections, method of pesticide application, etc. will be exactly as described previously. The treatment design will be an onion selection by fungicide factorial with treatments established as a randomized complete block design and replicated four times. Applications will begin in late-June when SLB lesions are first detected. Additional applications will be made at 7-day intervals for approximately 6 weeks or until the crop has matured normally. Products that previously have shown efficacy against SLB and other fungal pathogens in conventional onions and those whose efficacy is unknown will be evaluated. Disease assessments will be made weekly within the center of each plot. Disease lesions will be assessed by counting the number of lesions per leaf and by visual estimation of the severity on 20 leaves per plot. Leaves will be incubated in humid containers for 7 days and observed under the microscope to identify fungi associated with lesions under the microscope. Bulbs will be harvested, weighed and inspected for disease as mentioned previously.The best performing OMRI-approved crop protectants will be evaluated in season-long programs to manage onion thrips and SLB on semi-glossy and the standard waxy phenotypes. The location of these field trials, onion cultivars, plot size, plant spacing, method of application, harvest and grading, etc. will be exactly as described previously; however, the experiments will be conducted in subsequent years. The treatment design will be a 5 crop protectant program (3 potential crop protectant programs, a standard spray program and an untreated control) by 3 onion selection factorial. Treatments will be established as a randomized complete block design with four replicates per treatment. Applications will begin in mid to late-June when onion thrips reach an action threshold of 1 thrips/leaf and when SLB lesions are first detected. However, if these events do not occur simultaneously, the sequences of insecticides and fungicides can be staggered in time after the initial thresholds are reached. Additional applications will be made at 7-day intervals for approximately 6 weeks or until the crop has matured normally. However, reductions in application frequency will be made if thrips densities are well below threshold on certain dates in certain onion selection by OMRI material program treatments. Efficacy of treatments, yield assessment, etc. will be determined as described previously.The best IPM strategy for onion thrips and SLB identified in small plot studies will be evaluated in organic growers' fields in New York and Wisconsin. Growers will transplant onions and maintain all aspects of the crop, with the exception of controlling insects and diseases; we will make all crop protectant applications on the farm. This experiment will be conducted using two cultivars: a thrips-resistant, semi-glossy wax cultivar with medium amounts of wax and a standard waxy cultivar of similar maturity that is grown on the organic farm. The OMRI-approved crop protectant program identified above will be used for thrips and SLB control on half of the thrips-resistant onion cultivar and half of the standard waxy cultivar. The organic growers' insect and disease management program will be followed on the other half of the onion plots. Thus, there will be four treatments: thrips-resistant selection + OMRI-approved program, thrips-resistant selection + grower's management program, standard waxy cultivar + OMRI-approved program, and standard waxy cultivar + grower's management program. Each treatment will be replicated 3 times on each farm. Crop protectants will be applied using the equipment and approach described above. Thrips densities and SLB lesions will be monitored weekly in all fields. Thirty plants will be randomly selected within each plot and the numbers onion thrips larvae and adults recorded. A visual rating of thrips damage on these thirty plants will be made every other week. SLB lesions and severity of lesions on the leaves also will be assessed weekly from 30 randomly selected plants within each plot. After onions have matured, they will be harvested within each plot to measure bulb yields and sizes.New early-maturing, multiple-pest-resistant onion cultivars will be released for organic growers. An existing onion selection with resistance to two other pathogens will be crossed with best selection with thrips resistance. This multiple-pest-resistant selection is early maturing, has waxy foliage, and produces bulbs with relatively good storage abilities for marketing over the fall and winter months. This inbred will be crossed with the best semi-glossy selections that support fewer thrips and suffer less feeding damage, and F3 families produced. Semi-glossy F3 families will be visually identified and gas chromatography mass spectrometry used to measure amounts of cuticular waxes, selecting families with higher amounts of waxes. Semi-glossy families will be grown in replicated field plots in organic fields in Wisconsin with commercial cultivars. These plots will not be sprayed and thrips numbers and damage will be assessed as described previously. Maturity of families will be scored and bulb yields, sizes, and storage ability over the winter measured. Plants from the early maturing families with good bulb production and storage will be intercrossed and seed will be separately harvested off of each plant to produce half-sib (HS) families. At the end of the project, these HS families will be evaluated for maturity in replicated trials in organic fields in New York and Wisconsin. Bulbs from the best performing families will be harvested and intercrossed to produce early-maturing, yellow-bulb, well storing, and multiple pest-resistant populations to be released to growers and seed companies. Because populations will possess male-fertile cytoplasm, growers will be able to produce their own seed and make selections in their specific environments. Over the long term, populations can be used to develop superior male-sterile lines for hybrid production.

Progress 09/01/17 to 08/31/22

Outputs
Target Audience:Knowledge gained from our on-farm research trials were shared through presentations at organic grower meetings in New York and Wisconsin. We also shared knowledge with a broader stakeholder audience through extension articles published via Cornell Cooperative Extension newsletters like VegEdge as well as the trade magazine, Onion World. Finally, we published our research results in multiple peer-reviewed journals to reach scientific audiences. Changes/Problems:The lack of effective insecticides for onion thrips control and lack of insecticides for Stemphylium leaf blight control precluded our ability to evaluate a season-long OMRI-listed pesticide program from these two pests. Instead, we examined the relationship between thrips abundance and bacterial rot incidence as well as the relationships between thrips and yield and bacterial rot and yield for both the hybrid 'USDA-Maia' (B5336AxB5351C) and Bradley cultivars. We learned that only occasionally thrips abundance will be positively correlated with bulb rot, but that this relationship is relatively weak in both cultivars. Therefore, thrips control is important, but should not be expected to lower levels of bacterial bulb rot in both cultivars. COVID restricted the rate of progress due to limited access to greenhouse and lab facilities and hiring personnel to assist in research projects. However, the no-cost extensions were invaluable to allow us to successfully complete all of the objectives of this project. What opportunities for training and professional development has the project provided?Two post-doctoral researchers were trained at Cornell during this project. Lindsy Iglesias worked on this project during the early years, and is now employed as an Entomologist Lead, Discovery Biology with Greenlight Biosciences in Durham, NC. Pin-Chu Lai continued this project and is currently searching for a position in academia or industry. In addition to training that Lindsy and Pin-Chu obtained working in the Nault lab, both engaged in a Post-doctoral Workshop Series at Cornell that helped them in their professional development. Both received a certificate of participation for this workshop. The last graduate student (Derek Hunsaker) at Wisconsin who was supported by this project graduated in August 2020. He is now employed as an Assistant Scientist with the Crop Innovation Center at the UW-Madison. How have the results been disseminated to communities of interest?Details about how results were disseminated to communities of interest are recorded in other sections of this report. We targeted organic vegetable growers who grow onions, the biopesticide industry, crop consultants, extension educators and the scientific community. Results were communicated via face-to-face presentations, extension articles, trade magazine articles and peer-reviewed journal manuscripts. Information also was made available on the websites managed by the PI and Co-PIs. What do you plan to do during the next reporting period to accomplish the goals?In New York, there are no immediate plans to present information from this project. However, information generated from this project likely will be relayed to stakeholder audiences at future meetings. PI Brian Nault and collaborators will continue to update their websites with results from this project as well as general information on organic onion production and management of onion thrips and Stemphylium leaf blight. In Wisconsin, GCMS analysis of additional sources of semi-glossy foliage associated with thrips resistance will be completed in 2023 and one more publication will be published in 2024.

Impacts
What was accomplished under these goals? Objective 1 Objective 1 consisted of two projects: 1) to evaluate OMRI-Listed bioinsecticides in combination with different adjuvants and 2) to evaluate plastic mulches and resistant cultivars in combination with bioinsecticides to manage onion thrips. Both of these trials were completed and results and findings were shared at grower-based meetings and published in extension newsletters, trade magazines, and peer-reviewed publications. Growers now are award of the best options for managing thrips in organically produced onion. Objective 2 On-farm trials were conducted on two organic farms in NY from 2019 to 2021 and one organic farm in WI in 2020. These trials combined the best OMRI-listed insecticides, a semi-glossy thrips resistant cultivar, and silver reflective mulch for onion thrips management. Trials were completed successfully. Results from these trials were summarized, and results have been published in an extension article, trade magazine and peer-reviewed journal focusing on the performance of the semi-glossy resistant cultivar and the relationship between thrips and bacterial bulb rot. Growers now are award of the best options for managing thrips in organically produced onion as a result of this research. Objective 3 The USDA officially released the hybrid 'USDA-Maia' (B5336AxB5351C) in February 2021, the first hybrid onion with semi-glossy foliage showing thrips resistance for production on high organic (muck) soils of the eastern USA and Canada. Seeds of the inbred parents (B5336A, B5336B, and B5351C) were provided to 16 companies or public-sector breeding programs for use in their respective programs and production of the hybrid 'USDA-Maia'. Although the inbreds of this hybrid were selected and developed over many years before the OREI grant, funds from this grant were imperative to documentation of the level of thrips resistance exhibited by the hybrid. The 'USDA-Maia' hybrid has round bulbs with yellow skins and excellent storage ability, resistance to pink root and Fusarium basal rot, and has lower pungency compared to current eastern-storage hybrids. A major publication on the genetics of resistance to Fusarium basal rot was published. Development of semi-glossy onions with Fusarium resistance was a major goal of this project. A major publication (Hortscience 5:1059-1063) on the natural phenotypic diversity for epicuticular wax profiles on was published and identified germplasm accessions with unique wax profiles useful for development of thrips resistant onions. Objective 4: Results from the on-farm trials were published in peer-reviewed journals, an trade magazine article (Onion World - most popular trade magazine for onion growers), and an article in the Cornell Cooperative Extension (CCE) VegEdge magazine in 2022. Other results were reported in previous years and are shown in the annual progress reports.

Publications

Type: Journal Articles Status: Published Year Published: 2022 Citation: Lai, P.-C., L. Iglesias, R.L. Groves, M.J. Havey, and B.A. Nault. 2022. Performance of a semi-glossy onion hybrid in certified organic onion fields infested with Thrips tabaci and bulb-rot causing bacteria. Crop Protect. 160 (1-9). https://doi.org/10.1016/j.cropro.2022.106037.
Type: Journal Articles Status: Published Year Published: 2021 Citation: Hay, F. S., Stricker, S., Gossen, B. D., McDonald, M. R., Heck, D. W., Hoepting, C. A., Sharma, S., and Pethybridge, S. J. 2021. Stemphylium leaf blight of onion: A re-emerging threat to onion production in eastern North America. Plant Dis. 105:3780-3794. https://doi.org/10.1094/PDIS-05-21-0903-FE
Type: Journal Articles Status: Published Year Published: 2022 Citation: Hay, F. S., Heck, D. W., Sharma, S., Klein, A., Hoepting, C., and Pethybridge, S. J. 2022. Stemphylium leaf blight of onion. Plant Disease Lesson. The Plant Health Instructor 22: 10.1094/PHI-P-2022-01-0001
Type: Journal Articles Status: Published Year Published: 2022 Citation: Havey, M.J. 2022. Variation for epicuticular waxes among plant introductions of onion. Hortscience 5:10591063. https://doi.org/10.21273/HORTSCI16697-22
Type: Other Status: Published Year Published: 2022 Citation: Lai, P.-C., and B. Nault. 2022. Are onion thrips allies of bulb-rot causing bacteria in organic onion production? Cornell Cooperative Extension, Cornell Vegetable Program. VegEdge 18(16): 9-10. https://rvpadmin.cce.cornell.edu/pdf/veg_edge/pdf247_pdf.pdf
Type: Other Status: Published Year Published: 2022 Citation: Lai, P.-C. and B. Nault. 2022. Do thrips facilitate bulb rot disease? Onion World 38(8): https://issuu.com/columbiamediagroup/docs/onion_world_december_2022?fr=sMzU1YzQ5MDQ1MjQ

Progress 09/01/20 to 08/31/21

Outputs
Target Audience:The fourth year of the project continued research on two organic farms in NY focusing on optimizing onion thrips management in organic onion production systems. For reasons related to the COVID-19 pandemic, we elected to not have a 2021 summer workshop or demonstration trial. Rather, knowledge gained from the on-farm trials from 2019 to 2021 will be shared through a handout and/or a presentation at 2022 Organic Vegetable Production Conference in February 2022 in WI, Empire state producers EXPO in January 2022 in NY, and 2022 NOFA-NY Winter conference in January 2022 in NY. We also plan to share the knowledge with a broader audience through extension articles in Cornell Cooperative Extension newsletters like VegEdge and the trade magazine, Onion World, in early 2022. Changes/Problems:The lack of effective insecticides for onion thrips control and lack of insecticides for Stemphylium leaf blight control precluded our ability to evaluate a season-long OMRI-listed pesticide program from these two pests. Instead, we examined the relationship between thrips abundance and bacterial rot incidence as well as the relationships between thrips and yield and bacterial rot and yield for both the hybrid 'USDA-Maia' (B5336AxB5351C) and Bradley cultivars. We learned that only occasionally will thrips abundance will be positively correlated with bulb rot, but that this relationship is relatively weak in both cultivars. Therefore, thrips control is important, but should not necessarily be expected to lower levels of bacterial bulb rot in both cultivars. COVID restricted progress due to limited access to greenhouse and lab facilities in Wisconsin. We could also not hire an undergraduate student for help with work due to COVID restrictions of lab access. What opportunities for training and professional development has the project provided?The previous postdoctoral researcher who worked on this project is now employed as an Entomologist Lead, Discovery Biology with Greenlight Biosciences in Durham, NC. We recruited another postdoctoral researcher to continue the on-farm trials in 2021. She presented results from the on-farm trials conducted in 2019 to 2021 at the Entomological Society of America Annual Meeting in November in 2021. She will be involved in extension conferences and grower meetings in early 2022 to share results from this study. She is also preparing a manuscript and several extension articles documenting the findings from the on-farm trials. The last graduate student (Derek Hunsaker) at Wisconsin who was supported by this project graduated in August 2020. He is now employed as an Assistant Scientist with BASF Vegetables in Brooks, OR and works with onion breeding and genetics. How have the results been disseminated to communities of interest?Efforts to transfer knowledge about our research in 2021 were stymied by COVID-19. Therefore, there there were no presentations to onion growers and other stakeholders in 2021 due to COVID restrictions. Efforts will be made to disseminate our results to growers in 2022. However, results from the on-farm trials were presented at the Entomological Society of America Annual Meeting in November in 2021. Additionally, a summary of the thrips resistance work will be presented at the 2022 National Allium Research Conference in February 2022. What do you plan to do during the next reporting period to accomplish the goals?In New York, we will focus on dissemination of the information obtained from the on-farm study. More specifically, a manuscript summarizing the findings of the on-farm trials will be submitted for publication in 2022. A handout with highlights of the results was created and will be disseminated in extension conferences and meetings in early 2022, which include 2022 Organic Vegetable Production conference, NOFA-NY Winter conference, empire state EXPO, and regional growers meetings in NY. The website of the Brian Nault Laboratory will be updated with results from both years of the project and general information on organic onion production, onion thrips, and stemphylium leaf blight. In Wisconsin, we are completing GCMS analysis of additional sources of semi-glossy foliage associated with thrips resistance. These analyses should be completed in the spring of 2022 and expect one more publication will be submitted in 2022: Havey, M.J., and D. Hunsaker. 20--. Variation for epicuticular waxes among plant introductions and a synthetic population of onion. HortScience (in preparation).

Impacts
What was accomplished under these goals? Objective 1 Objective 1 consisted of two projects: 1) to evaluate OMRI-Listed bioinsecticides in combination with different adjuvants and 2) to evaluate plastic mulches and resistant cultivars in combination with bioinsecticides to manage onion thrips. Both of these trials were completed in 2019. Results and findings were published as in two publications in 2021. Objective 2 The on-farm trials were conducted on two organic farms in NY from 2019 to 2021 and one organic farm in WI in 2020. These trials combined the best OMRI-listed insecticides, a semi-glossy thrips resistant cultivar, and silver reflective mulch for onion thrips management. Trials were completed successfully. Results from these trials were summarized, and a manuscript is being prepared focusing on the performance of the semi-glossy resistant cultivar and the relationship between thrips and bacterial bulb rot. Objective 3 The USDA officially released the hybrid 'USDA-Maia' (B5336AxB5351C) in February 2021, the first hybrid onion with semi-glossy foliage showing thrips resistance for production on high organic (muck) soils of the eastern USA and Canada. Seeds of the inbred parents (B5336A, B5336B, and B5351C) were provided to 16 companies or public-sector breeding programs for use in their respective programs and production of the hybrid 'USDA-Maia'. Although the inbreds of this hybrid were selected and developed over many years before the OREI grant, funds from this grant were imperative to documentation of the level of thrips resistance exhibited by the hybrid. The 'USDA-Maia' hybrid has round bulbs with yellow skins and excellent storage ability, resistance to pink root and Fusarium basal rot, and has lower pungency compared to current eastern-storage hybrids. A major publication on the genetics of resistance to Fusarium basal rot was accepted for publication. Development of semi-glossy onions with Fusarium resistance was a major goal of this project. Objective 4: Results from the on-farm trials were presented at a national entomological conference in 2021. We plan to provide information and knowledge obtained from this project to onion growers, University Extension educators and faculty, and the public via a handout that will be distributed during the 2022 Organic Vegetable Production Conference, Empire state producers EXPO, and NOFA-NY Winter conference, and via an updated article in Onion World (most popular trade magazine for onion growers), an article in the Cornell Cooperative Extension (CCE) VegEdge magazine in early 2022.

Publications

Type: Journal Articles Status: Published Year Published: 2021 Citation: Havey, M. J., Hunsaker, D. J., and E.D. Munaiz. 2021. Genetic analysis of the unique epicuticular wax profile of Odourless Greenleaf onion. J. Amer. Soc. Hort. Sci. 146:118-124. https://doi.org/10.21273/JASHS05024-20
Type: Journal Articles Status: Published Year Published: 2021 Citation: Iglesias, L., R. L. Groves, B. Bradford, R. S. Harding, and B. A. Nault. 2021. Evaluating combination of bioinsecticides and adjuvants for managing Thrips tabaci (Thysanoptera: Thripidae) in onion production systems. Crop Prot. 142: 105527. https://doi.org/10.1016/j.cropro.2020.105527
Type: Journal Articles Status: Published Year Published: 2021 Citation: Iglesias, L., Havey, M. J., and B. A. Nault. 2021. Management of onion thrips (Thrips tabaci) in organic onion production using multiple IPM tactics. Insects. 12:207. https://doi.org/10.3390/insects12030207
Type: Journal Articles Status: Awaiting Publication Year Published: 2022 Citation: Straley, E., J. Marzu, and M.J. Havey. 2022. Genetic analyses of resistance to Fusarium basal rot in onion. MDPI Horticulturae

Progress 09/01/19 to 08/31/20

Outputs
Target Audience:The third year of the project focused on research on two organic farms in NY and one in WI. Additionally, we held a workshop at the 2020 NOFA-NY Winter Conference in January 2019 in Syracuse, NY titled "Updates on Organic Onion Pest and Disease Management". Efforts to transfer knowledge about our research results will continue early next year. We had intended to repeat one field experiment on our research farm and hold another field day on at Cornell AgriTech to show onion growers, University Extension educators and faculty, and the public our progress, but due to the COVID-19 pandemic, research and extension activities were cancelled on the research farm. Changes/Problems:The onset of the COVID-19 pandemic resulted in major unexpected challenges for the 2020 research season. Research trials were reduced by 70%, which included cancelling our plans to repeat objective 1 cultural control trial for a third year. COVID limited undergraduate and graduate student workers for assisting with field work.COVID-19 also resulted in a cancellation of our annual 2020 field day in cooperation with NOFA-NY. Although the NOFA-NY 2021 Winter Conference will be held virtually, the number of workshops was reduced so significantly, that we were unable to secure a spot for this year. What opportunities for training and professional development has the project provided?The project involved mentoring a postdoctoral researcher who continues to focus on this research as a major component of her appointment. She presented results from the first and second years of the project at the Entomological Society of America Annual Meeting in November 2019 and 2020 and a CCE workshop in 2019. She also organized and presented results from both years of the project at the NOFA-NY Organic Winter Conference in Jan 2020. She has also published articles in major onion commodity and extension magazines with results from the first two years of the project. When she works in the field, she works closely with growers and provides updates on the projects during her visits. This experience continues to provide her with opportunities in professional development and science communication opportunity. How have the results been disseminated to communities of interest?The objectives of the project and research progress have been disseminated to onion growers, University Extension educators and faculty, and the public. Efforts to transfer knowledge about our research occurred primarily at the NOFA-NY Winter Conference, CCE Ag In-Service workshop, professional conferences, outreach publications, and research field sites during site visits. Due to the COVID-19 pandemic, we were unable to conduct our annual field day in 2020. Additional conference and Extension presentations, field visits, and workshops will occur next year. What do you plan to do during the next reporting period to accomplish the goals?Research plans for next reporting period include repeating the experiment on action-threshold levels in onion grower's fields. This experiment tests three different thresholds for onion thrips in combination with the best suite of OMRI-listed products and thrips-resistant onion varieties for managing onion thrips and Stemphylium leaf blight in onions. Results of the project will be shared at the Eastern Branch Meeting of the Entomological Society of America in March 2021. An e-Organic eXtension article is planned that focuses on onion thrips biology and organic management. Three articles summarizing the findings of our project will be submitted for publication in 2021. One is currently accepted and two others are in preparation. A field day will also being planned for the summer of 2021 with NOFA-NY to share the results of the research project to our stakeholders at our on-farm research site. The website of the Brian Nault Laboratory will be updated with results from both years of the project and general information on organic onion production, onion thrips, and stemphylium leaf blight.

Impacts
What was accomplished under these goals? Objective 1 Objective 1 consisted of two projects: 1) to evaluate OMRI-Listed bioinsecticides in combination with different adjuvants and 2) to evaluate plastic mulches and resistant cultivars in combination with bioinsecticides to manage onion thrips. Both of these trials were completed in 2019. Objective 2 The on-farm trials were conducted on two and one organic farms in NY and WI, respectively. Results from these trials that combined the best OMRI-listed insecticides and fungicides for onion thrips and Stemphylium leaf blight management have not been summarized, but the trials were successful. Objective 3 In 2019, bulbs of 'B5336 x B5351' were harvested from families showing relatively high levels of resistance to both soil-borne diseases and semi-glossy foliage; these were intercrossed in 2020 to produce elite onion populations with resistances to Fusarium basal rot, pink root, and onion thrips. Cytoplasmic male-sterile plants will be included with these selections to develop male-sterile lines for eventual hybrid development. Seed will be provided for final thrips evaluations in 2021. Objective 4: We provided information about this project to onion growers, University Extension educators and faculty, and the public via an article in Onion World (most popular trade magazine for onion growers), an article in the Cornell Cooperative Extension (CCE) VegEdge magazine, and presentations at the CCE Ag In-Service Training Meeting and two professional entomological meetings.

Publications

Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Havey, M.J., D.J. Hunsaker, and E.D. Munaiz. Genetic analysis of the unique epicuticular-wax profile of Odourless Greenleaf onion. J. Amer. Soc. Hort. Sci.
Type: Journal Articles Status: Accepted Year Published: 2020 Citation: Iglesias, L., R. L. Groves, B. Bradford, R. S. Harding, and B. A. Nault. Evaluating bioinsecticides for managing Thrips tabaci (Thysanoptera: Thripidae) in onion production systems. Crop Prot.
Type: Journal Articles Status: Published Year Published: 2020 Citation: Munaiz, E.D., P.A. Townsend, and M.J. Havey. 2020. Reflectance spectroscopy for non-destructive measurement and genetic analysis of amounts and types of epicuticular waxes on onion leaves. Molecules 25:3454. https://doi.org/10.3390/molecules25153454
Type: Journal Articles Status: Published Year Published: 2020 Citation: Khosa, J., D. Hunsaker, and M.J. Havey. 2020. Identities and phenotypic variation for epicuticular waxes among leaves and plants from inbred onion populations. Hortscience https://doi.org/10.21273/HORTSCI15414-20
Type: Journal Articles Status: Published Year Published: 2020 Citation: Munaiz, E.D. and M.J. Havey. 2020. Genetic analyses of epicuticular waxes associated with the glossy phenotype of White Persian onion. J. Amer. Soc. Hort. Sci. 145:67-72. https://doi.org/10.21273/JASHS04840-19
Type: Journal Articles Status: Published Year Published: 2020 Citation: Munaiz, E.D., R.L. Groves, and M.J. Havey. 2020b. Epicuticular leaf waxes among onion accessions selected for reduced damage by onion thrips. J. Amer. Soc. Hort. Sci. 145:30-35. https://doi.org/10.21273/JASHS04773-19
Type: Other Status: Published Year Published: 2020 Citation: Iglesias, L., and B. Nault. 2020. Bioinsecticides and cultural controls for onion thrips in organic onions. VegEdge, 16(11): 5-7.

Progress 09/01/18 to 08/31/19

Outputs
Target Audience:The second year of the project continued to be focused on field research on our research farm, but also included research on two organic farms. Additionally, we held a field day on August 15th at Cornell AgriTech to show onion growers, University Extension educators and faculty, and the public our progress. The field day was advertised by NOFA-NY and was titled "Organic management of onion thrips and Stemphylium leaf blight in onion". Efforts to transfer knowledge about our research results will continue early next year. Changes/Problems:None What opportunities for training and professional development has the project provided?The project involved mentoring a postdoctoral researcher who continues to focus on this research as a major component of her appointment. She organized a workshop that was scheduled to be held at NOFA-NY's winter meeting in early January 2019, but the workshop was cancelled due to a catastrophic snow storm. She presented first-year results of our project at the Eastern Branch Meeting of the Entomological Society of America (EB-ESA) in March 2019 and results from first and second years of the project at the Entomological Society of America Annual Meeting in November 2019. She also organized and presented results from both years of the project at the NOFA-NY Organic onion field day in August 2019. This experience continues to provide her with opportunities in professional development and science communication opportunity.Also, both high school andundergraduate student workersgained field experience examining the efficacy of insecticides and crop maintenance. This projected supported a graduate student at University of Wisconsin who completed evaluations for pink root and Fusarium resistances in semi-glossy selections from the USDA onion breeding program. An undergraduate worker gained field experience with seed and bulb production of onion. How have the results been disseminated to communities of interest?The objectives of the project and research progress have been disseminated to onion growers, University Extension educators and faculty, and the public. Efforts to transfer knowledge about our research occurred primarily at the field day, research field sites during site visits. Additional conference and Extension presentations, field visits, and workshops will occur next year. What do you plan to do during the next reporting period to accomplish the goals?Research plans for next reporting period include repeating the experiments in onion grower's fields. These experiments combine the best OMRI-listed products and thrips-resistant onion varieties for managing onion thrips and Stemphylium leaf blight in onions. Results of the project will be shared at the Northeast Organic Farmers Association of New York (NOFA-NY) Annual Winter Conference in January 2020 and the Eastern Branch Meeting of the Entomological Society of America in March 2020. A field day will also being planned for the summer of 2020 with NOFA-NY to share the results of the research project to our stakeholders at our on-farm research site. The website of the Brian Nault Laboratory will be updated with results from both years of the project and general information on organic onion production, onion thrips, and stemphylium leaf blight.

Impacts
What was accomplished under these goals? Objective 1 In New York, several OMRI-listed insecticides were combined with three additional products (referred to as adjuvants) and evaluated for reducing onion thrips infestations and improving bulb yield at Cornell AgriTech. The insecticides evaluated were Entrust SC, Neemix 4.5, Azera and PFR-97. Each of these insecticides was combined with one of three adjuvants: M-Pede, Trilogy and NuFilm P. Applications were made weekly. Onions also were harvested and graded. Results were similar to those in 2018. The insecticide Entrust (spinosad) reduced overall season mean numbers of thrips more than any other insecticides evaluated in this study. The addition of M-Pede and Trilogy to Entrust reduced thrips densities more than the combination of Entrust and NuFilm. However, M-Pede caused some phytotoxicity when applied under sunny and hot conditions, so this product would need to be applied in the early hours of the day or at a reduced rate. None of the other insecticide and adjuvant combinations provided acceptable control of onion thrips. Onion yield was also affected by the insecticide treatment. Total onion yield was higher in the Entrust plots than the other insecticide treatments. Entrust (regardless of adjuvant) had a higher proportion of large onions (colossal and jumbo) compared with the other treatments. The results of the evaluation of OMRI-listed insecticides and adjuvants indicated that Entrust co-applied with either M-Pede or Trilogy was the most effective insecticide + adjuvant combination for managing onion thrips in organic onions and improving yield. Results of the 2019 field trial examining various OMRI-listed insecticides for thrips control in Wisconsin were not available in time for inclusion in this report. Similarly, a 2019 summary of the performance of OMRI-listed fungicides were not available to include in this report. In both cases; the trials were successful. In another field trial, two partially thrips resistant cultivars also were evaluated in 2018 and 2019, 'Rossa di Milano' and B5336 x B5351. Additionally, both were grown on either white on black or reflective mulch. Onions were either protected from thrips weekly with Entrust SC + Trilogy or were not protected from thrips. Fungicides were applied weekly to manage Stemphylium leaf blight. Rossa di Milano reduced onion thrips densities in both years, while B5336 x B5351 reduced densities only in 2018. Despite the differences in thrips control, B5336 x B5351 had significantly greater bulb yields than Rossa di Milano. Mulch had inconsistent significant effects on thrips densities and bulb yield was similar for both mulch types. Entrust + Trilogy provided excellent contrl of onion thrips, which translated to significantly greater bulb yields than untreated plots. Objective 2 Results from the on-farm trials that combined the best OMRI-listed insecticides and fungicides for onion thrips and Stemphylium leaf blight management have not been summarized, but the trials were successful. Objective 3 In 2019, bulbs of 'B5336 x B5351' were harvested from families showing relatively high levels of resistance to both soil-borne diseases and semi-glossy foliage; these will be intercrossed in 2020 to produce elite onion populations with resistances to Fusarium basal rot, pink root, and onion thrips. Cytoplasmic male-sterile plants will be included with these selections to develop male-sterile lines for eventual hybrid development. Seed will be provided for final thrips evaluations in 2021. Objective 4: We provided information about this project to onion growers, University Extension educators and faculty, and the public via an article in Onion World (most popular trade magazine for onion growers), a field day in New York and two professional entomological meetings.

Publications

Type: Other Status: Published Year Published: 2019 Citation: Iglesias, L. and B. Nault. 2019. Tackling thrips in organic onions. Onion World 35(5): 7-9.
Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Iglesias, L., and B. A. Nault. 2019. Host-plant resistance and plastic mulches: Potential for managing onion thrips (Thrips tabaci) in organic onion production. Entomological Society of America Annual Meeting, November 20, 2019, St. Louis, MO.
Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Iglesias, L., and B. Nault. 2019. Integrated approaches for managing onion thrips, Thrips tabaci, in organic onions. In: Breaking Ground: Research Highlights from ECPs and non-Academic Track Eastern Branch Members. Entomological Society of Americas Eastern Branch meeting. Blacksburg, VA. March 11, 2019.
Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Iglesias, L., F. Hay and B. A. Nault. 2019. New tools for managing onion thrips and foliar disease in organic onion production. NOFA-NY Field Day at Cornell AgriTech, August 15, 2019, Geneva, NY.

Progress 09/01/17 to 08/31/18

Outputs
Target Audience:The first year of the project was focused primarily on field research, which was still in progress at the end of this project period. However, we were able to provide information about the ongoing field research to onion growers, University Extension educators and faculty, and the public. Efforts to transfer knowledge about our research occurred primarily at the research field sites. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project involved mentoring a postdoctoral researcher who will focus on this research as a major component of her appointment. She has also been invited to give a talk about the results of the project at the Eastern Branch Meeting of the Entomological Society of America (EB-ESA) in March 2019. This experience will provide an excellent professional development and science communication opportunity. This project also involved mentoring a high school student during a summer internship and an undergraduate student during Cornell University's Summer Scholars Program. Both students were mentored in experimental design, sample collection and processing, insect identification, and organic agriculture. This projected supported a graduate student at University of Wisconsin who completed evaluations for pink root and Fusarium resistances in semi-glossy selections from the USDA onion breeding program. An undergraduate worker gained field experience with seed and bulb production of onion. How have the results been disseminated to communities of interest?The objectives of the project and research progress have been disseminated to onion growers, University Extension educators and faculty, and the public. Efforts to transfer knowledge about our research occurred primarily at the research field sites during site visits. Additional conference and Extension presentations, field visits, and workshops will occur in year two of the project. What do you plan to do during the next reporting period to accomplish the goals?Research plans for next reporting period include repeating the experiments from year 1 during year 2 at University research farms in NY and WI. Additionally, the best OMRI-listed products and thrips-resistant onion varieties for managing onion thrips and Stemphylium leaf blight in onions will be evaluated together in an experiment on a grower's farm in both states. Results of the project will be shared at the Northeast Organic Farmers Association of New York (NOFA-NY) Annual Winter Conference in January 2019, the Great Lakes Fruit and Vegetable EXPO in December 2018, and the Eastern Branch Meeting of the Entomological Society of America in March 2019. A field day is also being planned for the summer of 2019 with NOFA-NY to share the results of the research project to our stakeholders at our on-farm research site. The website of the Brian Nault Laboratory will be updated with results from year 1 of the project and general information on organic onion production, onion thrips, and Stemphylium leaf blight. There will be an international Allium symposium in Madison WI in July 2019, at which the team will have the opportunity to present research results to growers, processors, and researchers in the public and private sectors.

Impacts
What was accomplished under these goals? Objective 1: OMRI Thrips Trial (NY) - Nault OMRI-listed insecticides (4) and adjuvants (3) were evaluated for their combined effect on thrips and yield of 'Bradley' onions at a Cornell AgriTech research farm in Geneva, NY. The insecticides evaluated were spinosad, azadirachtin, azadirachtin + pyrethrin, and Isaria fumosorosea and an untreated control. The adjuvants were potassium (K) salts of fatty acids, neem oil, or terpene polymers. Applications were made weekly for 7 weeks and replicated 4 times. In situ counts of immature thrips were collected on 15 plants/plot each week. Onions were graded into four size classes (colossal, jumbo, standard, and boiler) for collecting yield data. Entrust co-applied with either M-Pede or Trilogy was the most effective insecticide + adjuvant combination for managing onion thrips in our trial. However, the combination of Entrust with these adjuvants did not have a similar benefit on onion yield. Neemix and PFR-97 co-applied with NuFilm provided some control of onion thrips; however, only Neemix had yields similar to Entrust. The use of Entrust with either M-Pede or Trilogy rotated with Neemix + NuFilm may be used effectively for onion thrips management in organic systems while maintaining resistance management programs. These products will be included in on-farm experiments in subsequent years of this project. OMRI Thrips Trial (WI) - Groves This trial was conducted at Crossroads Community Farm, WI. Four replicates of 16 foliar treatments and one untreated control were arranged in a RCBD. Each three-row plot measured 6 ft wide by 12 ft long. There were three weekly foliar applications applied with a CO2-pressurized backpack sprayer equipped with a four-nozzle 6 ft-wide boom fitted with flat-fan nozzles. Post-treatment thrips counts were obtained by counting the total number of thrips on 5 randomly selected plants from within each plot 2, 9, 14, and 21 days after first application (DAT). On 2 and 9 DAT, there were no differences in the number of thrips/plant. On 14 DAT, Entrust+M-Pede had significantly fewer thrips/plant compared to Venerate XC (2 qt/a) +NuFilm, Neemix+Trilogy, Azera+M-Pede, Azera+Trilogy, PFR-97 (2 lb/a)+NuFilm (8 fl oz/a), and the untreated control. There were no differences on 21 DAT. Examining the total number of thrips counts/plant over the season, Entrust+M-Pede had significantly fewer thrips than all other treatments except the other two Entrust treatments (Entrust+Trilogy and Entrust+NuFilm), and the two Venerate treatments co-applied with Neemix (Venerate XC (1 qt/a)+Neemix+NuFilm and Venerate XC (2 qt/a)+Neemix + NuFilm). The addition of M-Pede with Entrust numerically reduced the number of thrips/plant than the addition of NuFilm or Trilogy, which is similar to what was found in NY. OMRI SLB Trial (NY) - Hay, Pethybridge The trial consisted of 10 treatments (non-treated, eight OMRI listed products and one non OMRI-listed product) by three onion varieties (Ailsa Craig, Bradley and Avalon) arranged in a RCBD with four replicates of each treatment combination. The trial was located at the Cornell AgriTech, Geneva, NY. Applications of Entrust (8 fl oz/acre) and Trilogy (1%) were applied for thrips control on Jul 7 and Jul 13. Plants were inoculated with conidia of S. vesicarium on Jul 31 using a back-pack sprayer, with each plot receiving approximately 2.1 × 105 conidia. Fungicide treatments were applied with the wetter Nufilm-P at 0.5 pints/ac at six times using a CO2 back-pack sprayer equipped with a 38-in boom fitted with nozzles. Plots were assessed visually three times during the season for % leaf length blighted. On Oct 10, bulbs were graded by number and weight into boiler, standard, jumbo, colossal or cull size classes. Significant differences in S. vesicarium were apparent on 13 Sept with the non-OMRI listed product Oso, Badge X2, and Kocide 3000-O reducing disease compared to the control. On Sep 13, Bradley and Ailsa Craig had similar disease measurements, both significantly less than Avalon. This suggests Bradley may be less susceptible to SLB. Bradley has waxier leaves than Avalon, suggesting that leaf waxes are important in reducing SLB susceptibility. For fungicides other than Oso the mean incidence of S. vesicarium was high (>87.5%), irrespective of variety. However, for Oso, the mean incidence of S. vesicarium was high in Avalon (95.0%) and Ailsa Craig (82.5%), but substantially less in Bradley (62.5%). This suggested that the efficacy of Oso was higher when applied to a variety less susceptible to SLB. Despite differences in disease incidence and severity during the season, fungicide treatment had no significant effect on yield in comparison to the non-treated control. This suggested that none of the fungicide products were able to reduce S. vesicarium incidence or severity sufficiently to observe a yield response, or that factors other than SLB such as thrips pressure, were more important determinants of yield in this trial. In this trial, copper based products had some activity against SLB, and these are currently the only option for organic growers. Oso (FRAC 19) may also have a role in fungicide resistance management for conventional growers. Oso has labelled activity against several onion diseases including purple blotch, downy mildew, neck rot/leaf blight, and rust. Objective 2: This objective will be completed in years 2 and 3. Objective 3: Seed of an experimental hybrid (B5336AxB5351C) showing resistance to onion thrips for field evaluations. Inbreds W440 and W446 show resistance to the soil-borne diseases pink root and Fusarium basal rot; B5351 is susceptible to both diseases. W440 and W446 both have waxy foliage and are severely damaged by onion thrips; B5351 has semi-glossy foliage and suffers significantly less damage by onion thrips (Damon et al. 2014). Segregating F3 families were developed from the cross of W440 or W446 with B5351, and all families were screened for resistance to pink root and Fusarium basal rot. Families were also grown in the field and those with semi-glossy foliage visually identified. In 2018, F3 progenies from two segregating families with semi-glossy foliage were intercrossed to increase seed. One of these families (24384) showed 74% FBR resistance, 77% PR resistance, and bulbs with excellent storage ability and no doubles. The second family (24604) showed 92% FBR resistance, PR 51% PR resistance, and had good bulb quality after storage. In 2019, seed of these increases will be provided to for thrips evaluations, and evaluated for amounts and types of epicuticular waxes at the University of Wisconsin. Additionally, 219 F3 progenies were self-pollinated to produce F4 families which will be screened for resistance to PR and FBR, as well as for foliage waxes. In 2019, bulbs will be harvested from families showing relatively high levels of resistance to both soil-borne diseases and semi-glossy foliage; these will be intercrossed in 2020 to produce elite onion populations with resistances to FBR, PR, and onion thrips. Cytoplasmic male-sterile plants will be included with these selections to develop male-sterile lines for eventual hybrid development. Seed will be provided for final thrips evaluations in 2021. Onion cultivars (Avalon, Bradley, Rossa di Milano, and Ailsa Craig with low and high wax controls) used by in spray trials in NY were grown in WI and sampled for GCMS analyses of leaf waxes. All GCMS runs have been completed, and data is being analyzed. Objective 4: We provided information about the ongoing field research to onion growers, University Extension educators and faculty, and the public. Efforts to transfer knowledge about our research occurred primarily at the research field sites. The laboratory website (B. Nault) was updated with information about the project objectives. We also trained a post-doc, undergraduate student and high school student during the reporting year (see section below).

Publications

Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Marzu, J. C., E. Straley, and M. J. Havey. 2019. Genetic analyses and mapping of pink-root resistance in onion. J. Amer. Soc. Hort. Sci. (submitted July 18, 2018; accepted October 23 2018)