Source: N Y AGRICULTURAL EXPT STATION submitted to NRP
BUILDING RESILIENT FOLIAR DISEASE MANAGEMENT STRATEGIES FOR THE ORGANIC TABLE BEET INDUSTRY
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1020475
Grant No.
2019-51300-30246
Cumulative Award Amt.
$500,000.00
Proposal No.
2019-03050
Multistate No.
(N/A)
Project Start Date
Sep 1, 2019
Project End Date
Aug 31, 2024
Grant Year
2019
Program Code
[113.A]- Organic Agriculture Research & Extension Initiative
Recipient Organization
N Y AGRICULTURAL EXPT STATION
(N/A)
GENEVA,NY 14456
Performing Department
Plant Pathology and Plant Microbe Biology Section
Non Technical Summary
This is an Integrated (Targeted) research and extension project in New York (NY). NY is the center of table beet production in the United States for processing into cans/jars, snack foods and juices. Table beets are also popular for fresh market sales. The viability of the organic table beet industry is critically threatened by the lack of efficacious and sustainable disease management practices. The priority fungal diseases are Cercospora leaf spot (CLS; caused by Cercospora beticola), and Phoma leaf spot (PLS; caused by Phoma betae). These diseases deleteriously affect foliar health and defoliation makes harvesting by top-pulling machinery impossible resulting in crop loss. In conventional production, foliar disease management relies upon synthetic fungicides. Our goal is to identify components of an integrated disease management program of immediate benefit to organic farmers focusing on improved OMRI-approved seed treatments for P. betae control, OMRI-approved foliar sprays for CLS and PLS, cultivars with enhanced disease resistance, and UV-C for CLS control. Dissemination of findings is ensured through on-farm trials and collaboration with Cornell Cooperative Extension. Our project aligns with FY19/20 USDA-OREI program priorities: (1) and (6).
Animal Health Component
80%
Research Effort Categories
Basic
(N/A)
Applied
80%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21201991160100%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants;

Subject Of Investigation
0199 - Soil and land, general;

Field Of Science
1160 - Pathology;
Goals / Objectives
The long-term goal of this project is to ensure the sustainability and profitability of the organic table beet industry by implementing integrated disease management strategies for foliar diseases using immediately available knowledge for short-term practical solutions and optimization of UV-C for field deployment.1. Quantify the efficacy of OMRI-approved seed treatments for P. betae management, and OMRI-approved materials for CLS and PLS management in on-farm trials;2. Evaluate cultivar susceptibility to CLS and PLS to identify those with improved resistance;3. Optimize UV-C dosage for CLS control in table beet and evaluate performance on-farm; and4. Disseminate findings as integrated disease management strategies and provide decision making tools to farmers through a broad range of outreach methods.
Project Methods
Objective 1. OMRI-approved seed treatments for seedborne Phoma betaeand OMRI-approved materials for foliar disease management (Pethybridge, Taylor and Kikkert).The efficacy of OMRI-approved foliar sprays for CLS and PLS will be evaluated in on-farm trials. This trial will be conducted at two locations in each of two years. These field trials will also be established in organic, broad-acre table beet fields in western New York in 2020 and 2021. Trials will be established within the commercial field following planting and crop establishment when crop stand is evaluated for homogeneity to ensure plant population is not a confounding factor in the analysis of treatment. The experimental design for each trial will be a completely randomized block with five replications of each treatment. Treatments will be the nontreated control and four treatments. Each plot will be two rows wide (0.6 m between rows) and 6.1 m long rows separately by 3.1 m within rows, and two rows between blocks. Treatments will be applied with a carbon dioxide-pressurized backpack sprayer with four TeeJet 8002VS flat fan nozzles at an approximately volume of 250 L/ha. Products will be applied five times at 7 to 10 day intervals.CLS and PLS incidence and severity will be assessed at five, regularly spaced intervals throughout the season on each of 20 arbitrarily selected leaves. This data will be used to calculate temporal disease progress in each plot according to the area under the disease progress stairs (AUDPS). A hand-held multispectral radiometer will also be used to measure canopy reflectance in the near infrared range (830 nm) on the same day as the disease severity assessments. Yield components will be quantified according to the protocol described for trial 1a to provide data on dry foliage weight, root weight, and root shoulder diameter.Objective 2: Table beet cultivar susceptibility to CLS and PLS (Pethybridge and Kikkert).These small-plot, replicated trials will be conducted on organic-certified land at the field research facilities of Cornell AgriTech at The New York State Agricultural Experiment Station, Geneva, New York.The susceptibility of up to ten table beet cultivars to infection by local populations of P. betae and C. beticola will be assessed in each trial. The trials will be physically separated as CLS epidemic progress is likely to be more rapid than PLS which may compromise our results for the latter disease. We will include cultivars of known susceptibility from our previous studies (Rhonda, Ruby Queen, Merlin [organic industry standard and highly susceptible to both diseases], and selected others based on conversations with seed companies and industry stakeholders for suitability for organic production. For example, Bejo has several cultivars reported as less susceptible to CLS: Bresko, Manolo, Boro, and Bohan. All cultivars will be established from organic and/or untreated seed as available. Each trial will be planted using an identical, randomized block design and cultivars replicated five times. A plot will consist of two rows (76 cm between rows) each 4.6 m long. Two buffer rows of cv. Ruby Queen will separate plots among rows and a 1.5 m unplanted buffer area established between plots within rows. The trial will be established with a Monosem vacuum planter at an in-row planting density of 30 seeds/m.The entire areas of each trial will be inoculated with isolates representative of the New York populations of P. betae and C. beticola at around 40 DAP when plants have approximately 6 to 8 true leaves. In-row plant density, and PLS and CLS incidence and severity will be evaluated in each plot. In-row plant density counts (number of plants/m) will be conducted at 25 to 30 DAP following stabilization of plant stands. Disease incidence and severity will be evaluated on 20 arbitrarily selected leaves from each of two rows (20 leaves per plot) as described in Objective 1. Disease assessments will be made five times throughout the season and epidemic progress calculated using AUDPS. Trials will be harvested by hand (~ 85 to 90 DAP). Plants will be removed from two 0.5 m sections within each plot and separated into foliage and roots. The fresh and dry weight of foliage will be calculated, fresh weight of roots recorded, and a subsample of 20 roots randomly selected from each plot for measurement of shoulder diameter (Objective 1).Objective 3. Optimize UV-C dosage for CLS control in table beet and test on-farm (Pethybridge, Gadoury, Rea, Radetsky, and Kikkert)In vitro. We will expose C. beticola conidia and mycelia to varying quantities of UV-C (100 to 1,500 J/m2). We will collect conidia by culturing isolates of clarified V8 agar medium and incubating at room temperature for 6 days with a photoperiod of 12 h of white fluorescent light. Conidia will be harvested by flooding the plates with 5 ml of sterile distilled water, dislodging the spores using a sterile glass spreader, and passing the suspension through three layers of sterile cheesecloth. Aliquots of the conidial suspensions will be transferred onto 3% water agar (WA) plates and exposed to UV-C. Five replicates of each isolate and dose combination will be evaluated.In planta. The goal of the in planta experiments is to identify the optimal time for UV-C application and the efficacious of different doses on C. beticola fecundity, CLS severity, and leaf area. Table beet cultivar Merlin plants will be grown in the greenhouse with organic production practices from seed and inoculated when 7 to 8 weeks old (3 to 6 true leaves) with a conidial suspension prepared as described above, using a hand-held spray bottle. Two doses of UV-C from the in vitro studies will be used (one low; 200 J/m2 and one high; 1,250 J/m2): (i) pre-inoculation; (ii) post-inoculation (24 h); (iii) at early disease development (1 CLS lesion per leaf); and (iv) sporulation (pseudostromata and conidia visible in lesions). Nontreated and noninoculated controls will also be included in the experiment. Five replicate plants will be included for each treatment and the entire experiment will be repeated twice.Phytotoxicity. We will evaluate the potential for phytotoxicity from UV-C within in planta trials in five cultivars popular amongst organic growers, including those showing enhanced resistance to CLS from trials in Objective 2. Ten replicate plants will be exposed within each cultivar at various growth stages ranging from seedling, 4 to 8 true leaves, 10 to 12 true leaves, and 18 to 20 true leaves, representing different crop development stages.Field studies. The goal of this study is to apply the findings from the in vitro and in planta trials to the field and design the fabrication of a UV-C dosing apparatus to be built and operated by organic farmers. As in several other funded studies, the LRC will work closely with the farmers to design and engineer a prototype mobile UV-C field unit that will provide the prescribed dose from the laboratory studies and can connect to the farmer's tractor. The farmers will build the unit from commercially available UV-C equipment under the direction of LRC staff. This trial would take place in an organic field identified in collaboration with Love Beets USA in the second year of the study.Objective 4. Extend research findings... (All Team Members).Wewill synthesize information for farmers, to include both efficacy in disease control and cost-effectiveness. Findings will be disseminated through innovative content delivery and engage farmers in the projects with experiential learning activities in visits to the on-farm trials. Guides will be developed to the technical aspects of disease management in organic table beet production.

Progress 09/01/19 to 08/31/24

Outputs
Target Audience:The target audience reached throughout this project were organic vegetable growers that include table beets in their rotations and conventional table beet growers considering shifting to organic production to meet exponential growth in demand. The organic table beet processors (Love Beets USA, and associated growers) that purvey the roots into value added products were highly engaged in this project. The Love Beets USA factory is located in Rochester, NY, but sources organic table beet roots from across the United States, including growers in CO, TX, GA, OH, IL, WI, MN, and eastern Canada.Organic table beet growers in these states (and NY) received updates on findings from this project magnifying our reach and impact.Each year, the stakeholder advisory panel met twice (~November/December and April/May) to review the project findings and directions for the next cropping season, including advice on treatments within the trials. The stakeholder advisory panel consisted of 10 growers, extension educators, and industry purveyors. These growers also provided access to their crops for sample collection, monitoring, and on-farm trials. Some members of the stakeholder advisory panel also visited the research farm trials in July/August of each year, to discuss how the efficacious treatments could be evaluated on a broader scale on their farms. Results and outcomes were disseminated to the stakeholder advisory panel and broader grower communitythrough multiple avenues including factsheets, extension commodity presentations, and research articles. Over the entire project, approximately 1,000 growers were reached in these various formats, over 50% of which participated in presentations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has provided agraduate student (Pratibha Sharma) with training and professional development in organic agriculture and vegetable production. They were involved in all objectives of the research. The student presented their researchat the International Congress of Plant Pathology Conference (Lyons, France; August 2023), Plant Health 2023 (Pittsburgh, PA; August 2023), Plant Health 2024 (Memphis, TN; August 2024), and APS Northeast Division Meeting (2023). The expected date for the student's graduation is May 2025. A Post Doctoral Research Associate was also supported partially on this project in Years 2 and 3. The experience they gained in fungalidentification and applied plant pathology research and extension enabled them to secure a position as Senior Extension Associate at the Long Island Horticulture Research and Extension Center in vegetable pathology. How have the results been disseminated to communities of interest?Results have been disseminated to the communities of interest and target audience through our multimodal extension and outreach program within Objective 4.We also engaged our advisory group on a regular basisto ensure our research and treatment selection (where relevant) was of practical significance, and to ensure our extension messages were targeting the most effective venues. Results were highlighted at presentations at grower conferences in the Northeast region (NY, PA, and New England) which reached over 500 participants. A foliar disease guide and regular research updates were also published in the Cornell Cooperative Extension publication, VegEdge (distributed to over 200 growers weekly) each year.Several extension bulletins/disease fact sheets were prepared and provided in English and Spanish. These are available for free download from the Cornell Vegetables website. In the final two years of the project, we also regularly conducted foliar evaluationsof organic table beet crops with management suggestions that were publishedin the Cornell VegEdge weekly newsletter. These recommendations were combined with monitoring of our CLS forecasting program in organic table beet production (also published weekly in Cornell VegEdge). These recommendations were published in newsletter format and growers voluntarily also received a personal text update. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objective 1a. Seedborne disease research. Experiment 1 -Phoma betae. Initial research documented the mycoflora associated with 38 commercial organic table beet seed lots using plate testing. The incidence of P. betae in the seed lots was further quantified by plate testing and PCR. Nearly half (45.7%) of the seedlots had no detectable P. betae. Of the seed lots in which P. betae was detected, incidence varied between 0.7% and 3.7%, but between 9.3% and 9.7% in seed lots that were nontreated and rejected for commercial sale. The mean incidence of P. betae in infested seedlots was 3.2%. The incidence of P. betae estimated by plate tests was positively correlated with the number of sub-samples testing positive by P. betae by PCR. Small plot, replicated field trials were conducted in each of two years at two locations. The trials were conducted with two cultivar seedlotsand for each cultivar, two seedlots were used. One of the seedlots for each cultivar consisted of seed rejected for commercial sale due to a high incidence of P. betae, and the other with no detectable P. betae. Treatments applied to the seed were different OMRI-approved boron and copper treatments. Each seed treatment was replicated four times within each of the four cultivar/seedlots.The number of roots was significantly increased by an average of 117.4% in plots established with seed treated with OMRI-listed copper and copper+ boron, and not different from each other.Total root weight and average root weight was not significantly affected by seed treatment. The incidence of root decay was also significantly reduced by seed treatment (<1%) compared to nontreated plots (18.8%), and not significantly different between treatments. This research has been resubmitted to Annals of Applied Biology. Experiment 2-Cercospora beticola. In seed plate testing, the fungus, Cercospora beticola(cause of Cercospora leaf spot (CLS)) was also found to be at high incidence in over 75% of the organic table beet seed lots. Seed-to-seedling transmission of C. beticolahas been reported.We evaluated the localization of C. beticola in table beet seed and contribution of infested seed to CLS epidemics in field studies. In seed dissection experiments, C. beticola was more frequently isolated from the pericarp and operculum compared to the true seed. Field trials in Geneva and Freeville, New York (NY) showed significantly higher CLS incidence, severity, and epidemic progress in plots established from the infested seed lot than those from the noninfested lot. Cercospora beticola populations collected from infested seeds and field plots were genotyped using 11 microsatellite loci. The infested seed lot population exhibited high genotypic diversity, mating type equilibrium, and linkage equilibrium, suggesting random mating. Field populations showed mixed mating types and microsatellite linkage patterns, indicating a mixed mode of reproduction. Two clonal lineages of C. beticola were identified. Populations from infested seeds and infested seed lot plots grouped into cluster 1, while cluster 2 contained populations from noninfested seed lot plots. The background population in NY was dominated by a few multilocus genotypes and genetically distinct from the infested seed lot population. Our findings highlight the potential of C. beticola-infested seed to serve asprimary inoculum. This information can shape management strategies to reduce the impact of seedborne inoculum of CLS in organic table beet production. This research has been submittedto the journal, Plant Disease. Objective 1b. Foliar disease control.Small-plot replicated field trials were conducted in each year of this project to evaluate the efficacy of OMRI-listed products for CLS and PLS control. For PLS control,LifeGard, Cueva and Double Nickel significantly reduced PLS severity compared to nontreated control plots, and were not significantly different between each other. These products showed consistently moderate reductions in disease severity. For CLS control, Double Nickel + Cueva was also highly efficacious and significantly decreased final CLS severity and AUDPS by 94.3% and 88.8%, compared to the nontreated control, respectively. LifeGard, Cueva and Double Nickel (each applied alone) provided moderate control. These results were published in Plant Disease Management Reports in each year of the project and presented at all extension events to our target audience. Objective 2. Cultivar susceptibility to CLS and PLS. The susceptibility of selected table beet cultivars (Bohan, Bresko, Manolo, Pablo, Red Cloud, Ruby Queen, Subeto, and Bazzu/Irazu) and suitability for organic production were evaluated in glasshouse experiments and small plot-replicated trials.Bohan wasmoderately and highly susceptible to CLS and PLS, respectively. Bresko was moderately susceptible to CLS, and among the least susceptible to PLS. Manolo was one of the least susceptible toPLS but highly susceptible to CLS. Pablo and Red Cloud were moderately or highly susceptible to both diseases. Subeto was moderately susceptible to CLS but the least susceptible to PLS. Ruby Queen, the processing standard, was the least susceptible to PLS, and moderately susceptible to CLS. Bazzu and Irazu (2021 and 2022, respectively) were among the least susceptible to PLS and the only cultivars tested with reduced CLS susceptibility. These findings emphasize the need to evaluate table beet cultivar susceptibility to the spectrum of foliar diseases. This information may underpin cultivar selection based on the varying importance of diseases in specific production situations.Growers from our stakeholder advisory panel also trialled the most promising of these cultivars (Bazzu/Irazu) with decreased susceptibility to CLS on their own farms in large plots (~20-30 acres) compared to the organic standard with similar susceptibility results and favorable root yields and quality. Some adjustments had to be made to harvesting equipment because the tops of the plants of the newer cultivars were overly healthy! Objective 3: UV-C control of CLS.We evaluated the efficacy of nighttime applications of UV-C for suppression of CLS in table beet. In vitro lethality of UV-C to germinating conidia increased with increasing dose, with complete suppression at 1,000 J/m2. Greenhouse-grown table beet tolerated relatively high doses of UV-C without lethal effects despite some bronzing on the leaf blade. A UV-C dose >1,500 J/m2 resulted in phytotoxicity severities greater than 50%. UV-C exposure to ≤750 J/m2 resulted in negligible phytotoxicity. Older (6-week-old) greenhouse-grown plants were more susceptible to UV-C damage than younger (2 and 4-week-old) plants. Suppression of CLS by UV-C was greater when applied within 6 days of C. beticola inoculation than if delayed until 13 days after infection in greenhouse-grown plants. In field trials, there were significant linear relationships between UV-C dose and CLS control and phytotoxicity severity, and a significant negative linear relationship between phytotoxicity and CLS severity at the final assessment. Significant differences between UV-C doses on the severity of CLS and phytotoxicity indicated an efficacious dose near 800 J/m2. Collectively, these findings illustrate significant and substantial suppression by nighttime applications of UV-C for CLS control on table beet, with potential for incorporation in both conventional and organic table beet broadacre production systems. Objective 4. Dissemination of research findings. As detailed earlier, ~1,000 growers were reached over this project through our multi-modal extension programming. A final stakeholder advisory panel meeting has also been conducted in which the feedback on integration of foliar sprays and less susceptible cultivars for organic table beet production could be immediate. The panel was also strongly interested in the development of the UV-C research to reduce the dependence upon foliar sprays.

Publications

  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Pethybridge, S. J., Rea, M., Gadoury, D. M., Murphy, S. P., Hay, F. S., Skinner, N. P., and Kikkert, J. R. 2023. Nighttime applications of germicidal ultraviolet light (UV-C) to suppress Cercospora leaf spot in table beet. Plant Dis. 108:2518-2529.
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2024 Citation: Sharma, P., Murphy, S. M., Kikkert, J. R. and Pethybridge, S. J. 2024. Susceptibility of table beet cultivars to foliar diseases in New York. Plant Health Progr. 25: 399-409.
  • Type: Peer Reviewed Journal Articles Status: Published Year Published: 2025 Citation: Sharma, P. S, Murphy, S. P., Kikkert. J. R., and Pethybridge, S. J. 2025. Evaluation of foliar fungicides for Cercospora leaf spot management in table beet in New York. Crop Protection 188:107028.
  • Type: Other Status: Published Year Published: 2024 Citation: Pethybridge, S. J., Sharma, P., Murphy, S., Simangunsong, R., and Kikkert, J. R. 2024. Efficacy of fungicides for Cercospora leaf spot control in table beet, 2023. Plant Dis. Manage. Rep. 18:V022.
  • Type: Other Journal Articles Status: Submitted Year Published: 2025 Citation: Sharma, P. S., Murphy, S. P., Kikkert, J. R., and Pethybridge, S. J. 2024. Role of infested seed as primary inoculum for Cercospora leaf spot epidemics in table beet. Plant Dis. PDIS-12-24-2624-RE. Submitted 11 December 2024.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Sharma, P., Branch, E., Murphy, S., Kikkert, J. R., and Pethybridge, S. J. 2024. Residue management as an alternative to manage Cercospora leaf spot of table beet and its effect on the soil microbiome. Proc. APS-North East Division Meeting, Ithaca, NY. Pp. 11. 6 March 2024.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Sharma, P., Murphy, S., Kikkert, J. R., and Pethybridge, S. J. 2024. Role of infested seed as a primary inoculum source in Cercospora leaf spot epidemics in table beet. Proc. APS Annual Meeting, Memphis, TN. Phytopathology. Technical Session.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2024 Citation: Pethybridge, S. J. 2024. Building resilient foliar disease management strategies for the organic table beet industry. USDA NIFA Organic Programs Project Directors Meeting Abstracts. Pp. 10.


Progress 09/01/22 to 08/31/23

Outputs
Target Audience:The target audience reached during this project period were organic vegetable growers that include table beets in their rotations and conventional table beet growers considering shifting to organic production. Table beet industry stakeholders (personnel of companies that receive and process organic table beets) were also reached and engagedin multiple ways including as members of the stakeholder advisory panel providing advice on experimental design and treatments, land and crops for on-farm trials, and giving feedback on the results and findings of the project. The stakeholder advisory panel, consisting of 10 growers, extension educators and industry personnel, met twice during this period (December 2022 and April 2023). Stakeholders also visited the trials personally during July 2023. Results have been distributed through multiple avenues including factsheets, extension commodity presentations, and research articles. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?In this reporting period, the graduate student received training in conducting a small plot replicated training evaluating the efficacy of OMRI-listed products (Objective 1b) and quantifying the efficacy of trade-offs of using UV-C for CLS control (Objective 3). The graduate student was also involved in all aspects of our extension and outreach activities (Objective 4). The student was able to present parts of this research at the International Congress of Plant Pathology Conference (Lyons, France; August 2023). How have the results been disseminated to communities of interest?Results have been disseminated to the stakeholder advisory panel (organic table beet growers and industry stakeholders) in a broad range of formats. Evaluations of the health of organic table beet crops throughout the 2023 cropping season were published in the Cornell VegEdge weekly newsletter with recommendations and links to our results from Objective 1b. Results from our CLS forecasting program in organic table beet production were also published on a weekly basis supporting the in-seasoncontrol recommendations. These recommendations were published in newsletter format but growers also received a personal text on a weekly basis to facilitate rapid disease management decisions. Moreover, recommendations surrounding cultivar selection based on disease resistance were also discussed with the stakeholder advisory panel and individual growers directly summarizing the results of Objective 2. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, results from all objectives will be compiled for the communities of interest. Four scientific publications are being prepared for submission to journal articles (one each from objectives 1a, 1b, 2, and 3). This information will also be rephrased to reach organic table beet growers in extension presentations and factsheets. We will also present an overview of the results to our stakeholder advisory panel, and continue discussions to expand the findings of objective 3 (UV-C foliar disease control) to the next stages for larger unit deployment for use by organic table beet growers.

Impacts
What was accomplished under these goals? Activities undertaken in 2022/23 were approved under the no-cost extension. Objective 1a. OMRI-approved seed treatment research was completed in 2021. Objective 1b. A small-plot replicated trial was conducted to evaluate the efficacy of selected OMRI-listed pesticides for the control of Cercospora leaf spot. The trial had 12 microbial biopesticides and plant defense activators. The trial was inoculated with a mycelial suspension of selected C. beticola isolates representing the genotypic diversity of NY populations. Treatments were applied four times at 7-day intervals. Results identified several microbial biopesticides, including Theia and Howler, that provided moderate control of CLS. Copper hydroxide (as Champ) provided excellent CLS control. This is the third year that copper hydroxide has been identified as a superior product and equivalent to several of the fungicides with site-specific modes of action. Given the high prevalence of resistance to single site mode of actions fungicides, including the strobilurins, the inclusion of copper hydroxide in the foliar disease program will be beneficial for both organic and conventional growers. The information obtained from this trial will form the basis of our extension recommendations for organic table beet growers that will be discussed in extension presentations and summarized in factsheets. The results will also be submitted to the technical journal, Plant Disease Management Reports in November 2023. Objective 2. Work within this objective was completed in 2022. Objective 3. In 2023, a small plot replicated trial was conducted to evaluate the reproducibility of the CLS control obtained with UV-C. Promising results were again obtained and the efficacious dose was identified as 750 Watts/m2, providing CLS control equivalent to moderately effective fungicide without incurring yield-limiting phytotoxicity. Results from the field trials and in vitro studies performed in the first two years of this project will now be combined for an article to be submitted to the journal, Plant Disease. Results have also been discussed with the stakeholder advisory panel, after visits to the field trial. There is considerable enthusiasm from stakeholders to extend this technology to a broad-acre reality. We are discussing the next steps to achieve this objective with the project team. Objective 4. Results were presented to members of the stakeholder advisory panel (twice throughout this reporting period) and to the broader vegetable community. We estimate a reach of approximately 150 growers and industry stakeholders.

Publications

  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Heck, D. W., Sharma, P., Kikkert, J. R., and Pethybridge, S. J. 2023. Sampling, a new iOS application for assessment of damage by diseases and pests using sequential sampling plans. Plant Dis. 107:1714-1720.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Saif, M. S., Chancia, R., Hassanzadeh, A., Pethybridge, S. J., Murphy, S. M., and van Aardt, J. 2023. Forecasting table beet root yield from spectral and textural features from hyperspectral UAS imagery. Remote Sensing 15:794.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Branch, E. B., Pethybridge, S. J., Murphy, S. M., and Kikkert. J. R. 2023. Efficacy of fungicides for control of Rhizoctonia damping-off and root rot in table beet, 2022. Plant Dis. Manage. Rep. 17:V026.


Progress 09/01/21 to 08/31/22

Outputs
Target Audience:The target audiences reached during this period were current organic table beet growers and those considering growing in the subsequent season to meet exponentially increases in demand. The organic table beet processors that purvey the roots into value added products were also highly engaged in this project. Love Beets USA (located in Rochester, NY) is the predominant processor of organic table beets in the United States and sources roots from multiple states (CO, FL, TX, GA, VA, MN and WI). Organic table beet growers in these states (in addition to those in NY) also received updates on findings from this project enhancing our reach and impact.The direction of the project and results were reviewed by the project advisory group (consisting of 10 growers, extension educators, and purveyors) met twice during this reporting period(December 2021 and April 2022). Personnel from Love Beets and Seneca Foods also visited the trials personally during July 2022. The project was also featured at annual research and extension commodity events (January 2021) organized by Cornell Cooperative Extension and the Mid-Atlantic Vegetable and Fruit Convention (Hershey, 2022). Changes/Problems:A no-cost extension on this project was granted until 31 August 2023 to allow for the COVID delays at the start of the project and to concentrate on extension of the findings to communities of interest. What opportunities for training and professional development has the project provided?The Graduate Student received expert training in plant pathology and agronomy, organic production, conducting field trials, and extension and outreach techniques. They also presented research on fungicide efficacy for CLS control at the Plant Health 2022 conference (Pittsburgh, PA; August 2022). How have the results been disseminated to communities of interest?Results from this project have been connected to the organic table beet growers and purveyors, and organic vegetable growers in the region. We have engaged our advisory group at 6- monthly intervals to ensure our selection of treatments are highly relevant to production and would be easily adoptable if shown to be efficacious. We have also participated and presented results at the Mid-Atlantic Fruit and Vegetable Convention (Hershey, PA) which attracts organic vegetable growers from across the region. Several extension bulletins were prepared and provided in English and Spanish. What do you plan to do during the next reporting period to accomplish the goals?The next reporting period for this project is a no-cost extension to concentrate on extension of results to the communities of interest (scientific audience through journal articles; and organic growers through a broad range of extension programming). We will also provide a final overview of the results to the project advisory meeting to assist in identifying future directions for our organic table beet research.

Impacts
What was accomplished under these goals? Objective 1a. OMRI-approved seed treatment research was completed in 2021. Results from 2020 and 2021 are now being combined for a journal article and extension materials for a diverse audience. Objective 1b. A small-plot, replicated trial was conducted to evaluate the efficacy of OMRI-listed materials for CLS and PLS control. In addition, two demonstration style on-farm trials were conducted with collaboratoring organic growers at North Rose, and Clarence, NY. The small plot trial contained a broad range of OMRI-listed copper products and several microbial biopesticide and plant defense activators. The trial was inoculated with mycelial suspensions ofCercospora beticolaand products were applied three times at 14-day intervals. Disease incidence and severity was assessed at six intervals throughout the growing season and harvest was conducted in the first week of September by removing plants and separating foliage and roots to quantify yield components. Results from this trial will form the basis of our extension messages for 2022-23. The on-farm trial at North Rose identified an-OMRI listed product (FungOut) that the grower reported excellent foliar disease control. The field at Clarence will be harvested in October and the OMRI-listed program will be compared to a nontreated control by evaluating disease incidence and severity. In addition, two trials have not been conducted to evaluate the efficacy of OMRI-listed products for the control of Phoma leaf spot and root decay. This information is awaiting publication in the journal, Plant Diseasehttps://doi.org/10.1094/PDIS-11-21-2506-RE. Objective 2. The second year of evaluating cultivar susceptibility to PLS and CLS has now been completed. This small-plot replicated trial was harvested in the second week of September. The trials contained the same 10 red table beet cultivars newly emerging from private and public table beet breeding programs. These trials were inoculated with the respective pathogens (Phoma betaeandCercospora beticola) and disease incidence and severity evaluated on six regular occasions throughout the cropping season. Yield components were also evaluated that were of relevance to the grower (foliage architecture and biomass; root number, weight, diameters, sugar content). Results from the two years of trials will be combined and analyzed for submission as a journal article and results included in extension outputs. Objective 3. Two years of small plot replicated trials have now been conducted to evaluate the efficacy of UV-C on CLS. Five different doses (identified from in plant and in vitro trials) were identified and applied at night with UV-C lights on a wagon. Preliminary analysis has identified that doses of 500 to 750 Watts/m2 are optimal for CLS control and do not incur substantial phytotoxicity. Results from this objective over the two years of trials will be combined and analyzed for submission as a journal article and results included in extension outputs. Objective 4. In this reporting period, we developed extension bulletins on the important diseases affecting organic table beet production in English and Spanish, to assist in diversifying the outcomes of our project. Results were also presented to the table beet advisory board and purveyors of organic table beet. We estimate direct contact with approximately 300 growers, while extension bulletins and resources have been placed on websites so they are freely available for download and distributed at events.

Publications

  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Heck, D. W., Kikkert, J. R., Hanson, L. E., and Pethybridge, S. J. 2021. Development of a sequential sampling plan using spatial attributes of Cercospora leaf spot epidemics of table beet in New York. Plant Dis. 109:2453-2465.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Sharma, S., Kikkert, J. R., Heck D. W., Branch, E. A., and Pethybridge, S. J. 2022. Cercospora leaf spot of table beet. Disease Lesson. The Plant Health Instructor 22: 10.1094/PHI-P-2022-02-0101.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Spanner, R., Neubauer, J., Heick, T. M., Grusak, M. A., Hamilton, O., Rivera-Varas, V., Hamilton, O., de Jonge, R., Pethybridge, S. J., Webb, K. M., Leubner-Metzger, G., Secor, G. A., and Bolton, M. D. 2022. Seed-borne Cercospora beticola can initiate disease in sugar beet (Beta vulgaris L.). Phytopathology 112:1016-1028.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J., Murphy, S., Hay, F. S., Branch, E. B., Sharma, P., and Kikkert, J. R. 2022. Control of Phoma leaf spot and root decay of table beet in New York. Plant Dis. Just Published 15 June 2022.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Pethybridge, S. J., Sharma, P., Murphy, S., and Sharma, S. 2022. Efficacy of fungicides for Cercospora leaf spot control in table beet, 2021. Plant Dis. Manage. Rep. 16:V039.
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J. 2022. Cercospora leaf spot. Chenopodiaceae Chapter in World Handbook of Vegetables.
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J. 2022. Black leg. Chenopodiaceae Chapter in World Handbook of Vegetables.
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J. 2022. Bacterial leaf spot. Chenopodiaceae Chapter in World Handbook of Vegetables.
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J. 2022. Aphanomyces root rot. Chenopodiaceae Chapter in World Handbook of Vegetables.
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2022 Citation: Pethybridge, S. J. 2022. Southern root rot. Chenopodiaceae Chapter in World Handbook of Vegetables.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Sharma, P., Murphy, S., Kikkert, J. R., and Pethybridge, S. J. 2022. Fungicide based control of Cercospora leaf spot in table beet. Plant Heath 2022 Meeting. Abstract.


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

Outputs
Target Audience:The target audiences reached during this period were organic table beet and mixed vegetable farmers across New York. Vegetable farmers and beet growers in neighboring states and Wisconsin were also reached through our communication of results. The project advisory group met twice during this period to review results (December 2020 and March 2021) to discuss results and plan trials for 2021. The project was also featured at annual research and extension commodity events (January 2021) organized by Cornell Cooperative Extension. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The Post Docoral Research Associate employed partially on this project received training in plant pathology and agronomy, conducting field trials, and trouble-shooting in the construction and deployment of the UV-C wagon. They also gained experience in preparing extension bulletins and presenting their findings to a scientific audience remotely through attendance of the online Plant Health 2021 conference. How have the results been disseminated to communities of interest?The results of this project have been disseminated to the communities of interest including the advisory group at regular (6-monthly) meetings and vegetable growers and industry stakeholders throughout NY and the Northeast region (including Wisconsin, which also grows table beets), reaching over 200 participants. Four new extension bulletins were published in the Cornell Cooperative Extension publication, VegEdge (distributed to over 200 growers weekly). What do you plan to do during the next reporting period to accomplish the goals?Objective 1 (a and b). Research results will be compiled from the last two years and prepared for submission to a scientific journal. Objectives 1 and 2. This research will also be combined and used to form the basis of the third year combination treatments in demonstration style plots for organic growers. Objective 3. Results will be discussed with the project team, repeated in 2022, and determined if sufficient data is present to deploy to larger on-farm demonstration plots with a larger machine. Objective 4. We will continue to disseminate our researching findings to the communities of interest including on-farm trials, additional research bulletins, field inspection of trials, and regional and local extension meetings. The advisory committee for this project will also be regularly engaged (December and March). Impact of the project will be evaluated through summative and formative assessments as described in the proposal.

Impacts
What was accomplished under these goals? Objective 1a (Year 2). A small-plot replicated field trial was again conducted to evaluated the efficacy of OMRI-approved seed treatments on damping-off and root disease and decay caused by the fungus, Phoma betae, and table beet populations. The trial was conduted with two cultivar seedlots (Ruby Queen and Kestrel). These seedlots had been rejected for commercial sale because of the high incidence of P. betae and obtained through our seed industry partners on the advisory group for this project. Our laboratory tests found an incidence of P. betae of around 20% in each seedlot. The trial was planted on 15 June and included three boron and copper treatments and compared to a nontreated control for each cultivar. Regular assessments of plant population and foliar disease incidence and severity have been made. This trial will be harvested in late September. At this time, the weight of foliage and roots will be quantified. Roots will also be measured using digital calipers and the incidence of root disease assessed at harvest and following storage for 8 weeks. The effect of cultivar seedlot of treatment will be evaluated with a two-way analysis of variance. Objective 1b. OMRI-approved foliar disease control for CLS. A field trialwas conducted at Cornell AgriTech in Geneva, New York. The crop was planted on 20 May using a Monosem planter at the rate of 17 seeds/ft with 30-in. row spacing. Treatments (n = 5) were arranged in a randomized complete block design with four replications, including a nontreated control. The trial was irrigated as necessary using solid set sprinklers for optimal plant growth and disease development. Plots consisted of 10-ft sections of two adjacent rows, with a nontreated buffer of 5-ft between plots within rows. Two nontreated rows separated adjacent plots. Fungicides were applied using a CO2-pressurized backpack sprayer (15.9 gal/A; psi = 30), with three TeeJet 8002VS flat fan nozzles spaced 19 in. apart along a 38-in. boom. Fungicides were applied at 53, 61, 68, and 75 DAP. A backpack sprayer was used to apply an inoculum suspension (4.1 × 103 viable cfu/ml) at 65 and 66 DAP, containing a mixture of eight Cercospora beticola isolates representative of the New York genotypes. Plant density was assessed at 19 DAP by counting the number of plants in a 3.2-ft section within each row. Cercospora leaf spot (CLS) severity (%) was quantified by estimating the area of the leaf covered by disease compared to the entire leaf area on 20 arbitrarily selected leaves within each plot (10/row) at 47, 63, 71, 78, and 85 DAP, and used to calculate epidemic progress (area under the disease progress stairs; AUDPS). At 85 DAP, the normalized difference vegetative index (NDVI) was measured using a GreenSeeker hand-held radiometer by scanning the entire length of one row, 3.2-ft above the canopy. At 92 DAP, the effect of treatment on foliar biomass was evaluated by removing foliage from plants within a 3.2-ft section of each plot and recording weight after drying at 140ºF for 48 h. The effect of fungicides on average CLS severity at 85 DAP, AUDPS, NDVI, root number and weight, and dry weight of foliage was analyzed using a generalized linear model. Means for each variable were separated by a Fisher's protected least significant difference test at P = 0.05 (Genstat Version 17.2). Final CLS severity in nontreated plots was of moderate intensity with an average of 64.4%. Plant density was not significantly different across the trial at 19 DAP (P = 0.267) and varied between an average of 23 and 29.4 plants per 3.2-ft section. Root number at 92 DAP was not significantly affected by treatment (P = 0.861). Treatment also had no significant effect on root weight (P = 0.784). All treatments significantly reduced CLS severity at 85 DAP and AUDPS. Four applications of Double Nickel + Cueva was also highly efficacious and significantly decreased final CLS severity and AUDPS by 94.3% and 88.8%, compared to the nontreated control, respectively. Four applications of LifeGard provided moderate CLS control and final CLS severity was six times higher than plots receiving only Double Nickel + Cueva. The separation of treatments based on NDVI were also reflected in the dry weight of foliage. The dry weight of foliage was also significantly higher than the nontreated control plots in all other treatments except for the LifeGard and Double Nickel + Cueva rotation and those receiving only LifeGard. OMRI-approved foliar disease control for PLS. A second field trial was also conducted to evaluate a range of OMRI-approved products for the control of PLS. The trial was established in the same manner as for the CLS trial outlined above, and inoculated with 1,500 conidia/ml of five P. betae NY isolates with a backpack sprayer. As in the first year of this trial, LifeGard, Cueva and DoubleNickel significantly reduced PLS severity compared to nontreated control plots, and were not significantly different between each other for PLS control. The trial will be harvested in late September 2021. Objective 2. Cultivar susceptibility to CLS and PLS. Two replicated field trials were conducted with eight selected red table beet cultiars to evaluate their susceptibility to CLS and PLS. The cultivars were selected with on advisory group member, Bejo Seeds.The trials were inoculated with C. beticola and P. betae NY isolates at around 40 DAP and disease severity was evaluated five times throughout the season. Both trials will be harvested to evaluate yield components in early October 2021. Objective 3. UV-C based control for CLS. A field trial was conducted to evaluate the efficacy and safety of five selected UV-C dosesat Cornell AgriTech, Geneva. To deliver the UV-C doses, a field wagon was designed and constructed in collaboration with the team from Mt. Sinai Lighting Research Center. The dose was varied according to the duration of the exposure to UV-C based on a sensor within the wagon. UV-C doses were applied (in the early evening) on eight different occasions following inoculation of the trial with C. beticola isolates from NY. Disease incidence and severity (and phytotoxicity) were evaluated on five different occasions. This trial will be harvested in late September 2021 to evaluate the effect of dose on yield components including root quality. Objective 4. Disseminate research fndings. In this reporting period, results were presented at two advisory group meetings, a vegetable extension meeting, and five different extension bulletins. Overall, we estimate a reach of approximately 250 growers and industry stakeholders. The results will be combined across years for preparation into scientific manuscripts to reach this audience as well.

Publications

  • Type: Other Status: Published Year Published: 2021 Citation: Pethybridge, S. J., and McGrath, M. T. 2021. FIFRA 2(ee) recommendation for control of the unlabeled pest Cercospora leaf spot of table beets. Double Nickel LC. EPA Registration 70051-107. New York State Department of Environmental Conservation. Division of Materials Management Pesticide Product Registration. Accepted 12 March 2021.
  • Type: Journal Articles Status: Under Review Year Published: 2021 Citation: Sharma, S., Kikkert, J. R., Heck D. W., Branch, E. A., and Pethybridge, S. J. 2021. Cercospora leaf spot of table beet. Disease Lesson. The Plant Health Instructor Accepted with revisions 17 January 2021. R2 submitted 10 May 2021.


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

Outputs
Target Audience:The target audiences for this research in this reporting period include organicorganic growers including table beet farmers across New York, and field and vegetable crop farmers in the Northeast and other regions with similar precipitation patterns. The research team has had regular engagement with the advisory group including table beet farmers, organic vegetable farmers, extension educators, andindustry stakeholders. This group met at project initiation (November 2019), March 2020, and will meet in December 2020 to discuss results from Year 1. The broader vegetable grower community has also been informed of the research and preliminary findings at annual research and extension commodity events in collaboration with Cornell Cooperative Extension with additional events planned for winter 2020/21. Results from these studies will also be communicated to the scientific community in presentations and scientific journal articles prepared in Year 2. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The Post Doctoral Research Associate employed partially on this project received advanced training in fungal identification, agronomy, planning and conducting field trials, phylogenetics, and plant pathology. They also gained experience in public presentation of their findings to a local scientific audience through a campus-wide seminar, and the distilling of information to appropriate target audiences through extension bulletins and extension presentations (see products listed). How have the results been disseminated to communities of interest?Selected organic table beet and broad-acre vegetable growerswere engaged through hearing of results and providing advice on treatments and direction, and practical aspects for implementation of results, at the six-monthly advisory group meetings held in 2019 and 2020. This included summaries of results that were presented to members of the advisory group. Initial results have also been highlighted at presentations at grower conferences in the Northeast region (NY and PA) which reached over 200 participants. A foliar disease guide was also published in the Cornell Cooperative Extension publication, VegEdge, which is distributed to over 200 growers weekly. What do you plan to do during the next reporting period to accomplish the goals?Objective 1a. Additional OMRI-approved table beet seed treatments are being refined over winter 2020/21 within in vitro and glasshouse trials to enable the selection of treatments for a small-plot replicated field trial and demonstration-style trial on organic farms in the 2021 cropping season (as planned). Objective 1b. Two replicated field trials will be conducted to evaluate the reproducibility of the OMRI-approved treatments identified as efficacious for PLS and CLS control in table beet (as planned). Objective 2. The field trial conducted in Year 1 evaluating cultivar susceptibliity to PLS and CLS will be repeated in Year 2. Moreover, these results are also being evaluated in greenhouse trials over winter 2020/21 (as planned). Objective 3. Our collaborators of the Lighting Research Center at Rensselaer Polytechnic Institute continue to build a tractor-mounted lighting array with specifications suited to broadacre table beet production capable of providing doses suitable for disease control and reducing potential phytotoxicity for deployment in field trials in 2021. Objective 4. We will continue to disseminate our research findings throughout the next reporting period including on-farm trials, an additional two research bulletins for organic growers and distributed through eOrganic, one field day in summer (if allowed by COVID-state regulations), at regional and local extension meetings, and the beet advisory committee for this project (held every six months; March and December 2021).The impact of the project will also be evaluated through formative and summative assessments.

Impacts
What was accomplished under these goals? Objective 1a: Efficacy of OMRI-approved seed treatments (Phoma betae).For the seed treatment research, asmall plot, replicated field trial wasconducted. The trials were conducted with two cultivar seedlots (cv. Ruby Queen and Pablo) and for each cultivar, two seedlots were used. One of the seedlots for each cultivar consisted of seed rejected for commercial sale due to a high incidence of P. betae. The other seedlot of each cultivar had no detectable P. betae. Treatments applied to the seed were different OMRI-approved boron and coppertreatments applied as either a seed soak or treatment.A nontreated control was also included for each cultivar within each trial. The incidence of P. betae and other fungi and seed germination in plate tests was evaluated within 10 days of treatment application and 22 to 30 days prior to planting. The trial was establishedwith a single row Jang JP-1 push seederat a within row spacing of 5.1 cm and 76 cm between rows. Supplemental irrigation by overhead sprinklers (5 mm/h) was provided to optimize crop growth as required. Plotsconsisted of a single 1.52 m long row separated by an unplanted 0.6 m between plots within rows. The randomized complete block experimental design in each of the trials was identical. Each seed treatment was replicated four times within each of the four cultivar/seedlots. Table beet plant populations were assessed by counting all plants within the entire plots at two occasions after emergence. The severity of PLS was also assessed at mid-season on two occasions.To confirm the association of PLS lesions with P. betae, 30 symptomatic leaves were randomly selected along a diagonal transect across the entire trial (15 from cv. Pablo and 15 from cv. Ruby Queen) on the same day as the disease severity evaluations were conducted in each year.The effect of treatment on table beet yield components was assessed by digging all plants within each plot. Plants were removed and separated into foliage and roots by hand. The weight of foliage was recorded after drying at 60ºC for 48 h. Roots were also counted, weighed and shoulder diameter using digital calipers.In addition, 20 roots were randomly selected from each plot and placed in a paper bag at 7.2°C following harvest. Roots will be removed in 4 weeks and evaluated for the presence of decay and boron deficiency, and isolations conducted. The effect of cultivar seedlot and seed treatment will be assessed as a two-way analysis of variance with replicate as a random effect. Least squares means (P = 0.05) will be used to separate significant treatments. Objective 1b: OMRI-approved foliar disease control (CLS and PLS). Two small-plot, replicated trials were conducted to evaluate the efficacy of OMRI-approved products for Cercospora leaf spot (CLS) and Phoma leaf spot (PLS).For CLS, the experiment was conducted at Cornell AgriTech,Geneva, New York. Treatments (n = 3) were arranged in a randomized complete block design with four replications, including a nontreated control andapplied using a CO2-pressurized backpack sprayer (16.8 gal/A), with three TeeJet 8002VS flat fan nozzles spaced 19 in. apart along a 38-in. boom. Fungicides were applied at 46, 56, 66, and 76 DAP. A backpack sprayer was used to apply an inoculum suspension (1.32 × 104 cfu/ml) at 48 DAP, containing a mixture of eight Cercospora beticola isolates representative of the New York genotypes. CLSseverity (%) was quantified by estimating the area of the leaf covered by disease compared to the entire leaf area on 20 arbitrarily selected leaves within each plot (10/row) at 41, 62, 68, 77, and 80 DAP, and used to calculate epidemic progress (area under the disease progress stairs; AUDPS). The effect of fungicides on average CLS severity at 80 DAP, AUDPS,and dry weight of foliage was analyzed using a generalized linear model. Means for each variable were separated by a Fisher's protected least significant difference test at P = 0.05 (Genstat Version 17.2). CLS severity in nontreated plots was high at 80 DAP with an average of 76%. All treatments significantly reduced CLS severity at 80 DAP and AUDPS. Final CLS severity and AUDPS were not significantly different between plots receiving the LifeGard, Cueva, and Double Nickel. These products were also tested for their efficacy to control PLS in a separate replicated trial. Inoculum (1,000 conidia/ml) of five selected P. betae isolates was used to inoculate the trial on the same day as for CLS. Disease assessments were made on the same days and in the same manneras that described above for CLS. PLS severity was significantly reduced by all three treatments (LifeGard, Cueva, and Double Nickel) and was not significantly different between them. Objective 2. Cultivar susceptibility to CLS and PLS. A replicated trial to evaluate the susceptibility of nine different table beet cultivars to PLS and CLS across three different planting dates was conducted on the farm of our co-operator, Bejo Seeds at Geneva, NY. Rows of each of the cultivars at each planting date were inoculated with liquid inoculum of each pathogen (Phoma betae and Cercospora beticola for PLS and CLS, respectively). Disease severity assessments were conducted 22 and 45 days after inoculation by evaluating ten arbitrarily selected leaves within each plot. There was significant variation in the susceptibility of cultivars to PLS and CLS which was consistent across the planting dates. For example, cultivar Pablo had significantly higher PLS and CLS than the other cultivars. One cultivar (Irazu) was identified that had significantly reduced PLS and CLS compared to the currently industry standard cultivars. Objective 3. UV-C based control for CLS. Several experiments were conducted to optimize and identify the UV-C dose for controlling CLS in table beet. In vitro experiments using conidial germination and mycelial growth consistently identified 600 J/m2 as optimal to prevent conidial germination with no significant differences in response across multiple and mixed C. beticola isolates. Experiments were also conducted to evaluate the phytotoxicity of a broad range of UV-C doseases across table beet cultivars. Plants of five cultivars (also used in Objective 2) were grown in the greenhouse (10 reps per cultivar). Ten replicate plants of each cultivar were exposed to the same range of UV-C doses (10 to 1000 J/m2) used for the in vitro experiments evaluating effects on conidial germination and mycelial growth. At the optimal dose identified for pathogen toxicity (600 J/m2) there was some phytotoxicity to table beet seedlings (4 to 8 true leaves; and 10 to 12 true leaves) identified in the form of necrosis on leaf edges. These plants are being evaluated to determine whether the phytotoxicity is lethal or plants are able to withstand the damage and continue growth without detriment. In preparation for field trials in 2021, our collaborators at the Lighting Research Center at Rensselaer Polytechnic Institute have been evaluating the practical aspects of broadacre table beet production to ensure the tractor-mouted lighting array due to be deployed in field trials fits the agronomic specifications of the farming system. Objective 4. Disseminate research findings. The goals and objectives of this project have been presented to our target audience over the first cropping season. Findings to date will continue to be disseminated through winter meetings over 2020/21 and future years within our vegetable extension meetings and extension newsletters, and direct discussions with our advisory group. In this reporting period, results were presented at two grower meetings (NY and PA), and published in two extension bulletins within the grower newsletter, Cornell VegEdge, distributed to over 400 growers weekly. Overall, through these venues, we have reached over 600 growers in this reporting period.

Publications