Recipient Organization
N Y AGRICULTURAL EXPT STATION
(N/A)
GENEVA,NY 14456
Performing Department
Plant Path/Plant Microbe Biol.
Non Technical Summary
New York is ranked second forapple production in the United States, producing approximately 29.5 million bushels annually. However, apple scab,caused by the fungal pathogen Venturia inaequalis, is one of the most economically important diseases affecting apple, which causes dark brown, scabbylesions on the fruit and leaves ofapple andresults in unmarketable fruit. In the absence of durable resistance, fungicide applications are the primary means of management, and as many as ten applications may be required per season in cool, wet climates. Two major consequences of this high fungicide input include negative environmental impacts and development of fungicide resistance. Scientific research is needed to ensure these impacts are minimized. Therefore, objective 1 aims to understand how the dose of fungicide application affects selection for resistance in orchard populations. To understand this relationship, field studies will be conducted where two different doses (high and low) of a single fungicide will be applied over the course of the growing season and subsequent fungicide sensitivity of resulting Venturia inaequalis populations will be evaluated. This will inform us of the application dose most appropriate to recommend for grower use in order to maintain longevity of these fungicides. Furthermore, objective 2 aims to increase sustainability of fungicide applications through evaluating more integrated management strategies that rely partially on biologically-derived products rather than solely on conventional chemicals. The goal of this objective is to incorporate more environmentally-friendly products in a management regime with modern horticultural practices and disease forecasting. To evaluate the commercial feasibility of this strategy, field studies integrating biological products with conventional products will be evaluated in comparison to a solely conventional fungicide program in the context of tree architecture and disease forecasting. Disease incidence data will be taken to understand control differences between the conventional and integrated program. Taken together, these experiments will contribute to more sustainable agriculture using safer practices, impacting not only apple growers but also consumers. Ideally, these findings may extend beyond apples and to all perennial crops necessitating considerable fungicide inputs.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
0%
Goals / Objectives
The goal of this project is to better understand development of antimicrobial resistance (AMR) and how we can maintain effective tools in disease management in an integrated manner using a whole systems approach with biological control and horticultural practices. Altogether, this will contribute to effective and sustainable disease management for years to come.Objective 1:Determine the effect of fungicide application dose on resistance development and establishment within an apple orchard: This objective aims to see the cumulative effect of continuous fungicide application using either a high or a low dose of the SDHI fungicide, fluxapyroxad, on fungicide resistance development in the apple scab pathogen,Venturia inaequalis.To evaluate this in a field setting, a. fungicide applications are made each season, b. isolates are collected from the field, c. samples are isolated from leaves, d. fungicide sensitivity assays are completed, and f. data is analyzed. For a second approach as a backup to address the same objective in case results are inconclusive, we will conduct a similar study in a controlled lab environment using repeated application of the SDHI fungicide, benzovindiflupyr on the causal agent of grey mold, Botrytis cinerea, inoculated on detached grapes. This experiment will follow similarsteps as above.Objective 2:Develop an integrated management program using contemporary horticultural practices,disease forecasting, and biopesticides as an alternative to environmentally unsafe broad-spectrum fungicides: This objective aims to combine the super spindle planting architecture, disease forecasting, and the highly effective SDHI fungicides to develop a management plan where biological controls could be used to replace broad spectrum fungicides like captan and mancozeb which have potentialoff-target effects.We hypothesized that by taking advantage of smaller tree canopies, we can effectively replace broad spectrum fungicides with biopesticides, while using single-site SDHI fungicides during critical infection periods as predicted by forecasting models.To evaluate this in a field setting, a. fungicide applications need to be made each season, b. disease ratings will be performed, c. isolates are collected and processed, d. fungicide sensitivity testing is completed, and e. data is analyzed.Objective 3:Disseminate research results to growers to develop innovative fungicide management programs to address challenges of antimicrobial resistance development and new production paradigms.Through understanding practices that decrease selection for AMR as well as decrease reliance on broad-spectrum fungicides, growers can more sustainably manage fungal diseases. Dissemination and incorporation of these research outcomes into growers' management programs will help ensure sustainable production of apple with off target effect. This will be done through presentation to growers at both formal and informal meetings.
Project Methods
Obj.1:Determine the effect of fungicide application rate on fungicide resistance development.1A:This experiment will continue to be carried out in two research orchards in Geneva, NY, with cultivars consisting of Jersey Mac, Empire, and Jonagold apples. These orchards have a history of consistent, high natural apple scab inoculum each year. With the start of each growing season in accordance with infection periods, four applications of the perspective treatments will be made (Table 1) in a repeated measures (years) randomized complete block design with four replicates. After the final application has been made, approximately 15-20 apple scab lesions will be collected from each replicate for a total of approximately 60 lesions per treatment. Lesions will be extracted from leaves as previously described (Villani and Cox 2014). Each isolate will be subject to conidial germination sensitivity assays using the SDHI fungicide fluxapyroxad, on 10x the previously determined EC50 value (Ayer et al., 2019). Conidial relative growth assays will be conducted as previously described (Villani and Cox 2014). Data will be analyzed using linear mixed models with repeated measures. Isolates with a relative growth exceeding 100% will be further investigated for mutations in the target gene conferring resistance. DNA will be extracted, and the VisdhB gene will be amplified via polymerase chain reaction (PCR) as previously described (Villani et al., 2016). Amplicons will be sequenced at Cornell's BRC sequencing facility and data will be analyzed in CLC workbench for the presence of a single nucleotide polymorphisms.Table 1. Fungicide, commercial product, and rate used for each treatmentTreatment 1: Untreated ControlTreatment 2: Fluxapyroxad (26.55%) at a rate of 7 fl. oz/ATreatment 3: Fluxapyroxad (26.55%) at a rate of 3.5 fl. oz/A1B:An isolate ofB. cinerea, previously determined to be sensitive to the SDHI benzovindiflupyr and lacking the documented H272Y/R mutation, will be used to inoculate across all three treatment groups. Each treatment group will have four replicates with 10 grapes per replicate. After inoculation with 106B. cinereaspores, each treatment will be sprayed with their perspective treatments (Table 2). Approximately seven days after inoculation, grapes will be rated for both incidence and severity and resulting mycelium will be plated on agar until sporulation occurs. Spores will be collected and diluted to 106 spore*ml-1. Strains will be repeatedly exposed to SDHI at their perspective rates on treated grapes over successive generations following recovery from and reinoculation to grapes. After each generation is complete, sensitivity assays will be performed to a previously determined discriminatory dose of benzovindiflupyr. Mycelial growth will be measured on each agar plate and relative growth will be determined as described above and results will be analyzed in linear mixed model analyses. When a reduction in sensitivity is observed in a treatment group, sequencing will be completed as described above, and results will be analyzed in CLC workbench for the presence of the H272Y/R mutation.Table 2.Fungicide, commercial product, and rate used for each treatment.Treatment 1: Untreated ControlTreatment 2: Benzovindiflupyr (9.63%) at a rate of 8.6 fl. oz/ATreatment 3: Benzovindiflupyr (9.63%) at a rate of 10.5 fl. oz/AThis experiment will be conducted out in two different research orchards in Geneva, NY both composed of 'Gala' apples trellised to a 'vertical axis' or 'super spindle' over the course of two years. The perspective treatments will be applied at the start of the season and continue throughout the summer. Programs following a calendar timing will be applied every 7-10 days usingBacillus subtilisor captan and mancozeb, with a benzovindiflupyr application every third time until the maximum of four benzovindiflupyr applications per season are used. Programs on a disease forecasting schedule will be treated withBacillus subtilisor captan and mancozeb during low risk infection periods, and an application of benzovindiflupyr will be used when a severe infection period is predicted (Table 3). Disease ratings for both incidence and severity will be taken every week on fruit and leaves to create disease progress curves to analyze epidemics in all treatments. To understand differences in disease ratings between 'super spindle' and 'vertical axis' trellising, weather stations will be affixed to the inside of the tree canopy on each cultivar and will collect leaf wetness data throughout the season. Leaf wetness data will be analyzed in the context of apple scab infection periods. Further, at the end of the season, lesions will be collected and isolated as described above. Conidial germination relative growth assays will be conducted for the SDHI fungicide, benzovindiflupyr as described above to understand how precision application timing of SDHIs using disease forecasting affect development of AMR.Obj.2: Develop an integrated management program using contemporary horticultural practices, disease forecasting, and biopesticides as an alternative to environmentally unsafe broad-spectrum fungicides.Table 3.Fungicide program, application timing, and trellis system usedTreatment 1: Untreated contolTreatment 2: Captan and Mancozeb rotated with benzovindiflupyr during infection periods applied using disease forecastingTreatment 3:Captan and Mancozeb rotated with benzovindiflupyr using calendar timingTreatment 4: B. subtilis rotated withbenzovindiflupyr during infection periods applied using disease forecastingTreatment 5:B. subtilis rotated withbenzovindiflupyrusing calendar timingObj.3: Disseminate research results to growers to develop innovative fungicide management programs to address challenges of AMR and new production paradigms.After completion of objectives one and two, it will be essential to disseminate information to growers and industry stakeholders to achieve transition to practice. Results would be distributed through extension publications such as Cornell's 'Scaffolds' and the 'NY Fruit Quarterly', as well as grower's conferences such as the ENY Winter Fruit School and the Lake Ontario Winter Fruit Schools. Results would also be shared through visits to grower's orchards during the Lake Ontario Petal Fall Meetings. Success would be measured through both contact hours with growers as well as using Qualtrics surveys or Poll Everywhere which is routinely conducted at the winter fruit schools to understand how growers will incorporate these changes to their management plans.