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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Research Project #441250

Research Project: Enhancing Virus Control in Lettuce and Melons by Optimizing Immunity Priming Approaches

Location: Crop Improvement and Protection Research

Project Number: 2038-22000-020-006-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Nov 24, 2021
End Date: Jun 30, 2024

Virus outbreaks in lettuce and cantaloupe routinely occur at vector densities well below those causing damage to crops through direct feeding, i.e., a small number of insects can initiate widespread infection, often before succumbing to chemical controls. Despite this, virus issues are driving increases in prophylactic applications of insecticides that pose high risks to human, aquatic, and terrestrial animal health (methomyl, EPA draft BE 2020) or pollinators (dinotefuran, imidacloprid, and thiamethoxam, CA DPR & CalEPA). Therefore, new IPM strategies are needed to reduce the frequency of virus infections and/or attenuate virus impacts on yields without increasing use of high-risk insecticides. One way to achieve this is by improving the innate virus immune response of existing lettuce and melon cultivars. Immunity priming agents that activate different defense systems are commercially available as labelled fungicides for various specialty crops, but remain underexplored as tools for virus management, especially in lettuce and cantaloupe. The project will identify elicitors, doses and application times for improving virus immunity in lettuce and cantaloupe. Effective active ingredients will be integrated with reduced risk insecticides and compared with grower standard, high-risk products for both crops for field efficacy and cost effectiveness. We will provide a model for expanding use of immunity priming to other specialty crops by taking a comparative approach in two crops with similar challenges.

Objective 1: Factorial greenhouse experiments to screen varying doses of elicitors (pesticides section) for efficacy in protecting key cultivars of lettuce from Impatiens necrotic spot virus (INSV) and cantaloupe from Cucurbit yellow stunting disorder virus (CYSDV), Cucurbit chlorotic yellows virus (CCYV), and Cucumber mosaic virus. Products with protective effects will be further screened to optimize application timing for prolonged protective effects. We expect to identify at least 1-2 products that prevent or attenuate virus infections in each crop. Objective 2: Integrate the top two priming products for each crop with reduced risk insecticide application programs and evaluate outcomes for virus prevention, attenuation, and crop yields. Field trials will be performed in the Salinas Valley (lettuce) and San Joaquin and Imperial Valleys (melon). Methods will employ a split plot design with grower standard (high risk) and alternative (low risk) insecticide treatments as main plots, and priming treatments (product 1, product 2, and no priming) as subplots. We will document virus incidence, symptom severity, and vector densities prior to and after deployment of treatments. Crop yield and quality will also be evaluated. We will then estimate the economic costs and benefits of low-risk insecticides + immunity priming virus management strategies relative to grower standard, high-risk insecticide practices.