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Research Project: Interregional Surveillance of Spinach and Lettuce Downy Mildew in California to Improve Management Practices - Coachella Valley

Location: Crop Improvement and Protection Research

Project Number: 2038-22000-019-022-A
Project Type: Cooperative Agreement

Start Date: Nov 1, 2020
End Date: Apr 30, 2023

California produces nearly 75 percent of the fresh market spinach and lettuce in the United States. It is costly to routinely apply fungicides to prevent establishment of downy mildew disease in these crops, especially when disease only manifests under specific environmental conditions. With limited resistant varieties, improving disease management strategies is imperative, and thus insights on spore loads at various locations in California is necessary for improved management and judicious fungicide usage. Therefore, the objectives of this current proposal are to: 1) multiplex two current detection assays into one for dual pathogen detection in a single reaction; 2) determine levels of downy mildew pathogens in different growing regions (Salinas, Imperial, and Coachella Valleys) of California; and 3) develop disease risk models using the information from spore trapping for Salinas, Imperial, and Coachella Valleys to guide fungicide application in a forecast system.

We will deliver and deploy two spore traps at two sites in each of the Salinas, Coachella and Imperial Valleys of California. USDA will coordinate repairs of spore traps with collaborators at each location. Collaborators will ship spore trap samples to USDA-ARS in Salinas, California for analysis. Quantitative PCR will be conducted in Salinas, California, to determine the quantities of each the downy mildew pathogens present. Neighboring fields of each spore trap sites will be monitored for the downy mildew incidence by USDA-ARS and the collaborators. Weather parameters will be collected from commercially and publicly available sources and correlated with pathogen quantities and disease incidence over time by linear regression.