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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Research Project #436605

Research Project: Development and Mitigation of Powdery Mildew Fungicide Resistance on Table Grape Production in California

Location: Crop Diseases, Pests and Genetics Research

Project Number: 2034-21220-007-25-T
Project Type: Trust Fund Cooperative Agreement

Start Date: May 1, 2019
End Date: Apr 30, 2020

Objective:
Objective 1: To evaluate efficacy of different fungicides to control Erysiphe necator on table grapes and to develop spray program with reduced risk of fungicide resistance development. Objective 2: Determine the distribution and development of fungicide resistant isolates on table grape.

Approach:
Fungicide spray trial on table grapes to be conducted by University of California Cooperative Extension. ARS will collect bi-weekly samples of powdery mildew isolates for molecular testing of fungicide resistance and diversity. Powdery mildew isolates will be collected from grapevines tested with treatments 1 through 6 in 2019 and 2020. Isolates will be collected from symptomatic leaves every 1-2 wks from each treatment prior to fungicide application starting with the 30 cm shoot spray. Single colonies will be collected using a cotton swab or tough dot and placed into 1.5 mL microcentrifuge tubes. Approximately 30-100 colonies from each treatment will be collected depending on disease severity. Collected colonies will be returned to the lab for qPCR and sequencing analyses and storage.