Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-045-069-A
Project Type: Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Dec 31, 2029
Objective:
Blossom blight and fruit rot caused by Botrytis spp. present significant challenges to blueberry production in the Pacific Northwest. Growers are increasingly concerned about how to design fungicide spray programs that minimize the risk of control failures associated with emerging multi–fungicide resistant Botrytis populations. To address this issue, we will:
1. Evaluate the fitness of field isolates of Botrytis harboring distinct sdhB mutations and exhibiting multi fungicide resistance, and
2. Assess the efficacy of selected biofungicides against field isolates of Botrytis with different sdhB mutations and multi fungicide resistance profiles.
Approach:
We will conduct a series of in vitro, in planta, and detached-fruit assays using a diverse collection of Botrytis isolates obtained from blueberry fields in Washington and Oregon. The specific mutations in each isolate associated with resistance to various fungicide classes have already been characterized. We will evaluate the fitness of fungicide resistant mutants by assessing their growth rates, sporulation, production of sclerotia, and their capacity to infect blueberry flowers and fruit. In addition, we will examine competitive interactions between fungicide sensitive and fungicide resistant isolates. A subset of both sensitive and resistant isolates will be exposed to multiple biofungicides to determine whether these materials provide effective control, particularly against fungicide resistant Botrytis populations.