Botrytis fungicide-resistance survey for grape growers

Participate in a fungicide-resistance survey for Botrytis in grapes.

August 26, 2014 - Author: Annemiek Schilder, Michigan State University Extension, Department of Plant, Soil and Microbial Sciences

Grape growers rely on fungicides for management of Botrytis bunch rot, caused by the fungus Botrytis cinerea, which is a threat to fruit yield and quality. The number of effective fungicides for Botrytis is relatively limited since this fungus is not sensitive to many fungicides commonly used for most other fungi. Erosion of fungicide efficacy against B. cinerea due to fungicide resistance development has been observed in other crops and regions of the United States. For instance, multifungicide resistance is common in Botrytis on strawberries in the southeastern United States. This may not be surprising as strawberries have a long harvest season and receive as many as 20 fungicide applications per season. Usually, the more fungicide applications are made per season, the greater the risk of fungicide resistance development for those fungicides that are prone to it.

Determining the resistance profile of B. cinerea on grapes in Michigan will help assess the current status of sensitivity of B. cinerea to commonly used fungicides and will help Michigan State University Extension specialists formulate appropriate disease and fungicide resistance management programs. This will benefit growers in the long run by extending the effective lifetime of available fungicides and reducing losses due to poor disease control or money spent on fungicides that don’t work.

For this survey, we are looking for grape clusters or berries with sporulating Botrytis bunch rot from 20 vineyards (10 random clusters per vineyard). If you have Botrytis bunch rot and would like your vineyard to be included in the survey, please contact Jerri Gillett at or 517-355-7539 to arrange for the samples to be sent to our lab at MSU. If you participate, you will receive a full summary report on the fungicide resistance survey with data specific to your vineyard only identified to the grower who supplied the samples. Thanks in advance!

Dr. Schilder’s work is funded in part by MSU’s AgBioResearch.

Tags: agriculture, fruit & nuts, grapes, msu extension

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