Late blight confirmed in St. Joseph County, MI.

Willie Kirk, Rob Schafer, Sandesh Dangi, Raechel Bayma, Paula Somohan and Noah Rosenzweig, Michigan State University Extension, Department of Plant, Soil and Microbial Sciences -

Recommendations for treatment remain the same at this time and include application of a listed translaminar fungicide.

Late blight was confirmed in a potato crop near the Indiana border in St. Joseph County on Aug. 5, 2013. Genotyping is currently underway. The source of the inoculum has not yet been found. The previous genotype found in Allegan County was US-23 and our initial lab experiments indicate that this is an aggressive isolate.

In Wisconsin last week, Dr. Amanda Gevens confirmed the presence of US-8 from a potato field along with other reports of US-23 appearing at new locations. This was confirmed by GPI allozyme analysis. Recommendations for treatment remain the same as in previous reports and include treating with one of the translaminar fungicides listed on the Late Blight Risk Monitoring website.

Conditions remain conducive for late blight in irrigated potato crops. Forecasts and DSV accumulations can be checked daily at the Late Blight Risk Monitoring website.

Dr. Kirk’s work is funded in part my MSU’s AgBioResearch.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

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