Late blight found in potatoes in Michigan’s Montcalm County

Late blight was found in Michigan potatoes July 15, 2014. Conditions remain conducive for late blight in irrigated potato crops.

UPDATED JULY 16, 2014: The isolates from Montcalm County have been confirmed as US-23 by GPI isomerase testing. Mating type and ridomil sensitivity are underway.

Late blight was found in a potato crop near Edmore, Michigan in Montcalm County on July 15, 2014 by ABC Consultants scouts. Genotyping is currently underway and the source of the inoculum has not yet been found. The previous genotype found in LaGrange County, Indiana was US-23 and our initial lab experiments indicate that this is an aggressive isolate. Recommendations for late blight treatment remain the same as in previous reports posted at Michigan State University Extension, and include treating with one of the translaminar fungicides listed at the Michigan Late Blight Risk Monitoring website.

Conditions remain conducive for late blight in irrigated potato crops. Forecasts and disease severity value (DSV) accumulations can be checked daily at www.lateblight.org.

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

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