Jul 24, 2024Potato Late Blight confirmed in Michigan
Potato late blight has been confirmed in a commercial field in St. Joseph County, Michigan marking the first detection of the disease in the area this year.
Dr. Amanda Gevens from the University of Wisconsin-Madison reported the presence of the US-23 genotype of the Phytophthora infestans pathogen on July 23. The disease was found in a small section, about 5 square feet, on the southwestern edge of the county, near the Indiana border.
US-23 can typically be managed with phenylamide fungicides, including mefenoxam and metalaxyl, said Dr. Jaime Willbur, assistant professor at Michigan State University, in a recent email sent out from Michigan Potatoes.
Rob Schafer of Mid-Michigan Agronomy quickly diagnosed and shared the information, allowing producers to take action to manage the disease.
Preventative foliar programs and diligent crop monitoring are strongly recommended. The current late blight risk in Michigan is low to medium, but recent heavy rain events have created favorable conditions for disease development, according to Willbur’s email.
Farmers are advised to stay vigilant and use late blight forecasting tools available through the UW-Madison Vegetable Disease & Insect Forecasting Network.
Willbur also noted that since early July, no other regional detections of the US-23 genotype have been documented in Michigan, though reports of potato and tomato late blight have come from Kent and Elgin counties in Ontario, Canada. No Phytophthora infestans DNA has been detected from experimental spore samplers in Montcalm County.
For more information on managing late blight, visit the USAblight website or contact the MSU Potato and Sugar Beet Pathology program at [email protected] or (517) 355-4754.
Suspected late blight detections can also be reported to MSU Plant & Pest Diagnostics at [email protected] or 517-355-4536.
