Potato late blight confirmed in Michigan

Michigan State University’s Department of Plant, Soil and Microbial Sciences has confirmed potato late blight in Clinton County, Michigan.

The samples came from a home garden plot. Clinton County is located in the central region of the state’s lower peninsula.

Typical water-soaked lesions with gray, fuzzy undersides were observed (see photos at right) and Phytophthora infestans sporangia were confirmed. Genotype testing was in progress as of Oct. 2.

In Michigan, most commercial potato fields are either undergoing harvest or have been vine-killed to prepare for harvest. However, late-planted fields with green canopies may still be at risk for infection.

This summer, late blight was confirmed in several neighboring areas, including 14 counties in Wisconsin, 10 counties in New York and nine counties in Pennsylvania. All tested isolates were determined to be the US-23 genotype of P. infestans. Late blight was also reported in Tennessee, North Carolina, Florida and Washington.

Visit the USA Blight Outbreak Map for more details.

Contact MSU Potato and Sugarbeet Pathology at 517-355-3863 to report potential late blight detections or visit the MSU Extension website for more information.