Hello,
I write to share that late blight on potato was confirmed this afternoon in St. Joseph’s County, Michigan. This is in the southernmost row of counties in MI on the southwestern edge, bordering Indiana. The genotype of the Phytophthora infestans pathogen was US-23. The disease was noted in a very small section of a commercial field (~5 sq. ft). Recall that US-23 can typically still be managed with phenylamide fungicides including mefenoxam and metalaxyl. Thank you to Rob Schafer of Mid-Michigan Agronomy for quickly working on this diagnostic and sharing the information so that producers in the region can take enhanced action to manage this disease.
Information to understand late blight:
https://vegpath.plantpath.wisc.edu/diseases/potato-late-blight/
Information to manage late blight:
https://vegpath.plantpath.wisc.edu/documents/
Scroll to access our A3422 Commercial Vegetable Production in Wisconsin – 2024 guide or the 2024 Fungicide listing for potato late blight in Wisconsin.
As a reminder, my lab (contact info below) and the UW Plant Disease Diagnostic Clinic https://pddc.wisc.edu/ offer late blight diagnostics at NO COST. My lab will work to determine the genotype or clonal lineage.
Regards,
Amanda
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Amanda Gevens
Chair, Professor & Extension Specialist
Administrative Director of the Wisconsin Seed Potato Certification Program
Fritz Friday Chair for Vegetable Production Research
Plant Pathology Department
1630 Linden Drive Room
University of Wisconsin-Madison
Madison, WI 53706
gevens@wisc.edu/608-575-3029
Potato & Vegetable Pathology Research and Extension
https://vegpath.plantpath.wisc.edu/
