August 9: Late Blight was Detected on Potato Plants in a Commercial Field in Presque Isle
By I. Kutay Ozturk, Ph.D., Assistant Extension Professor of Potato Pathology, University of Maine Cooperative Extension
Presque Isle – On August 9, 2024, late blight was detected on a few potato plants in a commercial field in Presque Isle. We recommend 5-day spray schedule given the weather that is coming in. All growers should be utilizing full rates of protectant fungicides, consider shifting towards excellent-rated protectants. For those growers that are off-schedule, consider utilizing products containing cymoxanil, which will provide some reachback. Those nearby Presque Isle may consider utilizing antisporulants such as products containing Triphenyltin hydroxide. Growers should be carefully scouting fields for signs of late blight. Strain identification is in progress.
The pathogen strain has been identified as US-23. This strain should be sensitive to mefenoxam fungicides such as Ridomil.
Thanks to Dr. Zachariah Hansen and Jason Ingram (USDA-ARS, Cornell University) for assistance with strain identification.
Late blight information for every home gardener in Maine can be found on Extension’s Potatoes’ Late Blight Gardener Alert page.
University of Maine Cooperative Extension
About University of Maine Cooperative Extension: As a trusted resource for over 100 years, Extension has supported UMaine’s land and sea grant public education role by conducting community-driven, research-based programs in every Maine county. UMaine Extension seeks to build thriving communities and grow the food-based economy, focusing on aspects from production and processing to nutrition, food safety and food security. Extension also conducts the most successful out-of-school youth educational program in Maine through 4-H which offers hands-on projects in areas like health, science, agriculture and civic engagement and creates a positive environment where participants are encouraged to take on proactive leadership roles.