New Late Blight Strain Identified

Published online: Aug 27, 2018 Articles, Fungicide
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Source: Potato News Today

According to Amanda J. Gevens, associate professor and extension vegetable plant pathologist with the University of Wisconsin's Department of Plant Pathology, a new late blight strain, US-25, has recently been identified in New York. Gevens says this strain has, to this point, been found only on tomato. In a weekly newsletter, she says that Christine Smart, a professor at Cornell University, has been keeping extension and research pathologists informed of this new type, which is now known to be mefenoxam-resistant and of the A2 mating type. Smart reported that under lab conditions, US-25 will infect potato as well as tomato. Gevens says that “all samples tested from the Great Lakes region in the U.S., including Wisconsin, Illinois and Michigan to date, have been US-23. The Minnesota tomato late blight finding from several weeks back was not genotyped.”

Outside of the Great Lakes region, late blight detections have been made this season in Florida, North Carolina, New York, Pennsylvania and Washington. While US-23 (mefenoxam-sensitive and A1 type) has been most predominant, US-8 has re-emerged in Washington, and this new US-25 type has emerged in New York, according to the researchers.

For more information about the new US-25 type, and information about late blight in the Great Lakes region, please contact Christine Smart ( or Amanda Gevens (