Jul 19, 2019

Late blight detected in central Wisconsin, southern Washington

Late blight has been confirmed in a potato field in central Wisconsin.

Testing done by University of Wisconsin-Madison showed late blight from a field sample from Wood County, associate professor and Extension specialist Amanda Gevens disclosed July 17.

“Late blight on potato has been confirmed in Wood County (on July 17),” Gevens said in a statement. “We have a sample on campus in UW-Madison Vegetable Pathology and my technician will type this first thing in the morning so that we have an understanding of the clonal lineage (strain), and likely character and mefenoxam (metalaxy-Ml) resistance status. Sporulation was present but light on most leaves. Lesions were quarter-sized on upper leaves.”

Late blight also was present in Wisconsin during both the 2017 and 2018 growing seasons.

Late blight can attack both potato and tomato fields and spreads quickly. Symptoms of late blight on potato and tomato leaves and stems typically appear as somewhat large, dark, oily areas, sometimes with a lighter border.

Columbia Basin

The pathogen also has been detected near Pasco, Washington. Scientists are encouraging growers in the region to treat their fields with fungicide every seven days.