Tomato late blight confirmed in Wisconsin

Tomato late blight has been confirmed in western Dane County, Wisconsin. Dane County is located in the central southern part of the state.

University of Wisconsin pathologist Amanda Gevens’ lab is investigating:

“My lab will be working on the strain/genotype and will share as soon as more information is available,” Gevens said in a statement. “The lesions appear to be roughly one week-10 days old. Please note that this was first noted as possible sunscald as the symptoms on tomato fruit can appear to be dark brown, sunken, and ‘dry’ under some conditions. The tell-tale sign of late blight is the white sporulation growing in some areas of the lesions. This is the first confirmation of late blight on tomato or potato in Wisconsin for 2024.

“It is imperative to stop the pathogen from sporulating to reduce further spread and crop damage. To do this on small scale, infected tomato plants can be cut at soil line and placed into black plastic bags, tied, and left in the sun. This will solarize and kill the plant tissues and associated late blight pathogen. The bags can then be included with garbage for disposal to a landfill. Other options including removing the infected plants and plant parts and burning or burying in areas unintended for future garden or ag production.”

Earlier this summer, potato late blight was found in two commercial fields in St. Joseph County, Michigan.