Tomato plants infected with late blight have been found in Portage County–a major potato growing area of Wisconsin. Late blight can also infect potatoes so gardeners and growers of any size who have infected tomato plants need to destroy those plants appropriately to prevent the spread of the disease to other areas and to protect Wisconsin’s commercial potato and tomato crops.

So far, late blight has not been found on any potato plants in Wisconsin and state agriculture officials want growers and gardeners in potato growing areas to remain on the lookout for late blight symptoms.

“This particular strain of late blight can be very aggressive on potatoes so the risk for spread from tomato to potato is still very great and gardeners and large commercial producers should not get complacent at this time,” explained Amanda Gevens, University of Wisconsin plant pathologist.

As of August 14, there were confirmed cases of late blight in tomatoes in five counties, Dane, Green, Rock, Portage and Lafayette. Previous reports of late blight in Langlade County were incorrect.

“Late blight spores can travel great distances on wind, rain and machinery. If your garden is infected, there is a potential risk to potato fields in your county,” said Brian Kuhn, Department of Agriculture, Trade and Consumer Protection plant industry bureau director. “Know the signs and symptoms of late blight. Check your gardens and your fields. If you’re unsure, contact your county extension office for guidance. If you have late blight, you need to destroy the infected plants to limit the spread of the disease.”