The first signs of tar spot are becoming visible in corn fields in Iowa. An agronomist with Pioneer and an Iowa State University student spotted the first lesions of the season in six central Iowa counties as well as Holt County in northwest Missouri.

The confirmed sightings are small, according to an Iowa State plant pathologist. But they do mean conditions are favorable to produce spores to start the disease. Tar spot infects the stroma of the plant and the fungus produces spores that continue to infect it throughout the growing season. An integrated management plan can help protect against losses from tar spot.

Farmers should be scouting fields now and for the remainder of the summer to identify tar spot quickly. Lesions can be found in the leaf and can easily be confused with bug or bird feces. Last week’s detection marks the earliest the disease has been found in Iowa.

Read more on tar spot here.