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Corn farmers encouraged to plan for tar spot

Midwestern corn farmers should be on high alert for tar spot. 

A technical services representative with BASF says the number of tar spot confirmations across the U.S. continues to climb.

Mike Probst, who covers central and southern Illinois, tells Brownfield, “We’ve seen it expand now to six different states, including one county that has now been confirmed in Illinois.  So, there’s nothing that really points to this is going to slow down.”

He says research suggests disease pressure this year could be as high as in 2021, which saw some untreated fields lose as much as 50 bushels per acre.

“We’ve seen that tassel timing really be the most optimum timing for fungicide applications,” he says.

Probst says weather outlooks are forecasting conditions conducive to tar spot development throughout the summer, so farmers need to scout fields regularly for signs of the disease.

“We’re not giving up on this crop yet.”  He says, “It’s the last thing that you can generally do to protect your corn crop is make that fungicide application.”

Brownfield spoke with Probst at the 2026 Field Insights event at the BASF Midwest Research Farm near Seymour, Illinois.

AUDIO: Mike Probst – BASF