Tar spot was first observed in 2015 in Indiana. Since then, it’s spread across the Corn Belt and has impact corn fields in many states. In this FREE resource from Farm Progress, Extension plant pathologists and technical agronomists from companies share their expertise and information to help farmers manage this quick-spreading disease.

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5 ways to manage tar spot

Scott Rountree, Pioneer technical agronomist, and Chad Threewits, Syngenta Crop Protection agronomist, share tips to manage this disease, including overwinter concerns, the impact of weather, scouting tips and more.

“Frequent rains when temperatures are in the right range can lead to serious infections in dryland corn,” Rountree says. “It’s your responsibility to know what is happening in your area in terms of risk for disease. Fungicide is a big help and can reduce yield loss, but you need to start with the most tolerant genetics you can find.”

Tar spot Q&A

Do you have questions about tar spot? Corteva Agriscience agronomists have answers. A panel of experts answer questions about fungicide spray timing, residue management, hybrids and more.

“Some early infection each year likely comes from inoculum which was in the field already, says Rountree. “Tillage would likely help with that. But it is such a small amount compared to all the inoculum from spores that are windblown.”

Download now: Tar spot management tips

More tar spot insight

Listen to the FP Next podcast with Missouri Ruralist editor Mindy Ward. She talks about the spread of the disease and answers more tar spot questions about yield loss and fungicide applications.

Tamra Jackson-Ziems, University of Nebraska plant pathologist, talks about the impact of irrigation on tar spot, particularly under pivots.

That’s something where we’ve been able to find it quicker, keeping in mind that this past year we had a pretty substantial drought over most of eastern Nebraska where the disease is. It was a pretty severe drought, and we didn’t see it, except for places where it was irrigated,” Jackson-Ziems says. “When we’re under drought stress and we have water available through irrigation, we tend to use it, and sometimes maybe overuse it in some areas. This might make us think differently about how frequently we irrigate.”

Also learn about tillage impact, new research and utilize a list of resources and videos that will help farmers manage tar spot this year, and in years to come.

Jim Donnelly, a Dekalb technical agronomist, adds, “Our field testing allows us to inoculate tar spot wherever we place our plots to help us study and learn more about this potentially devastating disease.”

Download Tar spot management tips now, and keep tar spot in check if it shows up in your corn fields this summer.