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Tar spot spreading in South Dakota

A plant pathologist says farmers should be on the lookout for tar spot.

“We found tar spot in 46 of our 66 counties last year.”

Connie Strunk with South Dakota State University Extension says the disease was found at harvest in eastern South Dakota and it will likely show up again this year, but it’s unclear how early.

“It can be on residues, but primarily, in South Dakota, we think it’s windblown. We’re going to watch for it earlier so we can see. If we do get it earlier, farmers might have to use a fungicide for it. That’s something we’ve not had to do yet in South Dakota.”

She says farmers should be watching for lesions on the corn plant around tasseling and to reduce yield loss, fungicide application timing must be just right.

“We don’t want to be too early in the application and then, if you go much past milk stage, you’re not going to see much benefit of a fungicide application.”

Strunk says different fungicide recommendations are available on the Crop Protection Network website.