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Iowa corn growers watch tar spot development

An extension agronomist says tar spot pressure is picking up steam in Iowa.

Iowa State University’s Meaghan Anderson tells Brownfield, “There have been a number of tar spot confirmations. All of them have been fairly low on the plant and for the most part very low severity.”

She says this year’s detections shouldn’t come as a surprise.

“If we think back several weeks ago and what was happening with our weather, we were quite a bit cooler and we had plenty of moisture in the air. It makes sense we’re seeing more tar spot now as a result of those weather conditions.”

Anderson says the disease has become more prevalent in the state the last few years. She says farmers have been able to manage it with fungicide applications.

“That’s a really critical piece of the puzzle that we always look for every year trying to make that evaluation ahead of time as to whether we expect we’ll have bad enough disease issues to provide an ROI when it comes to those fungicide applications.”

According to ISU research, air temperatures above 73 degrees Fahrenheit significantly slow or stop tar spot development.