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Growers ask about spraying for tar spot

A plant pathologist says tar spot remains the number one concern corn growers have going into the 2023 growing season. 

Dr. Damen Smith with the University of Wisconsin tells Brownfield tar spot can be a sneaky yield robber, and farmers want to know the best time to apply a fungicide. “We know that the most consistent timing is really around that start of tassel to about the R3 or milk growth stage. That’s really your window of opportunity.”

Smith says farmers should keep track of when they sprayed and consider a possible second fungicide application if tar spot starts to take off. “The longevity of many of these fungicides isn’t such that it can get you from say a V10 application all the way through to the finish, so that is something you have to just kind of keep track of in where you made that first application and then make that decision on whether you need the second one later on.”

And Smith says the new short statute corn varieties might help producers fight diseases. “Having that short-stature corn plant there, we can get a ground rig across it. We don’t have to rely on planes, and it will increase the flexibility on the spray timing.”

Smith spoke to Brownfield during the Wisconsin Corn-Soy-Pork Expo in Wisconsin Dells, Wisconsin Friday.