“Does the lesion go all the way through the leaf,” she says. “When we find tar spot, that lesion goes directly through the leaf and you can see a little black spot on the underside the leaf. Sometimes you’ll have to flip that leaf over and you see a spot there. Generally, if we can see that, it  indicates that this is tar spot.”

 

 

“As we get more and more reports and we start seeing the disease start to develop, that’s the important time frame to start really making a decision,” she says. “Is it going to be active in our crop canopy, do I need to make a fungicide application? The value of corn is down, so we really want to get a return on investment if we’re going to add that additional input.”