Now that planting is in the rearview mirror, disease and weed management take center stage for Indiana farmers. Plant disease was the topic on the Purdue Crop Chat Podcast.
“Does it stay wet and cool or is it going to get hot and dry on us?” That’s the big question from Purdue’s field crop pathology specialist Dr. Darcy Telenko. If it’s cool and wet, tar spot becomes a real concern. Last year brought the earliest confirmed case of tar spot in Indiana on June 9th. Growers are already scouting for it this year.
“V10, V12 corn, yeah, I might be looking to see if I’m seeing any lower diseases,” Telenko explains. “Luckily for tar spot in Indiana, it’s going to come up from the bottom just like gray leaf spot, so we can keep an eye out for it. That being said, some of the reports we’ve had it was actually insect frass. So, growers, if you’re out scouting and you find those little black dots, flip the leaf over because with the lesion on tar spot, usually you can find the identical lesion on the back side of the leaf. If it’s not all the way through, it’s probably something else.”
Despite the early finding, tar spot wasn’t the story in 2025. It was Southern Rust, a fungal disease that has rarely been found too far north in previous years. Last year, it made it all the way to Michigan on its way through Indiana.
The good news is, “So far, it hasn’t been found yet in the United States. So, once we start seeing that, then that’s when I watch when do the spores move up to Indiana to really worry about it.”
Telenko says disease resources can be found on her website, indianafieldcroppathology.com, but she highly recommends growers utilize the Crop Protection Network.
“So, there are maps of things that you can check. And some of those maps, even the tar spot and the southern rust, they have a nice little chart that shows you, if you find it in your field here, do you spray, not spray, when do you hold on. So, there’s a nice little chart there.”
Telenko reminds farmers that checkoff funding from the Indiana Corn Marketing Council and Indiana Soybean Alliance has been provided to cover costs of plants sent to the Purdue Plant Pest Diagnostic Lab to track all corn and soybean diseases.
Hear more in the Purdue Crop Chat, presented by the Indiana Corn Marketing Council and Indiana Soybean Alliance wherever you listen to your favorite podcasts or watch on our Facebook page.
The Purdue Crop Chat is part of the Hoosier Ag Today presents YOUR Purdue Extension podcast network presented by Indiana Farm Bureau– a unified voice for agriculture!
