Managing for the challenging tar spot disease
Tar spot management continues to challenge farmers across the Corn Belt.
Martin Chilvers, an associate professor with Michigan State University, outlined some ways to mitigate risk from the disease during the recent Tar Spot Summit by AgReliant Genetics.
“Hybrid tolerance or resistance is key for managing tar spot,” he says.
He tells Brownfield the timing and application of fungicide is also critical.
“In terms of actively managing during a growing season, once we’ve made hybrid selections, it’s fungicides. The Crop Protection Network has lists of fungicides and their fungicide efficacy, how they perform on tar spot and other diseases,” he says. “What we’re looking at in terms of fungicide timing, what we tend to repeatedly see is a fungicide somewhere between VT/R1 through to about the R3 growth stage. Typically, that single fungicide application in that window does the best job for us in terms of controlling tar spot and protecting yield.”
Chilvers says one of the most common practices to address crop diseases – scouting fields – is challenging for tar spot.
“It’s a small black spot and it’s hard to see,” he says. “…it tends to sneak up on growers and by the time they see it, it may very well be past the point of wishing we had the fungicide out a week ago.”
He says MSU is working on DNA techniques and spore trapping to help predict risk prior to symptoms on the plant.
Audio: Martin Chilvers