An extension plant pathologist sees a shift in the corn disease spectrum.
Daren Mueller with Iowa State University says when fungicide use started to become common, the main pathogens were northern corn leaf blight and gray leaf spot.
“And those are diseases that survive in the residue and they sort of hit that lower canopy and move up. And you sort of have this predictable, mid-season if you see it, and we can scout and make a decision during the season. That’s shifted.”
Now, he tells Brownfield the primary corn diseases are tar spot and southern rust.
“And those are diseases that really blow up at the end of the season. So I think we’re just at a point where we have to really be thinking about what is the best stewardship and use of fungicides
Mueller says tar spot hasn’t been widespread yet, but he expects the disease to “take off” as nights become cooler.
Southern rust has moved north all the way into southern Minnesota
