Farmers Asked To Scout For Corn Tar Spot

UNDATED -- Area farmers should be aware of a new threat to their corn crop.

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The University of Minnesota Extension is asking farmers to scout their corn for tar spot. This new corn disease was first detected in Minnesota in 2019, and has been found as far North as Stearns and Benton County.

Extension Educator Nathan Drewitz explains what to look for.

It's a fungal structure. They're small, black, raised, and very shiny. You want to rub that black speck and see if it comes off. If it doesn't come off, that's a good indication. It's going to be raised, you're going to feel it under your finger. And so that's typically what we'll be looking for - those structures.

For more details on tar spot, click here.

Drewitz says, if left untreated, tar spot has the ability to dramatically affect yields.

We're still trying to figure out what this actually looks like. And as far as I can tell, it's dependent upon when it comes in, if it gets in early enough, and they can desiccate those leaves. I've seen numbers in the 20 to 30%, yield loss in some cases.

Area farmers are asked to notify their agronomist or the University of Minnesota Extension office if they suspect tar spot in their crop.