‘Southern Rust’ Has Infected Corn From Likely Every Iowa County

It was far past knee-high for the 4th of July but there might be issues now.

Across a lot of Iowa, planting was done on the earlier side of the year and it was looking like we'd have a good harvest back in the spring.

How It Was Looking: Will Iowa Corn Be Knee High By The 4th Of July?

Now, ag experts are saying corn across the state of Iowa has become infected with southern rust.

Iowa State University Extension field crops pathologist Alison Robertson told AgriTalk that she has never seen it this widespread before and believes it is in every one of Iowa's 99 counties.

The infection can wipe out 30% or more of the state's corn.

Southern rust on corn shows up as light brown, round spots on the upper leaf and may be seen on the stalks, husks, ear shanks, and the lower leaf area. In fact, southern rust could be making humidity worse because the corn loses a bit more moisture than it normally would. Here's how Robertson put it:

We’re getting all these spots, pustules on those leaves that are producing spores. When the spores are produced, they burst through the leaf epidermis, and so because of that, those leaves are probably losing a little bit more moisture than they would do with something like Northern corn leaf blight, or gray leaf spot, or even tar spot.

You can still harvest corn that's infected with southern rust. But the severity of the infection and the stage of the corn's development can significantly impact this fall's yield.