Plant experts are warning Nebraska farmers to check their fields for a potentially devastating corn disease.

In 2006, southern rust hit south central Nebraska, causing a 30 percent lost in yield. Now the disease is back in at least three counties including Thayer, Clay and Hall.

Southern Rust is showing up in Nebraska corn fields for the third year in a row.

"They actually cause a lot of injury to the leaves themselves, and when you injure the leaves, it competes with grain fill, so in the end it actually competes and harms yield,” said Tamra Jackson, UNL Extension Plant pathologist

But experts are more concerned about another rust that's, well, more common.

"Common Rust is very widespread throughout the state right now. We actually are having an even bigger problem in the southwest part of the state where they're treating a lot of fields and they've never had to do that before,” Jackson said.

Farmers are rolling into CPI complaining of rust, but the coop encourages producers to think about the disease early in the season.

“We try to be proactive, talking with the farmers to apply the proper fungicides to help hold these diseases out,” said Dean Oberle, CPI sales manager.

Experts say the rust won't devastate the state's corn crop, but it is one more thing farmers have to deal with after an already hard year.

"We had a lot of rain earlier in the season that delayed planting. The late planted fields are at a higher risk for disease and for the damage caused by those diseases,” Jackson said.

That rainy and cool weather caused the increase in rust.

"The spores that cause the infection actually have to blow in from southern states every year, and since we had a lot of moisture earlier in the season, we've got a lot more rust diseases,” she said.

Jackson said warmer weather could help kill Common Rust but would help Southern Rust grow.

Experts say rust is not toxic, so consumers won't be affected by the diseases. But farmer's pocket books could be. Some treatments cost around $20 per acre.