VIOLA, Ill. — Despite an overall increase in corn yields this year, farmers across the Midwest are facing a serious problem: a fungal disease called tar spot, fueled by a summer of wet, humid weather.

The disease is hitting fields hard, weakening stalks and reducing kernel weight.

"Early on, you may find just a small lesion, but eventually it just keeps repopulating and takes over the plant," Chad Bell, owner of Bell Family Farms in Mercer County, said.

Tar spot appears as small, raised black spots on corn leaves. After a short period of time, a "halo" of dying plant matter surrounds the dots and consumes the leaf, leaving it brown and dry.

Once infected, corn plants cannot photosynthesize properly, producing smaller ears.

"So, we may have the same amount of kernels as a normal cro

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