Tar spot threatens Illinois corn for first time

An occurrence of the disease called tar spot has been confirmed in Illinois, according to a recent announcement from the Illinois Department of Agriculture.

Last week, the disease was identified in Indiana. Although common in Latin America, this is the first time that tar spot has been found in the U.S.

The initial diagnosis was made by plant pathologists at the Purdue University Plant Diagnostic Clinic and confirmed by the U.S. Department of Agriculture Animal Plant Health Inspection Service.

Indicators that corn crops are affected by tar spot include brownish lesions on leaves, followed by black, spore-producing structures that appear later, giving the leaf a rough or bumpy texture. It is easily spread with the combination of cool temperatures and high relative humidity.

In case of corn crops with those signs, growers should contact their local University of Illinois Extension office and work with the office to submit samples to the University of Illinois Plant Diagnostic Clinic.

"We anticipate minimal impact on yields with detection this late in the growing season," Agriculture Director Philip Nelson said. "However, it is important for farmers to report any suspected findings to prevent the spread of this disease and provide an accurate picture on statewide impact."