Plant pathologists say “tar spot” is a fungal disease that develops brown lesions on the corn leaf. Black ascomata later appear, protruding from the leaf. The structures produce spores which spread the “tar spot” fungus.
At this point in the growing season, experts believe there will be minimal impact on crop yields.
Even in places around the globe where “tar spot” is common, it has minimal impact on corn production and yield numbers. Mexico and Central America were cited in the release from Purdue Extension as locations where the disease is endemic.
A Purdue Extension spokesperson, however, says that the agency continues to work to determine the impact of the disease on Indiana crops.
Future steps include determining how the disease got to Indiana in the first place. Steps will also be developed to help prevent a future outbreak.