Area of impact: Leaves

Description: Gray to tan oval or circular spots that occur mainly on the leaves.

Pathogen involved: Cochliobolus carbonum (a fungus)

Timing/Conditions: Symptoms usually appear on lower leaves at silking or at full maturity and during warm humid weather.

Contributing factors: Overwinters on corn residue.

Management practices: Plant resistant varieties, use crop rotation, till debris at the end of the growing season and apply foliar fungicides if needed.