Northern leaf spot
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.