Gray Leaf Spot
Symptoms:
- Lesions first appear as small, necrotic spots with halos
- The lesions become rectangular, 2-4 mm to1-6 mm in size and have a gray appearance
- Mature lesions have distinct parallel edges and appear opaque when put up to the light
Pathogen Involved:
- Cercospora zeae-maydis (a fungus)
- Corn is the only known host of this pathogen
- Overwinter in corn debris on the soil surface
Time of Occurrence:
- This disease will occurs from silking to maturity
Conditions Favoring Disease:
- Susceptible hybrids or inbreds
- Corn on corn rotation
- Moderate to warm temperatures
- Extended periods of high humidity or wet weather
- Minimum tillage
Disease Management:
- Use resistant corn hybrids
- Conventional tillage where appropriate
- Crop rotation
- Foliar fungicides if economically warranted. Typically only used with susceptible inbreds; or a combination of susceptible hybrids, high yield potential, prolonged humid conditions, and evidence of disease development.