Field Crop Diseases
Information and Management for Illinois
Go to the Department of Crop Sciences home page.
University of Illinois
College of Agricultural, Consumer and Environmental Sciences
Corn Diseases Soybean Diseases Wheat Diseases Sorghum Diseases Alfalfa Diseases

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.

 Back to Corn Diseases

[Field Crop Diseases]
[Integrated Pest Management]

[Department of Crop Sciences]
[University of Illinois Extension]

[College of ACES]
© 2001
University of Illinois