Pathogen Facts

  • Anthracnose leaf blight in corn is caused by the fungal pathogen Colletotrichum graminicola.
  • The leaf blight phase of the disease typically shows up early in the season.
  • Anthracnose leaf blight does not generally have an impact on corn yield, as it usually only affects the lower leaves and corn quickly grows out of the disease.
  • Although they are caused by the same pathogen, the presence of anthracnose leaf blight has not been shown to correlate to anthracnose stalk rot later in the season.

Symptoms

  • Early symptoms appear on lower leaves prior to spreading up the plant.
  • Lesions are tannish brown with darker edges and generally spindly or oval-shaped.
  • On severely infected leaves, lesions may coalesce into large dead patches, causing the leaf to turn yellow and wither.
  • Necrotic tissues will have small spiky black fruiting bodies.

Life Cycle

  • The fungus overwinters as mycelium or sclerotia in corn residue.
  • Spores are spread primarily by splashing water during the spring.
  • Disease development is favored by wet weather during early crop growth with moderately warm temperatures.
  • Disease develops soon after planting and continues to develop until canopy closure.

Management Considerations

  • Anthracnose leaf blight rarely affects corn yield.
  • Infection is typically limited to lower leaves, which do not contribute to yield.
  • Anthracnose leaf blight tends to be more prevalent in fields planted to continuous corn.
  • Some fungicides are labeled for anthracnose leaf blight but treatment is unlikely to provide an economic benefit. 

References