Gray Leaf Spot is a fungus found in corn nearly every growing season.
“Spores are dispersed by wind and splashing water. Infection of corn leaves and disease development are favored by warm (80s°F), humid (>90% for 12+ hours) weather.”
Because Gray Leaf Spot (or Cercospora zeae-maydis) survives on corn residue, corn planted after the initial corn harvested can experience more severe damage. Crop rotation and tillage, as well as fungicides and resistant hybrid and inbreds can help to reduce the survival.
The fungus damages leaves by creating narrow, rectangular, light tan-colored leaf lesions up to 2 inches long. As lesions age they will turn gray. Although the lesions are typically apart from each other, they can connect killing entire leaves.
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