Grey leaf spot of corn

Grey leaf spot of corn is a cereal disease caused by the fungal pathogen Cercospora zeae-maydis. The fungus thrives in warm, humid conditions. It is often caused by diseased seeds or planting materials and promoted by poor air flow, low sunlight, overcrowding, improper soil nutrient and irrigation management and poor soil drainage.

Symptoms
Initial leaf infestation appears as tiny to slightly elongated, roughly parallel-sided spots with yellow margins. The later stage of infestation shows rectangular tan to gray spots that remain evident on completely blighted leaves. The fungal growth on the lesions gave a characteristic grayish cast, hence the name.

Treatment
Remove and destroy infected plants.

Prevention
Practice crop rotation. Use diseased-free seeds or use resistant cultivars. Observe proper planting distances and maintain sanitation by removing a disposing of infected plant materials. Avoid working when plants are wet.