Area of impact: Most visible on leaves but can spread to all aboveground parts

Description: White powdery patches resembling cotton. Eventually these patches turn a dull gray sometimes with black specks.

Pathogen involved: Erysiphe graminis (a fungus)

Timing/Conditions: Cool, cloudy, damp weather is ideal for this disease.

Contributing factors: A dense lush crop canopy.

Management practices: Plant resistant varieties and avoid overly dense lush canopies by controlling planting rates and nitrogen application.