Powdery Mildew

Causal Agent: Erysiphe graminis

Susceptible Turfgrass
Kentucky Bluegrass, fine-leaf Fescue, Bentgrass, Ryegrass, and Bermudagrass.

Symptoms

• The disease first appears on the leaves as individual tufts of fine, white mycelium.

• The tufts enlarge and coalesce, causing the leaves to have a greyish-white or powdery appearance.

• Severely infected turf turnsyellow, then tan and brown in colour.

• Stressed turf that is severely infected can die. Severely infected turf, especially in shaded areas, can become thinned.

Conditions favouring Disease

• Powdery mildew is favoured by humid, cloudy weather with temperatures between 15°C and 22°C.

• It occurs in areas under stress, with low light, and with high humidity.

• Powdery mildew is also common in areas with poor air circulation, but does not require a film of water to infect turf.

Solutions

Integrated Turf Management

• Water as needed to avoid drought stress.
• Avoid levels of nitrogen and irrigation that produce lush leaf growth.
• Raise the mower height.
• Prune tree limbs to improve air circulation and the amount of sunlight.
• Convert to a polystand of shade-adapted turfgrass.

Fungicidal Control
Banner, has a label recommendation for Powdery Mildew in South Africa.