Powdery Mildew
Causal Agent: Erysiphe graminis
Susceptible Turfgrass
Kentucky Bluegrass, fine-leaf Fescue, Bentgrass, Ryegrass, and Bermudagrass.
Symptoms
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The disease first appears on the leaves as individual tufts of fine, white mycelium.
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The tufts enlarge and coalesce, causing the leaves to have a greyish-white or powdery appearance.
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Severely infected turf turnsyellow, then tan and brown in colour.
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Stressed turf that is severely infected can die. Severely infected turf, especially in shaded areas, can become thinned.
Conditions favouring Disease
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Powdery mildew is favoured by humid, cloudy weather with temperatures between 15°C and 22°C.
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It occurs in areas under stress, with low light, and with high humidity.
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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.