Powdery Mildew
LOWErysiphales (various genera)
Overview
A widespread group of fungal diseases that produce a distinctive white powdery coating on leaves and shoots. It affects hundreds of tree, shrub, and plant species. Unlike most fungi, it thrives in warm, dry conditions with high humidity.
- Type
- Fungus
- Severity
- LOW
- Source
- USFS
Symptoms
White to gray powdery coating on upper leaf surfaces and young shoots, leaf curling and distortion, stunted new growth, premature leaf drop in severe cases
Affected Species
Geographic Spread
Treatments
Horticultural Oil or Neem Spray
Application of horticultural oil, neem oil, or potassium bicarbonate at first sign of infection. These contact treatments can prevent spore germination and reduce disease spread.
Improve Air Circulation and Site Selection
Plant susceptible species in locations with good air movement and full sun. Avoid overhead irrigation. Select resistant cultivars when available.
Recommended Products & Tools
Helpful supplies for managing Powdery Mildew. Always read and follow label directions, and confirm a diagnosis before treating.
Effective, low-toxicity control for powdery mildew.
Broad-spectrum protectant for many fungal leaf and bark diseases.
Preventive spray for needle cast, leaf spots, and blights.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is Powdery Mildew?
A widespread group of fungal diseases that produce a distinctive white powdery coating on leaves and shoots. It affects hundreds of tree, shrub, and plant species. Unlike most fungi, it thrives in warm, dry conditions with high humidity.
What are the symptoms of Powdery Mildew?
White to gray powdery coating on upper leaf surfaces and young shoots, leaf curling and distortion, stunted new growth, premature leaf drop in severe cases
Where is Powdery Mildew currently found?
Powdery Mildew is currently active in Alabama, Arkansas, Arizona, California, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, Wyoming. It has been reported in 49 total states across the United States.
What plants are affected by Powdery Mildew?
Powdery Mildew affects Red Oak, Flowering Dogwood, Common Lilac, Azalea, Crepe Myrtle. Susceptibility varies by species.
How do I treat Powdery Mildew?
Treatment options for Powdery Mildew include: Horticultural Oil or Neem Spray, Improve Air Circulation and Site Selection. Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.
Compare with Similar Ailments
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