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Horticultural Diseases and Pests - Alphabetically
Horticultural Diseases and Pests - by Host



There are many different powdery mildew fungi. The fungus spores overwinter on fruit trees. In spring, the fungus begins to grow, and spores are released to travel on the wind to young leaves. Powdery mildew thrives where cool nights follow warm days. Most common in shady, damp locations where plants are crowded, air circulation is poor and humidity is high. It is very common on crepe myrtle.


A white or gray powdery fungus appears on foliage and flowers. Round, white spots on upper leaf surfaces expand and merge, covering both sides of leaves. Infected leaves turn yellowish green to brown. New growth may be stunted, curled, and distorted. Infected blossoms may not set fruit; fruit may develop a rough skin or be covered with the powdery fungus. Fruit drops early or is dwarfed.


Plant resistant selections and plant susceptible species in locations that receive direct sun all day and spacing plants for good air circulation will prevent mildew, but you can also use fungicides if needed.

Please check the "Extension Agents' Handbook of Insects, Plant Disease and Weed Control".

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