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Powdery Mildew Frequently Asked Questions | |
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| | What does powdery mildew look like?
Powdery mildew lesions initially appear on the upper surfaces of the lower leaves as fine powdery white spots. They can spread rapidly over the entire surface of the plant. The tissue under the lesions may darken and even turn a purplish color. As the plant ages, small black fruiting bodies, about the size of a pin head will develop on the infected surfaces.
What conditions support powdery mildew growth?
Powdery mildew mostly develops on hot dry days (greater than 20 degrees Celsius) and when the nights are cool enough to form dew. Light rain spreads the disease, but heavy rain may wash it off the surface of the plant.
When should I scout for powdery mildew?
Scouting for powdery mildew should be frequent as the disease can rapidly spread through the field. Watch closely, the early stages of the disease are sometimes mistaken for the waxy surface of the pea leaf.
Will powdery mildew have any effect on desiccation?
Yes it will, especially in severe infestations of the disease. The powdery mildew will provide a barrier between the desiccant and the leaf surface, preventing the desiccant from entering the plant. The plant will take much longer to dry down, which can reduce the quality of the crop.
Can powdery mildew be controlled?
Resistant varieties are a good control option for disease management, along with good crop rotations. Resistant varieties are completely resistant to powdery mildew and many of the new varieties are resistant. The disease may be controlled with a fungicide application. Even after fungicide application, monitor the disease growth. Another application may be required in 7-10 days if control was not obtained. However, deciding to control depends on the value of your crop, and the stage of the crop when the disease shows up.
Field Pea Diseases
Kumulus DF-BASF pdf. 79 KB
Headline- BASF pdf. 259 KB
Prepared by Karla Bergstrom, Ag-Info Centre, Alberta Agriculture and Rural Development |
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For more information about the content of this document, contact the Ag-Info Centre.
This information published to the web on July 31, 2003.
Last Reviewed/Revised on March 31, 2005.
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