Thursday, April 3, 2008

Powdery mildew

Hi Anne,

I believe I have a powdery mildew problem. It seems to be getting worse too, even though we've been in a drought. It will show up every summer on my zinnias, crepe myrtles and boxwoods. We try to avoid chemical use in our yard, but will do so if it means saving our plants. What do you recommend?


Anne's Response:

I didn’t think boxwoods had a problem with powdery mildew. Plants will develop the disease when we have a cloudy, moist night and when there is not good air circulation around plants. So pruning to keep plants from being crowded together helps. Organic gardeners have found that spraying with lime-sulur just before the crapemyrtle leafs out in the spring will help control the disease. For the zinnia try using a wettable sulfur powder when the disease first appears.

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