The Q&A Archives: crape myrtle

Question: I have a white waxy powder substance on the leaves of my crape myrtle trees. What is it and how do I get rid of it?

Answer: Colin,

There are a number of options for powdery mildew control on crepe myrtles. Among your least toxic options are products that contain either of the following ingredients: neem oil (not just Azadirachtin, but instead "neem oil") or potassium bicarbonate. Potassium bicarbonate is similar to baking soda (which is sodium bicarbonate) and is sold under the brand name Green Cure. Read the label for application instructions and frequency. As a general rule, these sprays generally need to be applied on a 10-14 day basis when conditions favor powdery mildew development. Your County Extension Office can offer other options for powdery mildew control.

If you plan on planting additional crapes or on replacing some you already have choose a variety that is resistant to this disease. There are many to choose from and we can help you select one if you like.

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