The Q&A Archives: Powdery white substance

Question: For some time now, I have noticed a white powdery substance on the leaves of my Royal red maple. The leaves are starting to drop off and I am wondering if I should disregard this problem hoping that next year this problem will disappear. Louisa

Answer: A powdery white substance on foliage almost always means a fungal disease called powdery mildew. Be sure to rake up all the fallen leaves; next spring, just before the leaves unfurl, spray your tree with a preventative bordeaux (lime-sulfur). This is the same product used to protect apple trees from fungal diseases. Spray as the leaf buds begin to swell and it should protect your tree from further attacks.

Best wishes with your landscape!

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