Getting rid of powdery mildew

Question

My neighbor gave me two beautiful rose trees in large pots. The stems/flowers have white powdery mildew on them. How to I get rid of it?

Nancy

Danville

Answer

You can treat the powdery mildew with Monterey Bi-Carb. This is an old-fashioned but effective wettable powder (potassium bicarbonate) that kills the mildew on contact. It is safe for use in organic gardens. Another remedy is using Serenade spray. However, to prevent mildew in the future, you can spray roses with Neem or horticultural oil. The powdery mildew spores cannot penetrate the leaf through the oil film.

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