I apologize for this delayed reply to your gardening question and hope it is still helpful to you.
There are a number of products for controlling powdery mildew on plants. Among the least toxic are neem oil and potassium bicarbonate. These non systemic products will need to be reapplied periodically to maintain control. Bayleton is a synthetic option that is systemic and lasts longer.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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