What to do with lilac bushes with powdery mildew?

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Replies
Powdery mildew actually loves the heat of summer and flourishes in the warmth. Since I am not sure where you are, here are my best suggestions for trying to knock it down: 1, remove and discard (do not compost) all leaves and other fallen plant material in close proximity to the infected shrubs. 2. Open up the area by pruning if at all possible. When plants are close, the mildew spores easily travel between plants. 3. Open the lilacs up to the sunshine if possible, thinning them a bit to improve air circulation. One more idea: you can use a NEEM product early in the spring (and throughout the growing season) to help discourage the mildew. Fungicides and organic sprays are available too. Follow all label instructions. Good luck.