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I've been noticing a white powdery substance all over the limbs of my lilac tree. Please tell me what I can do to get rid of this "fungus". Thank you, Tammy


Powdery Mildew on Lilac Leaf Hi Tammy,
You are dealing with a common problem that lilacs sometimes have called "powdery mildew". It is a condition that doesn't immediately kill the shrub, but you should take steps to correct it so it doesn't become a long-term issue. The condition is caused by several different types of fungi that really like warm, damp weather. In the case of powdery mildew, the best course of action is NOT to buy a commercial fungicide because you will be fighting a never-ending battle trying the treat the symptom (i.e., the fungus) but not the basic problem. The best remedy for powdery mildew is to make sure the lilac is pruned properly to allow sunlight and air to get into the middle of the plant. This keeps the middle of the plant dry which deters the growth of fungus.

Steps to properly care for a mature lilac are:

1. After lilac blooms in the spring: Remove 1/3 of the oldest, woody stems each year-cut to the ground. This practice encourages air circulation through the plant. After you remove some of the old stems, you may also need to thin out some of the stems in the middle of the shrub to get light and air to reach the center.

2. If you have powdery mildew, do not fertilize lilacs.

3. Make sure the lilac is in full sun (7-8 hours /day). Anything less than full sun promotes fungus.

4. If you need to water lilacs, do not water the leaves, but place hose around the base of the plant and water the roots only.

Good luck and thank you for your question.

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About Linda Lillie

Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier landscape design and maintenance, tree care, lawn care, stonework, and carpentry service provider in southeastern Connecticut since 1997. She is a graduate of Connecticut College in Botany, a Connecticut Master Gardener and a national award winning landscape designer for her landscape design and landscape installation work.


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