Powdery mildew
Powdery mildew is a very common disease of many plants. It gets its name from the white powder appearance it gives to plants as the fungus grows over the leaves or shoots. The specific fungal organism that causes the disease is usually different for each plant affected. That is, the fungal organism that causes powdery mildew on lilac is not the same organism that causes powdery mildew on rose or phlox. Since the disease frequently develops under similar environmental conditions, however, many plants may be affected.
Pests and Problems

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