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Powdery mildew can diminish the beauty of landscape ornamentals; however, it can be controlled through cultural practices or chemical alternatives.
Powdery mildew is the name for the grayish white powdery coating of fungus mycelium and masses of spores growing on plant leaves, shoots and flowers. This disease is caused by a distinct group of similar fungi that attacks a wide variety of plants. Lilac, zinnia and many other flowers and shrubs can be damaged. Although plants infected with powdery mildew rarely die, the disease detracts from the natural beauty of ornamentals. Damage ranges from an unsightly white powdery coating on the foliage to malformation of leaves, destruction of flowers and stunted plant growth.