f grayish-white powder has recently appeared on the new growth of your crape myrtles, chances are the problem is powdery mildew. In extreme cases, entire twigs may be blighted by the mildew fungus. While it will not kill affected crape myrtles, blighted foliage detracts from the appearance of this popular Southern landscape plant.
Leaves infected early in the season by the powdery mildew fungus become curled and distorted as they expand. Infected younger leaves have blister-like areas which quickly become covered with the mildew. On older leaves, large white patches of fungus growth appear, but there is little leaf distortion. Flowers which originate from infected buds often become blighted.
Powdery mildew is most common in dry weather with warm days and cool nights. If an infection isn't excessive, affected twigs may simply be removed by pruning. Heavily infected plants, however, will probably require fungicide treatment for full recovery.
Homeowners who have had severe powdery mildew problems in past seasons should start fungicide application immediately after the first sign of the disease. It may be necessary to continue fungicide sprays until leaves are mature, at which time they are less susceptible to the fungus. Fungicide can also be applied during the flowering period to prevent blossom blight infection.
By the way, powdery mildew not only affects crapes, but roses, annuals, perennials, vegetables and others.
Fungicides to Wash It Off
- Consan Triple Action 20
- Neem oil
- Banner-based fungicides (Fertilome Liquid Systemic, Ortho Banner-based)
- Homemade baking soda spray (2 teaspoons of baking soda, 2 quarts of water, ½ teaspoon of dish soap or Murphy’s Oil Soap)
- Fungicides to Prevent It
- Banner-based fungicides (see above)