Powdery Mildew

• Powdery mildew is a fungal disease of almost every shrub and tree species, including maple. During the spring and summer months, the fungus infects leaves with a powdery, white coating. The parasitic fungus saps nutrients from plant cells, which causes leaf yellowing, leaf distortion and poor leaf growth. However, during the fall months, the powdery mildew fungus produces black circles on infected leaves. The black leaf spots are the fruiting bodies of the fungus, which reproduces and overwinters on leaves. Powdery mildew favors humid weather conditions for infection. Fungicides are effective for severe powdery mildew infections.