University of Maryland Extension

Powdery Mildew on Houseplants

powdery mildew poinsettia

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There are several fungal species that cause powdery mildew of house plants, but the symptoms are the same. The most obvious symptom is the white powdery coating on the surfaces of infected leaves and stems. The initial areas of mildew may start out as small spots of powdery white growth before growing together to form a white coating over the entire surface.

Management Strategies: Individual infected leaves can be picked off and destroyed. Any method that will lower the humidity, or increase air circulation will help to lessen the chances of infection. Space plants so that air can circulate between them to help reduce moisture. Registered fungicides can be used, but in most home conditions, removal of infected plant parts and adjustment of environmental conditions to promote better air circulation should help.

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