University of Maryland Extension

Fungal Leaf Spot Diseases on Houseplants

orchid leafspots
Leafspots on orchid leaves

There are many species of fungi that can cause leaf spots on house plants (leaf spot on prayer plant). Symptoms often include many tan to reddish brown to black roughly circular spots or lesions that may run together to cause large irregular shaped lesions (tuberous begonia) or blighting of the entire leaf. If the leaf spots attack the newest leaves near the top of the plant the growing point may be killed. Leaf spots can enlarge and grow onto branches and stems. Severe infections often cause extensive leaf drop and dieback.

leaf spot begonia
Leafspot on tuberous begonia

fungal leaf spot
Fungal leafspot on the leaf of a prayer plant

Management strategies

Individual leaves with spots can be picked off and destroyed. Any method that will lower the humidity, decrease leaf wetness or increase air circulation will help to lessen the chances of infection. Watering should be done early in the day to allow leaf surfaces time to dry quickly. 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 drier conditions should help.

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