P. obtusifolia cultivars are especially susceptible to Cercospora leaf spot. Be sure to spray the undersides of the leaves where the spores are located. Phyllosticta leaf spot Pathogen - Phyllosticta sp. Symptoms - Phyllosticta leaf spot occurs primarily on the watermelon peperomia. Leaf spots are dark brown to black and dryish and have concentric rings of light and dark tissue.
Spots commonly start on leaf margins and can spread across the entire leaf.
Control - Remove and destroy infected leaves. Rhizoctonia leaf spot Pathogen - Rhizoctonia sp. Spots are elliptical to irregularly shaped and concentric rings of raised and depressed tissue form in these areas. Under warm conditions, the web-like mycelium of the pathogen can be seen covering the affected plants. Control - Remove and destroy severely infected plants or areas in the stock bed.