A layer of mulch will help to prevent the fungi from splashing from the soil onto plants. Cercospora leaf spot commonly occurs in fall land-scape beds. It appears as a dry, brown blotch or as an irregular purple lesion, especially during cool weather. For serious infections of cercospora leaf spot, fungicide sprays containing thiophanate-methyl can be used. Apply all chemicals according to directions on the label.
Older plants affected by the disease turn yellow and have small crinkled leaves.
Close observation reveals a black discoloration moving up from the tips of the roots. Diagnosis may be difficult without professional help. Provide good drainage to plants and avoid overwatering. The disease can be suppressed, but not cured, with regular applications of fungicides containing thiophanate-methyl. Apply all chemicals according to directions on the label.