Common Periwinkle Diseases and How to Control Them

Overview

Periwinkles (Catharanthus roseus) are heat- and drought-tolerant bedding favorites, but susceptible to several fungal diseases that can devastate plantings if not managed.

Botrytis Blight

Small black dots on leaf edges spreading inward in wet conditions. Control: plant in full sun, remove infected leaves immediately, water via drip irrigation to keep foliage dry.

Phytophthora

Dark brown stem streaks spreading to leaves/flowers. Prevention: full sun, pH 5.5, well-drained soil. If infected, remove entire plants (don’t drop debris), rotate crops next year.

Root and Stem Rot

Stems turn black, leaves wilt brown as if drought-stricken—roots are nonfunctional. Remove affected plants immediately; treat remaining with fungicide to halt spread.