Cercospora spp.
Common fungal disease causing circular leaf spots on many crops. Particularly damaging to beets, Swiss chard, and peppers.
Circular spots with tan/gray centers and dark purple-brown borders. Spots may have concentric rings. Severe infections cause leaf death and drop.
Fungal pathogens that overwinter on infected debris and seed. Many species are host-specific.
Wind-borne spores. Splashing water. Contaminated seed. Spreads rapidly in warm, humid conditions.
Warm temperatures (75-90°F). High humidity. Extended leaf wetness. Dense plantings.
Use disease-free seed. Rotate crops. Space plants for air circulation. Avoid overhead irrigation. Remove crop debris.