Black-Eyed Susan Leaf Spots: Fungal Diseases, Cultural Control

Black-eyed Susans have black spots on leaves. Owner seeks remedy.

Cause

Several fungal leaf spots: Alternaria, Cercospora, Colletotrichum, Phyllosticta, Septoria. Favored by wet conditions.

Control

• Fungicides (e.g., Daconil) applied at first symptom.
• Avoid overhead watering—use drip irrigation or hand-water at base.
• Remove severely infected leaves.

Good sanitation and dry foliage reduce recurrence.