Pale yellow, slightly sunken spots with purple centers and yellow margins appear on the leaves. The spots enlarge rapidly, covering the entire leaf. In moist weather, the spots may be covered with a brown to black powdery growth. Bulbs in storage may be rotted around the neck and discolored inside.
To prevent infection in storage, dry harvested bulbs properly. Clean up and destroy plant debris at the end of the season. If transplants are used, be sure they are disease-free. Apply a fungicide labeled for this disease, following label instructions.