Diagnosing Dahlia Wilt and Tuber Damage: Pests, Diseases, and Crop Rotation

Dahlia Collapse in Dense Planting

Wilting despite watering, with black goo on tubers, suggests:

• Grubs, voles, or moles feeding on tubers.
• Fungal/bacterial rots (soft rot, Fusarium) encouraged by crowding and wet soil.

Management

• Rotate dahlias to a new bed each year.
• Inspect tubers at planting; discard any with soft spots.
• Space plants 18–24 inches for air flow.
• See American Dahlia Society disease guide.

Healthy tubers in clean soil rarely fail.