Cause Fusarium sp., a fungus that lives indefinitely in soil, moving into small roots and tubers. It may also survive the winter in infected dahlia tubers. During the growing season, the Fusarium fungus may attack vascular stem tissues, preventing water from moving up.
Symptoms In storage, tubers break down and rot and often are covered with a white-to-pink, fungal coating. Vascular system infection results in wilting stems accompanied by dying leaves.
Cultural control
- Dig plants carefully in early fall to avoid injury.
- In storage, provide good aeration and a cool temperature (above freezing).
- Destroy tubers that show visible infection or that have displayed a wilt or dieback during their growing period.
Chemical control
- Banrot 40 WP at 6 to 12 oz/100 gal water applied to 800 sq ft. Group 1 + 14 fungicide. 12-hr reentry.
- Postharvest soak.
- 42-S Thiram at 1.5 pints/8 gal water. 24-hr reentry.
- KleenGrow at 0.15 to 1.5 fl oz/gal water. Soak for 30 seconds and allow to drain.