Cause Ramularia beticola, a fungus. Most likely it is seedborne. It is believed to persist in beet debris at least 1 year. The disease is not considered an economic problem.
Symptoms Leaf spots, which occur on older leaves, are light brown and fairly large (4 to 7 mm). As they mature, they develop a gray to white center (sporulation of the fungus) and a dark to reddish-brown margin.
Cultural control
- At least a 3-year rotation out of beets is helpful.
Chemical control Materials labeled for Cercospora leaf spot should help to control Ramularia leaf spot.
- Affiance (Group 3 + 11) at 19 fl oz/A on 7- to 14-day intervals. Preharvest interval is 14 days. 12-hr reentry.
- Eminent VP (Group 3) at 8 to 13 fl oz/A. Do not make more than one (1) application of Eminent (triazole fungicide) or other Group 3 fungicide before alternating to a labeled fungicide with a different mode of action. Do not apply within 14 days of harvest. 12-hr reentry.