How to Manage Pests
UC Pest Management Guidelines
Erwinia Soft Rot
Pathogen: Erwinia betavasculorum
(Reviewed 11/05, updated 11/05)
In this Guideline:
SYMPTOMS AND SIGNS
The disease is not easy to detect until the rot is well advanced. The vascular tissue of the root becomes discolored and a pinkish to red brown rot develops. Root symptoms vary from a soft rot to a dry rot; the root may become hollow without dying. As the disease progresses, plants wilt. Occasionally brown, oozing lesions occur on petioles and crown.
COMMENTS ON THE DISEASE
Erwinia soft rot can cause serious damage. Disease potential is greatest when temperatures are in the range of 77° to 86°F (25° to 30°C). The bacterium is soilborne and infects plants if infested soil gets into the beet crown from dirty farm machinery, splashing water, insects, or other means. It invades the plant through an injury or wound to the crown or leaves and enters the vascular vessels of the root and petioles.
Beet varieties vary widely in their resistance or susceptibility to this pathogen. Commercial varieties in California are tested for soft-rot resistance: whenever possible, use resistant varieties. Excessive amounts of nitrogen fertilizer encourage Erwinia. Use the minimum amount of fertilizer necessary to achieve yield goals. Follow cultural practices that promote good soil structure. Avoid throwing soil and plant debris into beet crowns during cultivation, and adjust implements to minimize injury to crown and tops.
UC IPM Pest Management Guidelines:
S. Kaffka, Plant Sciences, UC Davis
Acknowledgement for contributions to Diseases:R. T. Lewellen, USDA, Salinas
C. A. Frate, UC Cooperative Extension, Tulare County