How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS AND SIGNS

Fusarium root rot is characterized by brick red lesions of variable size, with diffuse margins that develop on belowground stems and tap roots. The red color gradually turns brown with age. Longitudinal fissures develop in the cortical tissue of affected areas. In severe infections, the entire root system may be attacked and destroyed. If the surface of the lesion is scraped away, small red flecks can be seen in affected tissue; this is a good diagnostic characteristic. In some plants, roots are initiated above the lesion.

COMMENTS ON THE DISEASE

The causal fungi survive for several years as chlamydospores in the soil. The disease is most commonly encountered during mid- to late season in fields with a long history of bean culture. The disease causes little damage to unstressed plants but under conditions of reduced root growth caused by drought, poor nutrition, or oxygen stress caused by wet soil, Fusarium solani is one of the causes of early maturity (aka cut out) and marked reduction in yield.

MANAGEMENT

Long-term (3 years) crop rotation out of beans may reduce soil inoculum. Provide optimal growing conditions, avoiding stress caused by excess water, prolonged drought, soil compaction, etc. Although no bean line is immune, some cultivars are more tolerant to the disease than others.

PUBLICATION

UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446
Diseases
R. M. Davis, Plant Pathology, UC Davis
C. A. Frate, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Abiotic Disorders:
A. E. Hall, Botany and Plant Sciences, UC Riverside
Acknowledgment for contributions to Diseases/Abiotic Disorders:
S. R. Temple, Plant Sciences, UC Davis
Acknowledgment for contributions to Diseases (viruses):
R. L. Gilbertson, Plant Pathology, UC Davis

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