How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

This disease, also called ashy stem blight, is primarily a problem on blackeyes, garbanzo, lima, and common beans. Infection on roots causes a brown to black necrosis. If plants are grown under dry land conditions, young plants can be killed. In periods of high temperature and particularly following drought stress, the disease progresses rapidly and plants may die. At this stage the "charcoal dust" appearance on the surface of the stems is diagnostic evidence for this disease. This charcoal effect is due to the production of small black microsclerotia just below the epidermis and in the vascular tissue. This symptom is also called ashy stem blight. Typical symptoms are often seen on blackeye plants at the end of the season after pods have matured. This late onset of disease may be secondary.

COMMENTS ON THE DISEASE

The fungus is pathogenic on many crops including corn and sorghum. Although the fungus is capable of infecting plants at all stages of growth, severe disease is usually limited to times following drought stress and when temperatures are high.

MANAGEMENT

Avoid drought stress especially during periods of high temperature.

PUBLICATION

UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446
Diseases
R. M. Davis, Plant Pathology, UC Davis
Acknowledgment for contributions to Abiotic Disorders:
A. E. Hall, Botany and Plant Sciences, UC Riverside
Acknowledgment for contributions to virus sections in Diseases:
R. L. Gilbertson, Plant Pathology, UC Davis
Acknowledgment for co-authorship of Ascochyta Blight:
C. A. Frate, UC Cooperative Extension, Tulare Co.

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