How to Manage Pests

UC Pest Management Guidelines

Dry Beans

Bacterial Brown Spot

Pathogen: Pseudomonas syringae pv. syringae

(Reviewed 8/07, updated 8/07)

In this Guideline:


Bacterial brown spot symptoms on leaves appear as oval spots that have dead (necrotic) tissue in the center surrounded by a narrow zone of light-green to yellow tissue. Water-soaking and slimy ooze is rarely seen with this disease. The spots may grow together and the centers of the spots often fall out, resulting in an overall tattered appearance of the leaf. On pods, small dark brown spots develop that result in distorted pod growth.


Bacterial brown spot occurs sporadically and rarely in California. It is readily distinguished from the more serious common and halo blights based on leaf symptoms.


Control is similar to that for common and halo blights: plant certified bean seed, rotate crops, and clean crop and other host debris from the field after harvest to help prevent outbreaks of brown spot.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Dry Beans
UC ANR Publication 3446


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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