How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS AND SIGNS

Bacterial blight infections start as small, angular-shaped, water-soaked specks on leaves that are often surrounded by yellow borders. As the disease develops, specks enlarge and coalesce together into larger, irregularly shaped gray-to-tan spots. Leafspots are visible from both top and bottom sides of leaves. Symptoms may resemble those of the more familiar bacterial leafspot disease.

COMMENTS ON THE DISEASE

Recent research has identified this bacterial disease, which is caused by a pathogen related to, but distinct from, the bacterium that causes bacterial leafspot. For cole crops, bacterial blight has been found on broccoli, cauliflower, and Brussels sprouts. Other crucifer hosts include rappini, arugula, and rutabaga. The pathogen is seedborne and is splashed from plant to plant by rain and sprinkler irrigation. Bacterial inoculum may persist for short periods of time in soil.

MANAGEMENT

Plant clean and disease-free transplants. Rotation away from fields where the disease has recently occurred may reduce inoculum levels in soil or infected debris. A change from sprinkler to furrow or drip irrigation may limit its spread.

PUBLICATION

UC IPM Pest Management Guidelines: Cole Crops
UC ANR Publication 3442
Diseases
S. T. Koike, UC Cooperative Extension, Monterey County
K. V. Subbarao, Plant Pathology,UC Davis, Salinas

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