How to Manage Pests

Pests in Gardens and Landscapes

Citrus blast—Pseudomonas syringae

Bacterial blast infections of citrus occur during cool or wet weather during the winter or spring and usually start as black lesions in the leaf petiole and progress into the leaf axil. Once the petiole is girdled, leaves wither, curl, and eventually drop. Entire twigs may die back. Diseased areas are covered with a reddish brown scab. Infections result in small black spots on the fruit.

Solutions

Pruning out dead or diseased twigs in spring after the rainy period reduces the spread of bacterial blast. Scheduling fertilization and pruning during spring or early summer prevents excessive new fall growth, which is particularly susceptible to blast infection. Bordeaux sprays applied before the first rain may help prevent bacterial blast.

Black lesions
Black lesions in leaf petiole and axil

Withering leaves
Withering leaves


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/GARDEN/FRUIT/DISEASE/citrusblast.html revised: January 8, 2014. Contact webmaster.