Bacterial Blast and Canker

May 02, 2022

A point of interest in Northern California is the increased visibility of Bacterial Blast and Canker in young almond orchards. As a result of the extremely cold weather and periodic rain events, the perfect storm or conditions were created for development of Bacterial Blast and Canker, Pseudomonas syringae. This disease can kill flowers, spurs and cause leaf drop, symptoms referred to as Bacterial Blast, and can cause gumming and limb dieback which is referred to as Bacterial Canker. Bacterial Blast and Canker typically attack weak or stressed trees. Many factors come into play including variety, rootstock and compatibility of the variety with rootstock, plant nutritional levels and nematode feeding. Basically, any factor that weakens a tree will predispose the tree to disease. The pathogen, Pseudomonas syringae, lives on all plant surfaces and is easily spread via rain or sprinkler irrigations that contact the tree. Chemical control is very limited and timing of application as a preventative spray is critical. Maintaining healthy trees is your best offensive measure.

John Heier – Manager Sales – Colusa, CA