Pseudomonas syringae pv. syringae is ubiquitous in orchards, so bacterial blast can develop whenever environmental conditions are right (freezing or near-freezing and wet). While copper sprays have been used to protect trees from bacterial blast, resistance is common in P. syringae populations throughout the state. Unfortunately, it is no longer effective for controlling bacterial blast in some orchards, however, Kasumin® 2L has been shown to be effective. Continue reading →

In 2023, the cold, wet weather during bloom and leaf-out resulted in bacterial blast damage in many Sacramento Valley almond orchards. If conditions this year are cold and wet during bloom, we may see a recurrence of blast: make a plan now to keep blast damage to a minimum. Continue reading →

Blast is a challenging disease to control, given the limited number of available tools. This year, symptoms were common even in orchards which had received one or more copper dormant sprays (copper-resistant Pseudomonas populations are common throughout the state). Continue reading →