Bacterial Canker

Pseudomonas syringae pv. syringae

50 host plants

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

You'll spot sunken, oozing cankers on tree limbs that develop in spring, with small lesions on nearby leaves showing disease progression. This bacterial disease travels readily by rain splash and pruning wounds that provide entry points. Remove affected branches well below the visible canker margin, sterilizing all tools between cuts to prevent further spread. Avoid planting susceptible species in contaminated areas. Proper pruning technique during dry weather and tool sanitation are essential for control.

Sanitation measures have been helpful. Plant resistant cultivars. Prune affected branches well below visible symptoms and sterilize tools between cuts. Avoid pruning during wet weather, which spreads the pathogen through fresh wounds. Maintain plant vigor through proper watering and site management.

Quick Reference

Causal Agent
Pseudomonas syringae pv. syringae
Host Plants
50
Spread
wind, rain-splash, contact" # Wind, rain, insects, infected bud wood, nurser...
Favorable Conditions
Cool wet weather from fall through early spring. Frost events are the primary...

Management

Vulnerability Window

Fall leaf scar formation (October-November) through early spring growth. Natural leaf scars in fall and heading cuts in spring are the primary infection avenues leading to tree death. Dead bud disease starts in February. Cankers develop and expand during winter and early spring. Girdled limbs may leaf out in spring then yellow and die by late summer as water demand increases." # Source: PNW Plant Disease Management Handbook (Cherry - Bacterial Canker)

What Triggers Infection

Cool wet weather from fall through early spring. Frost events are the primary trigger — P. syringae produces ice nucleation proteins promoting frost damage at 28-25°F, creating wounds for bacterial colonization. Factors predisposing trees to cankers include: wounds, frost damage, early dormant season pruning, heading cuts, incorrect soil pH, poor nutrition, ring nematode damage, and co-infection by Cytospora, Verticillium, or Nectria." # Source: PNW Plant Disease Management Handbook (Cherry - Bacterial Canker)

Cultural Controls

  • Sanitation measures have been helpful. Plant resistant cultivars. Prune out all diseased wood as soon as it is noticed and especially before fall rains. Avoid late-summer nitrogen fertilizer applications, that can lead to winter injury Prune susceptible cultivars during dry weather if possible.
Regional Notes

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Host Plants (50)

Betula lenta Sweet Birch, Cherry Birch, Black Birch Euphorbia Wood Spurge Malus robusta Cherry, Crabapple Prunus americana Wild Plum American (Red) Plum August Plum, Goose Plum Prunus avium Sweet Cherry Prunus besseyi Sand Cherry, Western Sand Cherry Prunus blireiana Blireiana Plum Prunus caroliniana Carolina Cherrylaurel American Cherrylaurel Prunus cascade Prunus cascade Prunus cerasifera Cherry, Plum Prunus cistena Purpleleaf Sandcherry Redleaf Sandcherry Cistena Sandcherry Cistena Plum Prunus dream Prunus dream Prunus emarginata Bitter Cherry, Wild Cherry, Quinine Cherry Prunus first Prunus first Prunus fruticosa Steppe Cherry, European Dwarf Ground Cherry, Mongolian Cherry Prunus glandulosa Dwarf Flowering Almond Prunus ilicifolia Hollyleaf Cherry, Holly-leaved Cherry Prunus lusitanica Portugal Laurel Prunus maackii Amur Chokecherry Amur Cherry, Manchurian Cherry Prunus mume Japanese Apricotc Japanese Flowering Apricot Japanese Flowering Plum Prunus newport Newport Flowering Plum Prunus okame Okame Flowering Cherry Prunus padus European Birdcherry Common Birdcherry Prunus prostrata Rock Cherry, Mountain Cherry Prunus sargentii Sargent Cherry, Sargent's Cherry Prunus serotina Black Cherry, Rum Cherry Prunus serrula Birchbark Cherry, Paperbark Cherry, Tibetan Cherry Prunus serrulata Japanese Flowering Cherry Prunus snow Prunus snow Prunus subcordata Klamath Plum, Sierra Plum, Pacific Plum Prunus subhirtella Higan Cherry Prunus subhirtella var. autumnalis Autumn Flowering Higan Cherry Prunus tai Prunus tai Prunus virginiana Prunus virginiana Prunus virginiana var. demissa Western Chokecherry Prunus virginiana var. virginiana Common Chokecherry, Eastern Chokecherry Prunus yedoensis Yoshino Cherry, Somei-yoshino Cherry, Tokyo Cherry Solanum aviculare Kangaroo Apple Vaccinium angustifolium Lowbush Blueberry Vaccinium corymbosum Highbush Blueberry Vaccinium crassifolium Creeping Blueberry, Thick-leaved Whortlberry Vaccinium macrocarpon Cranberry American Cranberry Vaccinium membranaceum Big Huckleberry, Mountain Huckleberry Thinleaf Huckleberry Vaccinium moupinense Himalayan Blueberry Vaccinium ovalifolium Oval-leaf Blueberry Vaccinium ovatum Box Huckleberry, Evergreen Huckleberry Vaccinium parvifolium Red Huckleberry, Red Whortleberry Vaccinium sikkimense Sikkim Blueberry Vaccinium uliginosum Bog Blueberry, Bog Bilberry Vaccinium vitis Vaccinium vitis