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Bacterial blight (Leaf spot)

Pseudomonas syringae pv. viburni or Xanthomonas spp.

31 host plants

Last updated

Data Coverage 3 of 6 dimensions
Causal Agent
Host Plants
Symptoms
Management
GDD Threshold
Regional Notes

Leaves show dark lesions with water-soaked margins while shoots may develop expanding cankers. This bacterial disease spreads by rain splash. Improve air circulation and disinfect tools.

Remove blighted tissue promptly, cutting well below visible symptoms. Improve air circulation by thinning dense growth. Avoid overhead watering, especially during bloom and new growth periods when tissues are most susceptible. For recurring problems, preventive fungicide applications timed to protect new growth can reduce infection, but cultural controls should be your first approach.

Quick Reference

Causal Agent
Pseudomonas syringae pv. viburni or Xanthomonas spp.
Host Plants
31
Favorable Conditions
Cool temperatures; high humidity; rain or overhead irrigation; crowded planti...

Management

Vulnerability Window

Apply fungicides in September and again before fall rains.

What Triggers Infection

Cool temperatures; high humidity; rain or overhead irrigation; crowded plantings with poor air circulation

Cultural Controls

  • Plant resistant viburnums such as Viburnum burkwoodii 'Mohawk', V.
  • carlcephalum 'Cayuga', V.
  • lantana 'Mohican', or V.
  • rhytidophyllum 'Alleghany'.
  • Plant in full sun.
  • Space plants and prune to provide good air circulation.

Host Plants (31)

Viburnum bodnantense Viburnum, bodnantense Viburnum bracteatum Bracted Viburnum, Limerock Arrowwood Viburnum Viburnum burkwoodii Burkwood Viburnum Viburnum carlesii Koreanspice Viburnum Viburnum cassinoides Witherod Viburnum, Northern Wild Raisin Viburnum cinnamomifolium Cinnamon Viburnum Viburnum davidii David's Viburnum Viburnum dentatum Arrowwood Viburnum Viburnum edule Mooseberry Highbush Cranberry, Moosewood Viburnum, Squashberry Viburnum ellipticum Oregon Viburnum, Western Wayfaring Tree Viburnum farreri Fragrant Viburnum Viburnum juddii Judd Viburnum Viburnum lantana Wayfaringtree Viburnum Viburnum lantanoides Hobblebush Viburnum lentago Nannyberry Sheepberry Viburnum nudum Possumhaw Smooth Witherod Northern Wild Raisin Viburnum opulus var. americanum American Cranberrybush Viburnum Viburnum opulus var. opulus European Cranberrybush Viburnum, Guelder-rose Viburnum opulus var. sargentii Sargent Viburnum Viburnum plicatum Doublefile Viburnum, Japanese Snowball, Japanese Snowball Viburnum, Snowball Viburnum Viburnum plicatum var. plicatum Japanese Snowball Viburnum Viburnum plicatum var. tomentosum Doublefile Viburnum Viburnum pragense Prague Viburnum Viburnum prunifolium Blackhaw Viburnum Viburnum rafinesquianum Downy Arrowwood Viburnum, Rafinesque Viburnum Viburnum rhytidophyllum Leatherleaf Viburnum Viburnum rufidulum Rusty Blackhaw Viburnum, Southern Blackhaw Viburnum setigerum Tea Viburnum Viburnum suspensum Sandankwa Viburnum, Sandanqua Viburnum Viburnum tinus Laurustinus Viburnum trilobum American Cranberrybush Viburnum