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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Prunus > Discolored areas of branches or twigs

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Prunus > Trunk/Branches > Discolored areas of branches or twigs

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  • Image: Bacterial spot and canker 1
  • Image: Bacterial spot and canker 2
  • Image: Bacterial spot and canker 3

Bacterial spot and canker
Pseudomonas syringae pv. syringae

  • Sunken dark colored elliptical cankers form on branches
  • Sticky gums (gummosis) or sour-smelling liquid are excreted from infected branches
  • Blossoms turn brown, especially after frost damage
  • Angular, brown to black leaf spots that eventually drop out leaving holes and giving a ragged appearance on leaves
  • More information on Bacterial spot and canker
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  • Image: Branch cankers 1
  • Image: Branch cankers 2
  • Image: Branch cankers 3

Branch cankers
Valsa leucostoma, Leucostoma spp.

  • Cankers are brown to black sunken areas on branch that may have cracked bark and discolored reddish brown sapwood
  • Random dead branches seen throughout canopy
  • Raised black pimple like fungal structures form on cankers and dead branches, exude orange tendrils of spores in wet weather
  • Sticky gum exudes from branch cankers
  • Leaves on random branches wilt, turn yellow then brown
  • Infected branches don't leaf out in spring
  • Common on trees stressed by drought, winter injury, wounds, insect feeding or other factors
  • More information on canker
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  • Image: Scurfy scale 1

Scurfy scale
Chionaspis furfura

  • Infested twigs and branches show dieback in canopy
  • Adults are white and covered by a white cocoon-like armor, which gives the appearance of white bumps along the stem or branches
  • Crawlers or juvenile scales are light purple
  • Cocoon-like armor can be seen year round but crawlers can be seen in June
  • More information on scale insects

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