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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Prunus > Sticky gums exuded from branches or twigs

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Prunus > Branches > Sticky gums exuded from branches or twigs

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  • Image: Branch cankers 1
  • Image: Branch cankers 2
  • Image: Branch cankers 3

Branch cankers
Valsa leucostoma, Leucostoma spp.

  • Sticky gum exudes from branch cankers
  • Raised black pimple like fungal structures form on cankers and dead branches, exude orange tendrils of spores in wet weather
  • Cankers are brown to black sunken areas on branch that may have cracked bark and discolored reddish brown sapwood
  • Leaves on random branches wilt, turn yellow then brown
  • Infected branches don't leaf out in spring
  • Random dead branches seen throughout canopy
  • Common on trees stressed by drought, winter injury, wounds, insect feeding or other factors
  • More information on canker
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  • Image: Brown rot 1
  • Image: Brown rot 2
  • Image: Brown rot 3

Brown rot
Monilinia fructicola

  • Sunken, darkened areas on twigs from which gums are exuded, also known as gummosis
  • Sudden browning of blossoms or wilting of leaves
  • Part or all of the ripening fruit develop a soft brown rot, then become shriveled and dusted with powdery tufts of tan to gray spores
  • Rotten fruit may remain attached to the tree or fall to the ground
  • More information on Brown rot
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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

  • 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
  • Sunken dark colored elliptical cankers form on branches
  • More information on Bacterial spot and canker
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  • Image: Mechanical damage 1
  • Image: Mechanical damage 2
  • Image: Mechanical damage 3

Mechanical damage

  • Rubbery sap exudes from openings or wounds called gummosis
  • Areas of bark are missing from stem or branches
  • If bark removal encircles stem or branch, thinning canopy or branch dieback will be seen
  • Leaves are undersized and yellow

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