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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Elm > Clumps of stems/sprouts on trunk or branches

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Elm > Trunk/Branches > Clumps of stems on trunk or branches

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  • Image: Botryodiplodia canker 1
  • Image: Botryodiplodia canker 2

Botryodiplodia canker
Botryodiplodia ulmicola

  • Clumps of adventitious sprouts or shoots develop below cankers on large branches
  • Leaves growing beyond the canker turn yellow and wilt (Siberian elm) or fall off (American elm)
  • Reddish brown to black water soaked cankers form on branches 4 inches in diameter or smaller
  • Sap wood underneath the canker is reddish brown
  • Tiny raised pimple like fungal structures form on branches killed by the canker, causing bark to look rough
  • Damage is most severe on trees stressed by other factors
  • More information on canker
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  • Image: Elm yellows 1
  • Image: Elm yellows 2
  • Image: Elm yellows 3

Elm yellows or Elm phloem necrosis
Elm yellows group or clover proliferation group

  • Witches’ broom or dense leaf clusters at branch ends, common on red elms
  • Leaves in the entire canopy turn yellow, droop and fall off, often all in a few weeks time
  • Occasionally, leaves can shrivel, turn brown and remain attached to branches for several weeks
  • When bark is peeled back, the inner bark is yellow brown and smells of wintergreen (American elm) or maple syrup (red elm)
  • Damage appears mid to late summer; infected trees die within a year or two
  • All Minnesota elm species are susceptible
  • More information on Elm yellows

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