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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Maple > Sunken discolored areas along trunk/branches

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Maple > Branches > Sunken discolored areas along trunk/branches

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  • Image: Eutypella canker 1
  • Image: Eutypella canker 2
  • Image: Eutypella canker 3

Eutypella canker
Eutypella parasitica

  • Young cankers appear as round flattened, bark covered areas on main trunk or larger branch
  • As cankers age, the flattened surface turns black and bark begins to fall off revealing decaying wood in a target shape pattern below
  • Branch stub or other wound is often visible at center of the canker
  • White to buff-colored fungal growth may be seen around outer portions of expanding canker if bark is removed
  • Old cankers may develop a thick ring of wound wood surrounding the canker, making that area wider than the trunk above or below
  • Occurs on all maples but common on sugar maples in forest settings and Norway maples in urban settings
  • More information on Eutypella canker
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  • Image: Perennial nectria canker 1
  • Image: Perennial nectria canker 2

Perennial nectria canker
Neonectria ditissima

  • Sunken round to oval cankers with target shaped ridges of barkless wood on large branches or the main trunk
  • Small dark sunken area on twigs that can girdle and kill the branch
  • Red to reddish orange raised cushion like bumps can occasionally be seen on the edge of the canker
  • More information on Perennial nectria canker
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  • Image: Frost canker 1
  • Image: Frost canker 2

Frost crack

  • Vertical splits or sunken dead areas of trunk or branches that are primarily on the south and southwest side
  • Occurs during winter, often noticed early spring
  • More information on Frost crack
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  • Image: Branch cankers 1
  • Image: Branch cankers 2
  • Image: Branch cankers 3

Branch cankers
Botryosphaeria obtusa, Valsa spp. and other fungi

  • Cankers are brown to black sunken areas on branch that may have cracked bark and discolored sapwood
  • Random dead branches seen throughout canopy
  • Leaves on random branches wilt, turn yellow then brown during the growing season
  • 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: Coral spot canker 1
  • Image: Coral spot canker 2

Coral spot canker
Nectria cinnabarina

  • Sunken dark brown area on branch that is often cracked or has a ridge at the edge
  • Raised cushion-like bumps on affected branches, may be cream to orange or red, turn black with age
  • Dead branches and twigs, often first observed in early spring
  • Common on trees stressed by drought, recent transplant or other factors
  • More information on Coral spot canker

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