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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Maple > Irregular to circular discolored patches

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Maple > Trunk/Branches > Irregular to circular discolored patches

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

Eutypella canker
Eutypella parasitica

  • White to buff-colored fungal growth may be seen around outer portions of expanding canker if bark is removed
  • Young cankers appear as round flattened, bark covered areas on main trunk or larger branch
  • Branch stub or other wound is often visible at center of the canker
  • As cankers age, the flattened surface turns black and bark begins to fall off revealing decaying wood in a target shape pattern below
  • 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

  • Red to reddish orange raised cushion like bumps can occasionally be seen on the edge of the canker
  • 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
  • More information on Perennial nectria canker
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  • Image: Lichens 1
  • Image: Lichens 2
  • Image: Lichens 3

Several species

  • Colorful patches on the bark of trunk and/or branches
  • Can be wrinkled, in scalloped sheets, lace-like pads, bushy tufts, paint-like spots or splashes
  • Forms can be flat against the bark surface or raised in leaf-like lobes, finger-like or hairy projections
  • Colors may be shades of gray, green, blue, yellow, orange, or red
  • Lichens do not harm trees or shrubs and no management is necessary
  • More information on Lichens

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