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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Butternut > Sunken, cracked or discolored areas along branches or trunk

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Butternut > Trunk/Branches > Sunken, cracked or discolored areas along branches or trunk

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  • Image: Butternut canker 1
  • Image: Butternut canker 2
  • Image: Butternut canker 3

Butternut canker
Sirococcus clavigignenti-juglandacearum

  • Crown dieback that expands each year can be seen from a distance
  • Cankers appear as multiple cracks in bark along trunk and branches
  • Older cankers open into a barkless oval with ridges of wound wood on the edges
  • Wood is stained dark brown to black underneath cankers
  • Cankers quickly kill twigs and small branches while trunk cankers grow for several years
  • Sprouts may form below cankers
  • After several years, trees die
  • Common on butternut, very rare on black walnut
  • More information on Butternut canker
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  • Image: Perennial nectria canker 1
  • Image: Perennial nectria canker 2
  • Image: Perennial nectria canker 3

Perennial nectria canker
Neonectria ditissima

  • Early canker symptoms are small and difficult to see, usually forming a darkened, depressed area beneath smooth, young bark
  • Sunken round to oval cankers with target shaped ridges of barkless wood on large branches or main trunk
  • Red to reddish orange raised cushion like bumps can occasionally be seen on the edge of the canker
  • Dead branches and twigs killed by girdling cankers
  • 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: Flat headed apple tree borer 1
  • Image: Flat headed apple tree borer 2
  • Image: Flat headed apple tree borer 3

Flat headed apple tree borer
Chrysobothris femorata

  • Older tunnels cause cracks in bark, froth oozes from openings
  • Infested areas of tree show sunken, darkened areas of bark
  • Larvae tunnel under bark of large branches and trunk
  • Can cause dieback or entire tree can be killed, especially young trees
  • Larvae is yellow with no legs
  • Adult is ¼ to ½ inch long, flattened beetle, ranging from metallic brown to dull gray
  • More information on Flat-headed apple tree borer

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