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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Ash > Dead branches

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Ash > Trunk > Dead branches

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  • Image: Environmental stress, tree top - no leaves
  • Image: Environmental stress, brown leaves
  • Image: Environmental stress, missing leaves

Environmental stress
Drought, compact soils, flood damage, winter injury, other

  • Dead branches in the canopy
  • Leaves wilt and turn brown at the tips and the margins first, then completely brown
  • Many weak young shoots/sprouts at the base of the tree
  • Leaves appear drooped or wilted within canopy
  • More information on Environmental stress...
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  • Image: Stem girdling roots, trunk base 1
  • Image: Stem girdling roots, trunk base 2
  • Image:Stem girdling roots, tree

Stem girdling roots

  • A root circling the trunk of the tree may be seen at the soil line
  • The trunk may become sunken in or compressed where it contacts the root
  • If the girdling root is below ground the trunk will lack the natural widening or flare at the soil line, but rather will go straight into the earth like a telephone pole
  • Affected trees have slow growth, poor color, change color and lose their leaves early in the fall
  • Affected trees commonly exhibit water-stress symptoms such as marginal leaf scorch, wilting, sudden leaf fall.
  • Affected trees commonly exhibit excessive and abnormal winter damage including true frost cracks and dieback
  • More information on Stem girdling roots...
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  • Image: Branch cankers, crown with missing leaves
  • Image: Branch cankers, leaves up close
  • Image: Branch cankers, canker up close

Branch cankers
Botryosphaeria sp. (and other fungi)

  • Dead branches and twigs, often first observed in early spring
  • Sunken, discolored canker on branches, oval shaped to completely encircling the branch
  • Dark stained sapwood visible if bark is cut off of the discolored area of the branch
  • Leaves on affected branches may wilt and die
  • Small raised black pimple like bumps along edge of the discolored area
  • Common on trees stressed by drought, recent transplant or other factors
  • More information on Branch cankers...
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  • Image: Coral spot canker, crown with missing leaves
  • Image: Coral spot canker, cankers on branch
  • Image: Coral spot canker, branch with leaves and cankers

Coral spot canker
Nectria cinnabarina

  • Dead branches and twigs, often first observed in early spring
  • 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 back with age
  • Common on trees stressed by drought, recent transplant or other factors
  • More information on Coral spot canker...
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  • Image: Nectria canker, canker up close
  • Image: Nectria canker, large canker on trunk
  • Image: Nectria canker, reddish bumps around canker up close

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: Ash yellows, missing leaves in crown
  • Image: Ash yellows, yellow leaves
  • Image: Ash yellows, leaves up close

Ash yellows phytoplasma

  • Infected plants grow very slowly, and have a sparse thin canopy of leaves
  • Leaves are small, yellow, often folded or cupped and grow in clumps along the branch
  • Branches die throughout the canopy
  • Many weak young sprouts with small yellow leaves arise from the base of the tree
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  • Image: Ash bark beetles, bark holes up close
  • Image: Ash bark beetles, bark hole tunnels
  • Image: Ash bark beetles, bark holes with scale

Ash bark beetles

  • Exit holes first appear in May in trunks and branches
  • Exit holes are 1/8 inch wide and round
  • Galleries cut across the grain in sapwood; typically with two arms starting from a central chamber
  • Adults are 1/8 inch long and brown
  • Larvae are small, about 1/8 inch long, brown head, whitish body, lacks legs; is bent in a C-shape
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  • Image: Clearwing borers, bark holes on trunk
  • Image: Clearwing borers, exit hole up close
  • Image: Clearwing borers, larva in wood

Clearwing borers
Ash borer and banded ash clearwing

  • Exit holes first appear in June and July
  • Exit holes are round and 1/4 inch wide; frass (sawdust and excrement) can be conspicuous underneath
  • Galleries occur deep in sapwood
  • Pupae stick out of exit hole, empty pupal cases are commonly observed after moths have emerged
  • Adults are wasp-like, lacking scales on most of their wings
  • Larvae are caterpillars; have brown head and cream-colored body; up to 1 1/3 inch long
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  • Image: Redheaded ash borer, exit hole in bark 1
  • Image: Redheaded ash borer, exit hole in bark 2
  • Image: Redheaded ash borer, tunnels in wood

Redheaded ash borer

  • Exit holes first appear in June
  • Exit holes are round and 3/8 inch wide
  • Galleries start in phloem and eventually enter into sapwood; generally not very serpentine
  • Adults are 1/2 to 5/8 inch long; reddish brown with four yellow bands across their wing covers
  • Larvae are up to 4/5 inch long, whitish, cylindrical; area behind head enlarged and round, head generally inconspicuous; legless
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  • Image: Flatheaded borers, exit hole in wood

Flatheaded borers
Primarily Chrysobothris sexsignata

  • Exit holes first appear in May and June
  • Found nearly always in black ash
  • Exit holes are oval shaped and 3/16 inch wide
  • Galleries start in phloem and eventually enter into sapwood; generally not very serpentine
  • Adults are 1/2 inch long, bullet-shaped, and bronzed colored
  • Larvae are whitish, flattened, up to 1 inch long; area behind enlarged and flattened; head generally inconspicuous; legless
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  • img:Emerald Ash Borer damage 1
  • img:Emerald Ash Borer damage 2
  • img:Emerald Ash Borer damage 3

Emerald ash borers

  • Chewing damage caused by adults occurs late May to early August
  • Chews along the edges of leaves; defoliation is typically minor
  • Slender bodied, 1/3 - 1/2 inch long; iridescent green with coppery colored head
  • More information on Emerald ash borers...

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