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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Hickory > Canopy is thin with yellow or brown leaves

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Hickory > Leaves > Canopy is thin with yellow or brown leaves

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  • Hickory bark beetles 1
  • Hickory bark beetles 2
  • Hickory bark beetles 3

Hickory bark beetles
Scolytus quadrispinosus

  • Small, 1/8th inch, round exit holes in trunk and branches
  • Heavily infested trees typically have sparse, yellowed leaves
  • Premature leaf drop and broken twigs in crown can also occur when heavily infested
  • Weakened, stressed trees most likely attacked, rarely infest healthy trees
  • High Hickory bark beetle populations are often associated with Hickory decline
  • Adults dark brown to black, less than ¼ inch long
  • More information on Hickory bark beetles
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  • Hickory decline 1
  • Hickory decline 2
  • Hickory decline 3

Hickory decline
Ceratocystis smalleyi and Scolytus quadrispinosus

  • Leaves are wilted or undersized, thin canopy with dead branches
  • When bark is peeled back, numerous reddish brown oval cankers up to 1 ft. long can be seen
  • Bark surface often shows no symptoms, occasionally cracking or dark sunken area can be seen
  • Dark bleeding spots that appear in May or June indicate cankers below the bark
  • Groups of young green shoots (sprouts) often form along the trunk; these wilt and die within a year
  • Round 1/8th inch exit holes of hickory bark beetles on upper trunk
  • Larval galleries often visible in discolored sapwood
  • Trees can decline and die in as little as two years when beetle populations are high
  • More information on Hickory decline
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  • Ganoderma root and butt rot 1
  • Ganoderma root and butt rot 2
  • Ganoderma root and butt rot 3

Ganoderma root and butt rot
Ganoderma spp.

  • Leaves are small and may yellow and drop
  • Canopy appears thin with few leaves and multiple dead branches
  • Fungal conks, semicircle shelf fungi, can be found from the base of the tree up to 3 feet high on the trunk
  • Conks are reddish brown and shiny on top, white and porous underneath, a rim of white may be visible on the edge of the growing conks
  • Infected wood at the base of the tree is white, soft, stringy or spongy
  • Infected trees frequently break or fall over in storms
  • More information on Ganoderma root and butt rot
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  • Armillaria root rot 1
  • Armillaria root rot 2
  • Armillaria root rot 3

Armillaria root rot
Armillaria spp.

  • Infected trees have poor growth, dead branches in the upper canopy, undersized and/or yellow leaves
  • Flat white sheets of fungal growth (mycelial fans) between the bark and sapwood at the base of infected trees
  • Thick black, shoestring-like fungus can sometimes be seen under the bark, around roots and in the soil around the base of the tree
  • Wood is decayed, white, soft and spongy; this may extend from the base of the tree well up into the trunk
  • Trees frequently break or fall over in storms
  • Clusters of honey-colored mushrooms may grow at the base of the tree in fall
  • More information on Armillaria root rot
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  • Heart rot 1
  • Heart rot 2
  • Heart rot 3

Heart rot
Fomes fomentarius

  • Canopy may show no symptoms, or may have small, yellowing leaves or dead branches depending on the extent of decay
  • In cross section, the wood at the center of the trunk is white, mottled, soft and crumbly
  • Hoof-shaped, silvery-grey to brown, fungal fruiting bodies up to 8 inches across arise along the stem; often near a pruning wound, crack or other wound
  • More information on heart rot

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