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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Oak > Leaves wilted and completely brown

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Oak > Leaves > Leaves wilted and completely brown

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  • Image: Twolined chestnut borer 1
  • Image: Twolined chestnut borer 2
  • Image: Twolined chestnut borer 3

Twolined chestnut borer
Agrilus bilineatus

  • Leaves in upper canopy look wilted, turn brown but remain attached to branch for several weeks
  • 1/8 inch D-shaped exit holes
  • S-shaped galleries underneath bark
  • Bluish black bodies with two light stripes running down the wing covers
  • Larvae are approx. 1 inch long and white with 2 spines at abdomen tip
  • Damage visible mid to late summer
  • More information on twolined chestnut borer...
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Bur oak blight
Tubakia iowensis

  • Infects only bur oaks - small acorn variety
  • Spring and early summer, leaf veins on lower leaf surface have dark brown dots or short lines
  • Mid-summer and fall, random lengths of leaf vein turn brown; some expand into brown wedge shaped areas on leaves
  • Leaves may turn completely brown, some drop early
  • Small raised black dots form on the petiole (stem) of infected leaves
  • Some leaves remain attached through winter
  • Symptoms appear in lower, inner canopy first. Disease progresses upward and outward over multiple seasons
  • More information on Bur oak blight...
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  • Image: Botryosphaeria canker 1
  • Image: Botryosphaeria canker 2

Botryosphaeria canker
Botryosphaeria quercuum

  • Leaves on random branch tips throughout the canopy wilt, turn brown and remain attached to twig
  • Cankers with brown to black, sunken cracked bark can be found at the base of wilted twigs
  • If bark is peeled back from the canker, brown streaks can be seen in the sapwood
  • Small black raised pimple like fungal fruiting bodies can be seen scattered on infected twigs
  • Cankers only occasionally extend into larger branches
  • Damage easily confused with twig girdler damage
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  • Image: Twig girdler 1
  • Image: Twig girdler 2
  • Image: Twig girdler 3

Twig girdler
Oncideres cingulata

  • Dead twigs may be scattered in canopy
  • Small branches on ground; outer half is smooth while center is rough from where it has broken off
  • Adult is about 9/16 inch long, grayish brown with scattered yellow spots, with antenna as long as its body
  • Damage seen in August and September
  • More information on Twig girdler...
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  • Image: Oak wilt 1
  • Image: Oak wilt 2
  • Image: Oak wilt 3

Oak wilt
Ceratocystis fagacearum

  • Leaves wilt, leaf edges and tips turn brown, with a green center
  • In red oak group symptoms are first seen in the top of the canopy, disease progresses to the entire canopy and kills tree in 1 to 3 months
  • Infected trees drop their leaves
  • In white oak group symptoms appear in one branch, disease progresses slowly from 1 to 5 years before death
  • In white oak group - Peel back layer of bark on symptomatic branch to reveal brown streaking on wood
  • Symptoms appear in whole groups of trees as infection spreads through root graft
  • More information on Oak wilt...
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  • Image: Ganoderma butt rot 1
  • Image: Ganoderma butt rot 2
  • Image: Ganoderma butt rot 3

Ganoderma butt rot
Ganoderma applanatum

  • Leaves are smaller in size and turn yellow earlier than normal
  • Canopy appears thin with few leaves and multiple dead branches
  • Fungal conks, a 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 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 butt rot...
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  • Image: Drought 1
  • Image: Drought 2
  • Image: Drought 3

Drought

  • Leaf margins and branch extremities usually brown and wilt first
  • Uniform wilting or browning of leaves throughout the tree
  • Leaves often yellow (chlorotic)
  • Severe drought stress may cause dieback of individual branches
  • Drought-stressed trees and shrubs often drop their leaves abnormally early
  • More information on Drought...

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