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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Poplar > Leaves wilt, then turn yellow or brown

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Poplar > Leaves > Leaves wilt, then turn yellow or brown

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  • Image: Hypoxylon canker 1
  • Image: Hypoxylon canker 2
  • Image: Hypoxylon canker 3

Hypoxylon canker
Entoleuca mammata

  • Leaves on one or more branches are undersized, turn yellow then to brown and remain attached to stem
  • Cankers begin near wounds or at the base of a branch
  • Infected bark initially turns yellowish-orange; older infections are black at center with yellowish-orange margins
  • Bark first appears blistered and raised, then falls off to reveal blackened wood
  • Clusters of raised buff white to black bump like fungal stromata can be seen on 3 year old cankers
  • Damage most common on trembling aspen
  • More information on Hypoxylon canker
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  • Image: Valsa and Leucostoma cankers 1
  • Image: Valsa and Leucostoma cankers 2
  • Image: Valsa and Leucostoma cankers 3

Valsa and Leucostoma cankers
Valsa sordida and Leucostoma niveum

  • Leaves on random branches wilt, turn yellow then brown
  • Random dead branches seen throughout canopy
  • Sunken irregularly-elongated cankers with cracked bark at the edges occur on branches or the main trunk
  • Cankers are brown to black at the center with salmon to orange discoloration of the bark at the edges
  • In wet weather curled tendrils of orange spores emerge from pimple like fungal structures within infected branches
  • Common on trees stressed by drought, winter injury, wounds, insect feeding or other factors
  • More information on canker
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  • Image: Cryptodiaporthe canker 1
  • Image: Cryptodiaporthe canker 2
  • Image: Cryptodiaporthe canker 3

Cryptodiaporthe canker
Cryptodiaporthe populea

  • Leaves on infected branches turn yellow and drop prematurely
  • Random dead branches caused from girdling cankers seen throughout canopy
  • Bark on cankers may or may not be discolored, but the tissue beneath the bark will be brown to black
  • Multiple thin weak adventitious shoots develop
  • Callus tissue formed around edges of cankers causing bark to fall off and expose the wood beneath it
  • Common on Lombardy poplars
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  • Image: Armillaria root rot 1
  • Image: Armillaria root rot 2
  • Image: 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 (mycelia fans) grow 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, and this may extend from the base of the tree well up into the trunk
  • 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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  • Image: Ganoderma root and butt rot 1
  • Image: Ganoderma root and butt rot 2
  • Image: Ganoderma root and butt rot 3

Ganoderma root and butt rot
(aka. artist's conk)
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 tree base 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


  • Dried brown to gray-green leaves hang on the tree or foliage drops unseasonably and litters the ground under the tree
  • Foliage sometimes turn brown around the edges but more commonly turns a dull, gray-green color
  • Severe drought stress may cause dieback of individual branches starting at branch tips
  • More information on watering trees and shrubs

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