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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous > Cotoneaster > Leaves discolored brown to black

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Cotoneaster > Leaves > Leaves discolored brown to black

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  • Image: Winter Injury 1
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Fire blight
Erwinia amylovora

  • Infected flowers appear water-soaked, shrivel and turn brown or black
  • Leaves wilt, turn reddish brown; appear as though scorched by fire and cling to twigs
  • Infected shoots turn brown and bend into a shepherds' crook
  • Cankers on older branches cause bark to be dark, cracked and sunken
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  • More information on fire blight
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  • Image: Fire Blight 1
  • Image: Fire Blight 2
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Sooty Mold

  • Black, brown or gray soot-like covering on leaf surfaces, twigs or branches
  • Sticky, shiny secretions on leaves from sap-sucking insects (e.g., wooly apple aphid)
  • Insects or signs of insect damage (distorted, pin-prick feeding marks, etc.) may be seen on leaves or twigs above the most heavily affected moldy areas.
  • More information on Sooty Mold
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  • Image: Fruitworms 1
  • Image: Fruitworms 2
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Pear Sawfly (Pear Slug)
Caliroa cerasi

  • Larvae feed on upper surface of leaf between the veins, "windowpaning" the leaf as they feed
  • Damaged leaves often have a grayish appearance before turning brown
  • Larvae normally feed about 4 weeks beginning in June; a second generation may start in August
  • Larvae are one half inch long, shiny and slug-like and are normally dark olive green in color
  • More information on Pear Sawfly
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  • Image: Black Rot 1
  • Image: Black Rot 2
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Botryosphaeria canker
Botryosphaeria dothidea

  • Leaves on one or more branches wilt, die and turn brown
  • Bark on affected branches is darker, cracked, or blistered at the site of the canker
  • Wood beneath the canker is dark brown
  • Common on shrubs stressed by drought, winter injury and other factors
  • More information on Botryosphaeria canker

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