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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Mountain Ash > Spots, blotches or discolored fruit

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Mountain Ash > Fruit > Spots, blotches or discolored fruit

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  • Image: Fireblight 1
  • Image: Fireblight 2
  • Image: Fireblight 3

Fire blight
Erwinia amylovora

  • Infected fruit are shriveled and discolored
  • Branch cankers have dark, sunken and cracked bark, sapwood is streaked reddish brown
  • Drops of sticky honey colored liquid can be seen on infected plant parts in warm wet weather
  • Infected leaves wilt, turn gray then dark brown
  • Young shoots bend over forming a "shepherd's crook"
  • Infected blossoms first turn gray, then black
  • Infected leaves and blossoms remain attached to the tree, often even in winter
  • More information on fire blight
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  • Image: Branch cankers 1
  • Image: Branch cankers 2

Branch cankers
Botryosphaeria dothidea

  • Sunken brown spots on fruit, can grow to rot part or all of fruit
  • Leaves on girdled branches wilt, die and turn brown
  • Small blister like spots on branches exude, watery fluid
  • Branch infections grow to cracked, flakey, orange canker
  • More information on canker
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  • Image: Apple scab 1
  • Image: Apple scab 2
  • Image: Apple scab 3

Apple scab
Venturia inaequalis

  • Olive green to brown leaf spots with an irregular or feathered edge, eventually becoming a dark brown to black
  • Infected leaves turn yellow and drop prematurely
  • More information on Apple scab

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