Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension
www.extension.umn.edu
612-624-1222

Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Crab Apple > Branch dieback

Print Icon Email Icon Share Icon

Crab Apple > Branch > Branch dieback

1 of 8
  • Image: Winter Injury 1
  • Image: Winter Injury 2

Winter Injury

  • Injured branches leaf out and then die, or don’t leaf out at all
  • Injured shoots and branches die quickly after warm weather arrives
  • Common after very cold winters with little snow cover
  • Dark streaking can be seen in the sapwood of injured branches
  • More information on Winter Injury
2 of 8
  • Image: Black Rot 1
  • Image: Black Rot 2

Black Rot
Botryosphaeria obtusa

  • Leaves on girdled branches wilt, die and turn brown
  • Branch cankers can be sunken, reddish brown or rough looking or cracked bark; cankers may remain small or enlarge to become several feet long
  • Round leaf spots with a purple border and tan center
  • Large brown spots with brown rings form on fruit
  • Fruit is rotted but remains firm
  • Fruit may become mummified and remain on tree
  • Common on stressed trees and trees infected with fire blight
  • More information on Black Rot
3 of 8
  • Image: Fire Blight 1
  • Image: Fire Blight 2
  • Image: Fire Blight 3

Fire Blight
Erwinia amylovora

  • 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
  • Branch cankers have dark, sunken and cracked bark, sapwood is streaked reddish brown
  • Infected fruit are shriveled and discolored
  • Drops of sticky honey colored liquid can be seen on infected plant parts in warm wet weather
  • More information on Fire Blight
4 of 8
  • Image: White Rot 1
  • Image: White Rot 2

White Rot
Botryosphaeria dothidea

  • 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
  • Sunken brown spots on fruit, can grow to rot part or all of fruit
  • Fruit rot is soft, watery and extends to the core of the apple
  • More information on White Rot
5 of 8
  • Image: Drought Stress

Drought Stress

  • Severe drought stress may cause dieback of individual branches
  • Uniform wilting or browning of leaves throughout the tree
  • Leaf margins and branch extremities usually brown and wilt first
  • More information on Drought Stress
6 of 8
  • Image: Dogwood Borer 1
  • Image: Dogwood Borer 2
  • Image: Dogwood Borer 3

Dogwood Borer
Synanthedon scitula

  • Larvae feed in young trees often around lawn mower injuries, and in pruning scars of older trees
  • Feeding causes girdling and reduced sap flow
  • Brownish-red frass (excrement) is usually present at the feeding site
  • Adult is a black and yellow clear-wing moth, larvae are ½" long when mature, and white with a red-brown head
  • Adult emergence begins in mid-June, peaks in early July, and continues until August
7 of 8
  • Image: Oystershell Scale 1

Oystershell Scale
Lepidosaphes ulmi

8 of 8
  • Image: Black Root Rot 1
  • Image: Black Root Rot 2
  • Image: Black Root Rot 3

Black Root Rot
Xylaria mali and Xylaria polymorpha

  • Infected trees have slow growth, a thin canopy, dead branches, and small leaves
  • Black finger-like projections arise from the soil at the base of the tree
  • Infected roots are brittle and encrusted in black fungal growth
  • Infected trees produce many very small fruit

Don't see what you're looking for?