WSU Extension

Hortsense

Apple
 
Disease
Anthracnose and Bull's-eye rot 
Bitter pit 
Burrknot 
Crown and collar rot 
Crown gall 
Cytospora canker 
Fire blight 
Fruit russeting 
Nectria canker (European canker) 
Nectria twig blight (Coral spot) 
Perennial canker (Bull's-eye rot) 
Phytophthora fruit rot 
Powdery mildew 
Scab 
Virus diseases 
Insect
Aphids 
Apple ermine moth 
Apple maggot 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Earwigs 
Fruittree leafroller 
Leafhoppers 
Leafrollers 
Lecanium scale 
San Jose scale 
Spider mites 
Tent caterpillars 
Tentiform leafminer 



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Caption: Crown gall
Photo by: R.S. Byther
  
Apple : Crown gall
(revision date: 5/20/2014)


Biology
Crown gall is caused by a soilborne bacterium. The bacteria infect through wounds on the crown and roots. Young galls are fleshy, white, enlarged masses on the roots or stems. Older galls are hardened and turn dark brown and woody or corky in appearance. They range in size from less than an inch to several inches across. The bacteria can be spread from infected to clean soil by water movement or equipment. Damage varies with location and size of galls. Small galls are essentially harmless. Large galls on the crown may weaken or girdle trees. The growths can also be an aesthetic concern. Burrknot, a physiological problem of apple trees, can be mistaken for crown gall.
Management Options

Non-Chemical Management
  • Plant disease-free materials.
  • Remove and destroy declining trees with large crown galls. Also remove roots and surrounding soil where possible.
  • Prune out galls when practical. Sterilize pruning tools between cuts to avoid spreading bacteria to healthy tissue.
  • Avoid injuries to the bark, roots, and crown while planting.
  • Do not replant susceptible species in infected soil.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Crown gall
Photo by: R.S. Byther
Caption: Crown gall on roots
Photo by: R.S. Byther