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: Cytospora canker spore tendrils on apple
Photo by: R.S. Byther
  
Apple : Cytospora canker
(revision date: 5/20/2014)


Biology
The fungi which cause Cytospora canker attack through wounds on twigs and branches. The disease can spread to healthy tissues after the initial infection. Initial cankers are small, but enlarge quickly and may streak up and down the stems without girdling. The cankers may also girdle twigs, resulting in dieback above the infection site and causing "flags" of dead material to appear in the canopy. The leaves on the dead twigs turn color and droop, but often remain attached. The canker itself appears as a dark, sunken area of dead bark and wood. Pinhead-sized black fruiting structures of the fungi often erupt through the bark and produce reddish tendrils or droplets of spores in wet weather. Spores are easily spread by wind, rain, and insects. The cankers are often perennial, enlarging through several seasons.
Management Options


Non-Chemical Management
  • Avoid wounding trees.
  • Provide proper planting sites and culture. Healthy trees are more resistant to disease and winter injury.
  • Control insect and disease problems to minimize injuries.
  • Prune out and destroy infected tissues during dry weather. Make cuts at least 12" below visibly infected area. Sterilize pruning tools frequently.
  • Rake and destroy twig debris.
  • Correct pruning practices minimize injury and improve wound healing. For more information see PNW 400, Training and Pruning Your Home Orchard, or contact your WSU Master Gardeners or county Extension agent.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Cytospora canker spore tendrils on apple
Photo by: R.S. Byther