WSU Extension

Hortsense

Apple : Perennial canker (Bull's-eye rot)
(revision date: 5/20/2014)


Biology
Perennial canker is a fungal disease. It is similar to anthracnose, but occurs primarily east of the Cascades in Washington. The characteristic symptom of perennial canker is a sunken canker surrounded by rings of dead wood. Cankers are often associated initially with wounds. The fungus does not survive in the wood, but reinfects around old cankers each year, especially when woolly apple aphids are present. Aphid feeding provides wounds which serve as re-entry sites for the fungus. Winter injury and other weakening factors also contribute to disease severity. The disease also causes a bull's-eye rot of stored fruit. Infected fruits develop spongy light brown spots with darker margins. There may be additional rings around the spot, giving it a "bull's-eye" appearance.
Management Options

Non-Chemical Management
  • Plant resistant varieties such as 'Gravenstein', ' McIntosh', 'Red Delicious', 'Wealthy', and 'Winesap'.
  • Provide proper culture to maintain vigorous, healthy trees.
  • Avoid wounding trees and prevent winter injury.
  • Control woolly apple aphids.
  • Prune out and destroy infected tissues when practical.
  • Use correct pruning practices. For more information see PNW 400, Training and Pruning Your Home Orchard, or contact WSU Master Gardeners or your county Extension agent.
  • Keep fruit dry after picking and while in storage to minimize disease development.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

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Caption: Apple bull's eye rot
Photo by: G.G. Grove