Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Apple and Pear -- Nectria Canker (European Canker)
 
Cause: Nectria galligena, a fungus. The disease is found primarily in high rainfall areas along the coast and Willamette Valley and rarely in southern, central and eastern Oregon. The canker is perennial. White fungal structures (sporodochia) appear on the canker either the first spring or the next fall and winter. Round, red fungus bodies (perithecia) discharge another type of spore in the second winter and spring.Infection occurs during fall rains primarily through leaf scars but can also get in through wounds, pruning cuts, or where a young twig or branch has broken off.

'Gravenstein', 'Red Delicious', 'Gala', 'King', 'Macoun', 'Spartan', and 'McIntosh' are very susceptible. 'Golden Delicious', 'Rome Beauty', 'Jonagold', 'Northern Spy', and 'Jonathan' are less susceptible.
Symptoms: There are two types of canker: open and closed. Open cankers are a series of concentric calluses, one of which grows in the healthy tissue at the extreme margin of the canker each year. The next year, the fungus invades and kills the new callus of the previous year. The outer ring of the canker is irregular and roughened by cracks in the bark.

Closed cankers are more irregular than open cankers and are covered by dead bark. This fungus can also infect fruit, causing the disease known as eye rot on the calyx end and bull's eye rot at the lenticels similar to anthracnose and perennial canker.

Dead branch beyond the swollen canker.

 
Cultural control:

  1. Cut out and destroy cankers during dry weather.
  2. Disinfect pruning shears and wounds during wet weather.
Chemical control: Spray before fall rains begin for fruit rot control and during early, and again at mid to late, leaf fall for canker control. Fungicides protect leaf scars. May not be effective if not done in conjunction with canker removal.

  1. Copper-based products.
    1. Bordeaux 8-8-100. If an earlier spray is applied for anthracnose control, an application for Nectria canker may not be needed.
    2. Copper-Count-N at 8 to 12 qt/A. Post harvest only. 12-hr reentry.
    3. Cuprofix Ultra 40 Disperss at 8 to 10 lb/A. Post harvest only. 12-hr reentry.
    4. Kocide 3000 at 5.25 to 7 lb/A. 24-hr reentry.
    5. Nu-Cop 50 DF at 12 to 16 lb/A. Do not use if soil pH is 5.5 or below. 24-hr reentry.
  2. Ziram 76 DF or Ziram Granuflo at 6 to 8 lb/A. Do not apply within 14 days of harvest. 48-hr reentry.
References:
English, H., Dubin, H. J. and Schick, F. J. 1979. Chemical control of European canker of apple. Plant Disease Reporter. 63:998-1002.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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