Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Blueberry -- Godronia Canker
 
Cause: Godronia cassandrae (asexual: Fusicoccum putrefaciens), a fungus. The disease occasionally can interfere seriously with the establishment of new plantings in British Columbia and Washington. It is considered to be the most serious canker disease of blueberry in British Columbia. This disease also is known as Fusicoccum canker after the asexual spore stage (anamorph) of the fungus. It is less serious in established fields because only new wood can be infected. However, disease incidence has been increasing in older fields since the late 1980s.

The fungus overwinters in cankers on stems and crowns of infected plants. Conidia account for nearly all infections and disease spread. Conidia are released in wet weather and disperse by splashing rain. Conidia infect stems primarily at leaf scars from March through June. Natural openings in bark also may serve as infection sites. Conidia also are produced and released from August through October but probably account for few infections.

Symptoms: Infections appear on current-year stems at bud sites or wounded areas as small reddish brown areas in early spring. As these cankers enlarge, centers usually become gray and margins are reddish brown or dark brown, giving the canker a bull's-eye appearance. Cankers become progressively larger each year and eventually may girdle stems, causing them to wilt and die. Leaves on infected branches may turn color earlier in the fall.

Infections appear as reddish-brown areas in early spring.

 
Cultural control:

  1. Purchase healthy planting material and/or do not use plants with injured branches.
  2. Prune out and destroy cankered branches. Growers with infected prunings can obtain permits from local fire districts to burn prunings.
  3. Field observations have found 'Rubel' and 'Rancocas' resistant, while 'Berkeley', 'Bluecrop', 'Earlyblue', 'Jersey', and 'Pemberton' are highly susceptible.
Chemical control: No fungicide is currently registered for control.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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