WSU Whatcom County Extension

Integrated Pest Management for Blueberries

Godronia Canker
(Godronia cassandrae or Fusicoccum putrefaciens)

Diseases

 

Godronia

 

Symptoms

Godronia canker can be a serious canker disease of young blueberry plants; only new wood is infected, so infections in established plantings are less problematic. Infections can be identified as dark red, elliptical lesions around or near buds on a stem. Some lesions show a bull’s-eye pattern. Lesions enlarge over the years and become gray. Leaves on infected stems die and turn color earlier, giving a red flag effect. Cankers can girdle stems, ceasing growth above the lesion. Most cankers are near ground level, but some occur as high as 3 feet above the ground.

 

Life History

Godronia canker overwinters in infected stems. Conidia are produced in spring, released during wet periods and spread through splashing rain. New infections occur at leaf scars and other openings of the bark on new growing tissue. Infection can occur throughout the growing period, but are most common from March through June. Wounding is not required for infection. In optimal conditions, infection occurs within 48 hours at 50°F – 71°F (10°C – 22°C).

 

Monitoring:

Start monitoring for symptoms in December, before pruning so crew can be advised. Look for small lesions on current season’s wood on plants at each monitoring site. Continue monitoring for these symptoms throughout the season until petal drop. Train field crew to recognize cankers. Look for red flags of dead leaves on stems in mid to late summer.

 

Thresholds and Management

No threshold exists for this pest.  Low populations can be pruned out.  No products are currently available for treatment of higher incidence of this pest.

Prune out and burn stems with cankers. Control weeds around the base of plant to increase humidity and reduce disease pressure. Avoid overhead irrigation late in the day to allow stems to dry out. Use drip irrigation where possible. Some varieties may be resistant to Godronia canker.

 

References

Michigan State University, Michigan Blueberry Facts, Fusicoccum
http://www.blueberries.msu.edu/fusicoccum.htm

Oregon State University Extension, Online Guide to Plant Disease Control, Blueberry-Godronia Canker
http://plant-disease.ippc.orst.edu/ShowDisease.aspx?RecordID=180

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WSU Whatcom County Extension • 1000 N. Forest St., Bellingham, WA 98225 • (360) 778-5800 • whatcom@wsu.edu