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Extension > Garden > Yard and Garden > Trees and Shrubs > Golden Canker of Pagoda Dogwood

Golden canker of pagoda dogwood

Garret Beier
Edited by Michelle Grabowski

Importance

Pagoda dogwood infected with golden canker

M. Grabowski, UMN Extension

Pagoda dogwood with purblish red healthy stems and yellow stems infected with golden canker

Golden canker is a common disease of pagoda dogwood and can be found throughout most of the eastern half of the United States, including Minnesota. The disease discolors and kills branches and at times can progress from branch tips and into main branches and stems. Once in the main stem, the stem quickly dies, but it does not kill the roots of the tree.

Pathogen and susceptible plants

Golden canker is caused by the fungus Cryptodiaporthe corni. The fungus is only known to infect pagoda dogwood (Cornus alternifolia). The disease has not been found on any other dogwood species commonly grown in Minnesota.

Identification

Biology

G. Beier, UMN Dept. of Plant Pathology

Main stem of a pagoda dogwood with golden canker

Cryptodiaporthe corni survives within infected branches and stems during the winter. During the growing season in wet weather and times of high humidity spore tendrils are produced by the bright orange spore producing structures seen within branch cankers. It is still unclear if the spores enter the plant through wounds or through natural openings. Since the fungus has been isolated from plants with no visible wounds it appears that the fungal pathogen may enter through natural opening such as lenticels or leaf scars.

Although the fungus that causes golden canker can easily be isolated from the yellow branch cankers of diseased dogwoods, it can also be sometimes found inside stems showing no symptoms. A study on stems that appeared healthy revealed that the fungus is capable of living within branches of pagoda dogwood as an endophyte, a microorganism living within a plant without causing symptoms of disease. The fungus was present in 62.5% of apparently healthy stems collected from across Minnesota. It is still unclear what causes the fungus to change from a nonharmful resident of healthy branches to a pathogen capable of killing branches and stems.

Management

G. Beier, UMN Dept. of Plant Pathology

A diseased branch tip where the disease has been stopped at a branch attachment.

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