Have you seen this disease?

 

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SourDough News | July 1, 2014

 

Rust fungus on highbush cranberry leaf.
Rust fungus on highbush cranberry leaf.

Rust fungus on highbush cranberry leaf and stem.
Rust fungus on highbush cranberry leaf and stem.

Highbush cranberry (Viburnum edule) grows throughout much of Alaska and produces red or orange berries that turn ripe in late summer and early fall. Recently, the Forest Health Protection staff of State & Private Forestry has documented a fungal disease on the stems and leaves of these shrubs along Windfall, Herbert Glacier, and Brotherhood Trails in Juneau. Additional photos are found on the Alaska Region Flickr site.

 

The pathogen suspected to cause this disease is Puccinia linkii. Forest Service researchers are using molecular genetic techniques to confirm the identification of the pathogen. This rust fungus usually causes a disease that primarily affects the foliage of these shrubs. The high frequency of aggressive stem infection in Juneau is unusual, especially since this disease has not previously been reported here.

 

Mycological herbaria (fungus collection) records indicate the occurrence of this fungal pathogen in British Columbia and Washington, as well as other parts of Canada and the Lower-48. There are limited written records of this disease from Alaska, from Skagway, Seward and Matanuska. Given its known distribution, Forest Health Protection staff do not believe this disease in Juneau is caused by an exotic invasive fungus. However, they do hope to document its extent and the impacts on highbush cranberry, and ecologically and culturally significant plant.

 

That’s where you can help. Please contact Robin Mulvey at rlmulvey@fs.fed.us or (907) 500-4962) to report additional disease sightings. If possible, please provide GPS coordinates and photos or specimens (fresh or pressed/dried).

  

By Robin Mulvey, Forest Pathologist, State & Private Forestry