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United States Department of Agriculture

Agricultural Research Service

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Blackberry Rust
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Blackberry rust, Phragmidium violaceum, was discovered in Himalaya blackberries in Coos County Oregon in April 2005. It was subsequently confirmed in Himalaya patches from Eureka, California to Bellingham, Washington.

Distribution map of P. violaceum

Some commercial evergreen fields incurred complete losses while others incurred significant yield losses. There is an urgent need for management recommendations; however, there is little information on practices that will sustain and enhance the efficiency control of P. violaceum in commercial fields.


Blackberry rust


In collaboration with Dr. Ken Johnson, OregonStateUniversity, and Dr. Bill Pfender, USDA-ARS, we are examining the impact of leaf wetness/temperature interactions on disease development in order to develop disease forecasting models that can help growers efficiently time control measures. We are also examining the pathogen's diversity in collaboration with Dr. Nik Gr?nwald. The combination of laboratory and field research focused on the genetics of the pathosystem as well the environmental requirements of the causal organism will provide the foundation that underpins both immediate and long term management goals.


Our Mission

Powdery Mildew


Gray Mold



Scientist: Walt Mahaffee



Last Modified: 8/19/2016
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