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United States Department of Agriculture

Agricultural Research Service

Title: Rosette (Double Blossom) of Blackberry

Author
item Smith, Barbara

Submitted to: Proceedings of the North American Bramble Growers Association Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: February 11, 1999
Publication Date: N/A

Interpretive Summary: Rosette is a severe disease of blackberries in the southeastern United states which often limits commercial production if it is not controlled. Most blackberry cultivars adapted to the area are very susceptible to rosette which is caused by the fungus, Cercosporella rubi; however, many growers do not recognize this disease until it is wide-spread in their planting. This paper lists the cultural and chemical controls available to blackberry growers for control of this disease. If blackberry growers follow the control strategies consistently each year, the incidence and severity of rosette in their planting should be drastically reduced. These accomplishments will directly benefit the blackberry grower, extension agents and scientists conducting research on this disease.

Technical Abstract: Rosette is a severe disease of blackberries in the southeastern United States which often limits commercial production if it is not controlled. Caused by the fungus, Cercosporella rubi, rosette has a biennial disease cycle that matches the growth pattern of blackberries. Most blackberry cultivars adapted to the area are very susceptible to rosette; however, many growers do not recognize this disease until it is wide-spread in their planting. Usually few or no symptoms of rosette are evident in a new planting until about the fourth year when a large percentage of the plants suddenly display signs of infection as new growth emerges in the spring, and yield is drastically reduced. This disease can be controlled by following the cultural and chemical control methods listed in this paper. Cultural controls include eradication of wild blackberries near the commercial blackberry field, pruning out diseased stems in early spring and mowing severely infected plants. Chemical control is based on fungicide applications in early spring.

Last Modified: 7/23/2014
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