Plant Pathology Infobytes

May 1, 1997
Blackberry Rosette - Time to Start a Control Program

Blackberries are a great crop for Southern gardens, but unfortunately are susceptible to a fungus disease known as rosette. Unless rosette is controlled, blackberry plantings become heavily infected by the rosette fungus, and berry production is severely reduced.

Blackberry rosette is recognized by the bunchy growth which appears on infected canes in the spring. This bunchy growth (the rosettes) produces diseased flower buds which tend to be larger and longer than normal buds.

Flowers which form on rosettes also have more pink coloration and generally are sterile. As a result, few if any berries are formed on rosette growth. Since the disease becomes more severe in succeeding years, rosette control is necessary if home orchardists want to produce acceptable berry yields.

All popular varieties of blackberries are susceptible to rosette, and disease control requires spring pruning to remove rosettes and application of fungicides at intervals through the season to protect new cane growth from rosette fungus infection.


Written by the late Dr. Frank Killebrew

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