

Managing Rosette in Blackberries Helps Small
FarmersBy Tara
Weaver-Missick December 3, 1999New strategies for controlling
rosette disease in blackberries could open a new fruit market for small
farmers. Rosette, or double blossom, is one of the most severe fungal diseases of
blackberries grown in the southeastern United States. Many crops fall prey to
this disease, which reduces yields and fruit quality. Plant pathologist Barbara J. Smith has found a way to control the disease
using a modified fungicide spray schedule. Smith is with the Agricultural
Research Services Small Fruit Research
Station in Poplarville, Miss. ARS is
the U.S. Department of Agricultures
chief scientific research agency To control rosette, growers have been using information from the 1930s. This
information is outdated, since new cultivars have been developed and the
disease itself has changed since then. Smith has found the most effective way to control rosette is to apply four
fungicide applications at a 10-14 day interval beginning about six weeks before
berries ripen and continuing until three days before harvest. She also
recommends a fifth application immediately after harvest. Many farmers have been disappointed with fungicidal control of rosette,
because they thought spraying would control the disease in that years
crop. But thats not the case; fungicides applied this year help control
next years rosette problem. The most effective fungicide tested for controlling rosette, caused by the
fungus Cercosporella rubi, is benomyl. Few fungicides are registered and
available for controlling blackberry diseases. Smith plans to evaluate some new
fungicides and is also looking more closely at the pathogen and how it infects
the fruit. Rosette disease is one of the major reasons southeastern farmers dont
grow this specialty crop, which could yield $3,000 to $4,000 an acre.
Overcoming this disease offers a high- value crop that costs less to establish
than strawberries and blueberries. Scientific contact: Barbara J. Smith, ARS Small Fruit Research
Station, Poplarville, Miss., phone (601) 795-8751, fax (601) 795-4965,
[email protected]. U.S. Department of Agriculture | |