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Efficacy of fungicides for control of rosette and fruit diseases of 'Kiowa' and 'Chickasaw' erect blackberries grown in the southeastern United States

Smith, B. J., Miller-Butler, M.
Acta horticulturae 2016 no.1133 pp. 451-460
Cercosporella, azoxystrobin, blackberries, boscalid, cultivars, cyprodinil, disease control, fludioxonil, fruit diseases, fruit quality, fungi, leaf emergence, leaves, pyraclostrobin, spring, Mississippi
Rosette disease (caused by the fungus Cercosporella rubi) is often severe on erect blackberries grown in the southeastern US and if not controlled, may severely limit fruit production. Pre- and postharvest fruit diseases also reduce fruit production and quality. A series of trials were conducted in south Mississippi to determine fungicide efficacy for control of rosette, fruit, foliar, and cane diseases. In each trial 8 to 10 fungicides were applied to rosette-susceptible, erect, thorny blackberry cultivars from early leaf emergence through harvest. Fruit were harvested from each plot and assessed within 5 days for postharvest disease symptoms and fruit quality. Foliar and cane diseases were evaluated following harvest. Rosette severity was rated the following spring when symptoms were easily visible. Among the fungicides tested, azoxystrobin, cyprodinil + fludioxonil, and boscalid + pyraclostrobin were the most effective for rosette and postharvest disease control. The results of these trials demonstrated that fungicides are most effective for rosette control when applications began prior to bloom and continue until the fungus has ceased to sporulate. Fungicides effective against rosette also reduced postharvest fruit diseases and leaf and cane rust.