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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #317603
Title: Efficacy of Fungicides for Control of Rosette, Fruit, Foliar, and Cane Diseases of ‘Kiowa’ and ‘Chickasaw’ Erect Blackberries Grown in the Southeastern U.S.A.

Author
item Smith, Barbara
item Miller Butler, Melinda

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2015
Publication Date: 5/30/2016
Citation: Smith, B.J. and Miller-Butler, M. Efficacy of fungicides for control of rosette and fruit diseases of 'Kiowa' and 'Chickasaw' erect blackberries grown in the southeastern United States. Acta Hortic. 1133, 451-459. DOI: 10.17660/ActaHortic.2016.1133.69. http://dx.doi.org/10.17660/ActaHortic.2016.1133.69. 317603. 2016.

Interpretive Summary: Rosette and fruit rot diseases are often limiting factors in the production of blackberries in the southeastern. Fungicides usually will control these diseases if they are applied at the proper time. The trials in this study were designed to determine if the fungicides used to control rosette disease would also control the major fruit rot diseases, Botrytis gray mold and ripe rot. Three fungicides, azoxystrobin, cyprodinil + fludioxonil, and boscalid + pyraclostrobin, were identified that were effective for both rosette and post-harvest disease control. These same fungicides also generally reduced common foliar diseases such as Septoria leaf spot and leaf and cane rust. Fungicide treatments did not have any apparent, consistent effect on fruit quality.

Technical Abstract: Rosette disease, Cercosporella rubi, is often severe on erect blackberries grown in the southeastern U.S. and if not controlled, may severely limit fruit production. Pre- and post-harvest 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 post-harvest 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 (Abound), cyprodinil + fludioxonil (Switch), and boscalid + pyraclostrobin (Pristine) were the most effective for rosette and post-harvest disease control. The results of these and earlier 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 post-harvest fruit diseases and common foliar diseases such as Septoria leaf spot and leaf and cane rust.