Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/27/2007
Publication Date: 7/12/2007
Citation: Subbarao, K.V., Kabir, S., Martin, F.N., Koike, S.T. 2007. Management of Soilborne Diseases in Strawberry using Vegetable Rotation. Plant Disease. 91:964-972. DOI:10.1094/PDIS-91-8-0964 Interpretive Summary: Historically one of the primary reasons for soil fumigation in strawberry production in California was management of Verticillium dahliae, the pathogen responsible for Verticillium wilt. With the phase out of methyl bromide as a soil fumigant and increasing oversight on the use of soil fumigants in general, development of alternative measures for pathogen management that have less of an environmental impact than fumigation would be useful for the strawberry industry. This research paper is a report on the effect of certain crop rotations on the population density of several pathogens and the level of disease expression encountered in the field.
Technical Abstract: The influence of crop rotation on soilborne diseases and yield of strawberry was determined at a site infested with Verticillium dahliae microsclerotia and at another with no known history of V. dahliae infestation during 1997 - 2000. The rotations studied at the V. dahliae infested site were: 1) broccoli-broccoli-strawberry, 2) Brussels sprouts-strawberry, and 3) lettuce-lettuce-strawberry; the treatments at the site with no history of V. dahliae were: 1) broccoli-broccoli-strawberry, 2) cauliflower-cauliflower-strawberry and 3) lettuce-lettuce-strawberry. The effects of rotation on V. dahliae and Pythium populations, strawberry vigor, Verticillium wilt severity and strawberry fruit yield were compared with a standard methyl bromide + chloropicrin fumigated control treatment. Rotations did not alter total population levels of Pythium spp. at either study site. However, V. dahliae microsclerotia were significantly reduced with broccoli and Brussels sprouts rotations compared with lettuce rotations at the V. dahliae-infested site. Reduced propagules led to lower Verticillium wilt severity on strawberries in the broccoli and Brussels sprouts rotations than in lettuce-rotated plots. Strawberry vigor and fruit yield were significantly lower in lettuce-rotated plots than in broccoli and Brussels sprouts-rotated plots. Despite no detectable microsclerotia at the other site, strawberry vigor and fruit yield were greatest in plots rotated with broccoli, intermediate with cauliflower, and lowest with lettuce. None of the rotation treatments were better than fumigated control for all variables measured. In the absence of fumigation, rotation with broccoli and Brussels sprouts is an effective cultural practice for managing Verticillium wilt in strawberry production, whereas in fields with no detectable V. dahliae, broccoli is also a feasible rotational crop that enhances strawberry growth and yield, and perhaps suppresses infestation of the fields by V. dahliae. According to a cost-benefit analysis, the broccoli-strawberry rotation system could be an economically viable option provided growers are able to alternate years for strawberry cultivation.