|Njoroge, Samuel Mc|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2009
Publication Date: 5/1/2009
Citation: Njoroge, S., Kabir, Z., Martin, F.N., Koike, S.T., Subbaro, K.V. 2009. COMPARISON OF CROP ROTATION FOR VERTICILLIUM WILT MANAGEMENT IN CONVENTIONAL AND ORGANIC STRAWBERRY PRODUCTION. Plant Disease 93:519-527. Interpretive Summary: Wilt caused by Verticillium dahliae is a major disease in non-fumigated and organic strawberry production systems in California. A comparative study of the effects of broccoli and lettuce rotations on strawberry growth, Verticillium wilt, and yield were evaluated in conventional and organic production systems. Population densities of the pathogen the disease severity were lower in broccoli rotation plots compared to lettuce. The yield in broccoli plots was greater as well, indicating that rotation with this crop and the proper incorporation of crop residue into the soil after harvest may provide an additional management tool for moderating the impact of this pathogen.
Technical Abstract: Wilt caused by Verticillium dahliae is a major disease in non-fumigated and organic strawberry production systems in California. A comparative study of the effects of broccoli and lettuce rotations on strawberry growth, Verticillium wilt, and yield were evaluated in conventional and organic production systems. In both fields, strawberry was planted after two successive crops of broccoli or lettuce. The control treatment in the conventional field was strawberry planted in soils fumigated with methyl bromide + chloropicrin. To estimate population densities of V. dahliae, soil samples were taken at broccoli and lettuce planting and then at monthly intervals until the end of two strawberry cropping seasons. Population densities of V. dahliae in plots cropped with broccoli were significantly lower than lettuce rotation in both organic and conventional soils. Incidence and severity of Verticillium wilt on strawberry was significantly lower in plots under broccoli rotation in both organic and conventional systems than in lettuce plots under either system. While canopy diameters of strawberry plants grown in rotation with broccoli were not significantly different from those in fumigated plots, those from lettuce plots were significantly smaller. Yields in both conventional and organic fields were higher in plots rotated with broccoli relative to yields in plots rotated with lettuce in only 1 of two years. The strategy of using broccoli rotation coupled with its postharvest incorporation continues to show promise as an additional tool in the management of Verticillium wilt in both conventional and organic strawberry production systems.