Submitted to: Phytopathology
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2005
Publication Date: 6/1/2005
Citation: Mazzola, M., Cohen, M.F., Brown, J. 2005. Effect of brassicaceae seed meals on microbial communities and growth of apple in replant soils. Phytopathology. 95:S67.
Technical Abstract: The effect of Brassicaceae seed meals on soil microbes and suppression of the parasites and pathogens that incite apple replant disease was evaluated in greenhouse trials. Seed meal amendment significantly improved apple growth in all soils, but differences in pathogen suppression were observed. Brassica napus and Sinapis alba were superior to B. juncea in reducing infection by Rhizoctonia solani AG-5 and enhancing root biomass. This response was not associated with seed meal glucosinolate content. Only B. juncea seed meal did not stimulate resident Pythium spp. populations and subsequent root infection. All seed meals suppressed root infestation by Pratylenchus spp. however the impact on total soil nematode populations was independent upon seed meal type and physical properties. Seed meal amendments induced comparable initial increases in total bacteria and fluorescent Pseudomonas spp. numbers. Although uniform for B. napus the stimulatory effect of B. juncea and S. alba seed meal on streptomyces populations was soil-dependent, and characteristically was delayed or less robust. This is significant as suppression of Rhizoctonia root rot by these residues is associated with amplification of NO-producing Streptomyces in the apple rhizosphere.