Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 9, 2011
Publication Date: June 9, 2011
Citation: Mazzola, M. 2012. Resident biology restricts proliferation of Macrophomina phaseolina in brassicaceae seed meal meal amended soil. Phytopathology. 101:S117. Technical Abstract: M. phaseolina is a pathogen of emerging importance in strawberry production systems. Studies were conducted to assess the efficacy of brassicaceae seed meal amendments for control of this pathogen and to determine the relative importance of soil biology and chemistry in any observed disease suppression. Seed meals were sourced from Brassica napus (canola), Sinapis alba (white mustard) and Brassica juncea (oriental mustard). When inoculated with M. phaseolina all seed meal amended soils limited persistence of the pathogen relative to the non-treated control. This was observed irrespective of whether a biologically active chemistry (e.g. allyl isothiocyanate by B. juncea) was produced in response to the seed meal amendment. When assays were conducted in pasteurized soils infested with the pathogen, all seed meal amendments failed to suppress M. phaseolina. Seed meals also effectively suppressed disease development when strawberry was planted in a soil naturally infested with M. phaseolina. However, disease suppression was temperature sensitive, and exhibited failure as soil temperature was elevated above 32oC. Exposure to AITC emitted from B. juncea amended soils for up to 8 h had a fungistatic but not fungicidal effect on M. phaseolina. These findings indicate that the resident soil biology is the dominant mechanism contributing to suppression of M. phaseolina in response to brassicaceae seed meal amendments.