Submitted to: Phytopathology
Publication Type: Abstract only
Publication Acceptance Date: 5/10/2010
Publication Date: 6/1/2010
Citation: Weerakoon, M., Izzo, A., Mazzola, M. 2010. Brassica juncea seed meal amendment induces long-term suppressiveness to Pythium abappressorium under enclosed and open soil incubation conditions. Phytopathology. 100-S134. Interpretive Summary:
Technical Abstract: Pythium spp. contribute to development of aple replant disease. B. juncea seed meal (SM) soil amendment can effectively suppress Pythium via generation of biologically active allyl isothiocyanate (AITC). AITC is evaluated from soils with 48 h after SM application, yet preliminary evidence indicates that long-term control of this pathogen may be attained. Greenhouse trials were conducted to assess the capacity of B. junicea SM to suppress P. abappressorim in AITC evacuated soils. SM was incorporated into soil at a rate of 0.3% (wt\wt); one sytem was maintained under enclosed conditions and the other open to the atmosphere for two days. Soils were then incubated in slightly covered containers to maintain moisture conditions. Soils were incubated in slightly covered containers to maintain moisture conditions. Soils were incubated for 2,4 and 8 weeks and then infested with P. abappressorium. Regardless of the time of pathogen intoduction after B. juncea SM amendment, disease suppession was consistently observed under both enclosed and open initial incubation conditions. However, disease suppression was significantly greater in soils incubated under enclosed conditions for the initial two days relative to soils incubated under open conditions during the same period. Evacuation of AITC from these soild prior to infectation with P. abappressorium suggests that disease suppression does not operated completely via chemical means. Disease suppression was associated with distinct changes in the resident fungal community prior to pathogen introduction.