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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to methyl bromide soil fumigation for vegetable and floriculture production Title: Exploring warm-season cover crops as carbon sources for anaerobic soil disinfestation (ASD)

Authors
item Butler, David -
item Rosskopf, Erin
item Burelle, Nancy
item Albano, Joseph
item Muramoto, Joji -
item Shennan, Carol -

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 11, 2011
Publication Date: December 30, 2011
Citation: Butler, D., Rosskopf, E.N., Burelle, N.K., Albano, J.P., Muramoto, J., Shennan, C. 2011. Exploring warm-season cover crops as carbon sources for anaerobic soil disinfestation (ASD). Plant and Soil. DOI 10.1007/s11104-011-1088-0.

Interpretive Summary: Anaerobic soil disinfestation (ASD) has been shown to be an effective strategy for controlling soilborne plant pathogens and plant parasitic nematodes in vegetable production systems. Soil treatment by ASD relies on a supply of readily-available carbon (C) to stimulate bacteria to generate anaerobic soil conditions in moist soils covered with polyethylene mulch. The use of cover crops can be very beneficial for crop production as they add organic matter back into the production field and may also be useful as a C source for generating ASD. To test the effectiveness of warm-season cover crops as carbon sources for ASD, a greenhouse study was conducted using a sandy field soil in which several warm-season legumes and grasses were grown and incorporated. The level of anaerobicity achieved using each cover crop and each cover crop combined with composted broiler was measured. A number of important soilborne pathogens, nemaodes, and weeds were also used as bioassay targets for testing the efficacy of each cover crop for ASD. Results using the fungal plant pathogen that causes Fusarium wilt were very consistent and the inoculum of this pathogen was reduced by as much as 97% when compared to the untreated control. Another fungal plant pathogen, which causes Southern blight, was not consistently controlled using the cover crops, but was controlled using molasses as the carbon source. Warm-season cover crops have potential to serve as a C source for ASD in vegetable production systems, but more work is needed to improve consistency and further elucidate mechanisms of control of soilborne plant pathogens and weeds during ASD treatment.

Technical Abstract: Anaerobic soil disinfestation (ASD) has been shown to be an effective strategy for controlling soilborne plant pathogens and plant parasitic nematodes in vegetable production systems. Soil treatment by ASD relies on the supply of labile carbon (C) to stimulate microbially-driven anaerobic soil conditions in moist soils covered with polyethylene mulch. To test the effectiveness of warm-season cover crops as carbon sources for ASD, a greenhouse study was conducted using a sandy field soil in which several warm-season legumes and grasses were grown and incorporated. Pots were then irrigated to fill soil porosity and covered with a clear polyethylene mulch film to initiate a 3-week ASD treatment prior to planting tomatoes. Soilborne plant pathogen inoculum packets, yellow nutsedge tubers, and Southern root-knot nematode (Meloidogyne incognita (Kofoid & White) Chit.; M.i.) eggs and juveniles were introduced at cover crop incorporation. In nearly all cases, ASD treatment utilizing cover crops as a C source resulted in soil anaerobicity values that were equal to the molasses-amended fallow control and greater than the unamended fallow control. In trial 1, Fusarium oxysporum Schlechtend.:Fr. (F.o.) survival was reduced by more than 97% in all C source treatments compared to the unamended control but there was no effect of C source in Trial 2. Carbon source treatments were inconsistent in their effects on survival of Sclerotium rolfsii Sacc. (S.r). In general, the number of M.i. extracted from tomato root tissue and root gall ratings were minimal in all treatments with composted poultry litter and an added C source. Germination of yellow nutsedge (Cyperus esculentus L.) tubers was highest in the unamended control (76%), lowest in the molasses control (31%), and intermediate from cover crop treatments (49 to 61%). Warm-season cover crops have potential to serve as a C source for ASD in vegetable production systems, but more work is needed to improve consistency and further elucidate mechanisms of control of soilborne plant pathogens and weeds during ASD treatment.

Last Modified: 10/22/2014
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