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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #289630
Title: Soil microbial community structure and target organisms under different fumigation treatments

Author
item DANGI, SADIKSHYA - University Of California
item Gerik, James
item Tirado-Corbala, Rebecca
item AJWA, HUSEIN - University Of California

Submitted to: Applied and Environmental Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2015
Publication Date: 3/27/2015
Citation: Dangi, S.R., Gerik, J.S., Tirado-Corbala, R., Ajwa, H. 2015. Soil microbial community structure and target organisms under different fumigation treatments. Applied and Environmental Soil Science. DOI: org/10.1155/2015/673264.

Interpretive Summary: Fumigants are used for controlling nematodes, plant pathogens, weeds and insects. However, most of the fumigants are known to have broad biocidal activity and their effect on soil microbial community structure is not known until recently. It is very critical for them to recover because they play an important role in sustaining the health of agricultural and natural soil systems. Therefore, the main objectives of this study were to determine the efficacy of fumigants such as InLine®, Pic-Clor 60 EC, methyl bromide (MeBr) and Telone C35 on both target (Pythium spp. and Fusarium oxysporum) and non-target organisms (Gram positive bacteria, Gram negative bacteria, fungi, arbuscular mycorrhizal fungi, actinomycetes and protozoa) in soil and to compare these organisms in fumigated vs. non-fumigated control soils. In both the Moss Landing and Parlier, CA trials soil fumigation reduced the populations of both pathogenic and non-pathogenic microorganisms. Populations of Pythium spp. were reduced to a greater extent than populations of F. oxysporum by both InLine® and Pic-Clor 60 EC. Also, microbial community structure was least impacted with InLine® (187 L/ha) in the Moss Landing trial and Telone C35 (299 L/ha) under polyethylene tarp in the Parlier trial. These fumigants may be better options for per-plant soil fumigation because of less interference with beneficial soil microorganisms.

Technical Abstract: Several high-value crop producers in California rely heavily on soil fumigants to control key diseases, nematodes, weeds and volunteer crops. Fumigants with broad biocidal activity can affect both target and non-target soil organisms. The ability of non-target soil organisms to recover after fumigation treatment is critical because they play an important role in sustaining the health of agricultural and natural soil systems. This study focusses on the effects of soil fumigants such as InLine®, Pic-Clor 60 EC, methyl bromide (MeBr) and Telone C35 on target and non-target soil organisms using field samples. Fumigation trials were conducted in Moss Landing and Parlier, CA. Results indicated that the populations of target organisms, such as Fusarium oxysporum and Pythium spp., were reduced at all rates of primary fumigants. InLine® and Pic-Clor 60 EC were much more effective in controlling Pythium spp. compared to F. oxysporum. Microbial community structure using phospholipid fatty acid (PLFA) analysis indicate that all major non-target soil microbial groups such as Gram positive bacteria, Gram negative bacteria, fungi, arbuscular mycorrhizal fungi (AMF) and actinomycetes are affected, regardless of fumigant type or application method. In general, the effects of InLine® (187 L/ha) in Moss Landing trial and Telone C35 (299 L/ha) under polyethylene tarp in Parlier trial had the least impact on microbial community structure and better effect on controlling target organisms; and therefore, indicated the better option among fumigants.