Skip to main content
ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #221233
Title: PERENNIAL CROP NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS: EFFECT ON WEED COMMUNITY COMPOSTION

Author
item SHRESTHA, ANIL - UNIV OF CALIF, PARLIER
item Browne, Greg
item LAMPINEN, BRUCE - UNIV OF CALIF, DAVIS
item Schneider, Sally
item SIMON, LEO - UNIV OF CALIF, BERKELEY
item Trout, Thomas

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2008
Publication Date: 4/1/2008
Citation: Shrestha, A., Browne, G.T., Lampinen, B.D., Schneider, S.M., Simon, L., Trout, T.J. 2008. PERENNIAL CROP NURSERIES TREATED WITH METHYL BROMIDE AND ALTERNATIVE FUMIGANTS: EFFECT ON WEED COMMUNITY COMPOSTION. Weed Technology 22:267-274

Interpretive Summary: The relative prevalence of different species of weeds in weed communities can change within a few years in response to changes in agricultural management systems. We hypothesized that transition from use of methyl bromide (MeBr) for pre-plant soil fumigation to use of alternative fumigants for this purpose may cause shifts in weed species composition. This hypothesis was tested in four perennial crop nurseries in California. At each test site, the following pre-plant treatments were applied with tractor-mounted shanks: a non-fumigated control; MeBr with (i.e., covered by) high density polyethylene film (HDPE); iodomethane (50%) plus chloropicrin (50%) with HDPE; 1,3-dichloropropene (1,3-D) with HDPE; 1,3-D (61%) plus chloropicrin (35%) with HDPE or virtually impermeable film (VIF); and, at two of the nurseries, 1,3-D (62%) plus chloropicrin (35%) with HDPE was applied using sub-surface drip tubing. All the fumigation treatments reduced the population of common major weed species and had similar weed species composition as the MeBr treatment. None of the fumigants, including MeBr, controlled species such as California burclover, Spanish clover, little mallow, or Asteraceae family weeds such as Conyza sp., common groundsel, or annual sowthistle. The results suggested that, in perennial crop nurseries, transitioning from pre-plant soil fumigation with MeBr to that with alternative fumigants will not immediately lead to shifts in weed species composition. However, it appears that additional weed control measures will be required to manage weed species of Fabaceae and Asteraceae family that are not controlled by either MeBr or the alternative fumigants.

Technical Abstract: Weed communities can respond dynamically to shifts in management systems. Thus, transition from methyl bromide (MeBr) to alternative fumigants for pre-plant soil treatments may cause shifts in weed species composition. This hypothesis was tested in four perennial crop nurseries in California. The following pre-plant treatments were applied with tractor-mounted shanks: a non-fumigated control; MeBr with (i.e., covered by) high density polyethylene film (HDPE); iodomethane (50%) plus chloropicrin (50%) with HDPE; 1,3-dichloropropene (1,3-D) with HDPE; 1,3-D (61%) plus chloropicrin (35%) with HDPE or virtually impermeable film (VIF); and, at two of the nurseries, 1,3-D (62%) plus chloropicrin (35%) with HDPE was applied by sub-surface drip tubing. All the fumigation treatments reduced the population of common major weed species and had similar weed species composition as the MeBr treatment. None of the fumigants, including MeBr, controlled species such as California burclover, Spanish clover, little mallow, or Asteraceae family weeds such as Conyza sp., common groundsel, or annual sowthistle. The results suggested that, in perennial crop nurseries, transitioning from MeBr to alternatives will not immediately lead to a shift in weed species composition. However, it appears that additional weed control measures will be required to manage weed species of Fabaceae and Asteraceae family that are not controlled by either MeBr or the alternative fumigants.