Effects of reduced-rate methyl bromide applications under conventional and virtually impermeable plastic film in perennial crop field nurseries.
BACKGROUND
Producers of perennial crop nursery stock in California use preplant soil fumigation to meet state phytosanitary requirements. Although methyl bromide (MB) has been phased out in many agricultural industries, it is still the preferred treatment in the perennial nursery industry and is used under Critical Use Exemptions and Quarantine/Preshipment provisions of the Montreal Protocol. The present research was conducted to evaluate reduced-rate MB applications sealed with conventional and low-permeability plastic films compared with the primary alternative material.


RESULTS
Reduced rates (100-260 kg ha(-1)) of MB applied in combination with chloropicrin (Pic) and sealed with a low-permeability plastic film provided weed and nematode control similar to the industry standard rate of 392 kg ha(-1) MB:Pic (98:2) sealed with high-density polyethylene (HDPE) film. However, the primary alternative chemical, 1,3-dichloropropene (1,3-D), tended to provide slightly lower pest control even on sites with relatively low plant parasitic nematode, soil-borne pathogen and weed pest pressure.


CONCLUSIONS
If California regulations change to allow the use of low-permeability films in broadcast fumigant applications, the results of this research suggest that reduced rates of MB in perennial crop nurseries could serve as a bridge strategy until more technically, economically and environmentally acceptable alternatives are developed.
Hanson
Bradley D
BD
United States Department of Agriculture, Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Parlier, CA, USA. bhanson@ucdavis.edu
Gerik
James S
JS
Schneider
Sally M
SM
D000818:Animals; D018556:Crops, Agricultural / Q000187:drug effects* / Q000254:growth & development; D005651:Fumigation / Q000379:methods*; D006842:Hydrocarbons, Brominated / Q000737:chemistry / Q000494:pharmacology*; D010539:Permeability; D010571:Pest Control / Q000379:methods*; D010969:Plastics / Q000737:chemistry*; D020959:Polyethylene / Q000737:chemistry; D012621:Seasons
D006842:Hydrocarbons, Brominated; D010969:Plastics; D020959:Polyethylene; C005218:methyl bromide