On-Farm Trials of Alternatives to Methyl Bromide for Raspberry Nurseries

Methyl bromide has been phased out due to its activity as a stratospheric ozone depleter. Exemptions allowing the use of methyl bromide are increasingly difficult to obtain. Raspberry nurseries rely upon preplant soil fumigation with methyl bromide:chloropicrin (mb:pic) combinations to produce disease- and nematode-free plants.   Successful alternatives to mb:pic must provide full control of plant-parasitic nematodes, Agrobacterium tumefasciens, and Phytophthora rubi.  Trials  in commercial raspberry nurseries (Macdoel CA, Burlington WA and Lynden WA) evaluated  mb:pic and alternative fumigants, including: Midas^® (Methyl Iodide:cloropicrin), Telone^® C-35 and Pic Clor 60 (Telone:cloropicrin) under conventional (HDPE) and virtually impermeable (VIF) films.  P. rubi and A. tumefasciens control was evaluated with a greenhouse biossay; A. tumefasciens control was also evaluated by soil dilution plating on a selective medium. All of the treatments controlled P. penetrans and buried bags of perennial quackgrass and nutsedge propagules. Midas^® applied at 350 lb/A under a conventional (HDPE) tarp consistently provided excellent control of all weeds and pathogens. VIF film enhanced efficacy of Midas^® applied at 225lb/A and of Telone^® C-35 applied at 39 gal/A for controlling Agrobacterium and P. rubi.