Alternatives to Current Fumigation Practices in Western States Raspberry

Red raspberry production in the western United States is heavily reliant on preplant soil fumigation to ensure the successful establishment and productivity of a planting. However, due to issues related to the regulation, availability, and economics of soil fumigation, alternatives are needed for current fumigation practices. Trials were conducted in commercial raspberry fields in California and Washington to evaluate alternatives to current fumigation practices in each region. In Washington, tarped bed fumigation with 1,3-dichlorpropene (1,3-D):chloropicrin (Telone C-35) performed as well as, and sometimes better than, the industry standard nontarped broadcast fumigation with Telone C-35 for the control of the soilborne pathogen Phytophthora rubi and the plant-parasitic nematode Pratylenchus penetrans. In one of the Washington trials, yield of raspberry grown in tarped bed-fumigated areas was 47% greater than the yield of plants grown in nontarped broadcast-fumigated areas. In California, a combination of chloropicrin:1,3-D (Pic-Clor 60) performed as well as the industry standard of methyl bromide:chloropicrin. Raspberry plants grown in soil fumigated with either of these fumigants were approximately 26% taller than plants grown in nonfumigated soil. Our results indicate that there are viable fumigation alternatives to the current fumigation systems used in Washington and California raspberry production systems.