|WALTERS, TOM - Walters Ag Research|
|BOLDA, MARK - University Of California|
Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2017
Publication Date: 7/1/2017
Citation: Walters, T., Bolda, M., Zasada, I.A. 2017. Alternatives to current fumigation practices in western states raspberry. Plant Health Progress. 18:104-111. doi: 10.1094/PHP-RS-16-0068.
Interpretive Summary: The majority of the red raspberries grown in the United States are produced in California and Washington. In both of these regions,raspberry production is threatened by two soil borne pests: a water mold which cause root rot (Phytophthora) and a microscopic soil worm (Pratylenchus) which feeds on the roots of the plant. Raspberry growers control these pests by injecting fumigants, volatile compounds, into the soil to enable the production of raspberry plants free of these pests. This research was conducted to identify modifications to current pest control practices in raspberry production systems. In Washington it was discovered that a smaller area of a raspberry field can be treated with a fumigant to achieve the same control achieved by treating an entire field. In California, an alternative compound to methyl bromide, an ozone depleting compound, was identified that allowed for similar yields of raspberry. These results are significant because they will help guide the selection of fumigants and allow for the modification of current fumigation practices for soil borne pest control in raspberry. These findings will be used by raspberry growers to improve current management practices targeting soil borne pests.
Technical Abstract: Red raspberry production systems in the western United States are 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 need for current fumigation practices. Trials were conducted in commercial raspberry fields in California (CA) and Washington (WA) to evaluate alternatives to current fumigation practices in each region. In WA, it was discovered that tarped bed fumigation with 1,3-dichlorpropene (1,3-D):chloropicrin (Telone C-35) performed as well, and sometime better than nontarped broadcast fumigation with the same fumigant (the industry standard) for the control of the soilborne pathogen Phytophthora rubi and the plant-parasitic nematode Pratylenchus penetrans. In one of the WA 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 CA, a combination of chloropicrin:,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. Combined, our results indicate that there are viable fumigation alternatives to the current fumigation systems used in WA and CA raspberry production systems.