UC Davis

California strawberry production has relied on soil fumigants for more than sixty years. Fumigants are injected into the soil prior to planting to treat pathogens and other soilborne pests. In the last decade, a number of these fumigants have had significant use restrictions imposed to protect human health and the environment; some are no longer available for use in California. To maintain the state’s role as the predominant strawberry producer in the United States, finding effective alternatives to traditional fumigation practices is critical. In addition to non-fumigant alternatives, fumigant application methods that mitigate human health risks by reducing emissions can play a role. This thesis contributes to the literature by evaluating the economic viability of variable-rate fumigation, also called precision fumigation, compared to the industry-standard, single-rate fumigation. Based on data collected at two sites in Oxnard, California during the 2017/18 and 2019/20 growing seasons, I compare the average net returns of precision fumigation versus industry-standard fumigated plots using a partial budget analysis. I find that the variable-rate fumigation treatments generated net returns that were statistically the same as those for the constant rate treatment at the 5% level. I conducted a sensitivity analysis for key parameters—strawberry prices, testing and fumigation costs, yield, and labor costs—and the results were robust. This suggests that in some conditions, precision fumigation may be a viable management practice. Assessing how broadly this practice could successfully be applied requires further research, including evaluating the practice at new site locations in California and conducting multi-year, single site trials.