Priority 2: Reducing Chemical Inputs
Optimizing Fumigation Rate, Application Depth, and Plastic Mulch Use for Strawberry Production in Raised-Bed Systems
- Ruijun Qin, University of California-Davis, USDA-ARS, Water Management Research
- Oleg Daugovish, University of California, Ventura County Cooperative Extension
- Suduan Gao, U. S. Department of Agriculture, ARS, Pacific West Area
Project Summary and Objectives
Soil fumigation is an important practice used on commercial strawberry farms to control soil-borne pathogens and nematodes that decrease plant productivity. More than 55 percent of California strawberry fields are treated with fumigants applied directly through drip irrigation lines buried near the surface of the beds prior to planting. In the face of international pressure to phase out the most commonly used fumigant, methyl bromide, growers find themselves pressed to maximize the efficiency of allowable fumigants. In this project, Qin's team looked at the tarps used to restrict fumigants in the soil and the drip lines used to distribute those chemicals. Their objectives were to 1) compare the impact of drip-line placement on fumigant distribution and emissions in soil; 2) demonstrate that the use of totally impermeable film (TIF) tarp in drip fumigation can improve fumigant efficacy compared to standard polyethylene (PE) tarp; 3) evaluate the performance of recycled plastics film (RPF) on fumigant distribution in soil and fumigant emissions; 4) evaluate pest control efficacy under standard PE, TIF and RPF tarp from two different injection depths and application rates; and 5) monitor strawberry plant growth, root development and yield from different fumigation treatments in growers' fields. The study was conducted at DJ Ranch of Solimar Farms in Camarillo, Calif.
Project Outcomes and Impacts
Results showed that TIF reduced fumigant emission effectively. Half-rate fumigant concentration under TIF was similar to or higher than fumigant concentration applied at full rate under PE. These findings suggest that using TIF may help growers reduce fumigant input while achieving comparable pest control results. Fumigant emissions were reduced even further when applied deeper in the soil (7 inches), as opposed to the shallow application (2 inches) typically practiced. Various outreach methods were used to extend the research findings to growers, regulators and extension specialists. Findings from this study were shared with more than 800 participants at workshops, field days and conferences, including the 2013 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, the 2014 California Plant and Soil Conference, the Water Management in Strawberry field day and educational meeting and the Organic Strawberry Workshop at Tennessee State University. This project demonstrated that strawberry growers safely can reduce their chemical inputs by adopting lower fumigant rates under TIF for effective pest control.