Improving Fumigant Efficiency By Deep Application and Totally Impermeable Film Covering Raised-Bed Systems for Strawberry Production.

The coastal California (CA) is the primary productive strawberry region where strawberry is mainly grown in raised-beds covered by polyethylene (PE). Over 55% of raised-bed production systems have fumigants applied directly through irrigation drip-tapes, which are buried near soil surface for soil-borne pest control. However, the current drip fumigation method need to be optimized to cope with the high fumigant emission loss, which results in air quality issue and insufficient pest control. In August 2013, a field trial was conducted in a sandy loam soil in Camarillo, CA to evaluate the distribution, emission, and fate of the fumigants in Pic-Clor 60 EC (a mixture of 56.7% chloropicrin, 37.1% 1,3-dichloropropene, and 6.2% inert ingredients) as affected by application depth, fumigant rate, and film type. Result showed that total impermeable film (TIF) reduced fumigant emission effectively with further reduction by a deeper application. The deep application also improved fumigant distribution in soil profile compared to the shallow application. Fumigant concentration under TIF with half-rate was similar to or even higher than that under PE with full rate, suggesting that using TIF may help grower to reduce fumigant input but still achieve comparable pest control results to the conventional applications. The overall results indicate that the combination of TIF covering and deep application possibly lead to using less fumigant to achieve good pest control, while more trials are needed for optimizing the technology for its adoption in production fields.