Field Evaluation of a New Plastic Film (Vapor Safe) to Reduce Fumigant Emissions and Improve Distribution in Soil

Abstract

Preplant soil fumigation is an important pest management practice in coastal California strawberry production regions. Potential atmospheric emissions of fumigants from field treatment, however, have drawn intensive environmental and human health concerns; increasingly stringent regulations on fumigant use have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low-permeability film, commonly known as totally impermeable film (TIF), on fumigant emissions and on fumigant distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha in two location-separate field plots (0.4 ha each) in Ventura County, California, in fall 2009. One plot was surface-covered with standard polyethylene (PE) film, and the other was covered with TIF immediately after fumigant application. Data collection included emissions, soil-gas phase concentration profile, air concentration under the film, and soil residuals of the applied fumigants. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than from the PE field. Total through-film emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d film covering period, compared with 43% for 1,3-D and 12% for CP from the PE field. However, on film-cutting, greater retention of 1,3-D in the TIF field resulted in a much higher emission surge compared with the PE field, while CP emissions were fairly low in both fields. Higher concentrations and a more uniform distribution in the soil profile for 1,3-D and CP were observed under the TIF compared with the PE film, suggesting that the TIF may allow growers to achieve satisfactory pest control with lower fumigant rates. The surging 1,3-D emissions after film-cutting could result in high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.

Totally impermeable film (TIF) reduces emissions in perennial crop fumigation

“…2A). The flux values after tarp cutting (13 days after application) in the fall 2009 trial were substantially lower than those reported (over 200 µg m −2 s −1 ) when tarp cutting occurred 6 days after fumigant application (Qin et al 2011). Emissions of chloropicrin were lower than 1,3-D emissions (data not shown) because of the lower amount of chloropicrin applied and its faster degradation; following an application of Telone C35, it's 1,3-D that is the major concern for worker safety in an emissions surge.…”

“…Our research objective was to optimize the use of TIF to reduce emissions, improve efficacy and potentially reduce fumigant application rates. This research was also conducted to determine how to avoid the surge of emissions that had been observed when TIF was cut after 6 days, the cutting time that is commonly used for standard polyethylene film (Qin et al 2011). This paper includes our research data for fumigant concentration in the air under the tarps (above soil Data from three field trials conducted near Parlier, above, show that totally impermeable film (TIF) maintained higher fumigant concentrations under tarp and in the soil than polyethylene film.…”

“…Low-permeability films, such as TIF (Chow 2008), have been shown to effectively control emissions and improve fumigation efficacy in annual crops such as strawberry by retaining higher fumigant concentrations and creating a more uniform distribution of fumigant in the soil profile compared to standard polyethylene tarp (Qin et al 2011). However, the benefits of TIF for soil fumigation in perennial crops have not been evaluated.…”

Fumigant emission reductions with TIF warrant regulatory changes

“…Emission flux and cumulative loss estimated using dynamic flux chambers were reported in Qin et al 2011. Emission flux of chloropicrin and 1,3-D from Field 2 (TIF) was substantially lower than from Field 1 (polyethylene film) during tarp covering.…”

Fumigant dosages below maximum label rate control some soilborne pathogens

“…Tarping fields with low permeability film, such as virtually impermeable film (VIF) or totally impermeable film (TIF), has been effective in retaining fumigants in soil (Gao et al 2013). These films can improve the efficacy of reduced fumigant application rates because they retain higher fumigant concentration and extend the exposure time (concentration × time) under the film compared to standard polyethylene film (Fennimore and Ajwa 2011;Qin et al 2011).…”