Emission reduction and efficacy with TIF in perennial soil fumigation
The low permeability TIF has been shown to effectively control emissions, improve fumigation efficacy, and reduce fumigant application rates in annual crops such as strawberry by retaining higher fumigant concentrations and a more uniform distribution of fumigant in the soil profile than standard PE tarp (Qin et al., 2011). However, the horticultural benefits of TIF for soil fumigation in perennial crops are uncertain because the needs for deep injection of fumigants and control of soil borne pests in deep soil. Although tarps have not normally been used for orchard replant, the potential of using TIF to reduce emission, improve efficacy and/or use reduced fumigant rates is evaluated for the ultimate goal of maintaining fumigant availability to growers by increasing fumigant efficiency and minimizing any potentially negative environmental impact.
During 2009 and 2011, three field trials were conducted to test the full rate of Telone C35 in comparison with reduced rates (50% or 25%) under TIF in broadcast applications. TIF reduced emissions >90% compared to standard PE film during a 2-week tarp-covering. A much smaller surge of emissions was observed following tarp-cutting compared to tarp-covering for only 6 days in an earlier trial. In addition to more effectively reduce emissions, the TIF maintained slightly higher fumigant concentrations in the soil than PE films. The 50% reduced rate under TIF provided similar efficacy as the full rate under the PE, but the differences between tarps and application rates were not significantly different. This was due to 100% kill of nematodes in all fumigated treatments and large variations among pests. This research continues to investigate the effects of reduced fumigant rates under TIF on pest control and to collect more field response data for conclusions.
Fumigant concentration under tarp one week after fumigant application of Telone C35 in a summer 2010 field trial. By Suduan Gao.