Submitted to: California Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2013
Publication Date: 11/25/2013
Citation: Gao, S., Qin, R., Cabrera, A., Hanson, B.D., Gerik, J.S., Wang, D., Browne, G.T. 2013. Totally impermeable film (TIF) reduces emissions in perennial crop fumigation. California Agriculture. 67(3):217-222. Interpretive Summary: Successful replanting and nursery crop production for fruit/nut trees and grapevines still depend on soil fumigation to control soil-borne pests. 1,3-dichloropropene and chloropicrin are important alternative fumigants being used to replace methyl bromide; but they are also highly regulated because emissions increase exposure risks and release of volatile organic compounds degrades air quality. Research strategies are being developed to minimize emissions, improve pest control efficacy, and reduce fumigation rates by tarping fumigated fields with low permeable films, such as the commercially named totally impermeable film (TIF). From 2009-2010, three field trials were conducted to test the TIF tarp performance in emission control and efficacy from full and reduced fumigation rates in broadcast application of Telone C35. Field data showed significant emission reduction (>90%) by TIF tarp compared to standard polyethylene tarp. A higher emission surge from TIF tarp was observed than from standard tarp; but lower emission flux was observed when the tarp was cut after two weeks in a 2009 trial as compared to when the tarp was cut after 6 days in an earlier trial. TIF tarp resulted in higher fumigant concentrations under the tarp and in soils indicating the tendency to improve efficacy in comparison with standard tarp. Reduced rates to half under TIF provided similar efficacy against nematodes, pathogens and weeds as full rate (~540 lbs/ac) under TIF, but the effectiveness of the reduced rate on satisfactory pest control require more field data to conclude due to large field variations and the complexity of soil/environmental factors. This research continues to collect field data/information towards safe use and adoption of TIF tarp in soil fumigation.
Technical Abstract: Orchard/vineyard replanting for fruit trees, nut trees, and grapevines in many situations still depends on soil fumigation for control of soil-borne pests and replanting diseases in California. Perennial tree and grapevine nurseries also rely heavily on soil fumigation to meet the state’s requirements for producing parasitic nematode-free crops. The important alternatives to methyl bromide, 1,3-dichloropropene (1,3-D) and chloropicrin (CP), are highly regulated because of emissions that increase exposure risk and degrade air quality. Tarping over fumigated fields with low permeable films such as the commercially named totally impermeable film (TIF) has shown promise in controlling emissions while improving pest control efficacy; but has also exibited concerns over emission surge upon tarp-cutting. Since 2009, our research objective has been to develop practices for using low permeability tarps to reduce emissions, improve efficacy, and potentially use reduced fumigation rates. Three field trials were conducted from 2009 to 2010 and tested the TIF tarp performances at the full rate (maximum allowed in CA, 540 lbs/ac) and reduced rates (0.5 or 0.25 full rates) in broadcast application of Telone C35. Greater than 90% emission reduction by TIF tarp were determined during a 2-week tarp-covering period. Emission surges following TIF tarp-cutting were observed, but the flux was much smaller than when the tarp was cut after 6 days in another trial. TIF tarp resulted in higher fumigant concentrations under the tarp and in soils indicating the tendency to improve efficacy in comparison with standard tarp. Although the reduced rates under TIF provided similar efficacy against nematodes, pathogens and weeds as full rate under TIF, the effectiveness of reduced rates on pest control needs more field data to conclude.