|Allen, Leon - Hartwell|
Submitted to: Journal of Environmental Science and Health
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/15/2004
Publication Date: 5/1/2004
Citation: Thomas, J.E., Ou, L.T., Allen Jr, L.H., Mccormack, L.A., Vu, J.C., Dickson, D.W.(2004) Persistence, distribution, and emission of telone c35 injected into florida sandy soil as affected by moisture, organic matter, and plastic film cover.. Journal of Environmental Science and Health. b39:505-516 Interpretive Summary: Methyl bromide as a soil fumigant is scheduled to be phased out by 2005. Emissions to the atmosphere of alternative fumigants must be decreased to minimize field-border set-back requirements, and to improve dispersion and retention in the treatment zone because alternative fumigants, such as Telone C35, a mixture of 1,3-dichloropropene (1,3-D)and chloropicrin (CP), are not as reliable as methyl bromide for pest control. ARS and University of Florida scientists at Gainesville, FL measured the effects of soil water content, organic matter, and type of plastic row cover on dispersion and emissions of 1,3-D and CP in Florida sandy soil. Fumigants were lost rapidly when the soil was too dry. Higher soil organic matter led to a more rapid decrease of CP than 1,3-D. Use of a virtually impermeable film (VIF) decreased emissions of 1,3-D and promoted better dispersion and longer retention in the soil than polyethylene (PE), which should improve efficacy for pest control and might decrease the amount of fumigant required.
Technical Abstract: With the phase-out of methyl bromide scheduled for 2005, alternative preplant soil fumigants are being sought. This study of Telone C35, a mixture of two isomers [(Z) and (E)] of 1,3-dichloropropene (1,3-D) with chloropicrin (CP), focused on emission from, and distribution and persistence in, Florida sandy soil in microplots with different soil water and organic carbon (C) contents, and which were covered with either virtually impermeable film (VIF), polyethylene film (PE), or left uncovered. Slower subsurface dispersion and longer residence time of the fumigants occurred at a soil water content near field capacity than when it was near air-dry. Increased percentage of organic carbon led to a more rapid decrease in concentration of CP than 1,3-D isomers. The VIF soil cover provided a more even distribution and greater persistence in all conditions than PE or no cover. Thus, near field capacity water content, low organic matter, and VIF cover provided the best conditions for emission control, consistent distribution, and longest persistence of Telone C35 in a sandy Florida soil.