|Allen, Leon - Hartwell|
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2003
Publication Date: 12/2/2003
Citation: Thomas, J.E., Allen Jr, L.H., Mccormack, L.A., Vu, J.C., Dickson, D.W., Ou, L.T. 2003. Diffusion and emissions of 1,3-dichloropropene in florida sandy soil in microplots affected by soil moisture, organic matter, and plastic film.Pest Management Science. 60:390-398. Interpretive Summary: The use of methyl bromide as a preplant soil fumigant for pest control in high-value crops is planned to be phased out by 2005. For alternative fumigants, it is necessary to decrease emissions to the atmosphere because of field set-back requirements; and to improve dispersion and retention in the target treatment zone because other fumigants, such as 1,3-dichloropropene (1,3-D), are not as reliable as methyl bromide for efficacious treatment. ARS and University of Florida scientists at Gainesville, FL measured the effects of soil water content and plastic film row covers on the dispersion and emissions of 1,3-D in Florida sandy soil. The fumigant volatilized too quickly when the soil was too dry, and the fumigant failed to disperse adequately when the soil was too wet. More importantly, a virtually impermeable film (VIF) decreased the emissions of 1,3-D from the soil surface and promoted better dispersion within the soil. This study showed that sufficient but not excessive water content in Florida sandy soil is needed to assure adequate and uniform 1,3-D dispersion. Furthermore, VIF retards emissions at the soil surface and retains fumigant longer, which should improve efficacy for pest control, and might decrease the amount of fumigant required.
Technical Abstract: The fumigant 1,3-dichloropropene (1,3-D) is a methyl bromide alternative for preplant soil treatment. The objective was to determine effects of soil water and plastic cover on dispersion and emissions of 1,3-D in a Florida soil (Arredondo fine sand). Liquid 1,3-D was injected at 30-cm depths at 8 points in a straight line 15 cm apart to emulate field injection. Soil gas sampling probes were installed at depths of 10, 20, and 30 cm at horizontal distances of 7.5, 15, and 30 cm from both sides of the centerline of injection. Soil gas samples and surface emissions were measured 4 hours after injection and daily for 4 days. In air dry soil, 1,3-D diffused to the 10-cm depth within 4 hours, but in nearly saturated soil dispersion was negligible even 4 days later. Dispersion in soil at field capacity was satisfactory. Virtually impermeable film (VIF) cover decreased emissions from the surface and promoted retention in the soil. In conclusion, adequate but not excessive water content in sandy soil is needed to assure adequate, uniform rates of dispersion. Furthermore, VIF retards emissions at the surface and retains fumigant longer, which should improve efficacy for pest control, and might decrease the amount of fumigant required.