Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: 11/6/2000
Publication Date: N/A
Technical Abstract: Methyl bromide is typically applied to soil by injection through hollow shanks. The available commercial chemical alternatives [1,3- dichloropropene (1,3-D), chloropicrin (CP), and metam sodium (a methyl isothiocyanate, MITC, generator)] can also be applied to soil by shank injection. The objective of this study was to determine soil distribution of water and fumigants (1,3-D, CP, and MITC) applied through drip irrigation systems under various soil conditions and different configurations of the drip irrigation systems. Variables evaluated include amount of water used to apply the fumigants, drip tape discharge rate, soil type, and use of virtually impermeable film (VIF) vs. standard plastic or polyethylene mulch. Studies were conducted on three soil types and several drip tape and bed configurations commonly used in California. Concentrations of 1,3-D (from InLine) in the soil gas were greatest after 24 to 36 hrs following application. Results for the Watsonville soil (a sandy loam soil) indicated that a minimum of 40 mm of water is needed to deliver sufficient fumigant horizontally 30 cm (i.e., to the edge of strawberry beds) using two drip tapes (each located 12 cm from the bed center). In general, higher amount of irrigation water resulted in greater fumigant concentration in the gas phase across the soil profile. Reduced rates of fumigants are possible if VIF is used in drip fumigation. Research will continue to optimize application techniques of fumigants through various configurations of drip irrigation systems for different soil types and climatic conditions.