VIEW ARTICLE

Movement of Benomyl in Field Soils as Influenced by Acid Surfactants. R. E. Pitblado, Graduate student, Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada; L. V. Edgington, Professor, Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada. Phytopathology 62:513-516. Accepted for publication 15 November 1971. DOI: 10.1094/Phyto-62-513.

Benomyl-surfactant mixtures were added to plastic tubes, shallowly inserted into soil of two types in the field. Fungicide movement into soil was detected after 24 hr by bioassaying soil at various depths. A 1% (v/v) concentration of the surfactants Tween 20 (polyoxyethylene sorbitan monolaurate), GAFAC RS-710, and GAFAC RA-600 (General Aniline and Film Corporation, New York, N.Y.), increased the solubility of methyl 2-benzimidazolecarbamate (MBC), the fungicidal breakdown product of benomyl. The GAFAC surfactants contain phosphoric acid moieties. Acidification with either phosphoric acid or GAFAC surfactants increased protonation, and thus, the water solubility of MBC. Greatest movement of the fungicide in soil was found in solutions of GAFAC RA-600 and acidified Tween 20. Thus, movement of the fungicide in soil is dependent upon both water solubility of MBC and surfactant properties.