STP1347

    Methodology for Evaluation of Glyphosate Formulations

    Published: Jan 1998


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    Abstract

    The objective of the study was to develop a simple procedure for the evaluation of glyphosate formulations. Surfactants are included in glyphosate formulations for improving the wetting of the leaf surface and enhancing the foliar uptake of the herbicide. Black nightshade (Solanum nigrum L.) and wheat (Triticum aestivum L), species differing greatly in wettability and uptake properties, were used for measuring the influence of three surfactants (Ethomeen T/25, polyoxyethylene (15) tallow amine; Atplus 201, polyoxyethylene (20) hexitan monolaurate ester, Sisterna L70-C, sucrose laurate ester) on dose-response relations. The unformulated isopropylamine salt of glyphosate was used and surfactants were included at 0.25% (w/v).

    The ED50 values for glyphosate applied on black nightshade and expressed as g ae/ha were 71 (no surfactant), 4 (Ethomeen T/25), 4 (Atplus 201), and 39 (Sisterna L70-C). With wheat the ED50 values for glyphosate were 300 (no surfactant), 15 (Ethomeen T/25), 12 (Atplus 201), and 28 g ae/ha (Sisterna L70-C). With both species, but particularly with black nightshade, the surfactant Sisterna L70-C was less effective than Ethomeen T/25 and Atplus 201.

    Spray retention and foliar uptake experiments indicate that in wheat the surfactant-induced spray retention (up to 3-fold) is the predominant factor explaining the influence of the surfactants on glyphosate phytotoxicity. In black nightshade, the surfactant-induced foliar uptake of glyphosate (up to 6-fold) was considered as the factor explaining the enhanced phytotoxicity of glyphosate. In both species, the surfactant Sisterna L70-C did not promote foliar uptake of glyphosate. We conclude that the influence of the surfactants on the ED50 in the two species roughly indicates the potency of these compounds to enhance spray retention and foliar uptake.

    Keywords:

    adjuvant, surfactant, Solanum nigrum, L., Triticum aestivum, L..


    Author Information:

    de Ruiter, H
    Senior Scientist and Research Assistants, DLO Research Institute for Agrobiology and Soil Fertility (AB-DLO), Wageningen,

    Meinen, E
    Senior Scientist and Research Assistants, DLO Research Institute for Agrobiology and Soil Fertility (AB-DLO), Wageningen,

    Uffing, AJM
    Senior Scientist and Research Assistants, DLO Research Institute for Agrobiology and Soil Fertility (AB-DLO), Wageningen,


    Paper ID: STP14172S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP14172S


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