Improved control of Stellaria media (L.) Vill in leys with Trifolium repens, using bentazone and benazolin with additives |
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| Authors: | D J TURNER |
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| Institution: | Agricultural and Food Research Council Weed Research Organization, Begbroke Hill, Yarnton Oxford OX5 1PF, U.K. |
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| Abstract: | In pot experiments, mixtures of ammonium sulphate with surfactants or oil additives increased the phytotoxicity of commercially formulated bentazone (‘Basagran’) to Stellaria media (chickweed). Ammonium sulphate with a proprietary oil adjuvant Actipron had similar effects with benazolin potassium salt, but not with an ethyl ester formulation of benazolin. The phytotoxicity of bentazone and benazolin salts to Trifolium repens (white clover) and Lolium perenne (perennial ryegrass) was almost unaffected by these additives. In a field experiment, a mixture of ammonium sulphate with Actipron improved the control of S. media by bentazone and benazolin salts. Oils and surfactants markedly increased rates of entry of 14C bentazone into leaves of S. media, white clover and Chrysanthemum segetum. Ammonium sulphate sometimes had similar effects but on other occasions reduced uptake. In some circumstances the additives apparently interacted synergistically, to increase uptake of labelled herbicide into the leaf or to enhance its transport within the plant. In these test species, differential absorption of bentazone could not explain differences in species susceptibility, suggesting that the main cause of resistance was the ability of plants to degrade the herbicide. |
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