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Bioassays to Detect Dissipation and Efficacy of Benomyl on Turf

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dc.contributor.advisor Hsiang, Tom Liu, Leon Xuecai 2021-07-29T17:27:46Z 2021-07-29T17:27:46Z 1993 1993-11 1993-11
dc.description.abstract Paper disc, soil-agar pellet, turfgrass-agar pellet, thatch-agar pellet, and sample agar mixture bioassays were developed and evaluated for detection of the fungicide benomyl and its major fungitoxic product methyl 2-benzimidazole carbamate (MBC) in leachate, soil, turfgrass clippings, and thatch. The bioassays could detect benomyl and MBC residues with a limit of detection of 0.2 μg/g and a limit of quantitation of 0.5 μg/g. In vitro soil and thatch degradation studies showed a half-life for MBC of approximately 18 days in thatch and 4 to 5 weeks in soil, depending on soil type. An adsorption equilibrium with benomyl in solution was reached within 1 h for thatch and 2 to 4 h for soils. MBC adsorbed by thatch was as much as twice that adsorbed by a Fox sandy loam which may represent a typical soil found on golf courses in Southern Ontario. When MBC was applied at 10 μg/g, up to 90% of the chemical in thatch and 68% in soil were not extractable with water. Methanol could extract up to three times the fungicide from soil or thatch as could water. Laboratory and field experiments showed that the wetting agent Aqua-Gro (AG) (polyoxyethylene ester and ether of cyclic acid and alkylated phenols) significantly reduced adsorption of benomyl by creeping bentgrass thatch. With AG, significantly less fungicide was initially adsorbed and significantly more fungicide was later desorbed from the thatch layer by 20 mm of water irrigation. Aqua-Gro increased movement, uptake, and biological availability of the fungicide and resulted in a higher residue level of fungicide in the grass clippings. Tersan 1991 (50% benomyl) applied at 2 kg/ha with AG gave control of dollar spot disease as good as the full rate (3 kg/ha) without AG. Field studies also showed that core cultivation 1 or 7 days before fungicide application gave better and longer-lasting uptake of the fungicide by turfgrass and resulted in better control of dollar spot disease. Core cultivation one day before fungicide treatment gave the best results both in long-lasting uptake of benomyl and control of dollar spot disease. en_US
dc.language.iso en en_US
dc.publisher University of Guelph en_US
dc.subject turfgrass en_US
dc.subject bioassay en_US
dc.subject benomyl en_US
dc.subject dollar spot en_US
dc.subject plant pathology en_US
dc.title Bioassays to Detect Dissipation and Efficacy of Benomyl on Turf en_US Doctor of Philosophy en_US Department of Environmental Biology en_US
dc.rights.license All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated. University of Guelph en_US

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