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Two-year-old highbush blueberry bushes (Vaccinium corymbosum L. `Collins') were treated in Mar. 1985 with diuron or simazine at 2.2 or 4.5 kg a.i./ha. No residues were detected by reverse-phase high-performance liquid chromatography-ultraviolet absorbance detection (HPLC-UV) from treated berries that were harvested in June. Methiocarb was applied in May 1986 at 0.84 and 3 kg·ha-1 over the top of 3-year-old `Collins' when the berries began to ripen. Reverse-phase HPLC-UV of berries treated with methiocarb at 3 kg·ha-1 had combined residues of methiocarb and its sulfone and sulfoxide metabolites of 13.1 ppm from unrinsed and 7 ppm from rinsed berries harvested on the day of treatment; 4.9 ppm from unrinsed and 4 ppm from rinsed berries harvested 4 days after treatment; and 2.4 ppm from unrinsed and 2.5 ppm from rinsed berries harvested 8 days after treatment. Unrinsed berries treated with methiocarb at 0.84 kg·ha-1 had 5.7 ppm residue on the day of treatment and 1 ppm 8 days later. Residues from berries treated with methiocarb at 0.84 or 3 kg·ha-1 were below the legal tolerance level of 5 ppm after the required 7-day waiting period. Chemical names used: n'-(3,4-dichlorophenyl)-N,N -dimethylurea (diuron); 6-chloro- N,N' -diethyl-1,3,5-triazine-2,4-diamine (simazine); 3,5-dimethyl-4-(methylthio)phenol methylcarbamate (methiocarb).
Abstract
Several Arkansas commercial grape growers operating tractor-mounted, low-boom vineyard spray rigs were monitored for potential dermal, respiratory, and internal exposure to paraquat (1-1′-dimethyl-4,4′-bipyridinium ion) during the 1980 and 1981 growing seasons. Workers followed their usual mixing and spraying routines with as little influence as possible from the test. Analyses by colorimetric methods revealed very low levels of paraquat exposure. Greatest dermal exposure levels averaging 0.015 mg paraquat/kg body weight were detected on persons operating the spray rigs. Respiratory exposure was minimal and there was no paraquat detected in any of the urine samples collected from each worker. Those persons receiving the highest levels of paraquat exposure had measurements which were well below those found to be toxic to laboratory animals. Hazards from using this material by this method of application should be low when used in accordance to label directions and precautions.