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- Author or Editor: R. E. Talbert x
Glyphosate (N-phosphonomethyl glycine) was applied to low-hanging foliage and basal shoots of ‘Concord’ grapevines (Vitis labrusca L.) at 2.2 and 4.4 kg/ha in August, September, and October 1979. All treatments were extremely injurious to grapevines. Injury was evident throughout the grapevine the following spring and during the full growing season. Growth on new shoots, visual ratings of growth reduction during the season, grape yield, and pruning weights indicate 50% or more reduction in growth as compared to the untreated check. The September treatment appeared more injurious than the August or October treatments.
Midsummer grapehoeing following spring application of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] or simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] plus paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) adequately controlled weeds growing in grapes (Vitis labrusca L.). When grapehoeing was used to control grape root borer [(Vitacea polistiformis Harris) lower initial rates of preemergence herbicide could be used. An additional half-rate of herbicide was required after grapehoeing to maintain weed control through the fall. Plots not grapehoed were almost completely weed free following a glyphosate [N-(phosphonomethyl)glycine] treatment. Injury to grapes the following spring was associated with fall glyphosate applications where low hanging foliage, that had not been removed, intercepted the spray. Glyphosate was most effective and paraquat more effective than dinoseb (2-sec-buty1-4,6-dinitrophenol) plus diesel fuel for postemergence control of weeds in grapes. Preemergence herbicides, napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], oxadiazon [2-tert-buty1-4-(2,4-dichloro-5-isopropoxyphenyl)-∆2-l,3,4-oxadiazolin-5-one], oryzalin (3,5-dinitro-N 4,N 4-dipropylsulfanilamide), and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], were effective as residual type treatments.
Preliminary greenhouse and field experiments showed that alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] were noninjurious to gladiolus (Gladiolus × hortulanus) and had potential for control of yellow nutsedge (Cyperus esculentus L.). In subsequent field experiments both herbicides at 2.2 and 4.5 kg a.i./ha preplant-incorporated gave good nutsedge control for 6 weeks. When alachlor and metolachlor at 2.2 and 4.5 kg/ha preplant-incorporated were repeated at 6 weeks, nutsedge control was extended for longer than 3 months. Little or no injury resulted from either herbicide applied once or repeated. Neither herbicide nor application method affected gladiolus height or flower production.
Five-year-old ‘Collins’ highbush blueberries were treated in August with glyphosate (N-phosphonomethyl glycine) at 0.36, 3.6 and 7.2 g/liter acid equivalent as a spot treatment alone or with pruning or applying paraquat (1, 1-dimethyl-4,4′-bipyridinium ion) at 1.2 g/liter to remove green tissue prior to glyphosate application. Initial response was terminal dieback of young canes. Symptoms the following spring included additional terminal dieback, leaf and cane morphological aberrations, and elongation of the flower corolla. One year after treatment, regrowth was normal. There was no effect on blueberry yield the season following treatment.
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).
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.