Atomizer type, spray volume, and herbicide rate influenced the effectiveness of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) in controlling vegetation. In general, paraquat controlled vegetation more completely when applied from atomizers that discharged sprays with the angle between the edges of the pattern less than 80°. Increasing spray volume increased control for marginal herbicide rates. Increasing herbicide rate increased control and tended to overcome less effective atomizer performance or reduced spray volume. Vegetation was effectively controlled with cone- or fan-pattern-type nozzles at spray volumes as low as 50 L/ha. Cone- and fan-pattern atomizers were equal to or more effective than either rotary or flooding-type atomizers in all tests.

Acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} and bentazon [3-(1-methylethyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] plus acifluorfen were applied through hydraulic flat-fan nozzles or controlled-droplet applicators (CDA) in water plus surfactant, soybean [Glycine max (L.) Merr.] oil and water emulsions, and soybean oil alone. Except for inadequate weed control with CDA applications at 7 L/ha, method of application did not affect weed control of common cocklebur (Xanthium strumarium L. #3 XANST) or smooth pigweed (Amaranthus hybridus L. # AMACH) at high rates of bentazon plus acifluorfen (560 plus 280 g ai/ha or above). With low rates (280 plus 140 g/ha or less), hydraulic flat-fan nozzles were more effective than CDA applications. Early CDA applications of acifluorfen in an oil carrier at a volume of 9 L/ha were as effective as hydraulic nozzle applications at a carrier volume of 47 L/ha. Later applications resulted in inadequate weed control. Increasing soybean oil concentration from 2.5 to 40% (v/v) in acifluorfen spray mixtures did not significantly increase the phytotoxicity of acifluorfen.