. Chemical weed-control equipment. Weeds; Spraying; Spraying equipment. duster than with a spray rig. However, there are significant reasons why the dusters available today are not more com- monly used for weed work. First, and most important, is the high loss through drifting of dusts. It is difficult, with drift- ing, to build up a sufficient amount of dust on weed growth to kill it. Second, if toxic dusts are being used, the drift may cause severe damage to near-by crops, shrubs, bees, and animals. Dusting can only be done under calm weather conditions. But ground or air- plane spraying can
. Chemical weed-control equipment. Weeds; Spraying; Spraying equipment. duster than with a spray rig. However, there are significant reasons why the dusters available today are not more com- monly used for weed work. First, and most important, is the high loss through drifting of dusts. It is difficult, with drift- ing, to build up a sufficient amount of dust on weed growth to kill it. Second, if toxic dusts are being used, the drift may cause severe damage to near-by crops, shrubs, bees, and animals. Dusting can only be done under calm weather conditions. But ground or air- plane spraying can be safely done under mildly windy conditions of 8 to 12 mph. However, this is not meant to imply that spray, particularly if applied by plane, does not drift. Spraying by ground rig or plane costs more per acre than dusting, but it gives much greater control of the drift factor, and is therefore preferred to Discharge equipment for ground dust- ers may be single-nozzle, multiple-nozzle, or boom type. Single-nozzle machines have been used very little outside of ex- perimental plots on hillsides and gulleys, where standard rigs cannot operate. Multiple-nozzle machines, such as are used for row crops, may have the nozzles spaced along a boom, to give uniform discharge over the application width. The boom type machine shown here is the one most commonly used at present. Booms may be tapered or straight, of metal or canvas. Tapered booms and internal baf- fles are used in attempt to control uni- formity of discharge. Long booms, like the one shown above, are generally sup- ported by outrigger wheels and jointed for flexibility in going over rough ground. The blower usually discharges into the 3- to 6-inch diameter boom at two points. Hoppers for carrying the dust vary in size, depending on the number of nozzles and the length of the boom. Agitation of the dust is necessary, and is accomplished by rods, scrapers, or brushes mounted in the hopper—generally over the discha
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Keywords: ., bookcentury1900, bookpubli, booksubjectspraying, booksubjectweeds
