These relatively new sprayer, also known as concentrate or mist sprayers, have been developed to apply pesticides in concentrated form. Substantial saving in labor costs is thereby effected since the quantity of water required as a diluent may be reduced from 20 to percent or more as compared with conventional dilute methods of spraying. Further savings are also reported in the quantity of chemicals used, since runoff from foliage may be reduced when the equipment is properly operated.
These sprayers are used for treating large acreages of fruit trees, large shade trees, vegetables and certain other crops. Large fruit trees may require thinning and pruning to permit proper penetration of the small airborne droplets to the inner and top-most branches. The swath or strip covered will vary with wind direction and velocity.
These machines are basically similar to power dusters in that a blast of air is employed to carry the chemical from the machine to the foliage to be treated except, of course, that the chemical is in liquid, rather than dry, form. The typical concentrate sprayer of the blower type utilizes a low-pressure, low-volume pump which forces the spray material under low pressure to the fan where it is discharged into the airstream in small spray droplets by a group of nozzles or a shear plate. The air stream assists in breaking up the liquid into small particles, acts as a diluent to prevent the drops from coalescing and serves as the vehicle to carry these fine droplets to the surface to be treated.