EFFECT OF DRIFT RETARDANT ADJUVANTS ON SPRAY DROPLET SIZE OF WATER AND PARAFFINIC OIL APPLIED AT ULTRALOW VOLUME

Adjuvants were evaluated to determine the effect on increasing spray d roplet size and reducing the amount of spray dispensed in small drifta ble size particles when applying water and paraffinic oil at ultralow volume. Spray solutions were applied with an air-assist system at liqu id flow rates of 28 and 56 ml/min and atomized with 14, 28, 42, 56, an d 84 kPa of air pressure. Water and paraffinic oil were applied alone and with two drift retardant adjuvants mixed individually in each. The two water soluble adjuvants were mixed at concentrations of 0.25, 0.5 0, 0.75, 1.0, and 2.0%; oil soluble adjuvants were applied at 0.125, 0 .25, and 0.50%. Adjuvants used in water and oil were effective at incr easing droplet size and reducing the amount of liquid dispensed in sma ll driftable size particles. Effectiveness of the adjuvants decreased as air pressures increased, with water soluble adjuvants being more su sceptible to air pressure. Volume median diameters > 200 mu m with wat er could be achieved without adjuvants; whereas with oil, an adjuvant was required.