Pesticides aerial application

Collins, B.D. 1964. An Evaluation of an Experimental Aerial Application of Toxic Baits for Squirrel Control — Kern County. California Dept. Fish Game, Pesticides Investigations. Mimeographed. 10 pp. 

One of the special rotary atomizers worth mentioning is the windmill type atomizer. In this atomizer, radial cuts are made at the periphery of a disk and the tips of segments are twisted, so that the disk is actually converted into a windmill that can rotate rapidly when exposed to an air flow at aircraft flight speed. The windmill type atomizer has been demonstrated 1171 to be an ideal rotary atomizer for generating a narrow spectrum of droplet sizes in the range most suitable for aerial applications of pesticides at relatively high liquid flow rates. 

Other than aerial application over swamps for mosquito abatement, disulfoton is not known to be used over water. Potential sources of release into surface water include discharge of waste water from disulfoton manufacturing, formulation, and packaging facilities (HSDB 1994). Leaching and runoff from treated fields, pesticide disposal pits, or hazardous waste sites may contaminate both groundwater and surface water with disulfoton. Entry into water can also occur from accidental spills. Small amounts of volatilized disulfoton may be removed from the atmosphere as a result of wet deposition and may enter surface water (Racke 1992). 

The Aerial Flagger. The aerial flagger, who had the highest HDE of all workers monitored, is not now commonly used in the aerial applications of pesticides to crops. Still, a flagger is sometimes used in special situations, and was therefore monitored. The flagger was the only worker that had a discernibly different exposure for different application rates. For example, the total HDE for XLR was 606 mg/h for a rate of 2 lb Al/acre and 408 mg/h for a rate of 1 lb Al/acre. 

Inhalation Route - Estimation of Vapour Exposure. In a study of drift exposure following aerial application of an organo-phosphorus pesticide, Crabbe t al (16) found that the vapour concentration in areas remote from the spray line increased gradually up to 10 hours after the spraying. Increasing temperature was undoubtedly the major explanation for this. Other factors such as volatility of the pesticide, windspeed and sorption properties of the target would also influence the actual vapour concentration on the target. 

Concurrent with the need to improve aerial application, needs have been expressed for techniques which will assist in accounting for pesticides released over forests. While a total accountancy or mass balance of aerially released spray may be an unattainable goal, 90 percent accountancy may be attainable. 

To illustrate this distribution, Figure 1 shows the result of an actual aerial application of a typical pesticide spray to a broadleafed tree species (3). The "application level" (A) simply assumes that all the spray leaving the aircraft becomes uniformly distributed over the target area (1.12 kg/ha), and the curve shows the parathion levels analytically detected on a statistical sampling of leaves. A major part of the applied pesticide (B) fails to reach the canopy, as corroborated by Barry (2) with conifers, and is assumed to represent airborne drift, volatilization, and, to a lesser extent, penetration to the ground. Once on the... 

Acheta domestlcus. toxicity of aminocarb, 218-20 Additives for spray dispersion performance, 100-15 ecotoxicity, 351-61 Adsorption of pesticides in aquatic sediment, 267 in soil, 195-96 Aerial applicators, exposure monitoring, 323-29... 

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