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United States Department of Agriculture

Agricultural Research Service

Title: COVERAGE AND DRIFT PRODUCED BY AIR-INDUCTION AND CONVENTIONAL HYDRAULIC NOZZLES USED FOR ORCHARD APPLICATIONS

Authors
item Derksen, Richard
item Fox, Robert
item Brazee, Ross
item Krause, Charles

Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: July 10, 2000
Publication Date: N/A

Interpretive Summary: Spray applications made to tall canopies, such as trees, vines and bushes, are considered a relatively high risk for producing off-site spray losses. Large droplet applications can significantly reduce the amount of drift but they can reduce deposition efficiency and pesticide effectiveness. This study was designed to evaluate the fate of sprays produced by conventional, disc-core nozzles and an air induction nozzle. For certain tank mixes, the air induction nozzle can produce relatively large, air-filled droplets. Conventional, disc-core, D3-25 and D4-25 nozzle sets and an air induction nozzle set, TD02, were used to apply the same rate of tank mix to the treatment area. The smaller droplet spectrum D3-25 provided the highest coverage TO upperside and underside surfaces of apple leaves. The large droplet TD02 nozzle produced the lowest coverage on underside leaf surfaces. There was little difference in the total amount of material measured on leaves treated with the D4-25 and TD02 nozzle sets. In general, the low-drift nozzle kept more of the off-target losses closer to the treatment area but it did not eliminate drift. The TD02 treatment produced the lowest losses to the ground from 4 to 128 m downwind. The D4-25 treatment produced higher airborne deposits on 1 and 3 m high air sampler filters out to 64 m. At 128 and 256 m, sedimentation and airborne deposits were similar for the D4-25 and TD02 treatments. These results should encourage farm managers to evaluate the suitability of low-drift, air induction nozzles in their pest management programs because of the possibility of reduced environmental and worker contamination without sacrificing pest control. Results will vary with carrier volume and pesticide formulation.

Technical Abstract: Concerns about off-target spray loss require regulators and applicators to re-assess how tall canopies, e.g., trees, vines and bushes, are treated with pesticides. These experiments were designed to learn how simple modifications, such as nozzle changes, affect the fate of spray in an apple-tree canopy and downwind off-site areas. Fluorescent tracers aided visualization of spray coverage and detection of downwind spray movement. Conventional, disc-core, D3-25 and D4-25 nozzle sets and an air induction nozzle set, TD02, were used to apply the same rate of tank mix to the treatment area. The air-induction nozzle is a new low-drift type nozzle producing relatively large droplets that, for certain tank mixes, generates air filled droplets. The smaller droplet spectrum D3-25 provided the greatest coverage on upperside and underside apple-leaf surfaces. The large droplet TD02 nozzle produced the least coverage on underside leaf surfaces. There was little difference in the total amount of material measured on leaves treated with the D4-25 and TD02 nozzle sets. In general, the low-drift nozzle kept more off-target losses closer to the treatment area but did not eliminate drift. The TD02 treatment produced the lowest sedimentation deposits from 4 to 128 m downwind. The D4-25 produced approximately three times higher deposits than the TD02 treatment on nylon screens mounted on a 10 m tower 8 m downwind from the treated row. The D4-25 treatment produced higher airborne deposits on high volume, air sampler filters out to 64 m. At 128 and 256 m, sedimentation and airborne deposits were similar for the D4-25 and TD02 treatments. Further studies are needed on efficacy of air-induction nozzles for different carrier volumes and tank mixes.

Last Modified: 10/31/2014
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