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Title: Evaluation of a solid stream radial nozzle on fixed-wing aircraft for penetration of spray within a soybean canopy

item Thomson, Steven

Submitted to: Journal of Plant Protection Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2013
Publication Date: 4/1/2014
Citation: Thomson, S.J. 2014. Evaluation of a solid stream radial nozzle on fixed-wing aircraft for penetration of spray within a soybean canopy. Journal of Plant Protection Research. 54(1):96-101.

Interpretive Summary: For effective control of disease and insects in crops, it is important that crop protection agents applied from aircraft penetrate the crop canopy effectively. New nozzle technologies are available to reduce off-target spray drift while providing adequate penetration of spray. The need for these technologies has increased importance in the face of pervasive plant diseases such as Asian Soybean Rust (ASR). A radial nozzle that uses a unique spraying principle has shown good success in forestry applications spraying trees from helicopters, but very little data exist on how well this nozzle performs from fixed-winged aircraft for spraying crops. To evaluate this radial nozzle (called the Accu-Flo®) for its ability to penetrate spray from fixed-winged aircraft, scientist in the USDA-ARS Crop Production Systems Research Unit, Stoneville, MS has conducted an experiment to compare this nozzle with more widely used straight stream nozzle and a rotary spray atomizer. Results indicated that the radial nozzle deposited 1.7 times more material within a crop canopy than either the straight-stream nozzle or rotary atomizer. This was a favorable result, which indicates good potential for use of the radial nozzle in combating disease and crop pests from fixed-winged aircraft with less material.

Technical Abstract: Experiments were conducted to evaluate the Accu-Flo® multiple orifice nozzle for penetration of spray into a soybean (Glycine max L.) canopy by comparing results to those from a popular straight stream nozzle and rotary atomizer. Water was applied at three different spray release heights in a random sequence using an Air Tractor 402-B agricultural aircraft. Sampler stands were placed at twenty four locations in the field with water sensitive paper (WSP) cards clipped onto rigid stands just above the canopy and one foot off the ground within the canopy. Weather data were recorded using two different stations on-site and wind was predominantly from the west and parallel to the direction of spray runs. Spray delivery systems compared were the Accu-Flo® nozzles, (64 needle 0.020 opening), CP®-09 straight stream with 5 degree deflection, and Micronair® AU5000 atomizers (14 mesh screen) at a low volume spray rate of 18.7 L/ha. A total of 54 spray runs were made over three days and heights were varied at 3.7m, 4.9 m and 6.1 m. WSP were scanned and analyzed for coverage per unit card area using an image analysis system. Altitude and [Nozzle X Altitude] interaction were significant effects on coverage at the 0.01 and 0.07 significance levels, respectively for the top cards. Nozzle type was not a significant effect on coverage for the top cards, but was significant at the 0.01 level for the bottom cards. Altitude alone had no obvious effect on coverage for the bottom cards, although it had an effect for the top cards. The highest percentage area of spray coverage was observed from the Accu-Flo® nozzles, especially for the bottom cards. Average spray coverage from the Accu-Flo® nozzles was 1.7 times higher than coverage from the CP® nozzles or Micronair® atomizers in the lower portion of the canopy.