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Title: Influence of herbicide active ingredient, nozzle type, orifice size, spray pressure, and carrier volume rate on spray droplet size characteristics

item CREECH, CODY - University Of Nebraska
item HENRY, RYAN - University Of Nebraska
item Fritz, Bradley - Brad
item KRUGER, GREG - University Of Nebraska

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2015
Publication Date: 5/21/2015
Citation: Creech, C., Henry, R., Fritz, B.K., Kruger, G. 2015. Influence of herbicide active ingredient, nozzle type, orifice size, spray pressure, and carrier volume rate on spray droplet size characteristics. Weed Technology. 29(2):298-310.

Interpretive Summary: Setting up agrochemical application equipment for a particular droplet size spray requires knowledge of how a spray nozzle interacts with both the active chemical product and any additional tank mix adjuvants. While the spray nozzle and pressure tend to be the dominating forces and are easily understood, the impact of chemical product, the mixing rate and additional tank mix products are less understand and documented. A series of controlled droplet sizing experiments were conducted for several formulation, adjuvant and nozzle combination with nozzle selection having the most influence on spray droplet size. Applicators and researchers can use this data to aid in the selection of the best nozzle, chemical and adjuvant combination to make the most efficacious spray application.

Technical Abstract: Recent concerns on herbicide spray drift and its subsequent impact on the surrounding environment and herbicide efficacy have prompted applicators to focus on methods to reduce off-target movement of herbicides. Herbicide applications are complex processes and as such few studies have been conducted that consider multiple variables that impact the droplet spectrum of herbicide sprays. The objective of this study was to elucidate the effects of nozzle 9 type, orifice size, herbicide active ingredient, pressure, and carrier volume on the droplet spectra of the herbicide spray. Droplet spectrum data were collected on 720 combinations of spray application variables that included six spray solutions (five herbicides and water alone), four study was conducted using a Sympatec laser diffraction instrument to determine the droplet spectrum characteristics of each treatment combination. When averaged over all other variables, nozzle type had the greatest impact on droplet size. Droplet size rankings for nozzles, ranked smallest to largest using the Dv0.5 values, were the XR, TT, AIXR, AI, and TTI nozzle with 176% change in Dv0.5 values from the XR to the TTI nozzle. On average, increasing the nozzle orifice size from a 11003 orifice to a 11005 increased the Dv0.5 values 8%. When compared to the water treatment, cloransulam (FirstRate®19 ) did not change the Dv0.5 value. Clethodim (Select Max®), glyphosate (Roundup PowerMax®), lactofen (Cobra®), and glufosinate (Ignite®20) all reduced the Dv0.5 value 5, 11, 11, and 18%, respectively, when compared to water averaged over the other variables. Increasing the pressure from a low to a medium pressure decreased the Dv0.5 23 value 25% while increasing to from a medium to high pressure decreased the Dv0.5 value 14%. Carrier volume had the least effect on the Dv0.5 value. Increasing the carrier volume from 47 to 187 L ha-1 increased the Dv0.5 value 5% indicating that the herbicides tested are not highly dependent on herbicide concentration in the tank. The impact on droplet size of the variables examined in this study in order of greatest impact to least were nozzle, operating pressure, herbicide, nozzle orifice size, and carrier volume.