Effect of nozzle selection on deposition of thiamethoxam in Actara® spray drift and implications for off-field risk assessment

Tracer dyes are often used as surrogates to characterize pesticide spray drift and it is assumed that they accurately reflect analytical measurement of active ingredients; however, the validity of this assumption remains inconclusive. Consequently, the influence of measurement technique on the magnitude of deposition of spray drift was investigated using spray drift samples evaluated by traditional analytical techniques (HPLC–MS/MS) and fluorimetry (1,3,6,8‐pyrene‐tetra sulfonic acid tetrasodium salt dye tracer). The experiment was conducted in a low‐speed wind tunnel under controlled meteorological conditions. The herbicide mesotrione was sprayed through three spray air induction nozzles (anvil deflector flat fan TTI11004; flat fan AI11004; flat fan AIXR11003). Spray drift deposition samples were collected using stainless steel discs pairs placed side by side in the center of the wind tunnel at distances of 5, 10, 20, 30, and 40 ft (1.5, 3.1, 6.1, 9.1, and 12.2 m) from the spray nozzle. The analytical technique determined pesticide concentration on one disc per pair, and the other was evaluated by fluorimetry. The experimental results, analyzed using the linear split‐split plot model, revealed that median deposition concentrations were 15% higher using the tracer dye fluorescence method relative to the analytical method, potentially due in part to procedural recovery inefficiencies of the analytical method (the mean overall procedural recovery result and RSD was 87% ± 6.4% (n = 12). This relationship was consistent and held true for the three nozzle types at all distances within the wind tunnel. © 2021 Society of Chemical Industry.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spray drift deposition comparison of fluorimetry and analytical confirmation techniques

Szarka

Kruger

Golus

et al. 2021

“…However, results were based on a single wind monitoring location approximately 328 ft (100 m) from the deposition sampling area which is beyond the recommendations in the ASABE S561.1 guidance. Studies by Brain et al 14 and Perine et al 12 both explicitly evaluated wind speed and direction effects related to spray drift deposition but also used a single weather station as the basis of their analysis.…”

Section: Introductionmentioning

confidence: 99%

“…4 Field-scale spray drift deposition studies have been conducted as a means to provide data and information related to pesticide spray drift under real-world conditions. Perine et al 12 conducted a field-scale study using a 600 by 400 ft (183 by 122 m) downwind, bare-ground sampling area to evaluate three nozzle types typically associated with an insecticide (thiamethoxam). Wind speeds during spray applications were between 7.0 to 12.0 mph (3.1-5.4 m s −1 ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of field‐scale spray drift deposition and non‐target plant biological sensitivity: a corn herbicide (mesotrione/s‐metolochlor) case study

Perkins

Abi‐Akar

Goodwin

et al. 2022

BACKGROUND: This work reports a combined, field-scale spray drift deposition and plant bioassay study for a pre-mixture of the herbicides mesotrione and s-metolachlor. Wind direction data and field dimensions were used to evaluate the potential for spray drift to bypass downwind sampling devices. Variability in resulting spray drift across downwind distances was assessed alongside wind speed measured at on-site weather stations. Measured wind angles were used to geometrically adjust traveled drift particle distances and enabling isolation of wind direction impact from wind speed. Further, the use of single and multiple in-field monitoring locations was compared to quantify the benefit of higher-resolution meteorological sampling. RESULTS: Generally, increased wind speed resulted in significantly greater herbicide deposition at distances proximal to the edge of the spray zone. According to the drift deposition curves that included wind speed data from single and multiple onsite weather stations, trials with relatively higher wind speeds were associated with greater spray drift deposition at relatively close sampling distances downwind from the application area. Only marginal improvement of linear mixed-effects model fit was observed when including data from three weather stations, compared to the fit from a single weather station or absence of weather data in the model. Using tomato and lettuce plant bioassay species, the overall no-effect distance was 3.0 m (10 ft).CONCLUSION: Results from this study are informative to refine pesticide risk assessment for non-target plants and indicate that a single weather station is sufficient to capture potential influential effects from wind speed and direction on spray drift.

Effect of oil‐based emulsion on air bubbles in the spray sheet produced through the air‐induction nozzle

Gong

Kang

2022

BACKGROUND: The air-induction spray featured by air bubbles involved in the spray sheet has attracted great attention in applications of agricultural spray due to its advantages of alleviating spray drift and promoting deposition. The objective of the presented study is to deepen the understanding of the mechanism of the air-induction spray through elucidating the effect of sprayed liquid on characteristics of air bubbles in the spray sheet. RESULTS:The air bubbles with relatively large sizes are stable for a long time span. As velocity of the water spray increases from 6.85 m s −1 to 17.87 m s −1 , average size of the air bubbles decreases from 383.21 ∼m to 236.47 ∼m. With the introduction of organosilicone surfactant, the surface tension of the sprayed liquid decreases from 67.38 mN m −1 to 31.32 mN m −1 ; accordingly, average size of the bubbles decreases from 383.21 ∼m to 160.9 ∼m. Compared to aqueous solutions spray, the oil-based emulsion spray is responsible for relatively small average size of air bubbles as the surface tension and spray velocity are respectively similar. CONCLUSION: Low drainage rate of the bubble lamella contributes to high stability of large air bubbles. The decrease of the average size of air bubbles is responsible for small volumetric median diameter of oil-based emulsion spray compared with water spray. Besides the increase of the spray velocity and the decrease of the surface tension, the Marangoni effect caused by dynamics of oil droplets at air-liquid interface also contributes to the decrease of average size of air bubbles.