Effect of solution and leaf surface polarity on droplet spread area and contact angle

Nairn, Justin J.; Forster, W. A.; Leeuwen, R.M. van

doi:10.1002/ps.4022

Cited by 25 publications

(33 citation statements)

References 44 publications

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“…However, we observed that the proportion of droplets impacting a pre-wetted surface increases with decreasing surface tension on both species, with the higher proportion in each case observed on avocado (the smoother, non-polar surface). This is consistent with the greater spread area of droplets on avocado compared to bean (Nairn and Forster, 2016). Adhesion was the dominant outcome of droplets impacting the pre-wetted surface of bean, irrespective of formulation.…”

Section: Additional Considerationssupporting

confidence: 81%

“…Since in each pair the formulation is the same, this effect must be attributed to leaf surface character (or the interaction between formulation and leaf surface character). Recent work has determined that while bean is more wettable than avocado (eg., the contact angle for bean with 20% acetone in water is lower than that for avocado), avocado has the smoother surface (Nairn and Forster, 2016). Thus, for easy-to-wet species, the onset of shatter appears to be determined by a complex competition between surface roughness, which tends to increase the likelihood of shatter, and chemistry with polarity that tends to decrease the likelihood of shatter, complicated further by chemical interactions between the surface and the adjuvants.…”

Section: Easier-to-wet Speciesmentioning

confidence: 99%

“…Contact angles were averaged over 21 measurements (2 µl droplets) across 3 leaves each taken from different plants to minimise variations between individual plants and hysteresis in individual measurements. Leaf roughness and polarity, fundamental factors known to govern leaf surface wettability (Holloway, 1970), are assessed using the wetting tension-dielectric (WTD) technique (Nairn et al, 2011;Nairn and Forster, 2016) which is based on contact angle trends, using solutions with varying dielectric constant (used as a surrogate for polarity), measured on each leaf surface. …”

Section: Plantsmentioning

confidence: 99%

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Spray droplet impaction outcomes for different plant species and spray formulations

et al. 2017

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A track-sprayer combined with a high-speed camera were used to visualize and identify droplet impaction outcomes for three formulations (water, 0.1% LI 700® (lecithin, a mixture of soya oils, propionic acid and surfactants) in water and 0.1% Pulse® (non-ionic surfactant, trisiloxane ethoxylate) in water) on four plant species (bean (Vicia faba L.), avocado (Persea americana L.), barnyard grass (Echinochloa crus-galli L. P. Beauv.) and cabbage (Brassica oleracea L.)) selected to represent a wide range of leaf surface characters. Droplet sizes and velocities were measured by image analysis and a multiple hypothesis tracking algorithm. Impaction outcomes were categorized into adhesion, bounce, or shatter. The probability of each outcome was estimated from logistic regression models related to the dimensionless Weber number. This approach is in contrast to various deterministic threshold criteria for droplet bounce or shatter that have been used to model droplet impaction events on leaves. It also provides a simple visual and numerical presentation of the complexity of impaction processes, and the relative influence of leaf surface character versus formulation for droplets with different impaction energies.

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Section: Additional Considerationssupporting

confidence: 81%

Section: Easier-to-wet Speciesmentioning

confidence: 99%

Section: Plantsmentioning

confidence: 99%

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Spray droplet impaction outcomes for different plant species and spray formulations

et al. 2017

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“…It is well known that surface roughness is a dominant factor in spray droplet adhesion . However, while droplet spreading generally decreases with increasing leaf roughness, spreading is also strongly tempered by leaf polarity . Nairn and Forster demonstrated that leaf surfaces can have a similar wettability, while their surface roughness and polarity may be very different, leading to differences in spreading .…”

Section: Introductionmentioning

confidence: 99%

“…However, while droplet spreading generally decreases with increasing leaf roughness, spreading is also strongly tempered by leaf polarity . Nairn and Forster demonstrated that leaf surfaces can have a similar wettability, while their surface roughness and polarity may be very different, leading to differences in spreading . Hence there is a need to characterise leaf surface polarity and leaf surface roughness separately, rather than as a combined effect on wettability.…”

Section: Introductionmentioning

confidence: 99%

Methods for evaluating leaf surface free energy and polarity having accounted for surface roughness

Nairn

Forster

2017

Pest Management Science

Self Cite

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The wetting tension-dielectric (WTD) method stands out due to its ability to isolate and quantify leaf surface roughness and polarity. A novel (WTD) roughness correction factor is proposed to improve SFE determination. The strong correlation between leaf polarity and leaf wettability for polar solutions (such as water) makes the WTD method a valuable tool for the evaluation of leaf surface-droplet behaviour and the advancement of agrochemical spray formulation technologies. © 2017 Society of Chemical Industry.

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Effect of dose and adjuvant on uptake of triclopyr and dicamba into Pinus contorta needles

Rolando

Gaskin

Horgan

et al. 2020

Plant Enviro Interactions

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Why this research Matters Management of dense infestations of wilding Pinus contorta in New Zealand requires high doses of herbicides; 18 kg active ingredient (a.i.) ha−1 triclopyr and 5 kg a.i. ha−1 dicamba are used in combination with a complex mix of adjuvants (methylated seed oil, non‐ionic surfactant and ammonium sulfate) and other active ingredients. From the perspective of cost and environmental impact there is a need to reduce the complexity of this tank mix and the rates of active ingredients. Using radiolabelled herbicides, this study evaluated the effect of dose and adjuvants (crop oils, non‐ionic surfactants, and organosilicones) on needle injury and uptake of triclopyr and dicamba into P. contorta needles at 24 hr or 7 days after treatment (DAT). The uptake of triclopyr decreased significantly with increasing concentration (0.75%–6%) resulting in the highest uptake dose at the equivalent of 18 kg a.i. ha−1 triclopyr at 7 DAT. When applied at 18 kg a.i. ha−1, none of the adjuvants tested significantly increased the uptake of triclopyr (applied as Grazon®), with ~50% uptake occurring at 7 DAT. The uptake of dicamba (applied as Kamba® at 5 kg a.i. and 10 kg a.i. ha−1) was significantly affected by dose and adjuvants. The uptake of dicamba applied at 5 kg a.i. ha−1 was low at 7 DAT with no adjuvant (31%); however, use of a methylated seed oil doubled the uptake. When triclopyr and dicamba were applied together, there was no evidence that either active ingredient negatively affected uptake of the other, with triclopyr enhancing uptake of dicamba. These results show potential to reduce the amount of herbicide used for conifer control without compromising efficacy.

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Effect of solution and leaf surface polarity on droplet spread area and contact angle

Cited by 25 publications

References 44 publications

Spray droplet impaction outcomes for different plant species and spray formulations

Spray droplet impaction outcomes for different plant species and spray formulations

Methods for evaluating leaf surface free energy and polarity having accounted for surface roughness

Effect of dose and adjuvant on uptake of triclopyr and dicamba into Pinus contorta needles

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