Makhnenko Iaroslav, Hoerning Cody, Sawall Dustyn D, Fredericks Steven A, Alonzi Elizabeth R, Dutcher Cari S
Department of Mechanical Engineering, University of Minnesota Twin Cities, Minneapolis, MN, USA.
Winfield United, River Falls, WI, USA.
Pest Manag Sci. 2025 Feb;81(2):884-891. doi: 10.1002/ps.8491. Epub 2024 Oct 29.
Sprayed agrochemical droplets have a dynamic evolution on the leaf surface, undergoing changes in shape and volume due to spreading, evaporation, and adsorption. To better understand these processes, an accessible imaging-based experimental methodology is presented to precisely measure droplet spreading, evaporation, and potential uptake by a leaf within a controlled relative humidity environment. Laboratory experiments were conducted to determine the effect of hydrocarbon surfactants, accelerators (light mineral oil), and humectants (high fructose corn syrup) on droplet spread, evaporation, and potential uptake when applied to sorghum (Sorghum bicolor 'Tricker') and cowpea (Vigna unguiculata) leaves.
Experiments on cowpea leaves showed uniform spreading and no change in evaporation compared to the predicted rate. In contrast, on sorghum leaves, results suggest that the volume loss rate exceeds the predicted evaporation rate (up to 23%), indicating a potential uptake by the leaves. Some accelerated dynamics on sorghum can be attributed to the lateral spreading observed on hairy leaves along the veins, increasing the contact area by an average of 65%. However, samples containing light mineral oil, typically considered an accelerant to aid in uptake, demonstrated the highest rate but exhibited minimal spreading.
The study demonstrates how droplet composition affects droplet dynamics on waxy and hairy leaves by using an imaging-based methodology to measure evaporation rates, volume loss, contact angle, wetted area, and spreading behavior. The findings highlight some of the complex coupling between the crop protection product composition and droplet life cycle on a leaf. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
喷洒的农用化学液滴在叶片表面会发生动态变化，由于扩散、蒸发和吸附作用，其形状和体积会发生改变。为了更好地理解这些过程，本文提出了一种基于成像的可获取实验方法，用于在可控相对湿度环境下精确测量液滴的扩散、蒸发以及叶片对其的潜在吸收。开展了实验室实验，以确定碳氢表面活性剂、促进剂（轻质矿物油）和保湿剂（高果糖玉米糖浆）在施用于高粱（双色高粱‘Tricker’）和豇豆（豇豆）叶片时对液滴扩散、蒸发和潜在吸收的影响。
对豇豆叶片的实验表明，与预测速率相比，液滴扩散均匀且蒸发无变化。相比之下，在高粱叶片上，结果表明体积损失率超过了预测的蒸发速率（高达23%），这表明叶片存在潜在吸收。高粱上的一些加速动态可归因于在有毛叶片上沿叶脉观察到的横向扩散，使接触面积平均增加了65%。然而，含有轻质矿物油的样品，通常被认为是有助于吸收的促进剂，显示出最高的速率，但扩散最小。
该研究通过使用基于成像的方法测量蒸发速率、体积损失、接触角、湿润面积和扩散行为，展示了液滴成分如何影响蜡质叶和有毛叶上的液滴动态。研究结果突出了作物保护产品成分与叶片上液滴生命周期之间的一些复杂耦合关系。© 2024作者。由John Wiley & Sons Ltd代表化学工业协会出版的《害虫管理科学》。
