Environmental Laboratory, U.S. Army Engineer Research and Development Center, Baton Rouge, LA, USA.
University of Florida, Center for Aquatic and Invasive Plants, Gainesville, FL, USA.
Pest Manag Sci. 2021 Oct;77(10):4447-4452. doi: 10.1002/ps.6479. Epub 2021 Jun 30.
Mesocosm experiments were conducted to evaluate the effect of floating plant density on over-the-top spray solution loss to the column using a tracer dye. Experiments quantified in-water rhodamine water tracer (RWT) dye concentration after foliar treatment at 935 L ha to waterhyacinth [Eichhornia crassipes (Mart.) Solms], waterlettuce (Pistia stratiotes L.) and giant salvinia (Salvinia molesta D.S. Mitchell) at 0, 25, 50 and 100% area covered (PAC).
As expected, spray loss to the water surface decreased with increasing plant density in all species. However, each species exhibited an unique relationship between density and percentage spray loss. The plant material required to result in 50% spray loss (ED ) was 32, 62 and 55 PAC for waterhyacinth, waterlettuce and giant salvinia, respectively. Greater ED estimates in waterlettuce and giant salvinia were attributed to plant architecture and leaf orientation compared to waterhyacinth, which grows more vertically and has a greater overall surface area to intercept and retain spray solution. However, when treated at 100 PAC, waterhyacinth and waterlettuce resulted in 20-25% spray loss, whereas giant salvinia resulted in only 10% loss. Consequently, giant salvinia exhibited a near 1:1 relationship between spray loss and PAC (slope = -0.93).
These data suggest that potential herbicide spray loss, as affected by plant density, is largely species-specific and dependent on leaf morphology and plant architecture. Further research will confirm these findings under field conditions as well as to identify other parameters that might affect spray loss when treating floating and emergent plants. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
为了评估漂浮植物密度对超顶喷雾溶液损失到水柱的影响，采用示踪染料进行了中宇宙实验。实验在 935L/ha 条件下对凤眼蓝[Eichhornia crassipes（Mart.）Solms]、水蕹菜（Pistia stratiotes L.）和大薸（Salvinia molesta D.S. Mitchell）进行叶面处理后，定量了水中罗丹明水示踪剂（RWT）染料浓度，植物覆盖率（PAC）分别为 0、25、50 和 100%。
正如预期的那样，随着植物密度的增加，所有物种的喷雾损失都减少到水面。然而，每种植物的密度和喷雾损失百分比之间都存在独特的关系。导致 50%喷雾损失（ED）的植物材料分别为水葫芦、水蕹菜和大薸的 32、62 和 55 PAC。与水葫芦相比，水蕹菜和大薸的 ED 估计值更大，这归因于植物结构和叶片方向，水葫芦生长更垂直，具有更大的表面积来拦截和保留喷雾溶液。然而，当处理到 100 PAC 时，水葫芦和水蕹菜导致 20-25%的喷雾损失，而大薸仅导致 10%的损失。因此，大薸的喷雾损失与 PAC 之间呈近 1:1 的关系（斜率为-0.93）。
这些数据表明，受植物密度影响的潜在除草剂喷雾损失在很大程度上是特定于物种的，并且取决于叶片形态和植物结构。进一步的研究将在田间条件下证实这些发现，并确定在处理漂浮和挺水植物时可能影响喷雾损失的其他参数。© 2021 化学工业协会。本文已由美国政府雇员做出贡献，其工作在美国属于公有领域。
