Agroscope, Plant Protection Products - Impact and Assessment, Wädenswil, Switzerland.
Agroscope, Vegetable-Production Extension, Wädenswil, Switzerland.
Pest Manag Sci. 2023 Aug;79(8):2792-2800. doi: 10.1002/ps.7455. Epub 2023 Mar 29.
Although co-formulants constitute a substantial portion of the total plant protection product (PPP) mass applied to crops, data on residue formation and the behaviour of these substances on plants are scarce. In an earlier study we demonstrated that co-formulants commonly used in PPPs can form considerable residues, i.e., in the low to medium mg/kg range, but normally decline rapidly within few days. In the field trial reported here, we aimed to identify the major decline processes of co-formulants. Residues of co-formulants were therefore monitored in parsley and lettuce grown in an open field as well as under foil tunnels equipped with either an overhead or a drip irrigation system.
Dissipation of three anionic surfactants was markedly faster when crops (parsley and lettuce) were exposed to natural rainfall or irrigation from above compared to drip irrigation. In contrast, the decline of three volatile organic solvents was not affected by rain or irrigation, but was dependent on the crop, with much shorter half-lives in lettuce than in parsley. Furthermore, dilution through plant growth contributed significantly to the reduction of residues over time.
In this work we substantiate earlier findings on the magnitude and dissipation of residues of anionic surfactants and solvents representing the most important co-formulant classes. The chosen experimental setup allowed differentiation between decline processes and we confirm that foliar wash-off is a major dissipation process for anionic surfactants. For volatile organic solvents, dissipation appears to depend on the properties not only of the substance but also of the plant (surface). © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
尽管共溶剂构成了施用于作物的植保产品（PPP）总量的很大一部分，但关于其在植物上的残留形成和行为的数据却很少。在早期的一项研究中，我们证明了 PPP 中常用的共溶剂可以形成相当数量的残留，即在低至中 mg/kg 的范围内，但通常会在几天内迅速下降。在本报告的田间试验中，我们旨在确定共溶剂的主要降解过程。因此，在露地和带有顶喷或滴灌系统的塑料薄膜温室中种植的欧芹和生菜中监测了共溶剂的残留情况。
与滴灌相比，当作物（欧芹和生菜）暴露于自然降雨或上方灌溉时，三种阴离子表面活性剂的消解速度明显更快。相比之下，三种挥发性有机溶剂的下降不受降雨或灌溉的影响，但取决于作物，在生菜中的半衰期比在欧芹中短得多。此外，随着时间的推移，通过植物生长进行稀释对残留的减少有很大的贡献。
在这项工作中，我们证实了早期关于阴离子表面活性剂和溶剂（代表最重要的共溶剂类别）残留量和消解的发现。所选择的实验设置允许区分降解过程，我们确认叶面冲刷是阴离子表面活性剂的主要消解过程。对于挥发性有机溶剂，消解似乎不仅取决于物质的性质，还取决于植物（表面）的性质。© 2023 作者。Pest Management Science 由 John Wiley & Sons Ltd 代表化学工业协会出版。
