Key Laboratory of Pesticide Toxicology & Application Technique, College of Plant Protection, Shandong Agricultural University, Tai'an, P. R. China.
Research Center of Pesticide Environmental Toxicology, Shandong Agricultural University, Tai'an, P. R. China.
Pest Manag Sci. 2021 Oct;77(10):4418-4424. doi: 10.1002/ps.6476. Epub 2021 May 27.
Increasing pesticide retention on crop leaves is a key approach for guaranteeing efficacy when products are applied to foliage. Evidently, the formulation plays an important role in this process. Microcapsules (MCs) are a promising formulation, but whether and how their adhesion to the leaf surface affects retention and efficacy is not well understood.
In this study, we found that the incorporation of polyethylene glycol (PEG) with different molecular weights into the MC shell affects the release profile of MCs and the contact area of these MCs to leaves by changing their softness. The cumulative release rates of pyraclostrobin (Pyr) MCs fabricated with PEG200, PEG400, PEG800 and PEG1500 were 80.61%, 90.98%, 94.07% and 97.40%, respectively. Scanning electron microscopy observations showed that the flexibility of the MCs increased with increasing PEG molecular weight. The median lethal concentration (LC ) of the MCs with different PEG to the zebrafish were 12.10, 8.10, 3.90 and 1.46 mg L , respectively, which also indirectly reflected their release rate. Rainwater had less influence on the retention of the MCs prepared with PEG1500 than with the other PEG, which indicates a better adhesion to the target leave surfaces. MCs with the highest residual efficacy had better control efficacy on peanut leaf spot in field trials.
Overall, adding PEG with an appropriate molecular weight to the MC shell can regulate the structure of the MC shell to improve the affinity between the MCs and leaves, which further improves the utilization of pesticides and reduces the environmental risks of pesticides. © 2021 Society of Chemical Industry.
提高作物叶片上的农药滞留率是保证产品施用于叶片时药效的关键方法。显然，制剂在这个过程中起着重要作用。微胶囊（MCs）是一种很有前途的制剂，但它们对叶表面的附着如何影响滞留率和药效还不太清楚。
在这项研究中，我们发现不同分子量的聚乙二醇（PEG）的加入会通过改变 MC 壳的柔软度来影响 MC 的释放特性和与叶片的接触面积。用 PEG200、PEG400、PEG800 和 PEG1500 制备的吡唑醚菌酯（Pyr）MC 的累积释放率分别为 80.61%、90.98%、94.07%和 97.40%。扫描电子显微镜观察表明，MC 的柔韧性随 PEG 分子量的增加而增加。不同 PEG 的 MC 对斑马鱼的半致死浓度（LC ）分别为 12.10、8.10、3.90 和 1.46 mg·L -1 ，这也间接反映了它们的释放速率。雨水对用 PEG1500 制备的 MC 保留的影响小于用其他 PEG 制备的 MC ，这表明它们与目标叶片表面的附着力更好。在田间试验中，具有最高残留药效的 MC 对花生叶斑病具有更好的控制效果。
总体而言，在 MC 壳中添加适当分子量的 PEG 可以调节 MC 壳的结构，提高 MC 与叶片之间的亲和力，从而进一步提高农药的利用率，降低农药的环境风险。© 2021 化学工业协会。
