Chinese scientists have developed nanoparticles that help pesticides adhere to plant leaves and prevent them from being washed off by rain. The research was carried out at the Hefei Institute of Physical Science of the Chinese Academy of Sciences. The development is expected to reduce pesticide wastage and minimise the need for repeat treatments, reports China Daily, a partner of TV BRICS.
Traditional spraying is extremely ineffective: the surface of leaves is covered with a waxy, water-repellent layer, causing droplets to roll off. Any pesticide that does settle is washed away by rain, whilst sunlight and evaporation break down the active ingredients. According to previous studies, up to 90 per cent of the pesticide may never reach its target, forcing farmers to reapply the treatment time and time again, increasing costs and exacerbating environmental pollution.
Bacteria provided the inspiration for this development. Some gut bacteria have hair-like structures – pili – which act like hooks and cling to surfaces to prevent the bacteria from being washed away. The researchers replicated this idea: they created hollow silicon dioxide particles with spikes on the surface and filled them with imidacloprid – a widely used insecticide. When applied to leaves, the particles embed themselves in the waxy surface and form hydrogen bonds, making the bond even stronger.
“This double grip helps the pesticide stay put, even in rain. The carriers also release the pesticide slowly and resist UV damage, making them even more efficient,” said Wang Guozhong, a researcher at the institute.
The formulation was tested on the leaves of cotton, soya and tomatoes. After a simulated rain event, 4.8 times more pesticide remained on the plants than with a commercial product. Tests on plants and Danio rerio (a species of freshwater fish) revealed no obvious signs of harm. According to Wang, the new pesticide is environmentally safe and could contribute to the development of low-dose, eco-friendly products.
Previously, Chinese scientists developed a membrane that captures carbon dioxide from industrial emissions. It has a long service life, is simple to manufacture and is designed to reduce energy consumption in industry.