Reducing pesticide spraying drift by folate/Zn²⁺ supramolecular hydrogels

The purpose of this study was to use folic acid and zinc nitrate to construct a biocompatible supramolecular hydrogel loaded with the herbicide dicamba as an ultra-low-volume spray formulation. The drift potential of the hydrogel was studied by simulating the field environment in a wind tunnel.

The three-dimensional network structure of the successfully prepared dicamba hydrogel system was observed using cryo-scanning electron microscopy. A rheological study of the dicamba hydrogel showed that it has shear-thinning and self-healing properties. Using a laser particle size analyzer, it was shown that the droplet size of the dicamba gel (approximately 100 μm) was significantly larger than that of the control group water and dicamba-KOH droplets. Droplet collectors and water-sensitive papers were arranged in the wind tunnel to evaluate the drift-reduction performance of the dicamba gel. Compared with dicamba-KOH aqueous solution, dicamba gel has a good effect in reducing drift.

This hydrogel containing no organic solvents showed biocompatibility and biodegradability due to its natural and readily available raw materials. The main way in which hydrogels reduce drift is by increasing the droplet size and this is due to the three-dimensional network structure inside the gel. This research provides a new strategy to reduce spray drift from the perspective of pesticide formulation, and also has prospects for the application of supramolecular hydrogels in agriculture.