A Facile Approach to Increasing the Foliage Retention of Pesticides Based on Coating with a Tannic Acid/Fe3+ Complex

Abstract

The effective utilization of many conventional pesticide formulations is less than 30%, which can increase the environmental impact of these substances. This degree of waste could be reduced by improving the adhesion of pesticides to foliage. In the present work, a complex comprising tannic acid (TA) and Fe3+ ions was used to encapsulate azoxystrobin and avermectin water dispersible granule (WDG) formulations (termed Az-WDG-TA and Av-WDG-TA) to improve adhesion. The treated pesticides exhibited improved photostability as well as sustained continuous release behavior. The retention proportions of the Az-WDG-TA and Av-WDG-TA on cucumber and lettuce foliage were improved by more than 50%. The ability of solutions of these materials to wet foliage was also enhanced after coating, such that the toxicity of Av-WDG-TA to aphids and the antifungal activity of Az-WDG-TA to Fusarium oxysporum were increased by nearly 50%. Given the low cost of TA and Fe3+ compounds and the simple synthesis process, this method represents a promising means of producing foliage-adhesive pesticide formulations with increased retention and bioavailability.

Layered Double Hydroxide Nanosheets Improve the Adhesion of Fungicides to Leaves and the Antifungal Performance

“…Azoxystrobin release followed first-order kinetics, and the R 2 values for the first-order equations fitted to the data were 0.9992 (sample 1), 0.9911 (sample 2), 0.9949 (sample 3), and 0.9982 (reference sample). The three samples also showed a convex release phenomenon at the start, and some particles were probably either barely or partly coated by LDHs, as seen in the TEM images …”

“…The three samples also showed a convex release phenomenon at the start, and some particles were probably either barely or partly coated by LDHs, as seen in the TEM images. 9 3.4. Adhesion of Az-WDG-LDHs to the Plant Leaf.…”

“…Farmers have been compelled to spray excessive pesticides to cure foliar diseases, such as rice blast, leaf blight, and so on, which leads to heavy soil and water pollution, thus posing ecological risks. Hence, there is an urgent need to design pesticide formulations or methods that promote efficient use of pesticides and decrease the risk to the environment. − For example, improvements in leaf adhesion can prolong the active period of a pesticide and improve the efficacy of the pesticide. , Recently, some researchers have focused on enhancing the interactions between pesticide droplets and foliage surface by modifying the particle surface by introducing hydrophilic groups, electrostatic interactions, and so on …”

“…4−7 For example, improvements in leaf adhesion can prolong the active period of a pesticide and improve the efficacy of the pesticide. 8,9 Recently, some researchers have focused on enhancing the interactions between pesticide droplets and foliage surface by modifying the particle surface by introducing hydrophilic groups, electrostatic interactions, and so on. 10 Developments in nanotechnology have paved the way for the use of nanocarriers as pesticide release systems.…”

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

“…Tannins, especially tannic acid, have been used in nanopesticide formulations (Table 1) as an additive to promote better foliage adhesion of particulates (Yu et al, 2019;Zhi et al, 2020). The ability of tannins to promote multiple and diverse secondary interactions towards virtually any surface has warranted their utilization to modify nanocarriers surfaces while adding UV protection and antioxidant properties (both useful to increase the lifetime of the active ingredient) (Guo et al, 2016).…”