Analysis of potential impaction and phytotoxicity of surfactant-plant surface interaction in pesticide application

Surfactant is an important additive in pesticide application due to its antifoaming or foaming, buffering or stabilization, sticking or wetting and toxicity properties. The molecular constituents of surfactants can be categorised into cationic, anionic, non-ionic and amphoteric groups. It coalesces in solution to produce smaller droplet sizes, lower contact angle and enhance uniformity of spray distribution. The extent of surfactant emulsification is determined by its hydrophilic-lipophilic balance (HLB) value. In solution, surfactant aggregates to form micelle above/from the critical micelle concentration (CMC) for interactive effect. An extensive research on surfactant-agrochemical composite spraying is ongoing with much emphasis on conventional spraying than electrostatic spraying of surfactant-pesticide formulations. This paper therefore analyses the potential impaction behaviour and phytotoxicity of surfactant-plants surfaces interaction in pesticide application. The surfactant is able to lower surface tension of spray and enhance droplets deposition, spread, retention and phytotoxicity on plant surfaces. In plant cells, surfactant reacts with lipo-proteins of the cuticular layer to attenuate cell membrane. An increasing surfactant concentration in pesticide formulation maximizes spray deposition, wettability and phytotoxicity levels. Hence, understanding surfactant activity will quantitatively inform the type and concentration needed to enhance droplets characteristics, deposition, spread and phytotoxicity, without superfluously overdosing plant species. The review proposes the superposition of charges on surfactant-pesticide composite spray to localize more droplets on target plants and enhance wraparound surface deposition.