Study of the Effects of Adjuvants Associated With Insecticides on the Physicochemical Properties of the Spray Solution and Characterization of Deposits on Wheat and Maize Leaves Under Simulated Rain

The association of adjuvants with phytosanitary products has been tested for several years but is commonly recommended without considering technical and scientific criteria. This study aimed to evaluate the influence of the association of insecticides with different adjuvants on surface tension, contact angle, coverage, hydrogen ionic potential (pH), and the formation of deposits exposed to rain. The insecticides thiamethoxam, imidacloprid, and lambda-cyhalothrin were tested at doses of 75 g ha−1, 150 g ha−1, and 150 g ha−1, respectively, with a spray volume of 200 L ha−1. Break-Thru 240®, Break-Thru 233®, Break-Thru Union®, Oleo FC Agraröl®, and Naturo'il® were added to each of these spray solutions. The results showed that the addition of adjuvants reduced the surface tension and contact angle, and consequently, increased droplet coverage. No deposit pattern was found in the thiamethoxam, imidacloprid, and lambda-cyhalothrin insecticides associated with the adjuvants and a higher amount of residue was observed on wheat leaves than on maize leaves. The use of adjuvants can be an alternative to improve the efficiency of insecticides, allowing the product to achieve its full control potential.