Synergistic effects of adjuvant A-134 on the herbicidal effects of glyphosate.

Undesirable side effects on ecosystems and strong selection for weed resistance demand an increase in the efficacy and a reduction in the dosage of glyphosate herbicide used. The synergistic effect of tank-mixed adjuvant KAO® A-134 (A-134) on the post-emergence activity of the commercial glyphosate formulation Roundup® (RDP) against crabgrass (Digitaria sanguinalis) was detected. Field study also showed that A-134 can increase the herbicidal effect of RDP. Meanwhile, A-134 concentration-dependently decreased the surface tension and increased the spreading area of RDP, causing faster penetration and improved uptake of glyphosate into crabgrass. Moreover, the tank mix with A-134 also increased the adhesion of spray droplets of glyphosate isopropylamine salt (GP) to the leaf surface after rainfall treatment, thus maintaining its herbicidal effect. Data suggested the necessity of using these synergistic properties of A-134 to reduce environmental exposure and glyphosate resistance selection. © Pesticide Science Society of Japan 2019. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License (https://creativecommons.org/licenses/by-nc-nd/4.0/).