The influence of a fatty amine surfactant on foliar absorption and translocation of the trolamine salt and iso‐octyl ester of 2,4‐D

The influence of the surfactant ‚Armoblen’︁ 600 (tallow amine block polymer containing a block of polymerized propylene oxide groups (12PO) and a block of polymerized ethylene oxide groups (5EO)) on the foliar absorption and translocation of 2,4‐dichlorophenoxyacetic acid trolamine salt (2,4‐D TR) and 2,4‐dichlorophenoxyacetic acid iso ‐octyl ester (2,4‐D IOE) was investigated. Absorption and translocation were monitored for 48 h after application. During this period, without surfactant the leaves of black nightshade ( Solanum nigrum L.) absorbed 2.4 times more 2,4‐D IOE than 2,4‐D TR whereas pea leaves ( Pisum sativum L.) absorbed 1.3 times more 2,4‐D IOE than 2,4‐D TR. Pea leaves absorbed more of both compounds than did those of black nightshade. Addition of surfactant (5 g litre −1 ) enhanced the absorption of 2,4‐D TR by black nightshade (4.8‐fold after 48 h) and pea (1.7‐fold after 48 h) but reduced the absorption of 2,4‐D IOE. Without surfactant the absorption of 2,4‐D TR and 2,4‐D IOE was not affected by drying of the drops. Addition of surfactant enhanced absorption of 2,4‐D TR after the drops had dried. Translocation of 2,4‐D TR in black nightshade and in pea, expressed as percentage of the amount absorbed, was reduced by the presence of surfactant. At the end of the observation period this reduction was no longer observed. The translocation efficiency of 14 C from 2,4‐D IOE was not influenced by the surfactant. The effects of the surfactant are discussed in relation to its possible mode of action.