Improved control of Stellaria media (L.) Vill in leys with Trifolium repens, using bentazone and benazolin with additives

Abstract

Summary In pot experiments, mixtures of ammonium sulphate with surfactants or oil additives increased the phytotoxicity of commercially formulated bentazone (‘Basagran’) to Stellaria media (chickweed). Ammonium sulphate with a proprietary oil adjuvant Actipron had similar effects with benazolin potassium salt, but not with an ethyl ester formulation of benazolin. The phytotoxicity of bentazone and benazolin salts to Trifolium repens (white clover) and Lolium perenne (perennial ryegrass) was almost unaffected by these additives. In a field experiment, a mixture of ammonium sulphate with Actipron improved the control of S. media by bentazone and benazolin salts. Oils and surfactants markedly increased rates of entry of 14C bentazone into leaves of S. media, white clover and Chrysanthemum segetum. Ammonium sulphate sometimes had similar effects but on other occasions reduced uptake. In some circumstances the additives apparently interacted synergistically, to increase uptake of labelled herbicide into the leaf or to enhance its transport within the plant. In these test species, differential absorption of bentazone could not explain differences in species susceptibility, suggesting that the main cause of resistance was the ability of plants to degrade the herbicide.

Nitrogen Fertilizer, Oil, and Surfactant Adjuvants with Nicosulfuron

“…Ammonium nitrate apparently was the effective component of UAN because the urea component usually reduced nicosulfuron efficacy and only enhanced efficacy when with X-77 and sodium bicarbonate. Urea also was not effective as an adjuvant with other herbicides (Bauer et al 1974;Manthey et al 1992;Thrner 1985). The effectiveness of ammonium nitrate and VRA was not the same with all surfactant or all adjuvants, but UAN did not reduce efficacy of any adjuvant.…”

Effect of Adjuvants on Bentazon Efficacy in Green Pea (Pisum sativum)

“…The efficacy of bentazon is often improved by adding adjuvants that increase herbicide retention and absorption (2,5,6,7,8). Control of weeds that are relatively tolerant to bentazon, such as redroot pigweed (Amaranthus retroflexus L.) and kochia [Kochia scoparia (L.) Schrad.…”