ABSTRACT
514The phytotoxicity of alloxydim-sodium [2-[1-(N-allyloxyarnino)butylidine]-4-mcthoxy-carbonyl-5,5-diamethylcyclohexane-1,3-dione] and fluazifop-butyl [(±)-2-[4-[[5-(trifluo-romethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid] in barley (Hordeum vulgare L.) and [methyl-2-[[[[N,(4-methoxy-6-methyl-l,3,5-triazin-2-yl)-methylamino]carbonyl]amine]sulfonyl]benzoate] in white mustard (Sinapis alba L.) was assessed when adding increasing amounts of various surfactants or mineral oils to the spray solution.
In all experiments, the adjuvants promoted the herbicide phytotoxicity increasingly with increasing amounts of surfactants or mineral oils added to the spray solution. A large concentration of a weakly cationic fatty amine ethoxylate resulted in a decrease in fluazifop-butyl activity; the optimum adjuvant concentration in the spray solution was about 1%.
The relationship between the enhanced herbicide potency and the amount of adjuvant added to the spray solution could generally be described by a linear relationship on either the original scale, a semilogarithmic scale, or a double logarithmic scale. These relationships are discussed in order to evaluate a general system for assessing the effect of adjuvants on herbicidal action.
