| Abstract: | Commercial formulations of flamprop-M-isopropyl and formulations of other members of this class of herbicide have always contained an oil adjuvant to increase herbicidal performance. Further increases of performance could be obtained by following the label recommendations to add further quantities of a commercial emulsifiable oil (e.g. ‘Swirl’). Nevertheless it was judged that, in view of current advances in adjuvant research, even greater improvements in herbicidal performance could be obtained with different types of adjuvants. Experimental trials using a cultivated oat (Avena sativa L.) assay under glasshouse conditions to test ranges of surfactants (alkyl aryl, alkyl saccharide, alkylamine and alcohol ethoxylates) and emulsifiable oils (paraffinic/naphthenic, rape seed, transmethylated rape seed) showed that all of these adjuvants were capable of increasing flamprop-M-isopropyl activity compared with that of an emulsifiable concentrate formulation containing no adjuvant. Alkylamine and alcohol ethoxylates, with no particular preference for the length of the alkyl chain, but optimum ethylene oxide content of 5 moles and 7–10 moles respectively, were the most efficacious and better than the current emulsifiable oil system. There was no additional benefit from mixture of these two types of adjuvant and an alcohol ethoxylate (‘Dobanol’ 25-7) was preferred on cost grounds. This adjuvant also gave substantial activity to the otherwise inactive suspension concentrate formulation. Final trials determined that the optimum application rate of ‘Dobanol’ 25–7 was in the range 1000–1500 g ha?1, and this information guided the design of subsequent field trials. |
