REINVESTIGATING ADJUVANTS FOR THE WILD OAT HERBICIDE, FLAMPROP-M-ISOPROPYL .1. GLASSHOUSE TRIALS

Commercial formulations of flamprop-M-isopropyl and formulations of ot her members of this class of herbicide have always contained an oil ad juvant to increase herbicidal performance. Further increases of perfor mance could be obtained by following the label recommendations to add further quantities of a commercial emulsifiable oil (e.g. 'Swirl'). Ne vertheless it was judged that, in view of current advances in adjuvant research, even greater improvements in herbicidal performance could b e obtained with different types of adjuvants. Experimental trials usin g a cultivated oat (Avena sativa L.) assay under glass-house condition s to test ranges of surfactants (alkyl aryl, alkyl saccharide, alkyl-a mine and alcohol ethoxylates) and emulsifiable oils (paraffinic/naphth enic, rape seed, transmethylated rape seed) showed that all of these a djuvants were capable of increasing flamprop-M-isopropyl activity comp ared with that of an emulsifiable concentrate formulation containing n o adjuvant. Alkylamine and alcohol ethoxylates, with no particular pre ference for the length of the alkyl chain, but optimum ethylene oxide content of 5 moles and 7-10 moles respectively, were the most efficaci ous 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. Thi s adjuvant also gave substantial activity to the otherwise inactive su spension concentrate formulation. Final trials determined that the opt imum application rate of 'Dobanol' 25-7 was in the range 1000-1500 g h a-1, and this information guided the design of subsequent field trials .