EFFECT OF ADJUVANTS ON THE PERFORMANCE OF THE NEW CEREAL FUNGICIDE, METCONAZOLE .1. GLASSHOUSE TRIALS

Metconazole, (1RS, 5RS; 1RS, thyl-1-(1H-1,2,4-triazol-1-ylmethyl)cyclo pentanol, is a highly active fungicide, in particular controlling seed -borne and foliar diseases of cereals, such as wheat (Triticum aestivu m L.) and barley (Hordeum vulgare L.). In order to maximize its foliar activity, an experimental survey of some types of surfactants and an emulsifiable oil was undertaken. Two types of metconazole formulation were investigated using a biological assay involving the therapeutic c ontrol of two diseases (Erysiphe graminis DC f. sp. tritici Marchal an d Leptosphaeria nodorum Muell.) of wheat. Enhancements of activity by 'Genapol' C12/C14 alcohol ethoxylates of an emulsifiable concentrate ( ECM) formulation of metconazole were approximately three- to four-fold . For its, initially, less active suspension concentrate (SCM) formula tion, enhancements were around 35-fold, so that with these adjuvants t he two formulations were of similar activity. The enhancement ability of these 'Genapol' surfactants was optimal at lower (5-10 moles) ethyl ene oxide content. These analogues induced marginally better enhanceme nts of activity than members of a range of nonylphenol ethoxylates ('A rkopal'), and emulsifiable paraffinic/naphthenic oil (HVI 60E) and a c astor oil ethoxylate ('Atlas' G1281) but were equivalent to a similar series of alcohol ethoxylates ('Dobanol') from another source. Varying the alkyl chain length between C-9-C-11 and C-14-C-15 in the 'Dobanol ' series had little effect on their high enhancements of metconazole a ctivity. It was determined from trials varying the application rate of the best alcohol ethoxylates that application rates of 1-1.5 kg ha(-1 ) were required for maximum activity. This implied the use of high adj uvant/metconazole ratios in one-pack adjuvant-containing formulations. A range of soluble liquid (SL) formulations were prepared with either 'Dobanol' 23-6.5 or 'Dobanol' 91-6/metconazole ratios varying from 5: 1 to 15:1. There were found to be highly active and were recommended f or field testing.