EFFECT OF ADJUVANTS ON THE PERFORMANCE OF THE NEW CEREAL FUNGICIDE, METCONAZOLE .2. FIELD TRIALS

Glasshouse trials had shown that the activity of metconazole formulati ons against cereal foliar diseases could be enhanced by alcohol ethoxy late adjuvants. A series of soluble liquid (SL) formulations of metcon azole had been prepared containing adjuvant:metconazole ratios of 5:1, 7.5:1, 10:1, 15:1 m/m (SL1, SL2, SL3, SL4) which glasshouse trials ha d shown could give equivalent performance to an emulsifiable concentra te formulation, (ECM) of metconazole at application rates up to three- or four-fold lower than that of ECM alone. A field trials programme w as undertaken to compare the performances of these SL formulations wit h ECM at 120 g AI ha(-1), through a range of application rates (48, 60 , 72, 84 g AI ha(-1)), in a non-orthogonal factorial trial design agai nst diseases that occurred naturally (Septoria tritici Rob., Puccinia recondita Rob., Pyrenophora teres Drechs., Erysiphe graminis DC) or by artificial inoculation (Leptosphaeria nodorum Muell.), on either Trit icum aestivum L. or Hordeum vulgare L. The results from trials in thre e locations showed that the commercially acceptable performance of ECM at 120 g AI ha(-1), in giving high levels of control of P. recondita, S. tritici and L. nodorum (both prophylactic and therapeutic activity ) on T. aestivum, and of E. graminis and P. teres on H. vulgare, could be matched or improved by SL2, SL3 and SL4 at 72 g AI ha(-1) Furtherm ore, control of E. graminis f. sp. tritici Marchal by these St, formul ations at this application rate was better than that by ECM at 120 g A I ha(-1), though the levels of control still remained below commercial acceptability for therapeutic activity. Nevertheless, substantial red uctions in the application rate of metconazole have been achieved by u sing one-pack adjuvant-containing formulations in field trials, while still maintaining excellent control of a range of cereal foliar diseas es. The choice between these SL formulations could therefore be made o n other grounds such as cost/performance and ease of formulation.