EFFECTS OF LATE-SEASON APPLICATIONS OF PROPICONAZOLE AND TRIDEMORPH ON DISEASE, SENESCENCE, GRAIN DEVELOPMENT AND THE WHEAT BREADMAKING QUALITY OF WINTER-WHEAT

One glasshouse and six field experiments investigated the effects of propiconazole plus tridemorph fungicide treatments at flag leaf and/or ear emergence of winter wheat (Triticum aestivum L.) in the UK from 1984 to 1990. Fungicide effects on diseases, green leaf area and breadmaking quality of cv. Avalon were studied. Additionally, three of the field experiments investigated grain filling, drying, and nitrogen accumulation, and two of these experiments tested fungicide effects over different cultivars. When averaged over all cultivars, the fungicide significantly (p < 0.05) increased grain yield and thousand-grain weight (TGW) in five, and specific weight in three field experiments. Grain crude protein concentration (CP) and Hagberg falling number (HFN) were significantly reduced once following Septoria tritici control, and HFN alone was reduced a second time following powdery mildew (Erysiphe graminis f.sp. tritici) control. Despite reductions in CP and/or HFN, overall loaf quality was improved by fungicide application. Fungicide application increased the rate of grain filling rather than its duration and delayed grain drying. In 1985 and 1986 there were a number of cultivar x fungicide interactions, which further demonstrated that degree of control against S. tritici and powdery mildew were associated with effects on grain nitrogen content, mean grain weights and specific weights in different years. In the glasshouse experiment the fungicide controlled powdery mildew and significantly increased CP. It was concluded that recommendations on fungicide use, based on obtaining an economic yield response, do not need to be altered to take effects on breadmaking quality into account.