The effect of strobilurin fungicides on the development of foliar diseases of winter wheat

The present paper reports the results of field research into the epidemic progress of fungal leaf diseases in winter wheat cv. Zentos. Experiments were conducted during the period 2003-2004 and were designed to study the impact of strobilurins krezoxim-methyl+ epoxyconazole+fenpropimorf, trifloxystrobin+propiconazole, azoxystrobin, piraclosrobin+ epoxyconazole and picoxystrobin on the epidemic progress of Stagonospora leaf blotch (Stagonospora nodorum (Berk.) Cast. and tan spot (Pyrenophora tritici-repentis (Died.) Drechs.) and to compare with triazoles epoxyconazole and propiconazole. In both years the pressure of fungal leaf diseases was severe. The unusually hot period during the wheat ripening stage in 2003 provoked the intense outbreak of tan spot. However, the warm and rainy prolonged ripening season in 2004 promoted the severe infection of Stagonospora blotch. Our experimental findings suggest that both strobilurin and triazole fungicides significantly suppressed the epidemic progress of Stagonospora leaf blotch and tan spot on the upper three leaves of winter wheat. The lowest AUDPC (Area Under the Disease Progress Curve) value in both years (2003 and 2004) was recorded in the treatment with piraclosrobin+epoxyconazole, while the highest, in the treatment applied with triazole propiconazole. AUDPC of the other strobilurin fungicides ant triazole epoxyconazole were comparable. AUDPC of both Stagonospora leaf blotch and tan spot on the upper leaves (F, F-1 and F-2) showed the strong negative linear correlation with the grain yield and 1000 grain weight (TGW).