Influenza di strategie anti-resistenza sulla sensibilità ai fungicidi in Cercospora beticola

In the years 2003 and 2004, the effect of different SBI and QoI fungicides, used alone, in mixture or in alternation, on the sensibility level of Cercospora beticola populations was studied. Sensibility was studied in laboratory using fungal isoltes collected in the experimental fields before the beginning of fungicide sprays and after three fungicide applications. A decrease of fungal populations’ sensibility was registered for tetraconazole, when it was used alone or in mixture with azoxystrobin at reduced rates. On the contrary, the use of tetraconazole and azoxystrobin at full rates, as well as the use of difenoconazole and fenpropidin, significantly reduced the proportion of isolates showing reduced sensibility to tetraconazole. No reduced sensibility was observed for azoxystrobin. Some isolates were less sensitive to difenoconazole in one experimental site that had been shown reduced sensibility to IBS fungicides.