Impiego di rimsulfuron, dicamba, nicosulfuron e sulcotrione a dosi ridotte nel diserbo del mais

Four field experiments were carried in central Italy form 1993 to 1998 on maize, wherein rimsulfuron and dicamba (two experiments, in 1993 and 1998) and nicosulfuron and sulcotrione (two experiments, in 1997 and 1998) were used alone and in mixture at three-five decreasing rates, from 1/1 to 1/8 of the labelled dosage. A dose-efficacy model was fitted into visually recorded weed control data, to derive ED90 values (doses giving 90% weed control efficacy), which were assumed as minimum thresholds of satisfactory efficacy. On a single weed basis, several species could be satisfactorily controlled with reduced rates of the above mentioned herbicides (ED90 lower than labelled rate). However, considering the overall plurispecific weed flora, a good control could only be achieved by using herbicides at rates not much lower than the recommended ones. As a consequence, the reduced rates approach seems to loose interest in the case of a complex plurispecific weed flora, as commonly found in Mediterranean regions.