RESIDUAL ACTIVITY OF HERBICIDES APPLIED TO COTTON ON CROPS CULTIVATED IN SUCCESSION

Abstract

Herbicides with high persistence in soil can cause problems for crops sown in succession to their application. Thus, the aim of this study was to estimate, in greenhouse conditions, the safe period of time after application of preemergent herbicides used on cotton crops (isolated or in mixtures) for the crops grown in succession (bean, corn, and soybean). The experimental design was completely randomized in a factorial scheme (5 x 11) + 1, with five repetitions. For each experiment, treatments combined different time periods between herbicide application and sowing of crops (280, 210, 140, 70, and 0 days before sowing of crops) with eleven herbicide treatments: fomesafen (625 g ha - 1 ) prometryne (1250 g ha - 1 ), diuron (1250 g ha - 1 ), S - metolachlor (768 g ha - 1 ), clomazone (1000 g ha - 1 ), fomesafen + prometryne (625 + 1250 g ha - 1 ), fomesafen + diuron (625 + 1250 g ha - 1 ), fomesafen + S - metolachlor (625 + 768 g ha - 1 ), fomesafen + clomazone (625 + 1000 g ha - 1 ), fomesafen + clomazone + diuron (625 + 1000 + 1250 g ha - 1 ), and fomesafen + clomazone + prometryne (625 + 1000 + 1250 g ha - 1 ), plus an untreated control. Applications of diuron showed the greatest persistence, causing the largest carryover effects for the three crops evaluated. The other treatments showed residual effects or affected crop development when sowings were performed up to 70 days after application. At later periods no significant damage was observed.