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

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. RESUMO: Herbicidas com alta persistência no solo podem causar problemas em culturas semeadas em sucessão a sua aplicação. Desta forma, o objetivo deste trabalho foi estimar, em condições de casa-de-vegetação, o período de tempo seguro após aplicações em pré-emergência de herbicidas utilizados no algodoeiro (isolados ou em misturas) sobre culturas semeadas em sucessão (feijoeiro, milho e soja). O delineamento experimental utilizado foi o inteiramente casualizado, em arranjo fatorial (5 x 11) + 1, com cinco repetições. Em cada experimento (cultura), os tratamentos foram constituídos pela combinação de intervalos de tempo entre aplicação do herbicida e a semeadura das culturas (280, 210, 140, 70 e 0 dia, antes da semeadura das culturas) e onze tratamentos com herbicidas: 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