MANAGEMENT OF VOLUNTEER CASTOR BEAN IN THE GLYPHOSATE-RESISTANT SOYBEAN CROP

ABSTRACT The goal of this study was to evaluate the management of volunteer castor bean with herbicide applications used in pre and post-seeding of soybean crop resistant to glyphosate. Two experiments were conducted in a greenhouse in a completely randomized design with three replications. The first experiment corresponded to applications of desiccation with treatments: glyphosate (1,080 g ha-1); glyphosate + 2,4-D (1,080 + 670 g ha-1); glyphosate + carfentrazone-ethtyl (1,080 + 20 g ha-1); glyphosate + flumioxazin (1,080 + 25 g ha-1); glyphosate + saflufenacil (1,080 + 35 g ha-1); glyphosate + chlorimuron-ethyl (1,080 + 12.5 g ha-1); diuron + paraquat (300 + 600 g ha-1); and the control without application. In the second experiment, the treatments corresponded to doses of 0, 90, 180, 360, 720, 1,440, 2,880 and 5,760 g ha-1 of glyphosate for applications in post-emergence in soybean RR. The applications took place when the castor bean plant had four to six true leaves. The evaluations done in both experiments were: control and plant height at 7, 14 and 21 days after application (DAA); and stem diameter, leaf area, root volume, dry mass of shoots and roots at 21 DAA. The treatments with diuron + paraquat and glyphosate associated with 2,4-D, carfentrazoneethyl, flumioxazin or saflufenacil are more efficient for castor bean control in desiccation in pre-seeding of soybean. Glyphosate doses from 720 g ha-1 are effective to control castor bean in post-emergence of the glyphosate-resistant soybean crop