The objective of this work was to evaluate the effectiveness of tebuthiuron associated with sugar cane straw to control weed under different conditions. Thus, an experiment was carried out in pots with four replications where, besides being applied with and without straw, tebuthiuron was applied on 5 t straw ha-1; on soil recently covered with 5 t straw ha-1;and on soil without straw cover and with and without simulation of different amounts of rain applied before or after herbicide application. The rate of Combine 500 SC (tebuthiuron) applied was 1,000 g a.i. ha -1 with 200 L ha-1 of spray volume application. The weeds used were Brachiaria plantaginea, Brachiaria decumbens and Ipomoea grandifolia. Weed control percentage was evaluated at 7, 14, 21, 28, 35, 42, 49 and 56 days after application (DAA) when tebuthiuron was applied in pre-emergence; and at 3, 10, 17, 24, 31 and 38 DAA when applied in post-emergence; dry matter weight was evaluated at 56 and 38 DAA, respectively. Regardless of the weed assessed, it was verified that the highest control rates were reached when tebuthiuron was applied on the straw, after rainfall simulation corresponding to 2.5 or 30 mm or for the treatments where the herbicide was applied directly on bare soil or covered with straw. Thus, for I. grandifolia, B. plantaginea and B. decumbens, the highest control levels were obtained when the herbicide reached the soil directly as well as leached through the straw by simulated rainfall after application.
herbicide; leaching; raw sugar cane; effectiveness
