This work had as objective studies the effect of different amounts of sugarcane straw picked without burns about effectiveness of some herbicides in the I. grandifolia control. The experiment was conduced in field in the Centro de Ciências Agrárias/UFSCar, in Araras, SP. The treatments consisted of herbicides herbicidas ametryn + trifloxysulfuron-sodium (1463 + 37 g ha-1), imazapic (84 g ha-1), imazapyr (200 g ha-1), ¹diuron + hexazinone (1170 + 330 g ha-1) and ²diuron + hexazinone (1330 + 160 g ha-1) applied in pre emergence of Ipomoea grandifolia and on five growing amounts of sugarcane straw ( 0, 5, 10, 15 e 20 t ha-1). The effectiveness of control of weeds was evaluated to the 7, 14, 21 and 28 days after application of treatments (DAT).The straw reduced the population of I. grandifolia even in the treatments without herbicide use. The measure that increased the amount of straw there was reduction in the effectiveness of the herbicides and with 15 t ha-1 of straw the control was considered unsatisfactory for all of the treatments. With 20 t ha-1 the control was null for all the treatments, however, was observed that in this case, the own straw was efficient in the suppression of these weed, since the number of emerged plants was smaller, even in the treatment without herbicides.
Saccharum spp.; mulching; chemical control
