Eficácia da associação entre os herbicidas clomazone e hexazinona no controle de plantas daninhas em cana-de-açúcar

Abstract

The aim of this study was to evaluate the association between the herbicides clomazone + hexazinone applied during a dry period and at different doses, on soil and sugarcane mulch, in the weed control. The experiment was applied in August 22, 2007 in Santa Maria, São Paulo, Brazil. The experimental plots were constituted of five sugarcane lines spaced in 1,5 m, with 6 m of length. In the plots were sown the weeds Brachiaria decumbens, Euphorbia heterophylla, Ipomoea grandifolia, Ipomoea nil, Ipomoea hederifolia, Ipomoea quamoclit e Merremia cissoides. The treatments were the herbicides clomazone + hexazinona at doses 720 + 180; 800 + 200; 880 + 220 e 1000 + 250 g ha-1 and imazapic at 147 g ha-1, applied over the soil and sugarcane mulch. Two herbicide untreated were also used as check, being one with and other without sugarcane mulch. The treatments promoted an efficacy control of weeds species evaluated, especially until 119 days after application (DAA). At 153 DAA were observed good control for M. cissoides, E. heterophylla, I. nil and B. decumbens for the association of clomazone + hexazinone. For I. quamoclit clomazone + hexazinone only at higher doses in the presence and absence of mulch and imazapic applied over the mulch promoted satisfactory levels of control. For I. hederifolia, to the 153 DAA, the combination of clomazone + hexazinone promoted unsatisfactory levels of control and imazapic applied on the straw promoted effective control of this species and I. grandifolia only imazapic and clomazone + hexazinone at the highest dose, both over the mulch promoted good control.