Revista Brasileira De Herbicidas 2014; 13(2): 88-96
Management of Merremia aegyptia with mixtures of herbicides under different rainfall simulation and in in the presence and absence of sugarcane straw
The high frequency of M. aegyptia in sugarcane harvested mechanically is related to its adapting behavior to this harvesting system, what resulted in an increased the infestation potential of this species in relation to other weeds. The aim of this study was to evaluate the management M. aegyptia by spraying pre-emergence herbicides, in the presence and absence of straw in clay soil, under different rainfall simulation. Two experiments were carried out in a completely randomized design with four replications. In each experiment was evaluated the mixtures of herbicides: mesotrione + atrazine (0.25 + 3.0 L ai ha-1) and diuron + hexazinone + sulfometuron-methyl (1386 + 391 + 33.35 g i ha-1). The treatments were arranged in factorial 8 x 2 x 2 design, composed by eight evaluated depths (0, 5, 10, 15, 20, 25, 30 and 35 cm), two covers (with or without straw) and two rainfall simulation after herbicide application (20 and 40 mm). Herbicides were applied to columns filled with clay soil and with 0 and 10 t ha-1 of straw coverage. After herbicide application, the columns were placed under simulated rainfall during the time necessary to apply the equivalent of 20 and 40 mm of rain. After this process, the columns remained for 72 hours in the horizontal position and opened longitudinally to sowing M. aegyptia (target plant). Mesotrione + atrazine presented, in greater depth (23 cm), control of M. aegyptia under 40 mm rainfall and the ineffective control under 20 mm of precipitation with or without straw. Diuron + hexazinone + sulfometuron had control until close to 15 cm depth in both rainfall simulations and the straw had little interference in the action of this mixture.
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