Efecto del rastrojo y precipitaciones en la efectividad del Sulfentrazone en el control de Amaranthus spp.

Agricultural production systems in recent times have been intensified by performing double annual cultivation. This means that summer sowings are carried out on stubble from the continuous use of direct sowing, in addition to the fact that there is today a great use of winter covers in order to reduce erosion and achieve greater control of weeds, not only on the basis of to chemicals, but including cultural controls. These cover crops through their stubble can suppress weeds, but may have the disadvantage of interacting with the pre-emergence herbicide, causing a decrease in its effect. On the other hand Amaranathus spp. the greatest control is given by the use of pre-emergence herbicides, one of them being sulfentrazone. The objective of this work was to evaluate the effect of the amount of stubble and the level of rainfall on the effectiveness of the herbicide sulfentrazone in the control of Amaranthus spp. The experiment was installed at the EEMAC under semi-controlled conditions. 100 Amaranthus spp. seeds were sown in pots. in each one. In those treatments that carried oat stubble, the same was placed, simulating the amount of 0, 3000 and 6000 Kg Dm/ha. The herbicide sulfentrazone was applied at different doses, 0, 0.5 L/ha and 1 L/ha (recommended dose). Then the precipitations of 0, 20, 40 and 80 mm were simulated. The evaluations began 5 days after application, counting the cotyledon emergence in each experimental unit. For the first two evaluations, stubble by herbicide and precipitation by herbicide interactions were significant. At 29 and 40 days after application, a triple interaction was verified. In the first evaluations there was a control of Amaranthus spp. by the stubble suppressing emergencies. In the herbicide treatments, the stubble did not generate a decrease in emergencies. Excellent weed control was obtained in all amounts of stubble, and there were also no differences in control between doses of herbicide. As the days passed, the action of the stubble on the herbicide began to be noticed, where the stubble generated a physical barrier retaining the herbicide. The greatest controls of Amaranthus spp. they were given with full-dose sulfentrazone application. Total control was achieved, regardless of the rain generated the day after the application. In the absence of stubble, sulfentrazone control was excellent. The interaction of the stubble with the herbicide varied in time and for the dose used. Without rainfall, and with higher amounts of stubble, 6000 kg/ha, it was essential to apply the recommended dose of the herbicide.