Efficacy of imazapic and sulfentrazone applied on Cyperus rotundus under different rain and sugarcane straw conditions

摘要

In the raw sugarcane harvest areas, straw affects weed germination and herbicide dynamics. Thus, this work was developed to evaluate the effects of applying sulfentrazone and imazapic, associated with sugarcane straw and simulated rain for Cyperus rotundus control. The experiment was arranged in a randomized block design in a 3 x 3 x 2 x 2 factorial scheme with four repetitions, totaling 144 plots. The treatments were the result of a factorial combination of three levels of the factor sugarcane straw (20, 10 t ha-1 and no dead cover on the soil); three levels of the factor herbicide (sulfentrazone at 800 g ha-1, imazapic at 147 g ha-1 and no herbicide); two levels of the factor intensity of rainfall (10 and 20 mm); and two levels of the factor simulated rain after herbicide application (24 and 168 hours). Number of plants per pot, dry mass of the aerial parts and underground system structures, and number of healthy tubers and bulbs were evaluated. Based on the results obtained, it was concluded that the presence of 20 t ha-1 of sugar cane straw reduced the efficacy of the herbicide sulfentrazone while the herbicide imazapic had a good performance with and without straw, causing a reduction in the varieties studied regardless of intensity of the rain. Rain intensity of 10 mm, was not sufficient to surpass the herbicide sulfentrazone in the amount of 20 t ha-1 of straw. However, 20 mm rain intensity was sufficient to cause herbicide leaching even at the largest amount of straw. The herbicide sulfentrazone showed a good resistance to straw since it was more efficacious than imazapic, when rain was simulated 168 hours after the application of the herbicides