Transposition of herbicides on straw sugar cane with different rainfall intensities

The sugar cane is one of the most important crops in Brazil, both in the economic as social and environmental. The sugar cane is of fundamental importance as a raw material for the production of sugar and alcohol, which enables the replacement of fossil fuels with renewable. Mechanized harvesting sugar cane without burning straw gave rise to a new production system called green cane. The straw originated this system, combined with the intensity of rainfall determined new concepts on transposition of herbicides to the ground. The work had as objective to evaluate the passage of tebuthiuron, imazapic, hexazinone and diuron herbicides applied to different amounts of straw sugar cane and rainfall. The experiment was conducted in the greenhouse. The experimental design was distributed in a factorial 4x3 (0, 10, 20 and 30 t ha-1 of straw cane sugar and 0, 10 and 20 mm of precipitation) with 6 repetitions. Visual assessment of the indicator plant, sorghum, was based on the scale of the Brazilian Society of Science of Weed at 28 days after herbicide application. The control efficacy of the hexazinone tebuthiuron, diuron and imazapic herbicides were reduced with increasing the amount of straw sugar cane deposited on the soil surface, and increased with greater precipitation. The herbicide hexazinone showed more efficient control while diuron, less control efficiency.