The efficacy and selectivity of the herbicide flazasulfuron, applied on Panicum maximum, Brachiaria plantaginea, and Digitaria horizontalis and sugarcane plants were evaluated during pre emergence under different soil surface water content conditions after the first five days of application. The following isolated Flazasulfuron rates were tested: 37.5, 50.0 and 75.0 g ha-1. The smallest rate (37.5 g ha-1) was mixed with 1000.0 g ha-1 ametrine or diuron and with 1536.0 g ha-1 acetochlor rates. All flazasulfuron rates alone or mixed were compared with the commercial herbicides isoxaflutole (112.5 g ha-1), tebuthiuron (1000 g ha-1), sulfentrazone (800 g ha-1), and diuron + hexazinone (1500 g ha-1), plus two checks, with and without weeds. All the herbicides were selective to the tested sugarcane plant cultivars RB 845257 and RB 855536. Flazasulfuron and some commercial herbicides provided excellent weed control in moist surface soil. Unsatisfactory results for P. maximum and B. plantaginea control in dry surface soil were obtained with flazasulfuron alone or mixed with ametrine, acetochlor and diuron. Flazasulfuron herbicide with the rate of 37.5 g ha-1 to B. plantaginea controlled 42.5% when the reduction of soil water content was 22% to 7% in the 0-2.5 cm layer. The control increased to 97.5% when the variation of soil water content was 25% to 21%, ninety days after application.
pre emergence; weeds; herbicides
