Alternatives to fenoxaprop-ethyl to control Johnson Grass (Sorghum halepense) irrigated rice

In january 2013, an experiment was established at the Cotaxtla Experiment Station located in the municipality of Medellin, Veracruz, aimed at determining the effectiveness of different herbicide treatments in the control of Johnson grass (Sorghum halepense (L.) Pers.), the selectivity to rice and the effect on grain yield. The Milagro Philipino rice variety was planted at a density of 125 kg ha(-1). A total of ten treatments were evaluated in an experimental randomized block design with four replications. The treatments were fenoxaprop-ethyl at 45 and 67.5 g ha(-1), bispyribac-sodium at 22.4 and 30 g ha(-1), cyhalofop-butyl at 270 and 360 g ha(-1), nicosulfuron at 40 and 60 g ha(-1), propanil at 4 320 g ha(-1) and an untreated control. At the time of treatment, the population density of S. halepense was of 875 000 plants ha(-1). The control of S. halepense and the toxicity for rice were evaluated at 15, 30, 45 and 60 d and after the day of application (da). After 60 d, control of over 95 % were observed with both nicosulfuron doses and the highest bispyribac-sodium dose. Fenoxaprop-ethyl at both doses caused a light toxicity in rice, which disappeared between the 15 and 30 da, with the lower dose and at the 30 and 45 da with the highest dose. The highest yields of rice were obtained with the highest doses of bispyribac-sodium and nicosulfuron, ranging between 4 509 and 4 630 kg ha(-1).