Revista Brasileira De Herbicidas 2000; 1(2): 147-152
Control of Euphorbia dentata in soybean with postemergence herbicides
DOI: 10.7824/rbh.v1i2.329
Euphorbia dentata is an annual weed which grows during spring and summer. Its has acquired importance mainly associated with soybean crops in the central area in Buenos Aires Province, Argentina. This weed is highly competitive in soybean fields and its control is very difficult. The objective of this work was to evaluate the effectiveness of Euphorbia dentata control with postemergence herbicides in soybean crops. Field studies were conducted in Azul Co., in a highly naturally infested soybean crop (110 plants of Euphorbia dentata/m2). The treatrnents were: imazethapyr 100 g/ha, chlorasulam-methyl 33.6 g/ha + no ionic surfactant 0.2% v/v, lactofen 96 g/ha + no ionic surfactant 0.2% v/v, chlorimuron-ethyI8.75 g/ha + no ionic surfactant 0.2% v/v, chlorasulam-methyI33.6 g/ha + lactofen 96 g/ha + no ionic surfactant 0.2% v/v, chlorimuron-ethyI8.75 g/ha + lactofen 96 g/ha + no ionic surfactant 0.2% v/v, untreated control and control without weeds which were removed by hand. The experimental design was a randomised complete block with four replications. Evaluations were made 20 and 45 days after application and on harvest. No treatment reached 70% control. The highest levels of effectiveness were obtained with imazethapyr (67%) and with the mixture chlorasulam+lactofen (65%) with no significant differences between them. Soybean yield showed a similar response: the productivity in those treatments were 2850 and 2650 kglha respectively. Crop productivity decrease by 35% in untreated control compared with the treatment without weeds whose yield was of2920 kg/ha.
189