Mechanical and chemical control of red rice (Oryza sativa L-var. sylvatica) in rice (Oryza sativa L.) pre-planting

Two field experiments were set up to assess the effectiveness of different herbicides and mechanical means for the pre-planting control of red rice seedlings. In the first experiment, carried out in the 1995-1996 period, dalapon-sodium (at 12.75 kg a.i. ha(-1)) was compared to mechanical control using a blade harrow and light mouldboard plough, both working at 8-10 cm depth. In this experiment, the weed control obtained with mechanical treatments ranged between 69 and 91%, while with dalapon it always exceeded 92%. Harrowing and shallow ploughing gave similar or lower yields to those obtained with dalapon. The effective workings time of the chemical treatment was only between 12 to 20% of that achieved with harrowing and shallow ploughing, respectively. In the second experiment, carried out in the 1995-1997 period, several herbicides were compared. In this experiment, the best results were obtained with cycloxydim, clethodim and dalapon-sodium, which resulted in red rice control that was always over 95%. (C) 1999 Elsevier Science Ltd. All rights received.