The influence of seeding rate and time of water introduction on the efficacy of pretilachlor in direct seeded wet sown rice [Oryza sativa; Philippines]
1986
Salinas, G.D.
This study was conducted to define the effect of different seeding rates and times of water introductions on the performance of pretilachlor for weed control in direct wet sown rice. Effect of seeding rates was conducted for three seasons and effect of time of water introduction was conducted for two seasons. Separate field plots seeded at 50, 80, 100 and 150 kg seed/ha did not show significant symptom of crop injury when these were treated with pretilachlor at 0.30, 0.45, and 0.60 kg ai/ha at 4 days after seeding. Plots treated with the standard herbicide, butachlor at 0.60 and 1.05 kg ai/ha showed appreciable crop injury resulting in reduction of crop stand. Grain yield data obtained from pretilachlor treated plots showed that rates of 0.30 to 0.60 kg ai/ha were higher compared to those obtained from plots treated with the standard herbicide. The data suggested that 0.30 kg ai/ha pretilachlor was the optimum rate at a seeding rate of 80 to 100 kg/ha. Higher herbicide rate is required at seeding rates of less than 80 kg/ha. The tolerance of young rice seedlings treated with pretilachlor was not affected by the delay of water introduction after herbicide application. The weed control efficiency of pretilachlor at 0.30 kg ai/ha was reduced with the delay of water introduction. However, delayed water introduction did not affect the efficacy of pretilachlor when applied at 0.45 kg ai/ha
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