Effect of Certain Weed Managements on Yield of Corn (<I>Zea mays</I>)

Abstract

Field experiment was conducted at Faculty of Agriculture, Chiang Mai University during July-October 1997. The objective of this study was to assess the efficiency of certain weed control methods on yield of corn (var. Suwan#3). The method of hand weeding 1 time at 15 days after planting could increase yield of corn 29.0% when compared to non weeding plot. The following of hand weeding at 30 days after planting gave higher yield 63.0%. However the following of hand weeding at 45 days after planting could increase yeild 75.8%. The application of preemergence herbicide propisochlor (2-chloro-N-(isopropoxy methyl-N-(2-ethyl-6-methylphenyl)-acetamide) 172.8 g ai/rai provided 37.1% higher yield of corn. The application of propisochlor and following with hand weeding at 45 days after planting was able to increase yield 57.2%. The application of propisochlor as preemergence herbicide and following with non-selective postemergence herbicide paraquat (1,1/-dimethyl-4,4/-bipyridinium ion) 110.4 g ai/rai at 45 days after planting could increase yield up to 45.9%. The application of paraquat alone 1 time at 45 days after planting for postemergence weed control showed higher yield of corn 28.8%. It was also found that the non weeding plot gave yield of corn only 327.83 kg/rai.