Weed Control Effect of Some Herbicides in Paddy Field

Abstract

The effects of some herbicides and herbicides combinations on the control of weeds in paddy field evaluated at the Chiayi Agricultural Experiment Station, Chiayi, Taiwan, in the second crop of 1967 are summarized. Broadleaves were the major weeds of the experimental plots at the early stage of growth. but grasses, particularly Paspalum scrobiculatum became the predominant weeds in some plots at the later stages. Sedges never became an important weed in the experimental fields, NPE, KN3, and Dichlobenil gave good control of weeds which were followed by EPTC/2,4-D, and Trifluralin. Pyridinol and Molinate controlled weeds poorly under the conditions of this experiment. MCPA+handweeding also resulted in a satisfactory control of weeds. In general, chemicals followed by MCPA gave more effective control of weeds than those applied alone. Rice plant was injured by Pyridinol, NPE, EPTC/2,4-D, and late application of MCPA. As a result, the growth of rice plant was inhibited in the early stage, showing the reduction in tillers per hill and plant height. Weed competition with rice became apparent at heading stage, and plant height and tillers per hill in the plots with heavy weed infestation were greatly affected. Weeded check, Pyridinol+MCPA, Dichlobenil+MCPA, Dichlobenil, KN3+MCPA and Molinate+MCPA outyielded non-weeded check, differences being significant statistically. Weed competition with rice caused a loss of yield by 926kg per ha or a reduction of 30. 5%. Single application of Pyridinol gave the lowest yield due to its toxicity to rice and poor control of weeds, whereas low yield of Molinate was caused primarily by heavy infestation of weeds.