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 926 kg 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.

本文係報告嘉義農業試驗分所與國際稻米研究所合作於民國56年第二期作舉辦之稻田殺草劑藥效觀察試驗之結果。 NPE，KN3與Dichlobenil殺草效果最佳，EPTC/2.4-D與Trifluralin次之，Pyrldinol與Molinate最劣，MCPA+人工除草之處理治草效果亦佳，試驗區之什草以濶葉草居多，故一般言之，各種殺草劑加用MCPA之處理，治草效果均較其單獨使用者為佳。 Pyridinol，NPE，EPTC/2.4-D與後期施用之MCPA對水稻均具藥害，水稻初期之株高，每株分蘗均受到抑制，其發育乃受影響，水稻受什草生長競爭之為害情形，在其抽穗期前後始顯出。一般治草效果較差之處理，其株高，每株分蘗均受到影響。 人工除草，Pyrid inol + MCPA，Dichlobenil + MCPA，Diohlobenil，KN3 + MCPA，與Moli-nate + MCPA之稻谷產量均超過不除草區，水稻因什草生長競爭而每公頃稻谷減產926公斤，達30.5%。Pyridinol單用處理因受藥害及什草競爭等雙重影響，致每公頃稻谷產量最低，Molinate單用處理之低產，顯受什草為害所致。