本省旱田常見之雜草計13科40餘種，一般旱田最主要者為野莧，小葉灰藋、絹毛指草、亡稷、稗草、牛筋草、馬齒莧等；冬裡作旱田則為鵝兒腸、小葉灰藋、早苗蓼等3種。而旱田主要多年生雜草如香附子、匍黍草、狗牙根、火炭母草則常見於蔗田、茶園、鳳梨園及其他果園。世界性主要旱田作物玉米及大豆，在不除草狀況下減產程度，前者在蘇聯30％、印尼40%、印度50%、德國45%，後者在溫帶地區為25%，熱帶地區則高達100%。本省玉米、小麥、大豆在不除草時，分別造成18、20及40%之減產，在主要雜糧及蔬菜作物中耕除草之費用，平均每公頃高達4,000元之多。旱田雜草分佈主要決定因素為季節及耕作制度的改變，臺灣周年氣候變化，對田間雜草總發生量影響較小，但對雜草族群的構成影響很大，致除草方式尤其是殺草劑的選擇上須適當考慮；此外在經常性旱田和冬裡作旱田及冬裡作整地與不整地旱田草相、草量的分佈均不相同，水田裡作不整地狀況下之雜草密度較低，僅為整地者一半，但不整地狀況下之草鮮重增加遠較整地者快速，在防治上須以田面燒草或接觸性殺草劑來配合萌前藥劑使用，以達防治效果。

There are more than 40 species of weeds, belong to 13 families, in upland field in Taiwan. In general, the most important upland weeds are Amarantlus L. Chenopolium ficifolium Sm. Digitaria sericea (Honda) Honda, Echinochloa colona (L.) Link E. crus-galli Beauv, Eleusine indica (L.) Gaertn. and Portulaca oleracea L. In catch crops Stelaria aquatica(L.) Scop. Chenopodium ficifolium Sm. and Polygonum lapothifolium L. are the majority of weeds. The perennical upland weeds as Cyperus rotundus L. Panicun repens L. Cynodon dactylm Pers. and Polygomm chinense L. are always occurred in sugarcane, tea and orchard. All over the world, under unweeding condition, corn and soybean yields are reduced severely. In Taiwan ,corn, wheat, and soybean yields are reduced 18%, 20% and 40% , respectively, by weed competition. The total cost in NT$4,000/ha on weeding in cereal and vegetable crops. The determining factors of weed flora in upland field are seasonal and cultivated changes. In non-tillage plot, the density of weeds distribution is less in tillage plot, but the weeds growth rate is always accelerated by tillage.