During 1988 to 1991, 160 species of 46 families of tobacco field weeds were found through investigation in the 12 main tobacco producing counies in different growing period, of them, gramineae, Caryophyllaceae, polygonaceae, Cyperoceae, compositae, araceae, Crassulaceae, Convolvulaceae, etc. are of common occurrence and great harm. And the herb community and its harm in different tobacco field relate closely to the cultivativation system and local ecological conditions. In the fields of tobacco-rice crop rotation, malignant herbs are annual or biannial gramineae, polygonaceae, etc. In the fiel...
