Investigation on Distribution and Damage of Weeds in Tobacco Fields in Liaoning Province

An investigation was carried out by inverted W-9 point sampling to study the distribution and damage of weeds in tobacco fields in Liaoning Province.The results showed that there were 51 weed species belonging to 20 families,including 40 kinds of broad-leaved weeds (accounted for 78.43%),6 kinds of gramineous weeds (accounted for 11.76%) and 5 kinds of the others (accounted for 9.80%); among them, there were 41 kinds of annual weeds (accounted for 80.39%) and 10 kinds of perennial weeds (accounted for 19.61%).The weeds whose relative abundance was more than 15% were Digitaria sanguinalis (L.) Scop., Acalypha australis L., Chenopodium album L., Amaranthus retroflexus L., Cyperus difformis L., Orobanche caerulescens Stephan, Commelina communis L.and Echinochloa crusgalli (L.) Beauv.,which were dominant weeds in Liaoning.Weed damages in different districts differed significantly,in Dandong area,the major injurious weeds were Centipeda minima (L.) A.Br.et Ascher.and Digitaria sanguinalis (L.) Scop.; in Tieling area were Acalypha australis L.and Chenopodium album L.; in Chaoyang area were Orobanche caerulescens Stephan, Portulaca oleracea L.and Amaranthus retroflexus L.; in Fuxin area were Orobanche caerulescens Stephan, Amaranthus retroflexus L., Chenopodium album L.and Chenopodium aristatum L.