Preliminary Investigation on Weeds Occurence in Sunflower Field in the Northwest Region of Jilin Province

Weeds occurrence in sunflower field in the Northwest region of Jilin Province were investigated via a inverted W shape 9 points sampling method.The results showed that there are total 19 families 49 species weeds in sunflower field.Among then,16 families 36 species of broad-leaf weed contains 73.5% of the total weeds,10 species of gramineous grass contains 20.4%,3 others species(1 species belongs to Orobanchaceae,2 species belong to Equisetaceae) contains 6.1%.35 species of annual weeds contains 71.4%,3 species of biennial weed contains 6.1%,11 species of perennial weed contains 22.4%.Relative abundance value of 4 families 11 species weed is above 10.According to the order from high to low of the relative abundance value,there are Orobanche coerulescens,Chenopodium album,Chenopodium aristatum,Amaranthus retroflexus,Echinochloa crus-galli,Panicum miliaceum var.ruderale,Phragmites communis,Xanthium sibiricum,Setaria viridis,Sonchus brachyotus,Chloris virgata are the main harmful weeds in sunflower field in the northwest region of Jilin Province.