The distribution of barnyard grass (Echinochloa crus-galli) is briefly described and it is the only one of the 10 worst weeds in the world to occur in Norway. It is most troublesome in coastal areas in Vestfold and Østfold and was probably introduced into Norway originally in unground forage grain or birdseed and more recently as a contaminant in onion and carrot seed. In a large consignment of carrot cv. Nantes Duke marketed in 1984 there were approx. 1200 E. crus-galli seeds/kg carrot seed. E. crus-galli requires high temp. for germination and so emerges in late spring or early summer in Norway, thereby avoiding normal chemical and mechanical control measures. In carrots, linuron and metoxuron are effective as soil-applied herbicides against E. crus-galli seedlings, but not against dormant seed. The greatest risk of weed increase is in barley crops where hand weeding is the only sure control. In other crops, however, trifluralin and alloxydim sodium have proved effective.