92 FARM WEEDS OF CANADA 



WILD MUSTARD (Brassica arvensis (L.) Ktze.) 



Other English names: Charlock, Herrick, Cadluck, Field- 

 kale, Ontario Mustard. 



Other Latin names : Brassica Sinapistrum Boiss., Sinapis 

 arvensis L. 



Introduced from Europe. Annual. Stems erect, branching, 

 1 to 3 feet high, rough, with stiff, somewhat downward directed 

 hairs. The purple at the junction of the branches with the 

 stem is a striking characteristic. Lower leaves stalked, usually 

 deeply indented or lobed, with the terminal lobe large; upper 

 leaves mostly stalkless. Flowers bright yellow, fragrant, 2/3 inch 

 across. Seed pods 1 to 2 inches long, knotty or slightly con- 

 stricted between the seeds, ribbed and rising obliquely on short, 

 thick footstalks, tipped with a long empty or 1-seeded, 2-edged 

 beak, which breaks away whole from the ripe pod. Each pod 

 contains about 15 to 17 seeds. 



The seeds (Plate 73, fig. 37) vary somewhat in size but are 

 generally about 1/16 of an inch in diameter, quite round, dark 

 brown or reddish black, almost smooth and without mucilage. 



Time of flowering: June to September; seed ripe by August. 



Propagation: By seeds. 



Occurrence: General throughout Canada in farm crops and 

 waste places. 



Injury: A gross feeder and a troublesome weed. The 

 commonest and one of the most injurious weeds belonging to 

 the Mustard family. 



Remedy: Sow clean seed and hand-pull to prevent it becoming 

 established on new or clean land. When ripe the pods split 

 and much of the seed is left on the land at harvest time; thus 

 the plant rapidly increases on land devoted to cereal grain, 

 particularly oats. Harrowing or discing the stubble lands 



