230 WEEDS 



August and September, or cut them out with hoe or spud in May and 

 June. 



Chomlrilla (Chondrilla juncea). Biennial. Destroyed by cultiva- 

 tion and fertilizers to encourage the growth of desirable grasses. 



Wild carrot (Daucus Carota). Biennial. In permanent pastures, 

 mow persistently as the flowers appear. Cutting the roots well below 

 the surface and hand })ulling are effective. Thorough cultivation 

 subdues it. 



Wild oats (Avena fatua). Annual. Stir the land when it is warm and 

 moist to cause the seeds to germinate, then cultivate to kill. Keep the 

 ground occupied or stirred. Omit oats from the rotation. Plow 

 shallow in late fall. In the spring, plow deep and summer fallow, 

 keeping the ground clean. Plant to grain the next season without 

 replowing. Then plow deep early the next fall. Then repeat the 

 fallow, followed by grain two years later, again without replowing. 



False flax (Camelina sativa). Annual. Omit winter wheat and 

 rye from the rotation, and raise crops that will permit full cultiva- 

 tion. Hoed crops are best, as they induce the seeds to germinate. If 

 well established in permanent pastures, plow and cultivate the land. 



Mustard, Charlock (Brassica Sinapistrum). An annual, destroyed 

 by early cultivation. Destroyed by spraying, when the plants are 

 just beginning to bloom, with iron sulfate, copper sulfate, common 

 salt, and sodium arsenite. Use 75-100 pounds of iron sulfate in 52 

 gallons of solution per acre; of copper sulfate, 12-15 pounds to each 

 52 gallons of water ; common salt, ^ barrel to each 52 gallons of water ; 

 sodium arsenite, ll pounds to each 52 gallons of water. Spray after a 

 rain, or in a wet season on a bright, still day. 



King-head, Greater ragweed (Ambrosia trifida). Annual. Culti- 

 vate to cause seed germination a sufficient time before cropping to allow 

 the killing of the weeds by a subsequent cultivation. If the weeds are 

 large on sunmier fallow, plow them completely under or collect and 

 burn. Spray, when the plants are tender, with common salt, copper 

 sulfate, iron sulfate, or sodium arsenite at the same rate and strengths 

 as for mustard, except that at least 100 pounds of iron sulfate should 

 be used for each 52 gallons. Throw the spray forcibly. 



Canada thistle (Carduus arvensis). Perennial. The plant should 

 never be allowed to produce seeds, and the underground stems, which 

 ire usually 3 to 12 inches under ground, must be removed or starved 



