Eradication by Spraying. 157 



The ivecds zvhich can he killed or seri- 

 ously checked by spraying include most of 

 the broad-leaved plants, such as those 

 included in the mustard family, kinghead, 

 ragweed, dandelion, and even the Canada 

 and bull thistles. Perennials and biennials 

 like these latter, however, must be sprayed 

 several times throughout the season to 

 prevent the growth of new shoots from the 

 roots. Other methods will usually be 

 found cheaper and better in fighting these 

 weeds, with the possible exception of dan- 

 delions in lawns. The spray, if properly 

 applied, will not injure the small grains, 

 or grasses which may have been sown with 

 the grain, as timotliy or brome grass. Flax 

 should not be sprayed after it is three or 

 four inches high. Spraying is injurious to 

 clover and alfalfa, and should not be used 

 on any grain field in which seeds of these 

 crops have been sown, or in meadows con- 

 taining them. It is not effective in fight- 

 ing wild oats, quack grass, foxtail, or 

 other weedy grasses. 



The best time to spray is when the first 

 of the mustard, Frenchweed, or false flax 

 plants are in blossom, but before they have 

 formed pods, as the plants are often jiot 



