227 



solution used is a two per cent, solution of Copper Sul- 

 phate (10 pounds to 50 gallons of water per acre). 

 These chemicals may be applied with either a hand or 

 power sprayer. Some men claim that Iron Sulphate 

 solution will kill all Mustards, Cow Cockle, Dandelion, 

 Canada Thistle, 

 Bindweed, Plan- 

 tain, Ragweed 

 and some other 

 weeds ; other in- 

 vestigators are 

 much less opti- 

 mistic regarding 

 the efficacy of 

 chemical sprays. 

 In any case the 

 practice of 

 s p r a y in g for 

 weed control is 

 expensive and 

 has not yet 

 therefore come 

 into general use. 



Pasturing. - 



When pasture is short, sheep aid in controlling Mustard, 

 Plantain, Thistles, Lamb's Quarters, Shepherd's Purse 

 and many other weeds but they seldom touch Stinkweed 

 or Blue Burr. 



Smothering. Leafy crops on spring plowing aid in 

 the control of Quack Grass by smothering. It is a fact 

 also that many young weed plants are prevented from 

 developing by the crowding and shading of a good stand 

 of any crop. This is why we find so many weeds where 



Fig. 79. Dandelion. 



A typical tap-rooted perennial. A bad weed in 

 lawns and waste places in Manitoba. 



