1909.] PUBLIC DOCUMENT — Ko. 31. 69 



Substances and Methods used in ExTEiiivirNATiNG 



Weeds. 



BY G. E. STONE. 



"Weedicide", " HerUcide", ''Weed Killer", etc. — The 

 preparations bearing proprietary names, snch as Weedicide, 

 Herbicide, etc., are, so far as we have bad occasion to examine 

 them, thoroughly reliable products, and the manufacturers make 

 no extravagant claims for them. Probably all of these contain 

 arsenic compounds; at any rate, when applied to walks, tennis 

 courts, etc., they destroy noxious weeds, and when apf)lied in 

 sufficient quantities new growth is checked. 



Sulfate of Iron, Copper Sulfate, etc. — Sulfate of iron is 

 extensively used in the west in exterminating weeds in grain 

 fields. It is employed in the eradication of mustard, Canada 

 thistle, ragweed, etc. Copper sulfate, common salt and sodium 

 arsenite are also used for this same purpose. Prof. H. L. Bol- 

 ley, who has experimented a great deal with these chemical weed 

 killers, has used them in the following proportions for the exter- 

 mination of weeds in grain fields : iron sulfate at tlie rate of 75 

 to 100 pounds to 52 gallons of water; copper sulfate at the rate 

 of 12 or 15 pounds to 52 gallons of water; common salt at the 

 rate of % to % barrel to 52 gallons of water; and sodium arse- 

 nite at the rate of 1% pounds to 52 gallons of water. Since 

 sodium arsenite is more poisonous than the other substances it 

 is a question whether it should be used in the hay field and 

 places where stock is likely to feed.^ 



Professor Bolley gives the following list of weeds which are 

 amenable to treatment by means of chemical sprays : false 

 ]ihlox, wormseed mustard, tumbling mustard, common wild mus- 

 tard, shepherd's purse, pepper grass, ball mustard, corn-cockle, 



1 Bulletiu No. 80, North Dakota Experimeut Station, liW8. 



