286 EXPERIMENT STATION BULLETIN. 



sprayer, which has no power capacity, cannot be made to serve the pur- 

 pose. 



"For use in grain fields, the cart should be fitted with a pole for 

 two or more horses. The wheels should be of low form and have wide 

 tires, 3% to 4 inches. For work on small farms the tank should hold at 

 least 52 gallons. 



"All parts in contact with the solution should be either wooden, brass 

 or rubber. Even galvanized iron is readily destroyed by the solutions 

 used to eradicate weeds. 



"The spray beam should carry nozzles sufficient to throw in a forceful, 

 misty spray from one to one and one-fourth barrels of liquid for each 

 acre of ground. The pump should give a pressure of about 100 or more 

 pounds per square inch, shown by a gauge attached. Many questions are 

 involved. The abundance and the sturdiness of the crop and the weeds; 

 the climate, the growing season ; whether the weeds are growing in dense, 

 persistent clumps, such as Canada thistles, and whether it is important 

 to undertake to save the crop in the particular spots or not. Do not 

 buy patent or highly advertised chemical-weed eradicators, but instead 

 buy chemical substances on the market. 



"The station has used, successfully, in various sorts of weed-eradica- 

 tion work, common salt, iron sulfate (copperas, green vitriol) copper 

 sulfate, (blue stone of blue vitriol), corrosive sublimate (mercuric bi- 

 chloride) and sodium arsenite (NaAs 2 ). Great care should be taken 

 in using some of these. 



"This chemical method of weed eradication has the peculiar merit 

 that the weeds may be attacked while a crop is being grown and the 

 crops will still give an increased yield. 'Chemicals act differently upon 

 the members of different families of plants.' 



"One field sprayer, with proper help, can spray from twenty-five to 

 forty acres per day. 



"Good field sprays cost from |60 to |150. Good hand sprayers, for 

 dandelions and patches of Canada thistles, etc., may be had at $8 to 

 $10. Iron surfate in powdered form, ready for use in solution, was 

 available in Grand Forks and Fargo for .90 to $1.10 per hundred 

 pounds. 



"The question as to when to spray must be settled by a number of 

 considerations, crop conditions, the weed growth, and weather. 



"Good results have been obtained in spraying oats, wheat and barley 

 when the grain is eight to twelve inches high, to kill mustard and king 

 head (giant ragweed). Mustard is most easily killed when it is just 

 beginning to blossom, though iron sulfate is effective against this weed 

 at all stages up to the forming of seeds. 



"The most effective spray for Canada thistle is sodium arsenite at the 

 rate of 1% to 2 pounds per 52 gallons of water. The next most effective 

 spray is common salt at the rate of one-third to one-half barrel to 52 

 gallons of water, in either case to be used where the thistles are in com- 

 pact masses. 



"In fighting the dandelion by means of chemical sprays, late experi- 

 ments indicate that spraying will eventually give marked success, by 

 using iron sulfate, spraying once a month. Plantain also gradully dies 

 out under the spraying. For ordinary lawn purposes the ideal appa- 



