WEEDS 



247 



FIG. 127. 



Wild mustard the proper 

 size for spraying 



sulphate or copper sulphate. One hundred pounds of iron 

 sulphate or 12 pounds of copper sulphate may be used in 

 50 gallons of water. In either case, about 50 gallons is 

 sprayed on an acre. It is necessary to have the spray hit 

 all the land. This is accomplished by using one of the 

 field-spraying out- 

 fits with plenty of 

 nozzles. (See Fig. 

 126.) With a prop- 

 erly equipped ma- 

 chine, 10 to 20 

 acres may be 

 sprayed in a day. 

 The spraying is 

 best done on a 

 bright, clear day, 



and should be done when the mustard has six to eight 

 leaves. Mustard may then be killed in any of the cereals, 

 or in peas, without hurting the crops. Beans, potatoes, 

 and cabbages must not be sprayed with this mixture, 

 as these crops would be killed. 



225. Control of Weeds in Walks. In walks, tennis- 

 courts and some other places, any plant is a weed. We 

 can then use a treatment that kills everything. Salt may 

 be used. Carbolic acid or sodium arsenate are more lasting 

 in their effect. A 3 per cent solution of carbolic acid or 

 a 2 per cent solution of sodium arsenate is about right. 

 In either case, about eight gallons will be needed per 

 square rod. Such treatments should not be given under 

 trees, as the trees as well as the weeds are likely to be 

 killed. 



