72 PROTECTION OF PLANTS, 1917-18 



Orchard Heating Oil has been used to destroy wild garlic but it destroys all 

 other vegetation at the same time. The spray should be applied at the rate of 

 75 gallons per acre and in the form of a fine mist. It is not poisonous and does not 

 injure the soil. , If applied early in the season a late crop may be grown. It can 

 be obtained from the Standard Oil Company. 



Fuel Oil is useful for killing plants on waste ground or garden paths. After 

 its use the soil remains sterile for a considerable period. 



The usual precautions in reference to spraying should be carefully observed ; 

 poisonous substances should be handled with great care and should not be used on 

 pastures where live stock are allowed to roam about; the spray should be applied 

 in the form of a fine mist; spraying should not be attempted if rain is expected 

 to fall within 24 hours as much of the spraying solution will be washed off the 

 plants before it has had time to take full effect. 



When weeds are growing in a field crop judgment must be exercised in apply- 

 ing a spray of such a nature or such a strength that the crop will not be injured 

 as well as the weed. The amount of injury inflicted by a spray on any plant 

 appears to depend largely on the nature of the external surface of the plant in 

 question as well as on the manner of its growth. Some plants have a smooth or 

 waxy surface to which the spraying solution does not adhere; in such cases no in- 

 jury follows the application of the spray. In those plants which are most sus- 

 ceptible to the action of the spray the surface is easily wetted by the liquid used. 

 In other cases the ends of the leaves are injured but as the growing parts of the 

 plant are deepseated and thus protected from the action of the spray new leaves 

 are soon formed and the plant recovers. 



Weeds, as a general rule, are more susceptible to the action of sprays when 

 they are very young; when they are older the spraying fluid cannot penetrate so 

 readily into the tissues of the plant. 



Among plants on which spraying fluids of the ordinary strength have no 

 effect are the following: — Grain crops such as wheat, oats, etc., also grasses 

 generally, both grasses used for hay and weed-grasses such as wild oats and quack 

 grass; stinkweed or penny cress, lamb's quarters, perennial sowthistle and various 

 others which do not occur in the Province of Quebec. 



It might be possible to add some gummy or adhesive substance to the spray- 

 ing solution which would cause it to adhere to smooth-leaved plants but this does 

 not appear to have been tried. A more serious difficulty would probably be the 

 danger of grain crops being injured at the same time as the weeds, but this might 

 be surmounted by spraying when the grain is very young when recovery from any 

 injury might be expected to take place in a short time. 



