1114 



Spraying of Cornfield Weeds. 



[Mar.,. 



At harvest time the three plots were kept separate to see 

 whether there was any improvement in the cereal crop owing to 

 the spray. The following are the results : — Plot 1. 32 bus. per 

 acre; Plot 2. 36 bus. per acre; Plot 3. 44 bus. per acre. 



Important Practical Points in Spraying. 7 — 1. One should 

 insist on having sulphate of ammonia in dry condition for this 

 purpose, as the damp, lumpy grades take much longer to dis- 

 solve, and the lumpy need to be broken down from time to* 

 time during stirring. 



2. Always strain the solution into the spray barrel. For 

 this purpose copper gauze is useless, as the spray fluid corrodes 

 it. The best way is to cut open a basic slag bag and strain 

 through one thickness only. The single thickness is very 

 effective in removing any foreign matter from the liquid and> 

 in preventing blocking up of the nozzles. 



3. Select a dry day for spraying. If the leaves are not dry, 

 the- solution is diluted and consequently less effective. Further, 

 the sulphate of ammonia solution dries rapidly on a fine, sunny 

 day. It is this " dry " sulphate of ammonia distributed 

 uniformly over the whole plant, which draws the moisture out 

 of the protoplasm of the cells and, as a result, kills the plant by 

 what is technically called " Plasmolysis." A dry day, there- 

 fore, increases the " killing pow T er " of the spray. 



4. A calm day is equally important, as it is impossible to 

 cover the leaves of weeds completely in a wind, and the fine 

 misty spray is largely w'asted. It also takes considerably more 

 spray fluid to cover an acre, whereas on a calm day 60 gallons 

 should spray about 1J acres provided one has a good man 

 driving the horse. 



5. Although Charlock can be killed after it comes into flower 

 it is much better to spray it as soon as possible after it comes 

 into rough leaf. The cereal crop then gets the benefit of the 

 manurial constituents of the soil which otherwise would have 

 been taken up by the charlock. 



6. Sulphate of ammonia spray fluid has a very corroding 

 effect on the usual charlock spraying machines, which are made 

 of copper or alloys of copper. Chemical action takes place 

 between the copper and the sulphate of ammonia, forming 

 sulphate of copper, and, if the sprayer w T ere not washed out 

 immediately with clear water, the nozzles and pump would 

 soon be choked up with blue sulphate of copper. Possibly this 

 difficulty could be overcome to some extent by lining the con- 



