140 



modified form on the farm at Garforth on which it was carried 

 out in 1919. 



A comparison of Plots 1 and 4 in the Kipling Cotes experiment 

 led us to believe that the presence of a large proportion of 

 Silica in the spraying mixture had exerted some inhibitive effect 

 on the action of copper sulphate. In making up the required 

 quantities of chemicals for the Garforth trials, therefore, a much 

 smaller proportion of Silica was added to make up the bulk, 

 and greater care was taken in the spraying to ensure an 

 even distribution on the plots. It was decided to omit nitrolim 

 Irom the test, and to include only one plot of sulphate of iron. 

 The latter substance is approximately 2J times cheaper than 

 sulphate of copper, but this advantage is more than outweighed 

 by the larger quantity which appears to be necessary to give 

 results comparable to those of sulphate of copper. 



Five plots, each l/60th acre, were marked out in a field 

 carrying Eye and Vetches — a thin crop which was spring sown. 

 There was an abundance of Charlock, which, on account of the 

 wet season and the open nature of the crop, had made luxuriant 

 plants bearing a quantity of flowers and seed pods. The follow- 

 ing table gives the treatment of the plots together with the actual 

 amounts of the chemicals and Silica applied to each : — 



Plot 1. Sulphate of Copper 

 2 



3. „ „ „ 



„ 4. „ „ „ 



5. Sulphate of Tron 

 The field selected 

 University farm at Garforth, and it was "thus possible to 

 await favourable weather conditions for the operation. This 

 was carried out on June 19th at 3.45 a.m. The w T eather 

 was very hot, and a thunderstorm occurred at 9 o'clock on the 

 previous evening, after which a heavy mist hung over the ground 

 from midnight onwards. In the morning the air was very calm, 

 and every leaf was drenched with moisture. No rain fell for 

 48 hours after the spraying, and the weather conditions may be 

 considered to have been ideal. 



Results. — After two or three days the plots presented a 

 remarkable appearance, and it was evident that the experiment 

 was a complete success. The previous experiments had shown, 

 however, that the full effect of dry spraying could not be judged 







Total oz. 







Spraying 



lb. per 



oz per 



oz. Silica Powder 



acre. 



plot. 



per plot, per plot. 



• 40 



lOf 



n is 



30 



8 



5 13 



20 





7f 13 



10 



n 



10| 13 



50 



m 



13£ 



for spraying was 



adjacent to t 



