136 



Dry Spraying of Charlock. 



[May, 



time, and that used was several years old. The sulphate of iron, 

 as is inevitable, was oxidised to some extent, but analysis showed 

 it to contain 87 per cent, of the ferrous salt. 



The field in which the experiment was conducted carried a crop 

 of barley in which Charlock grew abundantly. The spraying 

 was carried out on June 16th, 1919, and at this time the Charlock 

 was in full flower, and a considerable amount of seed was set. 

 The corn was, on an average, 9 in. high. 



Six plots, each having an area of l/40th acre, were marked 

 out and treated as follows: — 77 , 



Dry, hot weather prevailed, and, in order to ensure that the 

 powders should adhere to the plants, the spraying operations 

 were carried out at 3 a.m., immediately before sunrise when 

 the dew was on the leaves. The knapsack spraying machine 

 used was Strawson's " Coronette." The day succeeding the 

 spraying was fine, but rain fell 36 hours after the operation, and 

 the weather then remained unsettled for two or three weeks., 

 Results. — The plots were first examined on June 20th, four 

 days after spraying, and the following notes made : — 



Plot 1. No obvious effect. 

 „ 2. Untreated. 



,, 3. Leaves and flowers of the Charlock badly withered ; seed pods 



still green, but unhealthy in appearance. 



4. Similar to Plot 3, but effect more marked. 



5. Leaves of Charlock withered, but flowers and seed pods not 



greatly affected. 



6. Similar to Plot 5. 



Later examinations showed a quickly developing effect on Plots 

 3 and 4. On Plots 5 and 6 there was also further deterioration 

 of the Charlock leaves, and the flowers were also affected, but 

 the seed pods were only injured on the plot with the heavier 

 dressing of sulphate of iron. 



A final examination was made„on July 9th, three weeks after 

 spraying, and the following report made : — 



Plot 1. No visible effect. 

 „ 2. Untreated. 



1. Nitrolim ... 



2. Untreated 



3. Sulphate" of Copper 



lb. applied 

 per acre. 



140 



5. Sulphate of Iron ... 



45 

 100 

 200 

 400 



