1921.] 



L37 



Plot 'A. On 75 per cent, of the Charlock plants, not only were the leaves 

 and flowers dead, but the seed pods were so shrivelled, that 

 the seed within them had scarcely developed at all. 

 On the remaining plants only the larger seed pods were living, 

 and these appeared able to set seed. Thistles on the plol 

 were badly damaged, and Coltsfoot slightly damaged. 

 „ 4. Practically all the Charlock had been destroyed, including even 

 those plants bearing full grown seed pods. Thistles badly 

 damaged; many being killed. Coltsfoot badly damaged, 

 but not killed. 



„ 5. The leaves and flowers of the plants were badly withered, but 

 the seed pods were very little injured, and would apparently 

 set seed. Thistles were uninjured, aim" Coltsfoot very slightly 

 injured. 



6. The Leaves and flowers of the plants were killed, and in about 

 30 per cent, of the plants the seed pods were also dead. 

 Thistles and Coltsfoot slightly injured. 



No lasting deleterious effect on the barley was observed on any 

 of the plots. 



It is evident from the foregoing that the best results were 

 obtained with sulphate of copper, and, in the unbiassed opinion 

 of the farmer on whose field the experiments were conducted, 

 these plots were entirely successful. The sulphate of iron, 

 especially in the heavier dressing, also destroyed the leaves and 

 flowers of the Charlock plants, although its action was obviously 

 slower than that of the sulphate of copper, and would thus be 

 more liable to be checked in the case of rain falling soon after 

 the application of the spray. The total failure of the nitrolim 

 was thought to be due, possibly, to its having been kept for so 

 long beforehand, exposed to the air. 



The experiment was regarded as having fully demonstrated 

 the possibility of using dry sprays for the eradication of 

 Charlock, and it seemed probable that, by spraying earlier in the 

 season, equally good results might be obtained with smaller 

 quantities. In the case of sulphate of copper a still greater 

 advantage would certainly be gained if the substance could be 

 obtained in a finer state of division, since obviously the finer 

 the powder the more uniform and economical would its distribu- 

 tion become. It was decided, therefore, to carry out further 

 experiments in the following year, when the defects of the 

 experiments would be remedied as far as possible, and smaller 

 applications of the chemicals would be tested. 



Dry Spray Trials, 1920. — These were carried out at two 

 centres, viz. : — 



(1) Mr. TT. Beachell's farm, near Market Weighton. 



(2) Mr. Wilson's farm. Garforth, Leeds. 



