134 



Dry Spraying of Charlock. 



[May, 



DRY SPRAYING FOR THE 

 DESTRUCTION OF CHARLOCK. 



W. A. Millard, B.Sc, 

 Lecturer in Agricultural Botany, University of Leeds, 

 and S. Burr, 



Research Assistant in Agricultural Botany, University of Leeds. 



One of the most successful operations now commonly carried 

 out in farming practice is admittedly that of the destruction of 

 Charlock in corn crops by means of a spray, consisting generally 

 in this country of a 4 to 5 per cent, solution of sulphate of 

 copper (Bluestone), that is to say 4 to 5 lb. of sulphate of copper 

 to 10 gal. of water, applied at the rate of 40 to 60 gal. per acre. 



In certain parts of the country, however, where the shortage 

 of water is at all times a serious problem for the farmer, wet 

 spraying, if not a matter of impossibility, is at least one which 

 makes too great a demand on the limited water supply, or entails 

 more labour in carting water to outlying parts of the farm than 

 can be conveniently or economically spared. In such districts, 

 a considerable advantage would be gained if it were possible to 

 substitute a dry powder for the wet spray, provided the former 

 was equally efficacious, and not unreasonably expensive. 



It was with this object in view that the present experiments 

 with dry sprays of some powdered chemical substances were 

 arranged, and carried out during the last two years. 



From published reports it was found that a certain amount 

 of experimental work had already been done on the subject, and 

 a short summary of this is given below. 



SUMMARY OF FORMER TRIALS OF DRY POWDER 

 SPRAYS. 



The substances tested, of which records have been found, 

 were Calcium Cyanamide (Nitrolim) , Sulphate of Iron, 

 Nitrate of Lime, and Kainit. 



I. Calcium Cyanamide.* — The experiments recorded in 

 references 1-5 are of German origin, except No. 3 which is 

 Swiss; the quantity of calcium cyanamide applied varied from 



*(1) Jour. Board of Agric, Dec, 1907, p. 568. 



(2) Jour. Board of Agric, Dec, 1909, p. 761. 



(3) Jour. Board of Agric, Jan., 1909, p. 776. 



(4) Jour. Board of Agric, Oct., 1913, p. 618. 



(5) Jour. Board of Agric , April, 1914, p. 64. 



(6) "Charlock Destruction," Bull. I, Agric Dept., Univ. Coll. of N. Wales, 



Bangor." 



(7) Die Verbreituug u. Bekampfung der Ackerunkraeiiter in Deutschland, 



Bd. 1, May. 1918: Arbciten der D.L.G., Heft. 294. 



