36 N. S. ENTOMOLOGICAL SOCIETY. 



and plus the cost of additional hydrated lime and compound- 

 ing the mixture. From estimates received from various manu- 

 facturers, it is thought that the completed dust mixture, would 

 cost about sixty per cent more, than the materials to spray the 

 same area. 



The cost of the 2i-l dust as used by the writers on the 

 apple should be from $3.50 to $4.50 per hundred lbs., and the 

 cost of the 5-2 dust as used on the potato should be from $6.00 

 to $7.00 per hundred lbs. 



The greatest item in the cost of spraying, however, is not 

 the cost of materials but the cost of application. 



Most authorities will agree that it costs about two cents 

 per gallon to apply liquid spray and about one half cent per 

 pound to apply dust. Reckoning that the average barrel of 

 apples required eight gallons of liquid, or four pounds of dust, 

 for four treatments, the following costs are approximately cor- 

 rect for keeping one barrel of apples clean. 



Sulphur 90% arsenate of lead 10% dust 44 cents 



Bordeaux 4.10.40 arsenate of lime 1 lb. liquid 33 " 



Bordeaux 3.10 40 " " lib. " 30 " 



Bordeaux 2.10.40 " " 1 lb. " 27 " 



Lime sulphur 1.008 sp. gr. arsenate of lead paste2.40 25 " 



Lime sulphur 1.008 sp. gr. arsenate of lime 3-4 — 40 23 " 

 Soluble sulphur 1 — 40, hydrated lime 5 — 40, arsenate 



of lime 1-2—40 20 " 



New copper dust 2 1-2 metallic copper, 1 % metallic 



arsenic 17 cents 



New copper dust 5 % metallic copper, 2% metallic 



arsenic 27 cents 



While the prices mentioned may vary, those given are ap- 

 proximately correct for 1918 in Nova Scotia. 



The great drawback to the dusting method has been cost 

 of material, the second drawback, partial inefficiency in the con- 

 trol of pests, as compared with liquid spraying. The formula 

 outlined will probably do away with the first drawback to a 

 great extent, and may possibly do away with the second as well. 



This dust is a*s yet in no stage to be recommended to the 

 practical grower. The formulae, the proportions of copper 



