228 The Commercial Apple Industry 



encieo may intervene. The seasonal development of pests 

 and diseases varies greatly. The spray problem requires 

 individual study with careful regard for general principles 

 in control methods. 



Cost of spraying. 



The results of cost-production studies as applied to spray- 

 ing lack stability since labor rates vary greatly in different 

 regions and change from year to year even within a given 

 district. The cost of spray material suffers similar 

 changes. However, the amount of labor as expressed in 

 man and horse hours does not fluctuate greatly and affords 

 a reliable basis for comparison. The writers conducted 

 detailed cost studies in hundreds of orchards in various 

 regions of the United States and a number of important 

 points regarding the amount of labor involved and material 

 used were brought out. In the cost studies, a three-man 

 and two-horse crew operating a power spray outfit was 

 taken as a basis. Dusting and the spray-gun were not 

 used. 



It was found that such a crew sprayed on the average 

 of three to five acres of bearing trees in a ten-hour day. 

 It was noticeable that the northwestern growers sprayed 

 out more material in a day than those in other districts, 

 the average of Yakima and Wenatchee being 1,750 gallons 

 a day. The same size crew operating in western Xew 

 York averaged only 1,100 gallons a day. This disparage- 

 ment in favor of the efficiency of the western spray crew 

 may be explained partly by the fact that the presence of 

 water in irrigating ditches greatly facilitates the reload- 

 ing of spray tanks and in this way increases the efficiency 

 of the spray crew. 



