344 CONTROLLING INSECTS AND DISEASES 



windward sides will be covered, as the spray will not drift 

 back against the air currents. In spraying from one position, 

 however, many more of the leaves will be turned and well 

 coated with material when high pressures are used than when 

 ordinary pressures are employed. It is not expected that the 

 spraying operation will be carried on in the teeth of a strong 

 wind, but it is seldom that a still day is available for the work, 

 especially in the early spring. A steady wind from a constant 



(Mich. Exp. Sta.) 



Fig. 130. These men are using two platforms — one improvised at the 

 front of the sprayer. They are using single-nozzle guns and a pressure 

 of 600 pounds. Note how the mist hangs on the tree. 



quarter gives less difficulty than a fitful, shifting breeze, whose 

 antics cannot be anticipated. 



A method sometimes employed is to spray only with the 

 wind ; that is, to spray the windward sides of the trees and then 

 wait for the wind to change before completing the job. This 

 practice has not given good results and is not recommended. 

 Careful examination has disclosed many uncoated areas in the 

 tops, and very poor aphis control has been secured. In sections 

 where prevailing winds are from one quarter the grower might 



