August, '16] 



McCOLLOCH: DUSTING FOR CORN-EAR WORM 



395 



purchased, knowledge of the nozzle discharge at the required pressure 

 as well as the loss by friction in the pipe are necessary. Nozzle dis- 

 charge is easily determined with a spray pump and pressure gauge. 

 The following table of loss by friction of water in pipes shoAvs the loss 

 in pounds pressure per square inch for each 100 feet in length due to 

 friction. 



It is seldom advisable to use less than inch pipe as the loss by fric- 

 tion in smaller sizes is too great. The main might well be constructed 

 of Ij-inch pipe. A large mixing tank automatically emptying into 

 the spray tank is necessary to insure a continuous supply of insecticide 

 or fungicide. Drainage outlets at the lowest levels should be provided 

 for emptying the system after use. Where several fields of one or 

 two acres each require spraying a surface system easily and quickly 

 adjustable to be moved from one field to another might offer advan- 

 tages with certain crops. 



ADDITIONAL NOTES ON THE USE OF DUST SPRAYS 

 AGAINST THE CORN-EAR WORM^ 



By James W. McColloch, Assistant Entomologist, Kansas State Agricultural Experi- 



vient Station 



In the Journal of Economic Entomology for April, 1915, the 

 writer presented a paper on " Recent Results in the Use of Dust Sprays 

 for Controlling the Corn-ear Worm." In this paper the following 

 conclusions were drawn: 



(1) The amount of corn-ear worm injury can be greatly reduced by 

 the thorough dusting of the silks. 



(2) The cost of dusting is prohibitive where corn is raised for grain 

 and forage but is profitable where corn is grown for roasting ears, show 

 purposes, or for seed. 



' Contribution from the Entomological Laboratory, Kansas State Agricultural 

 College, No. 19. 



