UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 866 



Contribution from the Bureau of Chemistry 

 CARL L. ALSBERG, Chief 



Washington, D. C. 



August 24, 1920 



PICKERING SPRAYS 



By 



F. C. COOK, Physiological Chemist 

 Insecticide and Fungicide Laboratory 



CONTENTS 



Introduction 



Results of Previous Investigations 

 Purpose of Present Investigation 

 Preparation of Sprays Used . . 

 Results of Investigation : 



Potatoes 



Grapes 



Page 

 1 

 2 

 6 



7 



8 

 . 22 



Page 

 Results of Investigation — continued. 



Apples 29 



Cranberries 37 



Suggestions for the Preparation of Pick- 

 ering Spray on a Commercial Scale . 42 



Summary 44 



Bibliography ' 46 



WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



1920 



