6 THE HOP APHIS IX THE PACIFIC EEGIOX. 



Control of the hop aphis — Continued. Page. 



Quassia 28 



Effect of spray materials upon the quality of sprayed hops 30 



Direction in which to work 30 



Control on prune 31 



Field observations 31 



Spraying report 31 



Spraying machinery 31 



Boiling and mixing plant 32 



Field operations '. 32 



Supply wagon 33 



Exchange tanks 33 



Spray rods 33 



Nozzles 33 



The compressed-air spraying machine 33 



Cost of spraying 35 



Cultural methods 36 



Clean culture 36 



Stripping the vines 36 



Picking off infested leaves 37 



Fertilization and irrigation 37 



General summary, with recommendations 37 



The more important writings on the hop aphis 38 



Index 41 



