b THE HOP APHIS IN THE PACIFIC EEGION. 
Control of the hop aphis— Continued. p age< 
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 
