190 B.C. Entomological Society 



With these factors as the standard of excellence, the casemate spread- 

 er has appeared the most promising. Oil emulsions are a most worthy 

 competitor, but there is a decided element of danger in their use under 

 factors 2, compatibility, and 4, ease of preparation, as outlined above. 

 If we could be sure the growers would appreciate the element of chance 

 and use the necessary precautions in properly handling the oil emulsion, 

 the ranking of these two materials as spreaders might possibly be 

 changed, but in general the risk with oils is too great for their general 

 adoption. 



Casein Spreader 



In the tests at the Experiment Station and in the earlier field work, 

 ordinary commercial ground casein, mixed with hydrated lime, was em- 

 ployed. In the earlier commercial orchard tests, while growers "mixed 

 their own" casein spreader, not all reports were favorable. The process 

 of mixing the spreader and its addition to the spray solution were of 

 themselves subject to failure where any short cuts were attempted, also 

 the casein a\'ailable was variable in sizv? of particles and in character. 



With the opening of the season of 1921, some commei'cial companies 

 began tlie manufacture of a prepared casein sjireader. Of the powdered 

 forms, which were \)y far in the majoi'ity, it may be said that in general 

 tliej^ represented a high-grade casein, ground somewhat finer than the 

 ordinaiy commercial product and tliorougly mixed in definite propor- 

 tions with hydrated lime. 



These ccimmercial materials combined to a very satisfactory degree 

 the "essential factors" of a spreader. Particularly in the matter of 

 ease of preparation were they popular, because it was possible to sift 

 them directly into the spray tank, obviating any extra manipulations. 



Spreaders in the Arsenate Sprays 



The majority of the experimental work with spreaders at the station 

 and in the majority of the cases of their use in the field, they were 

 employed with poison spray solutions. The use of spreaders with the 

 poison spray solution constitutes, therefore, the primary object of this 

 enquiry. Summarizing our knowledge, it may be grouped imder the 

 following heads : 



1. Does the Addition of a Casein Spreader Increase the Efficiency of the 

 Poison Sprui/ in Apple-Worm Control'? 



Earlier investigations under rather carefully conducted controls at 

 the Oregon Station indicated a fairly marked increase in the percentage 

 of control obtained where spreaders were added to the poison spray solu- 

 tion. During the past two seasons results have been more variable, and 

 certainly less conclusively in favor of the spreaders. 



Reports from California are conflicting, some feeling that decidedly 

 better results are obtained, others finding little evidence of improved 



