ONE-SPKAY METHOD FOE CODLING MOTH, ETC. Ill 



the bureau on the curculio give an average percentage (average of 

 percentages) of fruit free from injury on the one-spray plat of 82.62 

 as compared with 82.40 per cent of sound fruit on plats receiving the 

 demonstration treatment. The percentage of sound fruit on the 

 unsprayed trees was 55.50. Results obtained by Eumsey (1. c.) 

 fully substantiate the foregoing. In his work a single spraying gave 

 87.5 per cent of crop free from injury as compared with 86.1 per cent 

 of sound fruit on the plat receiving four applications, the check plat 

 showing 67.9 per cent of uninjured fruit. In the case of the curculio 

 the degree of protection afforded by spraying varies much more 

 widely than for the codling moth, depending upon the abundance of 

 the insects and the quantity of fruit present on the trees, as may be 

 seen by reference to the tables on the subject in the foregoing pages 

 and in the previous report (Bui. 80, Pt. VII) . 



It would therefore appear from the foregoing that for the control 

 of the codling moth and plum curculio under eastern conditions, a 

 single thorough spraying is about as efficient as a schedule of treat- 

 ment requiring three or more applications; were these the only 

 troubles to be considered, the orchardist would hardly be justified in 

 making additional applications. 



The reader should bear in mind, however, that in the experimental 

 work reported applications have been made with an unusual degree 

 of thoroughness. It will be evident that the value of a single spray- 

 ing depends entirely on the extent to which the calyx cups of the fruit 

 are filled with the poison. Perfect spraying in this regard should 

 prevent all calyx entrance of fruit by the larvae. As a matter of fact, 

 in our plats sprayed most thoroughly we have not been able entirety 

 to prevent calyx entrances, though such a degree of thoroughness has 

 been obtained, as reported by other experimenters in the Western 

 States. The point can not be too strongly emphasized that thorough- 

 ness is the keynote in obtaining satisfactory results from the one- 

 spray method. 



The necessity of filling the inner calyx cup with poison, as insisted 

 upon by western entomologists, and the employment of a nozzle 

 throwing a coarse spray, as the Bordeaux, has not been, on the whole, 

 confirmed under eastern conditions. 



It appears that as good results follow the use of nozzles throwing a 

 fine spray as where coarse nozzles are used. It is also clear that under 

 our conditions there is no necessity to fill the inner calyx cup to con- 

 trol the codling moth successfully, and indeed this is prevented by 

 the stamen bars which remain turgid and shield the cavity below, 

 even after the calyx lobes are nearly closed. There can be no ques- 

 tion of the desirability of high pressure in spraying (175 to 250 

 pounds), and most orchardists appreciate this fact. The practical 



