THE PLUM CURCULIO IN APPLES 



49 



pected, since the greatest effect of destroying infested "drops" becomes ap- 

 parent the following season. 



AvRcnicnl Residue. 



LTnder Massachusetts conditions, the amount of arsenic trioxide which 

 remains on the fruit as spray residue at harvest is well below the legal tole- 

 rance of .01 grains per pound of fruit, following any of the recommended 

 spraj' schedules. Analyses in 1927 showed that even where fish oil, a most per- 

 sistent sticker, was used the residue on Mcintosh contained only .0036 grains 

 of arsenic trioxide, and on Baldwin .0035 grains, both about 1/3 of the amount 

 tolerated. 



Spray Schedule. 



The following adaptation of the standard spray schedule, based on the re- 

 sults of the experiments herein reported as well as on many orchard ob- 

 servations and other reports, is recommended for combating the plum 

 curculio in apples in Massachusetts under average conditions. Due considera- 

 tion should be given to the abundance of the insect, any abnormal seasonal 

 variation, and other factors peculiar to a specific orchard. A complete spray 

 schedule for apples in Massachusetts is printed in Massachusetts Agricul- 

 tural Experiment Station Bulletin 233, The Codling Moth in Massachu- 

 setts (1). 



ADAPTATION OF THE STANDARD ORCHARD SPRAY SCHEDULE 

 TO COMBAT PI.UM CURCULIO 



Dusting 



Dusting with modern equipment has not been thoroughly compared with 

 spraying as a means of combating the plum curculio in this work. Several 

 progressive fruit growers in the state have maintained excellent protection 



