96 



based on practically every apple the tree produced, including 

 the drops, and every fruit grower knows that such figures 

 would mean over 99 per cent, of sound fruit upon the trees 

 at picking time. Obviously, with such results from one 

 spraying, a second and a third application could not add 

 greatly to the returns. 



Theoretically, spraying during the second period, ilame- 

 ly about three weeks after the blossoms fall, should be more 

 efficient than applications at any other time, since it is then 

 that the young caterpillars are just beginning to feed and 

 enter the fruit. We tested the efficiency of this one spraymg 

 during two seasons and found that it was by itself, about 

 one-half or one-third as effective as the treatment given 

 during the first period, in each instance making comparisons 

 with the unsprayed trees as a standard. A spraying during 

 the second period, when given in addition to the first spray- 

 ing, produced only a very slight additional gain in the four 

 year period, namely but .09 of 1 per cent; surely no very 

 material advantage. 



The application in the third period, the latter part of 

 July or in early August, is designed to check the second 

 brood and is applied at about the time the young caterpillars 

 of the new generation are beginning their feeding. These 

 latter are the ones responsible in large measure for the side 

 wormy apples of the late summer. In our experimental 

 work this third treatment, in addition to the first and second, 

 gave an average of 99.22 per cent, of worm free fruit, a gain 

 for the third treatment, of practically IV2 per cent. (1-57 

 per cent). 



There are one series of figures which are particularly 

 significant, namely the percentage of end wormy apples. 

 That for the unsprayed or check trees was a little over one- 

 fifth of the total yield (21.73 per cent.) The trees sprayed 

 only once and during the second period, gave one-eighth of 

 the total yield (12.26 per cent.) of end wormy apples ; those 

 sprayed once and during the first period, practically one- 

 third of 1 per cent. (.353 per cent.) of end wormy apples; 

 those sprayed twice (namely once during the first and once 

 during the second period) yielded less than one-tliird of 1 

 per cent. (.308 per cent.) end wormy apples, while the trees 

 receiving the three applications bore less than one-fifth of 1 



