86 POMOLOGY 



With all the trees in the experiments, heading-back 

 resulted in a decrease in the number of fruit-spurs to which 

 the individual shoot gave rise, this being more marked with 

 increase in the severity of the heading. In other words, 

 fruit-spur formation on the individual shoot was correlated 

 with its length after rather than before the pruning. 



A statistical study of the two types of pruning as applied 

 to Grimes, Gano, Rome, and Esopus seemed to warrant 

 the following conclusions: 



1. A general heading-back of the shoots of a tree acted as 

 a stimulus to new growth. The amount of the stimulus 

 varied considerably with variety. 



2. An equally severe thinning acted as a check to new 

 growth, but this also varied somewhat with variety. 



3. Heading-back resulted in a more marked check to 

 fruit-spur formation than did equally severe thinning-out, 

 with such varieties as Grimes and Esopus. The reduction 

 was not so marked with Gano and Rome, as they bear a 

 large percentage of their fruit-buds laterally on the new, 

 terminal shoots, especially when young. 



4. Thimiing-out increased the production of fruit-spurs, 

 as compared with equally severe heading. On the other 

 hand, heading generally augmented the production of ter- 

 minal fruit-buds on the few shoots. In some varieties, 

 thinning was accompanied by a greater production of lateral 

 fruit-buds on shoots than equally severe heading; in other 

 varieties, the reverse was the case. In general, thinning- 

 out tends to increase flower and fruit production, while the 

 heading-back is likely to decrease those functions. 



These two types of pruning are further considered in detail 

 as they a]5ply to young trees. 



78. Detailed response of young trees. — As is described 

 and discussed above, thinning-out refers to the removal of 

 a portion of the limbs, branches or shoots in order to "open 



