414 FUNDAMENTALS OF FRUIT PRODUCTION 



great reduction, the checking influence differing greatly with the variety, 

 however. Varieties Hke Esopus and Grimes, that are much inclined to 

 develop spurs at an early age, show a relatively greater check in this 

 respect than those like Rome and Gano that as young trees produce 

 comparatively few spurs. In any case, however, pruning tends to reduce 

 their number. Data are presented showing also that severe pruning acts 

 in a similar manner in decreasing the numbers of fruit buds that form 

 on the spurs. ^^ Similar data on fruit bud formation in young apple 

 trees have been obtained in West Virginia^ and in England.'* The ratio 

 of flower clusters for the years 1909-1914 obtained by the English 

 investigators in one of their experiments was 52 for hard pruning, 100 

 for moderate pruning and 180 for no pruning. There were corresponding 

 differences in total yield. All these investigators show that heavily 

 pruned trees may be expected to come into bearing more slowly than 

 those pruned moderately, lightly or not at all. 



On the other hand, heavy pruning does not always result in decreased 

 yields. Data obtained in an experiment with Arkansas and York 

 Imperial apple trees that had been bearing for a number of years and 

 were somewhat lacking in vigor, summarized in Table 9, show steady 

 increments in yield with each increase in the severity of the pruning. ^ 



Table 9. — Influence of Pruning on Yields in a Declining Apple Orchard 

 {After Alderman and Auchter"^) 



AFKaiisas, iwit-ivdo i orK, lyit crop 



crops (bushels per tree) (bushels per tree) 



Arkansas, 1914-1915 



York, 1914 crop 



Heavy pruning . . . . 

 Moderate pruning . 

 Light pruning 



14.02 



11.94 



9.15 



The heavy pruning must have had the effect of reducing somewhat the 

 total number of fruit spurs, at least in comparison with the trees pruned 

 more lightly. Consequently the increased yields must have been due 

 either to the formation of a larger number of fruit buds or to the better 

 setting of the blossoms. This is an influence not unlike that already 

 pointed out as very frequently attending the judicious use of nitrogenous 

 fertihzers. 



Influence on Leaf Area and Fruit Size. — In Table 10 are presented data 

 on the influence of varying amounts of pruning on average size of leaf 

 and total leaf area in apple trees. Not only are the individual leaves of 

 the heavily pruned trees larger than those of the unpruned or lightly 

 pruned trees, but there are more of them. Consequently such trees 

 have a materially increased leaf surface. This in turn creates a greater 

 requirement for nutrients and for moisture; if this requirement is met, an 

 increased production of elaborated foods may be expected. 



