PRUNING— THE METHOD 423 



a condition of tree in many ways closely comparable to that of the privet 

 or osage orange hedge. 



Influence on Fruit-hud Formation and Fruitfulness . — The orchard 

 is grown and maintained not primarily for its shoot growth or for its 

 spurs, but for fruit. The grower therefore wishes to know the influence 

 of different pruning practices on fruit-bud formation. It has been 

 shown previously that this occurs at varying times in diverse plants 

 and that different species present entirely unlike fruit bearing habits. 

 That is to say, some bear on spurs, some on shoots; some bear terminally, 

 some laterally. If, then, pruning practices differ greatly in their influ- 

 ences on spur formation and shoot formation, corresponding, perhaps 

 greater, differences may be expected in their influences on fruit-bud 

 formation and fruiting. The practice that leads to greater fruitfulness 

 in one species may tend in the opposite direction in another. Thus 

 heading back may be a good practice in growing the peach because it 

 encourages new shoot formation on which the fruit buds are borne and 

 on the other hand, heading back may be a bad practice for the pear, 

 because it generally limits the formation of fruit spurs on which most of 

 the fruit of this species is borne. 



In contrast to thinning out, heading back generally tends not only to 

 reduce the number of spurs in spur bearing species but also to lower the 

 percentage that differentiate fruit buds. In these same species, thinning 

 out, though it may reduce somewhat the total number* of fruit spurs, has 

 been shown under some conditions to lead to the formation of fruit buds 

 and to the maturing of fruit on a larger percentage of those remaining. 

 Data on this question obtained from pruning experiments with j^oung 

 apple trees in Oregon are furnished in Table 12. The figures presented 

 in the last three columns of this table also show something of the influence 

 of these two pruning practices on fruit-bud formation on shoots. Though 

 the apple is not generally considered a shoot bearer, where this investiga- 

 tion was carried out, two of the varieties studied, Rome and Gano, bear 

 principally on shoots for the first few seasons. Thinning out generally 

 encouraged terminal and lateral fruit-bud formation on shoots more 

 than a corresponding heading back, though there were some exceptions. 

 In commenting on these data Gardner^- says: 



"The moderately thinned Grimes trees were somewhat more than twice as 

 productive of fruit buds as the correspondingly headed trees; the heavily thinned 

 Grimes trees were 10 times as productive of fruit buds as correspondingly headed 

 trees. The moderately thinned Rome trees were nearly twice and the heavily 

 thinned, nearly five times as productive of fruit buds as those correspondingly 

 headed. On the other hand, moderately thinned Gano trees produced but 

 slightly more fruit buds than those moderately headed, and heavily thinned 

 trees of this variety averaged distinctly fewer buds than those heavily headed. 

 The last statement also holds true of the heavily pruned Esopus trees. A more 



