GENERAL PRINCIPLES OF PRUNING 129 



tip of the leaders, then it ought to have a considerable influence 

 towards fruit-bearing. 



This seems to be a reasonable explanation. We have said 

 that rank growth does not favor fruit, while moderate growth 

 does. This is because it is necessary to have plenty of elabo- 

 rated plant food, such as starch and sugar in the cells to 

 produce the fruit bud. It is the lack of this elaborated plant 

 food which forces the little apple spur to produce merely a leaf 

 bud the year that it bears an apple. Now if the sununer prun- 

 ing is delayed until rather late in the season so that plenty of 

 leaf surface has been developed to majiufacture starch and sugar, 

 and if we then merely take out the growing tip we develop 

 exactly the conditions that will tend towards fruit. We have 

 taken away that part of the plant which Avas forming new leaves 

 and new wood and which was therefore using a large amount 

 of plant food (far more than it was itself producing), and we 

 have left the manufacturing end of the tree practically the 

 same as it was before. There is nothing left for the tree to do 

 but to develop fruit buds. 



Different Pruning for Old and Young Trees. — It is perhaps 

 worth Avhile to give one more general principle and that is that 

 the habit of growth is quite different in a young tree from that 

 in an old tree, aiid consequently the young tree requires a 

 different kind of pruning. This difference is shown in various 

 ways. In the first place the young tree grows more rankly, 

 producing longer shoots and larger leaves. 



In the second place young trees of most varieties tend to 

 make a much more upright growth while young than when they 

 get older. This is especially true of certain varieties of plums, 

 apples, and pears, but it applies more or less to nearly all kinds 

 of tree fruits except a certain few, like the Burbank and fSatsuma 

 plums, which are persistent sprawlers from the start (Fig. 57). 

 Now if one of these close-growing young trees is thinned out 

 during the first few years to what may seem the proper degree 

 of density then, when it comes into bearing, and the branches 

 spread, as they naturally will, with the load of fruit the top is 

 entirely too open. The pruner ought, therefore, to understand 



