144 THE PHYSIOLOGY OF PLANTS 



tion of wood can be stayed by close pruning. By doing so 

 the weak buds at the base of the shoot are caused to swell and 

 to develop more strongly than would normally be the case. 

 By this means strong shoots will later on be formed in the 

 neighbourhood of the main branches. 



If the general constitution of the tree is weak, it is essential 

 to create as large an amount as possible of assimilating leaf 

 surface. In such a case, therefore, it is advisable to prune the 

 shoots only slightly, giving at the same time sufficient water to 

 the roots. 



Varieties which flower sparingly should not be pruned in 

 closely, but this may take place in the case of plants which 

 produce a large number of flowering buds. 



The same close pruning is applicable to varieties in which 

 the growth of the apical buds predominates and which produce 

 very few lateral branches, so that the crown when left to itself 

 consists of long unbranching shoots. If the varieties branch 

 freely they should be only slightly pruned. 



The character of any variety is, however, greatly changed by 

 the stock on which it may be grafted. The so-called dwarf- 

 stocks of our pears and apples (paradise-stock and quince) cause 

 the production of shorter shoots, but, on the other hand, a greater 

 and earlier production of flowers, whereas the wild (crab) apple 

 and pear stocks favour the formation of strong woody shoots. 

 Grafts on the latter must therefore only be slightly pruned, 

 whereas the others may be closely pruned. 



The age of the tree, too, requires to be taken into consi- 

 deration. All young trees tend chiefly to develop vegetative 

 shoots, i.e., to run to wood, and should therefore be pruned 

 less closely than old specimens of the same variety and in 

 similar situations. 



In the case of trees grown against a wall, especially if the 

 artificial French shapes are the object of attainment, the pruner 

 must pay attention to the position of the branch. In the 

 "cordon" type the strong branches are kept horizontal. But the 

 more horizontal a branch, the smaller the supply of water to 

 the buds ; the nearer the branches approach the vertical, the 

 more copious is the supply of water and the larger the leaves and 

 intemodes. The shoots coming off from the horizontal branches, 



