92 PRINCIPLES AND PRACTICE OF PRUNING. 



degree with the loss of the roots. This may be done by thin- 

 ning out all the feeble shoots, so as to leave an even, well- 

 shaped head, and then cutting back a part of each remaining 

 one-year shoot (Fig. 123). Judgment must be exercised as to 

 the amount to be cut away from the tops. The 

 growth of new roots depends on the assistance 

 afforded by the leaves at the top ; if the leaves 

 are too few, the roots will not extend freely ; 

 if they are too many, the roots cannot furnish 

 proper supply for them, and they will be feeble 

 and sickly. Planters will learn a great deal 

 on this point by cutting away more or less on 

 different trees, and observing the result. Dif- 

 ferent kinds of trees require varying manage- 

 ment in this respect. The peach, for example, 

 readily reproduces new shoots, and it may, 

 FIG. 123. Figure consequently, be cut back very freely; two- 

 O f thinned and thirds to nine-tenths of each previous season's 

 shortened -back shoot m be remove a without detriment. 



young tree. * 



The grape, also, may be very heavily pruned, 

 as it throws out new vines with great vigor. The cherry, on 

 the contrary, is very sensitive, and young trees have been 

 nearly killed by a severe summer pruning. The young cherry 

 shoots should never be cut back in spring more than half their 

 length. The pear and apple are intermediate, and the heads 

 should be moderately and not severely pruned. 



The mutual relation between the roots and leaves has been 

 already alluded to. The leaves cannot exist without the moist- 

 ure received through the roots; and the roots cannot grow 

 without the nourishment afforded by the leaves. The only 

 exception is the temporary supply furnished by the cells in the 

 body of the tree. New roots are commenced before the leaves 

 expand, as may be seen on young seedlings, the roots of which 

 have been trimmed, and where the new white fibres protrude 

 just as the buds are swelling. The same occurs on the roots 

 of trees transplanted in autumn, after the leaves have fallen ; 

 but this effect is only temporary, continued growth requiring 

 that both leaves and roots should work together. On the other 

 hand, the nutriment laid up in the cells will sometimes supply 

 the leaves for a short period, provided care is taken to furnish 



