502 General Principles for the Management of Fruit Trees. 



from deriving advantage from the above important agencies as 

 regards vegetation ; these may be termed mechanical effects. 

 Physiologically considered, the progress of the sap is limited by 

 summer-pruning, and is directed towards the leaves and buds 

 on the lower parts of shoots, which are in consequence invigo- 

 rated, more especially as their free exposure to light, &c, 

 enables them better to elaborate this increased supply. But 

 although the foliage so left to act is increased in size and ef- 

 ficiency, yet the agency of this portion in producing roots is, 

 notwithstanding, less powerful than the whole mass would be, if 

 the shoots were allowed to grow wild throughout the summer ; 

 for in proportion to the mass of healthy foliage, so is the in- 

 crease of roots. Hence excessive vigour is moderated by sum- 

 mer-pruning, and this in a greater or less degree according to 

 the time and manner of performing the operation. The longer 

 the operation is deferred, and the less the portion cut off from 

 the shoots, the greater will be the strength which the roots will 

 derive ; and the earlier and shorter the shoots are cut, the less 

 will be the quantity of foliage, and proportionally so the quantity 

 of roots. Therefore, if a tree is too vigorous, summer-pruning 

 should commence by disbudding such shoots, as they appear, as 

 are not at all wanted to be retained for wood or spurs ; and, as 

 soon as the shoots intended to produce fruit spurs or buds at 

 their base have become furnished with five buds, the extremity 

 may be pinched off. As many as five buds are mentioned, be- 

 cause fewer do not complete one turn of the spiral, which may 

 be traced by following the arrangement of the buds on a shoot 

 of such fruit trees as are usually trained on walls. In the 

 course of a fortnight, the uppermost buds on the portion left 

 will have commenced to push; and they must be allowed to go 

 on for a longer or shorter time without stopping, according to 

 the greater or less danger of the buds at the base being also 

 developed into shoots, instead of remaining in the character of 

 fruit buds till next spring. If the roots, and of course the tree 

 generally, require to be invigorated, the shoots will not be so 

 numerous, and may be allowed to extend till after midsummer; 

 and then only shortened for a little at first, in order that as 

 much foliage as is consistent with the principles above explained 

 may be left to act. It is a very prevalent but no less erroneous 

 notion, that, in the case of an over-vigorous tree, as much wood 

 should be retained, and as many shoots allowed to grow, as 

 possible, in order that its vigour may be moderated by the ex- 

 penditure. Those who hold this opinion may rest assured that 

 the more a young tree grows, the more it is capable of growing ; 

 for growth is not a mere evolution of parts already formed, 

 evolved by a determinate amount of expansive power. If ten 

 buds give rise to a hundred others, these last have the power 



