DWAEFING. 153 



the European system of walls and espalier training, but 

 we shall do well to watch the application of the very im- 

 portant principles involved in their practice, since these 

 may be applied to our orchards with manifest advantage. 

 In reference to the form and management of trained trees, 

 it is established as an axiom that their permanency is de- 

 pendent upon an equal diffusion of the sap being kept up 

 throughout the whole extent of their branches. This oc- 

 curs naturally in all trees, because they develope them- 

 selves in the forms natural to them, but in our gardens 

 and orchards we make our trees assume unnatural forms. 

 The sap flows to the highest parts by a law which is well 

 known, though not so well understood ; as a consequence, 

 the lower branches do not receive their needed supplies, 

 and being smothered by those above them, they eventu- 

 ally die and decay, leaving a naked stem supporting a top, 

 or the common form of the natural tree. To maintain the 

 shape we desire — be this lie pyramid, the vase, or the es- 

 palier of whatever kind — certain operations must be per- 

 formed from time to time, as the conditions of the tree 

 may indicate. 



Among these, Du Breuil advises to prune the strong 

 branches short and allow the weaker ones to grow long, 

 and thus to restore the balance : This may be done at the 

 spring pruning, and also at any time during the growing 

 season, when it may be necessary to check excessive 

 growth at any one point: and upon this principle depends 

 some of the most important practice of the summer prun- 

 ing of our vineyards. The sap flows towards the leaves, 

 and by removing them from one part, and leaving a pre- 

 ponderance upon another, we change the direction of its 



