NUTRITION 17 



pruning makes more wood in the current year 

 than summer pruning, because the season's growth 

 is nearly or quite completed when the summer 

 pruning is performed ; but beyond this state- 

 ment it is not the purpose to venture at this 

 point (see Section 16, Chapter IV.). 



I have said that pruning, of itself, cannot be 

 injurious so long as it does not interfere with 

 the nutrition of the plant. It is important, 

 therefore, that I explain how this interference 

 occurs. A plant derives a certain portion of its 

 food from the soil in the shape of soluble inor- 

 ganic materials. These materials ascend to the 

 leaves through the young wood, and become 

 associated with organized compounds like starch 

 and sugar. These organized compounds are used 

 in the repair and growth of all parts of the 

 plant, and they are, therefore, distributed to 

 the leaves, twigs, trunk and roots. The growth 

 of the roots is, therefore, largely determined by 

 the amount and vigor of the top or leaf-bearing 

 portion. The removal of the greater part of the 

 top may interfere, therefore, with the vigor of 

 the plant by preventing the supply of a sufficient 

 amount of elaborated food. This difficulty is 

 sometimes experienced in the girdling or ringing 

 of grape-vines, which prevents the distribution of 

 the elaborated plant -foods to the roots. It 

 should be said, however, that the grape is 

 pruned the most severely of all fruits, and it is, 



