APPENDIX. 



441 



root area. The root system of a tree is comparable to the boiler of an en- 

 {,ine. A twenty-horsepower engine with a ten-horse boiler is capable of 

 doing only patial duty, so a tree lacking roots is only capable of making a 

 feeble growth when the demands of the branches cannot be fully met. An 

 insufficient food system means a partial food supply, lack of moisture, weak 

 and unsatisfactory growth, which invites the attacks of insects and fungus 

 diseases. 



Good culture and rational pruning will overcome such drawbacks, when 

 good stock is at hand to begin with. 



Fig. XXXI. Fig. XXXII. 



Trimming the top — If the whole of the top carried by a tree as it stands in 

 the nursery were to be retained when it is planted in the orchard, the 

 lessened root surface, together with the unsettled condition of the roots, 

 would soon prove that the balance between root and top had been interfered 

 with, and that the tree was top-heavy. The demand of the expanding leaves 

 and growing branches would soon prove too great for the reduced and dis- 



