PRUNING 91 



for the strongest mechanical structure. If this dense growth 

 is allowed to develop unchecked, it will result in an excess 

 shading of certain parts with a resultant condition that 

 might be loosely called starvation, followed by a dying of 

 the branches. 



If limbs or branches are removed, it is common knowl- 

 edge that certain shoots are likely to develop which would 

 otherwise remain as latent buds, and especially there is a 

 stimulation or increased cellular activity near the point 

 where the cut has been made. This response on the part 

 of the tree is a type of regeneration — a provision through 

 which some organisms replace lost parts — which leads to 

 the point here involved : why or how does the plant manifest 

 this increased activity near the point of injury? See Figs. 24 

 and 25. 



One theory commonly accepted is that a reduction in 

 the number of growing points and cambial area would make 

 available to the remaining parts an increased amount of 

 the tree's reserve food supply, from which at least the 

 initial growth is made. With this increased food supply, 

 the opening buds would make a much greater growth than 

 would have been possible had no growing points been re- 

 moved. 



A second theory would account for the growth response 

 following pruning by assigning the cause more particularly 

 to the increase in amount of moisture and mineral nutrients, 

 particularly nitrogen, to carbohydrates that are made 

 available to the parts remaining. That is, it is due to a 

 disturbance in the balance of the materials within the 

 tree. These two views may be considered briefly together. 



In the first place, it is well known that a fruit-tree usually 

 manufactures more food material than is utilized in the 

 various phases of growth, including the production of the 

 crop. The unused portion is translocated downward through- 



