96 



PRUNING AND GRAFTING 



spending tissues in the two parts. When the wound is healed 

 only a slight ring or swelling indicates the point where the scion 

 was inserted — so complete is the union of the vascular and cor- 

 tical regions. It is evident that pruning and grafting should be 

 done at a time when the cambium is most active, i. e., in the 

 spring. In the case of fruit trees it is now the practice to defer 

 the pruning until some time in June, because the cambium is 

 still active at this season and especially since the buds are form- 

 ing. By removing that portion of the branch which would only 

 produce leaf buds a better development of the flower buds is en- 

 sured. 



Fig. 66. A common method of grafting: A, insertion of two scions into 

 cleft of stock at cambium region. B, wound protected with wax to prevent 

 drying out of tissues. — After L. H. Bailey. 



Although the organic union between scion and stock is complete, 

 each part continues a separate and distinct existence. For ex- 

 ample, a scion from a plum grafted upon a branch of a peach tree 

 will develop a shoot bearing plums and the peach tree will also 

 continue its normal growth. Ordinarily only closely related 

 forms may be grafted, as tomatoes and potatoes, apples and 

 quinces, etc. It must be inferred from the above statement 

 that there is no interaction between stock and scion. Usually 

 this is not sufficient to change materially the character of either 

 but there are numerous instances showing that the chemical com- 

 position of the cells or even the form, coloration and productive- 

 ness of scion may be modified by the stock. Fruit growers take 

 advantage of this in grafting the cuttings from seedlings that 

 would not bear for several years upon fruiting trees, with the 

 result that the scion comes into fruitfulness the next season. 



