I02 



PRUNING AND GRAFTING 



region of the stock. The junction of the scion with the stock is 

 sealed with grafting wax to prevent decay and the drying out 

 of the exposed cells while the callus is joining together the corre- 

 sponding 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 July or when the apical bud 



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. 



is formed, because the cambium is still active at this season and 

 especially since the buds are forming. By removing that portion 

 of the branch which would only produce leaf buds a better 

 development of the flower buds is ensured. 



Although the organic union between scion and stock is com- 

 plete, each part continues a separate and distinct existence. For 

 example, 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- 



