GRAFTAGE GENERAL CONSIDERATIONS 149 



does not succeed on either pear or apple ; gooseberry may 

 be grafted upon only one species of currant (Ribes 

 aureum) but currants do not succeed on gooseberries ; apples 

 succeed commercially only upon apple stock; peaches and 

 plums will each grow upon the other. For years Prunet 

 tried to make chestnuts grow upon oak in the hope of 

 preventing certain diseases. His conclusions are that 

 the plan will not succeed commercially, though he was 

 successful in many instances. Daniel and others have 

 made many remarkable grafts between distantly related 

 species, so the theory that species must be more or less 

 closely related has been knocked on the head. But from 

 a commercial standpoint, the theory is still operative and 

 probably will continue to be. 



While species of the same genus may be grafted suc- 

 cessfully, it may not be profitable so to do. From a 

 physiological standpoint the best index of success is the 

 general thriftiness of the plant so produced; from a 

 business standpoint, the fact that nurserymen and other 

 plant propagators stick by the methods that make them 

 most money. To be successful, stock and cion must 

 both unite firmly without seriously checking plant ac- 

 tivity and continue growth until normal fruit is ripened. 



205. Common rules of graftage. Graftage in one form 

 or another and with various species of plants may be 

 done during almost any month provided the method be 

 adapted to the time of year and to other conditions. 

 Always it is essential that the parts fit snugly. Prefer- 

 ably the cambium layer of the cion should be in intimate 

 contact with that of the stock. This layer is most active 

 during early spring when the buds are swelling and the 

 leaves are expanding. A second period of activity occurs 

 usually soon after midsummer, but sometimes not until 

 early fall, dependent largely upon the amount of moisture 

 in the soil. During these two periods wounds heal most 

 rapidly and union between stock and cion is most cer- 

 tain. At other times, since the cambium becomes firmer 



