92 GRAFTING OPERATIONS 



the cambium will remain inactive until spring. Between 

 40 and 50 degrees Fahrenheit will give the best results, 

 but no great harm will result by a drop to 32 degrees. In 

 the spring as the temperature rises the grafts must be 

 watched and as soon as the buds begin to grow they are 

 transferred to the nursery. During the winter small 

 white calluses will form along the line of the union. Where 

 these are not found or where the union has turned black, 

 the cion will not grow and these should be rejected when 

 moved to the nursery. The rejected ones may be planted 

 by themselves. After growing for another year they may 

 again be grafted in the same way. 



Piece Root or Whole Root Grafts. Much discussion, 

 in recent years, has taken place as to whether, in making 

 whip grafts, the entire root of the seedling should be used 

 or if a piece of the root would answer. Most nursery 

 companies offer both, with a higher average price for the 

 whole root grafts. The use of whole roots makes it neces- 

 sary to use one or two-year old seedlings while the piece 

 roots may be cut from older trees. The latter are much 

 cheaper and are often the only ones available. Their 

 desirability for nursery work depends, not on the place 

 where the root was cut, but on the amount of root growth 

 on the mature nursery tree. The consensus of opinion 

 among investigators is that root development is somewhat 

 slower on the older piece roots, but where the roots are 

 healthy and vigorous the resulting tree will be just as good 

 as when the whole root is used. 



Some nursery companies, make and offer for sale cal- 

 lused whip grafts. This offers an opportunity for or- 



