20 SHADE TREES FOR NORTH CAROLINA. 



first place, to reduce the size of the crown to compensate for the reduced 

 root surface. This is far more necessary in forest-grown specimens, the 

 roots of which are frequently badly mutilated in lifting than in nursery- 

 grown stock, the roots of which are more compact and better provided 

 with fibrous rootlets. The severity of pruning required varies with the 

 species. Easily rooting species, like willows, true poplars, elms, and 

 maples, usually require, if nursery-grown stock, only a slight reduction 

 in the crown surface; while those species that root more slowly, as the 

 oaks, magnolias, yellow poplar, cucumber, hickories and walnuts, require 

 considerable crown-pruning. 



Crown-pruning, no matter how severe, should, in general conform to 

 the shape the tree is to assume. Species which form deliquescent stems 

 like those of the elm or maple (see PL IV, A) can be topped, but the top- 

 ping should take place at the height at which it is desired to form the 

 base of the crown. Species which do not produce deliquescent stems, but 

 whose growth is excurrent, consisting of a central shaft from which subor- 

 dinate branches spring, like that of the yellow poplar (PI. II, A), should 

 generally not be topped at all. Topping of such species as these is likely 

 to result in the formation of several stems or a forked stem and irregu- 

 larity of shape. It is a better practice to confine the pruning of trees of 

 this class to the removal or partial removal of lateral branches and not to 

 cut back the main leader at all. The base of the crown is determined in 

 trees of this class subsequent to planting, by the removal of the lower 

 branches. See also PI. V, A. 



It is usually preferable to plant small trees from •£ to 1 inch thick, at 

 the height of a man's shoulder, and from 6 to 8 feet in height. The cost 

 of handling trees of this size is much less than that of larger stock; they 

 can usually be removed with far better roots than larger trees; and on 

 account of their more rapid growth, they frequently outgrow larger 

 trees whose roots are not so well preserved. 



SUN SCALD OF YOUNG TREES. 



Small trees whose stems have been shaded, as those from very close nur- 

 sery rows, and forest-pulled specimens, especially of the sun-tender spe- 

 cies with their smooth bark, are subject to sun scald. This results from 

 the killing of the cambium or inner bark on the southern or southwestern 

 side of the tree by the beat of summer and autumn suns. The first indi- 

 cation of sun scald is the cracking of the bark in vertical, and then in 

 cro earns, as it becomes dry and brittle. In the later stages it fre- 

 quently peels off or curls up in long strips, exposing the sapwood, which 



