122 PRINCIPLES OF AMERICAN FORESTRY. 



of one shape. Study the natural form of each kind of 

 tree and encourage the development of this form. 



9. When trees are full of frost the wood cracks very 

 easily; therefore do not prune in very cold weather, for 

 bad wounds may then be easily formed. 



Treatment of Crooked Trees. It is common to have 

 some trees in the nursery that are of vigorous, healthy 

 growth, but so crooked as to be nearly worthless. The 

 proper treatment for most of our shade trees when in 

 this condition in the nursery, if anything is to be made 

 of them, is to cut them off at the surface of the ground 

 early in the spring and then select one of the good, strong 

 sprouts that come from near the roots of each tree, train 

 it into a straight stem, and cut away the others. Treated 

 in this way well-formed trees may soon be grown. Such 

 treatment may also be desirable with small street trees 

 that have their stems hopelessly injured. However, 

 trees that to the novice may seem hopelessly crooked 

 may only have crooks in them that will be outgrown 

 in a few vears. 



STREET TREES. 



Success with Street Trees is perhaps more dependent on 

 good soil about the roots than on any other one factor. 

 If the land is so very sandy or gravelly as to be subject 

 to drought, at least two cubic yards (two full two-horse 

 loads) should be taken from where each tree is to be planted 

 and the same amount of good clay or loam substituted 

 for it. If in subsequent years the trees outgrow the limits 

 of the material supplied, more of it should be added, 

 and if this consists largely of stable manure, so much 

 the better, provided it does not come into contact with 

 the roots of the trees. It is important to do this work 



