THE CARE OF STREET-TREES 107 



, Reserve Material. — All the products of assimilation are 

 not at once consumed by the tree, but some are accumulated 

 for future use. This surplus of reserve material is greatest 

 at the close of the growing season in the fall. It is stored 

 by the tree during the winter, and all growth of buds and 

 leaves of the succeeding spring is dependent upon this store 

 of elaborated food. 



WATERING 



Artificial watering of trees is necessary when they do 

 not get by natural means the moisture essential to maintain 

 the soil in a condition most favorable to vegetation. In 

 cities the water from rainfall runs off quickly, and very 

 little finds its way into the soil and subsoil around the roots 

 of trees where it is most needed. Watering depends upon 

 the climate, species of tree, and the nature and extent of 

 the soil and subsoil. Young trees need more frequent 

 watering than older ones. Trees that have surface roots 

 need more watering than deeply rooted ones ; also rapidly 

 growing trees more so than those of slow growth. 



Especially after transplanting, when they begin to rees- 

 tablish themselves and during their first season's growth, 

 trees need an abundance of water. Before the trees are 

 able to care for themselves, new roots must be formed to 

 take hold of the soil. In the meantime the evaporation 

 from the branches and the developing leaves must be sup- 

 plied artificially. 



How Much Water. — How much water to give trees, and 

 at what intervals, depend upon the extent of soil occupied 

 by the roots and the nature of the soil and subsoil. Young 

 trees, two or three years after planting, of which the roots 

 occupy a volume of about a cubic yard, require from twenty 



