PROTECTION FROM WIND AND SNOW 37 



cure good root action in the spring. If water stands above 

 this level the roots will not penetrate into it. Where con- 

 ditions are such that a dry season occurring during the 

 summer or fall is liable to affect the growth of the seedlings, 

 then if irrigation could be provided for, so much the better. 

 In the eastern and northern states the so-called " Skinner 

 System/' Fig. 11, of irrigation has been found to be highly 



FIG. 11. The Skinner System of Irrigation. 



efficient in helping to produce good growth. In the south 

 and west, the ordinary methods of irrigation where ditches 

 are used to convey the water between the rows is the com- 

 mon practice. 



Protection from Wind and Snow. In the northern 

 or colder part of the United States, some thought should 

 be given to protection for the nursery plat during the 

 winter months. A few large trees along one side of the 



