FROST PROTECTION. 



349 



to cover and protect it. After the earth has been placed 

 about the trees, it usually settles somewhat or is washed 

 down by the rain. For this reason it is usually best to 

 go over the work three or four weeks afterward and place 

 more earth about the tree. 



All grass and weeds should be cleaned away from 

 the trees and nothing but fresh, clean soil should be used 

 in banking. If weeds and grass are placed in contact with 



Fig. 78. Citrus trees banked to protect the trunks from frost. 



the trunks, wood-lice too frequently cause considerable 

 damage. They commence work first in the decaying vege- 

 tation and then transfer their attentions to the trunk. 

 One of the best ways to secure fresh, clean earth, free 

 from organic matter, is to remove the weeds and four or 

 five inches of surface soil from an area of two square feet 

 or so, then dig a hole deep enough to supply sufficient 

 earth for the tree. In spring the earth can be thrown 



