34 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



Fig. 33.— Branch die- 

 back or general decline 

 of honey locust caused 

 by soil fill and paving 

 over the root system. 



may be injurious (Fig. 34, 35, 36). Building a frame around a 

 tree (Fig. 36) may protect the trunk during construction, but 

 it will not prevent root injury caused by fill. 



To reduce injury caused by fill, adequate air must be supplied 

 to the roots. You can accomplish this by placing gravel or a grid 

 of tile and gravel over the root area of the tree before the fill is 

 made. But before any fill is made, remove all plants and sod from 

 the area to be filled, and break up the soil surface above the roots. 

 Then add fertilizer as needed. 



Coarse gravel may be spread over the soil surface beneath 

 the branch spread of the tree to provide adequate root aeration 

 (Fig. 37). In fills of 12 inches or more, start with 3-6 inches of 

 gravel beneath the tips of the branches and gradually increase 

 the depth toward the trunk of the tree until it is 8-12 inches or 

 deeper within 2 feet of the trunk. Extend the gravel upward 

 around the trunk to the level of the new fill and to a radius of 2 

 feet beyond the trunk. Place a thin layer of straw or hay over the 



