FILLING TREES 99 



Danger from water pockets, the most frequent 

 cause of failure in tree work, has been completely 

 avoided by the good drainage produced by 

 grounding the filling. 



In basal cavities which have progressed farther, 

 the decay working higher up the trunk, some of 

 those advantages may be realized which follow 

 the filling of simpler cavities of the same type, 

 while others may not be. The main difficulty is in 

 the removal of all the decay, especially when it 

 runs higher up in the trunk and perhaps into 

 several large limbs. In such a case the larger ex- 

 pense and the greater uncertainty as to effective- 

 ness demand that careful consideration be given 

 to the value of the damaged tree and to its possible 

 future value, before the work is started. 



When we come to large cavities in the upper 

 part of the trunk, oftenest caused by the break- 

 ing out of large limbs, involving bad crotches and 

 saddles, we come to the most difficult and most un- 

 certain class of cavity work. The trees are often 

 so old that their value is problematical at best. 

 The great strain on the filling makes indispensable 

 a great deal of expensive bolting through the 

 trunk, with its unavoidable damage to the conti- 

 nuity of the cambium. It can be pretty definitely 

 stated that fillings of this type cannot be done suc- 

 cessfully with concrete. Such a filling has to be 

 divided into small sections to accommodate the 



