78 



Mycologia 



and would prevent the entrance of new insects and fungi and 

 stop the disease already started from spreading. The filling of a 

 cavity in most cases involves as many problems as the filling of 

 a tooth and does not mean mere stuffing of the cavity with some 

 solid substance. The one about to fill a cavity must know whether 

 the disease has permeated the whole tree or is still in its first 

 stages. He must know whether the disease prefers dead wood or 

 live wood, or both; whether it is apt to attack the neighboring 

 trees of another species, and whether it is preferable to sacrifice 

 the whole limb or tree instead of filling it. He must be able to 

 recognize the presence of the fungus fibers in order to know when 

 to stop cutting into the cavity, and he must know how to destroy 

 the various insect enemies found within the cavity. He must 

 know whether the wood is naturally strong and pliable or soft 

 and brash, in order to determine the extent to which he can dig 

 into the cavity with safety. He must judge whether an ordinary 

 filling will hold or whether there is a call for mechanical devices 

 such as tin plates to hold the filling in a swaying young tree, or 

 iron bars to hold it between two split limbs. Finally, a knowledge 

 of> the nature of the species and general condition of the tree in 

 question will be serviceable in deciding the future possibilities of 

 the tree after treatment. 



Before filling the cavity, all diseased wood is removed from 

 it with the free use of the knife, chisel or gouge. It is far better 

 to enlarge the cavity by cutting out every bit of diseased wood 

 than it is to leave a smaller hole in an. unhealthy state, for any 

 trace of disease left within the cavity will continue its destructive 

 work behind the filling and later on destroy the tree just the same 

 as if there had been no filling at all. Where there are boring 

 larvae or beetles within the cavity, their destruction must be 

 assured before filling is commenced. It frequently happens with 

 large cavities and hollow trunks that the borers are so situated 

 that they cannot be reached individually ; in such cases a method 

 of fumigating the cavity has been resorted to by the writer which 

 consists in closing all orifices leading to the cavity with tar paper 

 and then filling it with vapor of hydrocyanic acid gas or that of 

 carbon bisulfid. Either of these gases will kill all animal life and 

 will penetrate the extreme burrows which the operator's syringe 



