PRACTICAL TREE SURGERY 



tensively used with good results. 

 Although one coating of this mix- 

 ture may at times he sufficient, it 

 is always safer to follow it with 

 a heavy coat of coal tar. 



A good grade of lead paint can 

 he suhstituted for the tar, if de- 

 sired, although it is not generally 

 considered as satisfactory; or 

 grafting wax may serve satisfac- 

 torily for small surfaces. Asphalt 

 and various preparations contain- 

 ing asphalt are excellent water- 

 proof coverings and would doubt- 

 less be more generally used were 



No. 1. It would be bet- 

 ter to make these cavi- 

 ties oval and pointed 

 instead of square or 

 round. 



No. 3. Injury shown in 

 No. 2 excavated and 

 ready for tarring prior 

 to filling. 



No. 2. An old in- 

 jury caused by 

 horses gnawing 

 the bark. 



PLATE No. 3. LONG CAVITIES EXCAVATED THROUGH SEV- 

 ERAL OPENINGS AND SHORT CAVITY EXCAVATED THROUGH 

 ONE OPENING. 



The entire shellacked and creosoted sur- 

 face must finally be waterproofed by 

 painting it with heavy coal tar. A 

 single application of a mixture of creo- 

 sote and coal tar (about one-fourth or 



it not necessary to apply them 

 hot. A good and possibly 

 more permanent method of 

 treating the scars is to char 

 the surface slightly with a 

 gasoline or alcohol blast torch 

 and then cover the hot sur- 

 face with heavy tar or hot 

 asphalt. Although heat is an 

 excellent sterilizing agent, it 

 does not penetrate so well as 

 creosote and it kills back the 

 cambium to a greater extent. 

 Perm a n e n t waterproofing 

 can be secured only when the 

 treated surfaces are watclud 

 from year to year and recoated when 

 any tendency to crack or peel is ob- 

 served. This is an important step, 

 which is almost invariably neglected 



one-third creosote) has been quite ex- by tree owners and tree surgeons. 



