PLANTING AND CARE OF TREES 



123 



conspicuous. Most experts use coal tar for dressing wounds. This 

 material makes an excellent dressing, but occasional samples 

 containing an excess of creosote or carbolic acid have caused 

 serious damage to the living bark around the wounds. When care 

 is exercised in preventing it from running down on the healthy 

 bark, it may be safely used. 



The larger wounds will require later applications every two or 

 three years unless they are permanently sealed up in some way. 

 Wounds six inches or more in diameter are sometimes covered 

 with zinc. When the work of "tinning," as it is commonly called, 

 is properly done it is a very effective means of taking care of 

 large wounds. The zinc plates should be cut out so as to fit 



Fig. 50. The failure to protect the woun,d with some kind of dressing 

 has allowed the entrance of wood-destroying fungi 



exactly inside of the cambium layer or inner bark. It is applied 

 immediately^ after painting and should be tacked down with large- 

 headed brads. The brads should completely encircle the plate and 

 should not be more than one inch apart. When put on in this 

 way, and before the paint has dried, there will be no danger of 

 moisture or disease spores getting beneath it. Within a year 

 or two the callous will form over the edge of the plate making 

 a permanently tight covering. 



