1907.] PUBLIC DOCUMENT No. 73. 



for a slight distance, rabbeting the edge of the wound, so that 

 the tin may be placed about one-fourth of an inch below the 

 surface of the bark. A piece of tin cut in proper shape is then 

 securely tacked over the cavity. For this purpose the use of 

 large tacks is necessary. It is often practicable to secure the 

 necessary supply of tin from cans and other waste material 

 found on dump heaps. Old tin roofs, particularly those laid 

 many years ago, when the quality of tin plate was much su- 

 perior to that which can be obtained at present, are also much 

 sought after for this work. In all cases the tin cap should be 

 thoroughly painted or covered with coal tar on both sides, to 

 prevent rusting. (See Plate, Fig. 8.) 



In cases where trees have been split by frost, or where the 

 cavity is of such irregular shape that it is impossible to close it 

 tightly by tinning, the use of a double layer of heavy burlap is 

 advised. For this purpose burlap of the heaviest and coarsc-i 

 quality is recommended, both layers being liberally treated 

 with coal tar, to prevent decay. (See Plate, Fig. 9.) As a 

 rule, trees so badly fissured or decayed that it is impossible to 

 cement or tin the cavities should be cut down. The above gen- 

 eral considerations, written with particular reference to orchard 

 trees, will apply equally to shade or forest trees which it may 

 be desirable to preserve. 



The time for pruning operations is a moot point with horti- 

 culturists and foresters, and in discussing it we are often obliged 

 to fall back upon the familiar directions of unknown author- 

 ship, " Trim when you have time and a sharp axe." A safe 

 rule to follow, however, is to carry on trimming operations 

 when the trees are dormant, particularly during the fall and 

 early winter months. Trimming done at this time seldom 

 results in much bleeding of the trees, as the wounds generally 

 dry out before the sap starts in the spring, except with the 

 maples. In the case of these trees it may be well to say tliut 

 during some twelve years' observation on the part of the writer 

 no injury has been noted from wounds, notwithstanding the 

 liberal spring flow r of sap where branches were removed. 



