1913.] rUBLIC DOCUMENT — No. 31. 77 



bleed, the exudation causing an unsightly appearance of the 

 bark. Bleeding to excess is very injurious. Sometimes the 

 death of trees from this cause is sudden, and in other cases 

 the tree will linger, gradually dying back at the top, and even- 

 tually collapsing. The exuded sap, known as " slimy flux," 

 usually contains a large number of micro-organisms which give 

 the sap a peculiar odor. Elm trees often show a white streak on 

 the bark caused by some injury resulting in bleeding, and ma- 

 ples are also quite often affected, sometimes going into a slow de- 

 cline, followed by death from bleeding alone. In one instance 

 we observed a maple of fairly good size which had frost cracked 

 so badly that it did not live for more than five or six weeks, 

 the numerous cracks extending from the top to the bottom of 

 the trunk. These injuries are a difficult class to treat, and at 

 present no satisfactory method is known. 



Injuries from Snow. 

 Vegetation is occasionally injured by snow. The leaves of 

 coniferous trees — Pinus Strohus, for example — • are sometimes 

 affected, and the needles on the lower limbs of small pines 

 which have been covered by snowbanks in the spring turn brown 

 and die. But injury from snow is not very common, and has 

 never been known to cause serious harm. 



Earth Fillings. 

 The remodeling and regrading of streets, lawns, etc., often 

 necessitate filling in around trees. These earth fillings are 

 usually fatal to trees, due no doubt as often to the effects of the 

 earth on the bark as to the lack of air to the roots from the deep 

 covering of the soil. We have seen trees growing on a bank 

 with one side of the root system and part of the trunk covered 

 with soil. Those parts covered with soil gradually died, and 

 finally the whole tree collapsed. The maximum depth of soil 

 around the trunk was not more than 8 inches, but the roots were 

 covered for 18 to 20 inches. The soil used for refilling was of 

 a fine texture, — undoubtedly more injurious than a loose- 

 textured soil would have been. In this case the death of the 



