112 ELEMENTARY FORESTRY. 



Sun-scald. Nearly all of our cultivated trees may be injured 

 by sun-scald. This occurs, almost without exception, on the 

 southwest side of unprotected trees of Hard and Soft Maple, 

 Basswood, Boxelder, Black Walnut, etc. Oaks and all other 

 trees are occasionally affected. It never occurs when the trees 

 are sufficiently close together to shade their trunks, and for this 

 reason the growth of shrubs and low branching trees should be 

 encouraged on the south and west sides of groves where they 

 do not crowd the principal kinds. Street trees liable to tlr's 

 injury may be protected by burlap sacking, straw, or other simi- 

 lar material. When injuries from sun-scald occur, the loose bark 

 should be cut off down to the live growth and the wood coated 

 with paint, to prevent its seasoning, or the wound wrapped in 

 cloth. Trees inclined to the northeast are most liable to sun- 

 scald, because the rays of the sun strike the trunk more nearly 

 perpendicular. 



Broken Branches and Decay. Large wounds are some- 

 limes formed by the breaking down of a branch, or by decay, 

 which may have started in a wound made by pruning. In such 

 cases the broken and decayed wood should be cleared away, and 

 the exposed surfaces treated with a very heavy coat of white 

 lead paint, grafting wax, or other material that will keep out 

 water and disease. If the wound is very large, or forms a hole 

 in which water is likely to stand, it should be cleaned and painted 

 as recommended, and then coveied with a sheet of zinc, care- 

 fully tacked on, and the joints closed with grafting wax to keep 

 out water. 



Fungus Diseases are quite common sources of injury to 

 trees of all kinds, including those of our forests. They attack 

 the foliage, trunk and roots. Occasionally very serious losses 

 occur here from those that cause the trunks to rot. They are 

 generally most numerous in sections where there is not much of 

 a circulation of air. This subject is too large for a detailed 

 account of any of them here, and only one is referred to, which, 

 although not very common, is occasionally quite injurious. This 

 is known as the toadstool root fungus, Agaricus melleus. This 

 fungus lives upon the roots of pines, spruces, firs, etc., and occa- 

 sionally kills them. At one stage of its growth it lives on the 

 decaying wood of oaks and similar trees. 



