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 this 
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- 
times 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. 
