26 BULLETIN 544. U. S. DEPARTMENT OF AGRICULTURE. 
and fungous attacks. Wet snow and sleet are also responsible for 
considerable damage to young spruce. The weight of snow will 
often bend the young trees over beyond the point where they can 
recover their erect position. 
FUNGOUS GROWTH, l 
Spruce is susceptible to injury by fungous growths of many sorts, 
which gain entrance into the wood through wounds resulting from a 
variety of causes. Some of the fungi can not thrive on a thrifty 
growing tree, but are secondary causes of death. Others, however, 
are unselective as to the thrift of their host. 
Three root parasites 2 which attack the spruce are Poly poms 
schweinitzii, Poria (Polyporus) subacida, and Fomes (Polyporus) 
annosus. Polyporus schweinitzii, the worst of these, is very preva- 
lent throughout the northern spruce and fir forests, where it attacks 
old and young trees alike, as does also Poria subacida. To what 
extent Poria subacida is the cause of the death of the tree, however, 
is not known, nor whether it attacks perfectly healthy trees; but it is 
known to be particularly destructive to dead timber. Fomes 
annosus, although very destructive in the forests of Europe, has not 
been accounted so in our eastern forests up to the present. These 
fungi usually spread through the soil and gain entrance to the tree 
through the roots, which makes them difficult to detect and still more 
difficult to combat. While it will not do to hunt out diseased trees 
as is done in Europe, it may prove of advantage whenever an infected 
group of trees is found in lumbering to cut all nearby trees. Decay 
will not, in many cases, have extended so far up the trunk as to 
prevent one or two merchantable logs being obtained. 
Three wound parasites 2 which do a great deal of damage to spruce 
are Trameies pini abietis, Fomes {Polyporus) pinicola, and Polyporus 
sulphureus. They gain entrance to the tree above ground through 
wounds on the trunk and branches, and spread up and down the 
trunk from the point of infection to the topmost branches and to the 
roots. Trameies pini abietis very commonly attacks both the 
heartwood and sapwood of spruce and literally riddles them with 
small holes. Fomes pinicola, while it attacks living trees, is generally 
found on those individuals which have a weakened vitality, and is 
one of the first to settle on suclj. trees as have met death through 
other causes. Polyporus sulphureus is found on spruce, but is more 
prevalent on hardwoods. There are undoubtedly many others of 
1 Those desiring detailed infonnation concerning fungous diseases and how to combat them should com- 
municate with the Division of Forest Patholog3 r , Bureau of Plant Industry, Washington, D. C. 
2 Von Schrenck. Herman: "Some Diseases of Now England Conifers," U. S. Department of Agriculture, 
Div. of Veg. Phys. and Path., Bulletin 25, 1900. 
