MISTLETOE INJURY TO CONIFERS. 25 
outer central area of the burl die soon after the death of the cor- 
tex, especially in burls on the larch, and open wounds are formed, 
inviting the attack of forest-tree insects and wood-destroying fungi 
(fig. 24). The abnormal thickness and the soft, spongy consistency 
of the inner bark of mistletoe-infected branches are attractive to 
various gnawing animals; they are also an index of the storage of 
food materials at this point (fig. 25). 
Fic. 24.—Cross section of a burl on a western larch caused by Rasoumofskya laricis. 
Diameter of burl, 2 feet. Note the presence of borers and fungi. The check ap- 
peared in seasoning. 
RELATION OF MISTLETOE INJURY TO FUNGOUS ATTACK. 
Some very interesting data have recently been assembled by the 
writer on the relation of mistletoe burls to fungous attack. From 
cutting areas on the dry bench lands of northern Idaho, 540 mistle- 
toe-infected living larches were examined. Out of 600 mistletoe 
burls found on these trees, 278 were inhabited by serious wood- 
destroying fungi and other unimportant species. According to 
frequency of occurrence the most important of these fungi are 
Trametes pint (Brot.) Fr., Yomes laricis (Jacq.) Murr., Polyporus 
sulphureus Fr. (four occurrences at 20 feet up on the trunk, a very 
in 
