ENEMIES. 15 



ENEMIES. 

 FUNGI (conk and GROUND-ROT). 



Few Western trees maintain so continual a warfare to preserve exist- 

 ence as does the Hemlock. Its shallow root S3^stem is exposed to 

 ground fires and also renders the tree unable to withstand heavy winds. 

 The l)ark is thin, afi'ording little protection against fire or other injury. 

 The tree is liable in old age to attack by several fungi, notably conk 

 {TiUi/ietes pini and Eclunodontlum tinctorkmi) and ground-rot {Poly- 

 poms schweinitzii). The latter is the more prevalent, and makes long- 

 butting necessary in many localities. Little can be done as yet to 

 prevent these timber diseases, but a better undei-standing of them may 

 impress upon the lumberman the advisability of utilizing infected 

 timber before it is ruined. Both conk and ground-rot are active, 

 independent enemies of trees, and not, as is often believed, merely 

 followers of disease due to unfavorable conditions. 



The "conk" or bracket seen on affected trees is the fruiting organ. 

 On its under side are innumerable minute spores or seeds. (PI. VI, 

 fig. 1.) These float through the air and lodge upon other trees. 

 Conk spores never enter through the bark, but usually through the 

 scars of broken branches. Once the spore is established, root-like 

 fibers grow inward, destroying the structure of the wood. When suf- 

 ficient nourishment has been extracted a small conk is produced, 

 which grows b}" annual layers on its under side, and in turn liberates 

 millions of spores. 



Conk spreads rapidly, especialh" where the trees are badly scarred. 

 Storms aid the disease by breaking man}^ branches. Trees which have 

 grown in an open stand in youth are apt to become conkj' because the 

 branches are large, and, when the}' finally die off', they leave wounds 

 which often do not heal over thoroughly. Damp climates and soils 

 are favorable to the growth of conk. 



In ground-rot the fruiting organs are on or near the roots. Hence 

 the spread to other trees is usually brought about either by direct 

 infection of interlacing roots or by the carrying of spores in the fur of 

 burrowing animals. Hence ground-rot is apt to spread more slowly 

 than conk and to be confined to spots in the forest. On the other 

 hand, since the tender growing ends of roots ma}' be infected without 

 first being scarred, the existence of one diseased tree is almost certain 

 to affect a group. Conk and ground-rot in Red Fir, Hemlock, and 

 Spruce are caused by the same fungi and may be communicated from 

 one species to another. 



It is evident, therefore, that the immediate cutting of diseased trees 

 is advisable, not only to save as much timber as possible, but in order 

 to prevent the infection of others. The merchantable stand of many 

 tracts of Red Fir in Washington has been reduced one-third by conk 

 in ten years. It would often be better policy to incur considerable 



