Fungus Diseases 43 
known to the uninitiated long after the mischief has been 
done. 
On the roots, besides the rot fungi, there are found others 
which attack the living parts and hence become directly a 
damage to the life function of the tree. 
While here too, as a rule, an injury or weakened condition 
invites the fungus attack, there are fungi which appear to 
attack perfectly healthy and uninjured roots. Thus the 
southern root rot which infests a large number of tree species, 
kills the roots so extensively as to produce a sudden wilting 
of the leaves and subsequent death of the tree. Poorly 
drained and poorly aerated soils seem to favor its develop- 
ment. 
The honey mushroom also kills young trees and weakens 
or stunts the growth of older trees which finally, if a dry, 
hot season occurs, may dry up for lack of water-supply. 
Its mycelium grows not only in, but alongside the roots 
through the ground, within a few inches of the surface and 
thus spreads from tree to tree, increasing the area infested. 
Some few plants other than fungi may be found as para- 
sites on branches and bole; they are mischievous, although 
rarely of importance unless extraordinarily developed. 
Among these are various species of mistletoe, which occa- 
sion objectionable burl-like malformations, due merely to 
the mechanical obstructions to the wood growth which their 
roots, imbedded in the cambium layer of the host, produce. 
The dying of the branch above this burl may be the con- 
sequence. ‘The trouble is spread by the seeds of the mistle- 
toe, which are covered with a sticky substance and are 
carried by birds to other branches and trees; hence its spread, 
at least, can be prevented by removing the affected branches. 
In addition to the parasitic fungi and other parasitic 
plants, there will be found on all trees epiphytes, 1.¢., 
