THE LARCH. 229 
disease begins in the root, and its progress is upwards. It is 
not confined to the centre of the trunk. Old trees, when cut 
down, are frequently found to be extensively diseased, where 
the centre and many of the first-formed circles of wood are 
perfectly sound. This, however, is not uniformly the case, 
but as the circumstance frequently occurs, it shows that the 
disease had not existed in the young plants, nor arisen in 
consequence of the treatment bestowed on it during the first 
stages of its growth. 
This disease has always been found to prevail most in larch 
plantations formed on ground which had previously yielded 
timber. The decaying roots, and the fungi which accom- 
pany them, tend to injure the roots of several sorts of forest 
trees. In this respect the larch is by far the most sensitive ; 
but instances have occurred of two-year-old oaks having been 
killed by the white fibrous matter, or spawn, from rotting 
wood, cutting off the tap-roots of the plants. I have known 
a few cartloads of manure composed chiefly of sawdust to 
create mycelium, and to kill several hundred thousand seed- 
ling larch plants in one season, and to render the ground 
unsuitable for that crop for many years. Every description 
of fresh manure is injurious to the health of the young plant. 
Where this disease is likely to occur, plants as young as pos- 
sible should be preferred in all cases where they are suitable. 
The natural figure of the larch tree is admirably adapted for 
being supported by a small root, and its root is generally 
found smaller than in any other genus, in proportion to the 
cubical contents of the tree. The natural figure of the tree, 
however, is changed in all neglected plantations, the expanse 
of branches in the body of the tree is destroyed by confine- 
ment, and when a plantation is newly opened by thinning, 
the trees which possess top branches only, seldom escape 
having their roots injured by the influence of wind. In 
such cases, the movements perceptible on the surface during 
a hurricane indicate the strain to which the roots are sub- 
jected. The injury they thus sustain is followed by decay, and 
no doubt this is an extensive source of rot in larch timber. 
