116 HEART-ROT 
The frequency of heart-rot in plantations which form the 
first rotation on cultivated soil. A large number of observa- 
tions have shown that heart-rot is especially to be appre- 
hended in coniferous woods when they are planted as the 
first forest rotation on land which has been previously 
cultivated. The same applies, though in a lesser degree, to 
first plantations on commons and heaths. I have personally 
seen plantations of larch damaged in this way on the Tintern 
estate, at Terringham Wood near Cinderford, in the Forest 
of Dean, on two separate plantations on the Duke of Bed- 
ford’s estate at Endsleigh, near Tavistock, and two or three 
more near Brentor in Devon, where in every case the larch 
was a first forest crop. Other instances have been reported 
in Britain, and Sir William Schlich tells me that in Germany 
heart-rot commonly affects the spruce, which is planted as 
a pioneer rotation, though the second rotation is usually 
free from it. As no adequate explanation has been advanced * 
for this phenomenon, I made a special study of a number of 
trees at Terringham Wood. Thirteen trees were uprooted 
with the object of finding out through what part of the root 
system the fungus entered. It was found possible to locate 
the path of infection, for, although all the roots of diseased 
trees were rotted to a certain extent, the rotted roots could 
be divided into two markedly distinct classes. Those which 
had what I shall term ‘ primary rot’ were rotted equally 
from the centre to the cambium ; the bark was dead and 
the wood had reached the pale yellow spongy stage, or had 
in some cases been destroyed by worms, the cavity sur- 
rounded by the hollow bark being filled with the worm- 
casts. Others showed only ‘ secondary rot’, i. e. they were 
rotted only in the centre, like the trunk; the rot was in 
an earlier stage, and the rotted wood was surrounded by 
a layer of gum. Outside this the young wood and phloem 
were living and active. It is reasonable to suppose that 
the roots which show the primary rot are those through 
* Mathes (1911) correctly ascribed root-rot to the presence of dead 
roots and dead roots to poor nutrition and soil aeration. See also Leslie 
(1915) and Ribbentrop (1908). 
