THE LARCH CANKER 19 
eventually be impossible to detect from the outside where 
the canker has been, but though the tree is to all appear- 
ances sound, there remains inside the blemish which the 
canker has left. 
At present larch canker is prevalent only in Europe. It 
has been recorded from Britain (until twenty years ago it 
was rarely found in Ireland, but has now become common), 
France, Holland and Belgium, Scandinavia, Russia, Ger- 
many, Austria, Hungary, Italy and the Balkans, and 
probably its boundaries here are coterminous with those of 
larch cultivation. Australian and American text-books do 
not include the disease among their own pests, but care will 
be needed to prevent its introduction to these countries 
with seedlings from Europe. Indeed it has already been 
reported from Newfoundland, so that the danger to America 
is imminent. 
Historical. It would be hard to say when or how the 
canker fungus was first introduced to Britain. According 
to Booth (1904) it was known to the Duke of Atholl at the 
beginning of the nineteenth century, and Loudon (1838, 
p. 2384) quotes as follows from de Candolle: ‘Sometimes, 
also, we see the larches having a wound of resinous cancer ; 
but this seems to proceed from some accidental cause, such 
as a blow or a knock, gvhich the tree may have received 
when it was in full sap. All these observations incline me 
to tpink that the cause of the diseases which attack the 
British larches must be sought for in some difference exist- 
ing in the physical nature or in the culture of your trees 
and ours.’ From this quotation we learn not only that the 
canker was fairly common in Britain by 1838, but also 
that it was less frequent in France than here. 
The suggestions offered by de Candolle on the etiology 
of the canker are not happy, and Loudon’s volume had 
reached the conventional age of manhood before the true 
1 I have been unable to find a copy of the Duke of Atholl’s book (1832) 
to confirm this reference. Schotte’s view (1917) that * canker, as a rule, 
has always been found where the larch occurs ’, may probably be accepted 
for Britain as well as Sweden. 
C2 
