THE LARCH CANKER 71 
proved its adequacy, it must be put forward somewhat 
tentatively. 
If dead branches are the cause of infection, then dead 
branches must be removed, and, since branches are attacked 
by Dasyscypha almost immediately they die, they should 
be removed before they have any chance of being infected. 
To be on the safe side they might be pruned a year before 
they would naturally have died if allowed to remain on 
the tree. In a wood planted with pure larch at 3x4 ft. 
lateral branches generally die when they are 5-6 years old, 
so that this is the age at which they should be cut. But 
cutting off branches will leave wounds, which Hartig has 
so strongly recommended us to prevent, and though, as has 
been shown on p. 62, the importance of wounds has been 
over-estimated, we may as well be on the safe side and cut 
the branches in dry weather, preferably in winter or early 
spring, when the spores of the fungus are not being liberated 
in large quantities. It may be objected that such a treat- 
ment is expensive, and that forestry is not sufficiently 
lucrative to allow of individual attention to the trees. But 
the expense of cutting off the small lateral branches would 
not be excessive so long as the woodman confined himself 
to plantations from 6 to 18 years old, since up to that age he 
can probably reach the still living branches without a ladder. 
Beyond this age the trees are much less liable to serious 
attacks of canker. 
In districts where the canker is comparatively infrequent 
the treatment would be unprofitable ; but where it has 
ravaged in the past, it may still prove to be possible to 
grow healthy plantations by this means, though it can 
only be determined empirically whether the increased value 
of the trees will repay the outlay. 
An experimental plot in Bagley Wood, near Oxford, was 
pruned in the manner suggested during the winter of 
1915-16. <A large number of dead branches had to be 
removed from the lower 5 ft. of the stems, and living 
branches were cut for about a foot above this. Unfor- 
tunately, owing to the war, this experiment could not be 
