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 DasyscypJut ahnost 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 oft' 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 chy weather, preferably in Avinter 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, OAving to the war, this experiment could not be 



