72 THE LARCH CANKER 
continued, and the trees have now grown too tall to be 
suitable for further work of this kind. But it is observable 
that those parts of the stems from which living branches 
have been removed are much less attacked by canker than 
the remainder of the trunks, and none of the wounds that 
were made while the work was in progress have become 
a source of infection. 
Since the cut branches form a suitable breeding-ground 
for the fungus, they should not be allowed to lie on the 
ground, but should be collected and burnt. This will 
reduce the number of fructifications in the neighbourhood 
of the trees, and will probably assist in lessening the chance 
of infection. 
Special treatment of individual trees must nevertheless 
be avoided as far as possible. It involves labour which is 
now a serious expense, and this is incurred early in the 
rotation, so that, with compound interest, it must deplete 
the already slender profits of forests. The chief of pro- 
phylactic measures will always be the correct sylvicultural 
treatment of the tree. Maintain the gencral health of the 
trees and canker will not be a serious pest. The point of 
first importance is to plant larch in mixturcs, which main- 
tain the soil in better condition than pure larch woods and 
stimulate better development of roots. Forbes’s views on 
this subject have already been quoted, and Schotte (1917), 
after a carcful survey of the larch woods of Sweden, adopts 
a very similar standpoint. The most suitable tree for 
mixture with larch is probably the beech, but where beech- 
growing is unprofitable other trees, such as hornbeam and 
chestnut, may be tricd, Among conifers Scots pine can, 
according to Schotte, ‘be unreservedly recommended’; but 
woods of larch and Scots pine in this country are apt tou 
open out in later life and need to be underplanted either 
with beech or with that most promising of shade-bearcrs, 
the western hemlock. Spruce should be avoided in mixture 
with larch on account of Chermes abietis, which has alternate 
generations on the two species, and Schotte states that in 
Sweden spruce is apt to shade the larch overmuch, and 
