228 OUR FORESTS AND WOODLANDS 
as to be quite spoiled for the production of 
valuable timber; and there can be no hope of 
stamping out the disease. The best thing that 
can be done is to exercise care in the selection 
of localities for growing it, in which respect a 
northern aspect most resembles the alpine climate ; 
to grow it only on suitable soils, such as good, 
deep, fresh limes or loams and the better classes 
of sands; and to raise it in mixed crops rather 
than in pure plantations. Neither tenacious clays, 
nor binding limes, nor poor soils, nor land that 
can be classed between moist and wet, are favour- 
able to its good growth and healthy development. 
Under any adverse circumstances, but especially 
when growing on uncongenial soil or on a hot 
exposure without depth enough to accommodate 
its deep tap-root properly, its natural vigour is 
diminished. It is then most apt to be attacked by 
the larch aphis (Chermes Jaricis) and the mining 
moth (Coleophora laricella), the injuries made by 
which form wound-spots soon infected by the 
canker-producing Peziza fungus. 
Larch develops a very strong tap-root, hence 
depth of soil is essential for its best growth. It 
is the most light-demanding of all our forest 
