Another enemy lies in wait for the tree that has been weakened by loss of its sap. A minute fungus (_Dasicypha calycina_), gaining access by its spores through any lesion of the bark, causes that incurable ill known as larch canker, which has now become so generally spread through British woodlands as to cause many landowners to give up planting larch at all. In this case, also, we have a parasite which may be found on larches in their native forests, but which the inherent vigour of the trees keeps in check. That this is the true and only reason for the excessive prevalence of larch canker in this country, causing incalculable pecuniary loss to many owners of woodland, is shown by the behaviour of the Japanese larch (_Larix leptolepis_). The fungus may easily be found upon this species; but so great is the vigour of the young trees that the fungus exists, and no more. The tree repels the inroads of mycelium into its tissues affording the invader foothold merely as a harmless guest.
Serious doubts are entertained as to whether the Japanese larch will prove as valuable a tree commercially as the European species; it has not been grown long enough in Britain to prove its quality as a timber producer. But the extraordinary rapidity and vigour of its growth in early years, its beauty and the readiness with which it takes hold when planted out, have induced many people to discard European larch in favour of this Asiatic species. Travellers in Japan report that the larches of that country never attain the bulk and stature of European larches; but it does not follow from this that they may not do so in this country. The holm oak, more commonly known as ilex, is a native of the hot and dry Mediterranean region, yet what is probably the tallest specimen in the world is growing in the moist atmosphere of County Wicklow. So with the horse chestnut, only to be found wild in a few spots in Macedonia and Asia Minor, lands which can show none to equal the noble trees of this species at Bushey and elsewhere throughout the British Isles.
Meanwhile, the lesson of our experience is that we must still treat the European larch as a foreigner of great distinction. Let it never be exposed to contact with the Norway spruce, a useful tree in its way, but, commercially, not half the value of larch. Let it not be planted as a pure crop, but let it be mixed with other trees, as it is usually found in a wild state. There is no better companion for it than the beech, none, indeed, equal to that beneficent tree, owing to the manner in which it screens the soil from evaporation and radiation, and refreshes it with an abundant annual leaf fall. Finally, let the utmost care be bestowed upon the critical operation of planting; see that in removal from the nursery the roots are not suffered to get dry, as they often become when sent to a distance by rail; and let these roots be fairly spread in the pit dug for them, instead of being rammed in a bunch into a mere notch in the ground, as is too often done. It is worth much effort to retain such a desirable denizen of our woodlands in health and vigour.