3 o8 ENGLISH ESTATE FORESTRY 



resin to escape at the surface of the ground, or to soak into 

 the dry wood. The gradual decomposition of the wood 

 ensues up to a certain point towards the centre of the stem 

 in the upper part of the tree, but in the roots and lower 

 parts of the stem the whole gradually becomes decomposed 

 into a mass of white mycelium. The fructifications are brown, 

 possess a scaly cap or pileus, and a long stalk which is thickened 

 at the base, and are easily identified again when once seen. 



The dangerous nature of this parasite lies in its power 

 to spread from tree to tree by means of its underground 

 rhizomorphs. Where it once gains a footing in a plantation, 

 the disease radiates from a centre until it is stopped by 

 some obstacle which prevents its further advance, or its supply 

 of feeding material is completely exhausted. As may be 

 inferred from its life - history, it is most troublesome on 

 ground planted with conifers after an old crop of hardwoods 

 has been cleared off it. Scots fir seems to be an especial 

 favourite for attack, while larch usually escapes. Hardwoods 

 generally are said to be only attacked when in bad health or 

 decaying, but conifers of all kinds are more or less subject 

 to attack. Its antiquity is proved by its having been found 

 in fossil wood of the coal measures ; and as it may reasonably 

 be presumed to have existed in this country since the Glacial 

 Period, and to be little if at all more virulent to-day than it 

 was a thousand years ago, the English forester ought not to 

 exaggerate its importance as a fungoid pest, although it is 

 undoubtedly troublesome in odd corners, and in places where 

 it is not wanted. 



Beyond the grubbing out of old roots before replanting 

 ground with pines or firs, the chief remedy seems that of 

 isolating infected areas by cutting trenches round them. 

 Whether this is worth doing on the chance of effectually 

 cutting off the rhizomorphs under the surface, must depend 

 upon the nature of the ground, and the value of the crop to 

 be benefited. The rhizomorphs are not supposed to attack 

 roots beyond a few inches below the surface (Hartig says 

 seldom more than 4 inches), but one is never sure of 

 extending the trench far enough from the centre of infection 

 to ensure all the rhizomorphs being intercepted. When a 

 trench is dug, however, it is advisable to fill it with gas or 



