112 TRANSACTIONS OF ROVAI. SCOTTISH ARBORICULTURAL SOCIETY. 



15. Soil Conditions affecting the Prevalence of 

 Fomes annosus [Tra metes radiciperda]. 



By M. L. Anderson. 



Fomes annosus ranks with larch canker as one of the most 

 serious fungoid diseases with which the forester has to deal. 

 The fungus is wide-spread, but appears to occur most commonly 

 in the drier parts of the country, towards the east and north- 

 east. In the wetter districts to the west, another root fungus, 

 Agaricits melkits, becomes more important. Fomes amiosiis 

 attacks the roots of coniferous trees and causes a form of 

 heart-rot and root-rot which is well known to every forester 

 and wood-cutter, although he may not have associated the rot 

 with the fungus. 



There has always been a good deal of doubt as to the cause 

 of heart-rot, more especially since, in most cases, evidence of 

 fungal attack is not obvious. Hartig states that the attack 

 takes place through the collar, but this is not strictly true 

 as an inspection of many stems, newly cut over at the base, 

 shows a wide ring of clean, healthy wood all round, through 

 which no entrance could have been effected. The attack, as 

 stated in a recent leaflet, No. 5, on conifer heart-rot, issued by 

 the Forestry Commission, takes place through the roots and 

 passes up into the stem. The same leaflet gives a description 

 of the fungus and its distinguishing features. 



Having had Fomes annosus under observation for some time 

 in different parts of Scotland, the writer proposes to make a 

 few suggestions, rather from the silvicultural than from the 

 mycological point of view, as to the reasons for the frequent 

 occurrence of the fungus, which is in reality a very serious pest. 



The fungus seems to produce fructifications but rarely on 

 sandy, open soils. On stiff clayey soils, on the other hand, the 

 white sporophores are usually conspicuous. Since these are 

 often the only external indication of the occurrence of the 

 fungus, the impression may be got that it is most common on 

 stiff soils. Such, however, is not the case, and it occurs with 

 at least equal frequency on light soils. It would appear that 

 the texture of the soil has a great influence upon the mode 

 of attack of the fungus. When it is remembered that mere 

 contact of the hyphae with a weakened rootlet is alone 



