THE ENEMIES OF ENGLISH WOODLANDS 309 



quicklime, or any other cheap fungicide, and to plant up the 

 ground, after a decent interval, with a 1 ^ hardwood species. 



TRA METES RADICIPERDA. 



This fungus behaves in much the same way as Agaricus 

 melleus, and, like the latter, is both a saprophyte and parasite 

 under certain conditions. Unlike that fungus, however, it 

 appears to attack larch as freely as Scots fir, and a certain 

 proportion of the heart-rot of that tree may usually be traced 

 to it. But a peculiarity with the rot caused by T. radiciperda 

 is its tendency to spread vertically rather than laterally, and 

 to follow the wood-rings of certain years more than others. 

 This may be due to certain wood-rings being harder and 

 more resinous than others, and more capable of resisting the 

 entrance of the mycelium. The same reason may possibly 

 explain the fact that it rarely rises above the roots of Scots 

 fir, owing to the greater abundance of resin at the collar or 

 base of the stem. 



The life-history of the fungus resembles that of A. melleus 

 in many respects. It is able to infect sound trees by the 

 mycelium spreading from root to root under the surface, 

 while its spores may be carried by wind, mice, or rabbits to 

 a considerable distance from the fructification which produces 

 them. In this country it is most conspicuous in Scots fir 

 plantations, in which it often causes considerable gaps when 

 allowed to spread unchecked. Larch and spruce are also 

 killed by it, and it may also be found attacking thorns in 

 hedges round plantations. 



The remedy for the attack of this fungus is the same as 

 that for A. melleus, isolating the infected area by means 

 of a trench, and filling in the latter with something that will 

 kill the mycelium, or prevent it from crossing. 



NECTRIA DITISSIMA. 



The cankers so often seen on ash and beech stems are 

 usually the work of this fungus, and the trees attacked are 



