132 PROTECTION OF WOODS AGAINST 



attacked young plants with their roots. Old conifers are 

 sometimes attacked ; they must be cut and replaced with 

 broad-leaved species, and the rotten stumps should be burnt. 



Pine blister (Periderniium pini). 



This disease is very common in pine woods in Great 

 Britain, and trees attacked by it 

 are often called ' foxy ' trees. On 

 infected pines orange-yellow tufts 

 or fructifications are seen breaking 

 through the bark in June. These 

 liberate their spores and then appeal- 

 white. The mycelium develops 

 chiefly in bark and bast, but also in 

 the timber, forming a canker which 

 is covered with resin. The canker 

 increases in size annually, working 

 round the stem, and if it gets com- 

 pletely round, the portion of the 

 stem above it dies. Pines of all 

 ages are attacked, but the damage 

 done is greatest in woods from fif- 

 teen to twenty years of age. 



This disease is probably the most 

 destructive one found in the British 

 Isles with the exception of the larch 

 canker. 



The only measure which can be 

 taken against it is to cut out all in- 

 fected trees in the thinnings. These 

 can be more easily distinguished in 

 June when the fructifications are 



visible, and they should therefore be marked for felling then. 



Silver fir canker (Mclampsorella Caryophyllacearuni). 

 This fungus is fairly common wherever silver fir is grown. 



Fig. II. Peridennium 

 pini, Wallr. (corticola), on 

 a 5-year-old shoot of a 

 mountain pine. The fructi- 

 fications are dosed (a), or 

 have already burst (b). 

 (Natiiral size.} 



