ioo TREE WOUNDS AND DISEASES 



attains its wonted vigour, and in any case the 

 timber is almost valueless in a commercial 

 sense. Remedies are almost out of the ques- 

 tion in the case of a plantation of larch becom- 

 ing affected, but isolated specimens may be 

 successfully treated by carefully cutting out 

 the diseased portions of wood and bark and 

 painting with tar. In order to partially avoid 

 the disease, plantations of pure larch should 

 not be established, mixing with hard-wooded 

 species such as the beech and sycamore being 

 recommended. Cleanliness of a plantation goes 

 far in warding off the larch canker, and for 

 this reason all dead and diseased trunks and 

 branches should be removed or burnt, and the 

 trees individually given a fair amount of room, 

 crowded plantations in low-lying, close situa- 

 tions being first attacked. 



The spruce in southern England is oc- 

 casionally infested with Peziza resinaria, the 

 attacks being similar to those of the larch 

 canker. It is a wound parasite, and mainly in- 

 duced by frost cracks, excessive or bad pruning, 

 or by leaving injured branches or snags on trees. 



The leaf-shedding fungus or pine-leaf scurf 



