THE CULTIVATION OF THE OAK 153 



the shoots but also nibble them off, and mice, squirrels, 

 &c., do their share of injury, as also do wood-pigeons 

 and other birds. In the North of Europe the young 

 plants suffer terribly from the ravages of a fungus 

 named Rosellinia^ the mycelium of which sends its 

 branches into the roots and kills them, consequently 

 entailing the death of the plant. The larvao of various 

 insects also damage the roots and bring about injuries 

 which may prove fatal. Cynips corticalis produces galls 

 on the lower parts of the stems. 



When the plant has passed into the condition of a 

 sapling its dangers are for the most part of quite other 

 nature, the injurious fungi especially being different. 

 The chief diseases of the roots now arise from their 

 spreading into unsuitable soil, the drainage of which 

 may be incomplete, and thus bring about a sodden, 

 acid, ill-aerated condition. The want of oxygen and the 

 low temperature combine to kill the root-hairs and 

 young rootlets, and the leaves above part with their 

 water faster than it can be supplied from below, and 

 they turn yellow and die off, the branches dry up, and 

 the tree dies. 



Other dangers arise from the persistent overshadow- 

 ing of other trees, which slowly kill the young oaks by 

 depriving their leaves of light ; the offending trees play- 

 ing the same inimical part, in fact, that grass and weeds, 

 &c., play towards the small seedlings. Or the roots may 

 be too thickly set in the soil if the trees are too crowded, 

 and each suffers from over-competition with others. 



