THE CULTIVATION OF THE OAK 158 
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 cf Europe the young 
plants suffer terribly from the ravages of a fungus 
named fosellinia, the mycelium of which sends its 
branches into the roots and kills them, consequently 
entailing the death of the plant. The larvee 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-aérated 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, 
