58 PROTECTION OF WOODLANDS. 



The diseases which are occasioned by plants will be treated in 

 the second section under the chapter " Damage caused by Plants" 

 as more properly belonging there ; but in the following the other 

 diseases of woody plants will be treated of in the briefest possible 

 manner, some reference, however, being made to the preventive 

 measures that can be employed against them. 



35. Diseases of more Common Occurrence, and their Prevention. 



(1) Results of External Injuries. 



Wound-rot, or rot in wounds, can take place, without the 

 presence and co-operation of fungal parasites, on portions of the 

 plant exposed to the air, in consequence of bruises, stripping of 

 bark by deer, scorching of the bark, and the like; although 

 fungoid growth, as a rule, finds its way into such weak spots. 

 The wood at the same time assumes a more or less dark colour ; 

 but when the process of decomposition has advanced further, 

 it resumes a lighter hue in consequence of the disappearance of 

 the dark humic solution. Through injuries to the roots, such 

 as are especially frequent in the case of shallow-rooting species, 

 and are caused by the extraction of timber, treading of cattle, 

 &c., rot can easily set in, which often works its way up into 

 the stem ; the brown patches noticeable on the stumps of mature 

 Spruce that have been felled are mostly the consequences of 

 such injuries. Covering the damaged places with moss or mould 

 stimulates the action and progress of the rot, and wood-ants 

 forming colonies often hollow out the stems up to a considerable 

 height. 



Stripping of the bark by red-deer, gnawing by mice, or extrac- 

 tion of resin from conifers, likewise give rise to wound-rot, and it 

 may also be occasioned by imprudent or badly executed removal 

 of branches ; for if the branch cut or sawn away be too thick, and 

 the wound arising therefrom too large, the place may be attacked 

 by rot before it has time to cicatrise sufficiently. In such cases 

 the rot often works its way deep into the stem. The avoidance 

 of all injuries so far as possible, caution in the felling and 

 extraction of timber, avoidance of the removal of branches that 

 have already attained large dimensions, and tarring of the wounds 



