DEFECTS AND GXSOUNDNESS. 73 



may be either red or white-rot, and may extend only to the 

 roots, stem or branches. 



Root-rot may occur in all species of trees. Old trees have 

 usually some of their roots rotten, especially the tap-root 

 and other central roots ; their large spreading side-roots then 

 nourish the tree, in which frequently rot of the central heart- 

 wood has commenced. The appearance of side-roots above the 

 surface of the ground is often a symptom of root-rot. Isolated 

 aspen, birch and sallows found in beechwoods often suffer from 

 root-rot, and especially the first when it springs from suckers. 



Scotch pine, spruce and other conifers frequently suffer 

 from root-rot, when the soil in which they are growing is not 

 sufficiently supplied with oxygen, and is cold, wet, or too 

 compact. 



In many cases unsuitable soils cause root-rot, but fangi do so 

 as well, as Agaricus mellcus and Trametcs radiciperda. As long 

 as root-rot does not proceed up the stem, it is not technically of 

 much importance. 



Branch-rot is caused by the death of large branches, wind- 

 break and lopping of trees. It usually spreads very slowly 

 down into the stem ; when, however, spores of parasitic fungi 

 germinate in the wounds, decay may spread rapidly throughout 

 the whole tree. 



Stem-rot, usually of the heart of the tree, is the worst form of 

 rottenness, and arises from root-rot or branch-rot, and may 

 sometimes affect the sapwood as well as the heartwood. In 

 certain cases the whole central part of the stem may have become 

 decayed, from the roots upwards. As a rule, however, only the 

 lower part of the stem suffers, and in some cases decay may be 

 localized to certain parts of the stem. When a tree has been 

 felled during the growing season the sapwood often becomes 

 decayed to a depth of 2 — 4 inches. In all these cases either red 

 or white-rot may be present. 



Red-rot is very common in the case of old spruce, silver-fir, 

 oak, sweet chestnut, elms, aspen, jDollard and maiden willows^ 

 the beech, hornbeam, sycamore and maples being more subject 

 to white-rot. On the whole, although all species of trees may 

 sufter from either red or white-rot, the latter is rarer, but may 

 follow red-rot in the same tree. 



