DISEASES OF THE LAECH AND SCOTCH PINE. 181 



DISEASE OF THE LAECH. 



The larch has saffered iu Scotland withiu the last thirty or forty years 

 from a disease which is becomiug very common, in fact universal, and 

 there has been found no remedy, short of cutting out diseased trees and 

 replanting, with no assurances then that it will not reappear in the new 

 plantation. It is said to be from atmospheric causes, and it first makes 

 its appearance in a fungus-like growth on the stem of the tree, generally 

 near the axils of the branches, then develops itself into or produces a 

 blister, and eventually a hole or wound, as if a branch had been roughly 

 broken off. 



Til is <^ause, together with a decline in prices from the importation of 

 foreign timber and substitution of iron in ship-building, has of late 

 years tended to a discontinuance of planting new forests of larch in 

 Scotland. Tbe decline iu prices may be judged from a statement made 

 concerning this timber on the estate of the Duke of Athol, which had 

 been valued at £1,000 per acre when mature, but would not now realize 

 more than £150 to £200. 



Siuc<) the appearance of the larch disease in Scotland, poplar wood has 

 been to a considerable extent employed for the uses to which the larch 

 had be«n formerlj' applied. It has, therefore, become an object of cul- 

 tivation, mixed with spruce or Scotch Sr and larch. The species most 

 suitable in that country is said to be the Populus monilifei-a, there called 

 the bli\ck Italian poplar. It will grow in sixty years to 120 feet in height 

 in saud3' alluvial river-banks. Its wood is tough and light, and when 

 2J to 3J feet thick at the base, is there worth Is. 4f7. per cubic foot and 

 upwards. 



The P. canescens yields wood of better quality, being light and strong, 

 while its rate of growth is equally rapid. 



DESTRUCTION OF THE SCOTCH PINE BY A FUNGUS PARASITE IN 

 THE ROOTS.^ 



In the communal forest of Marchiennes, in France, the pines when 

 about 50 years old were observed to be dying at a point which, widen- 

 ing in a circular way from year to year, showed, in 1874, after seven 

 years of progress, a dead area of about 150 yards across and about 500 

 trees destroyed. Its obviously contagious nature led to a careful ex- 

 amination, and the mycelium of a fungus was found upon the stumps, 

 the parasite itself being concealed in the ground. It proved to be the 

 Trametes radiciperda, as named by Robert Hartig, from observations 

 made near Xeustadt-Eberswalde, near Berlin. The mycelium is devel- 

 oped in the liber and wood of the roots of the Pinus sylvestris, and 

 sends out numerous filaments visible only under the microscope, but on 

 the bark it is quite visible to the naked eye. They present quite a vari- 

 able appearance, being sometinaes white, very thin, and branching, and 

 spreading over the bark, and at other times shorter, yellowish, grouped 

 in parallel bands, which come up over the bark and then descend to re- 

 appear again. Very rarely, under a lens, isolated filaments present an 

 irridescent play of colors. A root thus affected, when broken and ex- 

 posed some days to the air, will have the broken surface covered with 

 tissues as white as snow. When once estabbshed under the bark of the 

 roots the plant slowly dies, and the contagion reaching the root of an 



1 An exteuded notice of this malady is given in the Revue das Eaux et Forcts, xiv, 

 p. 105, 



