A New Disease on the Larch in Scotland. 
BY 
A. W. BORTHWICK, D.Sc., 
LECTURER ON Forest Botany, UNIVERSITY OF EDINBURGH. 
AND 
MALCOLM WILSON, D.Sc., F.L.S., 
LECTURER ON MycoLocy, UNIVERSITY OF EDINBURGH. 
With Plate XIII. 
On the 22nd May 1912, Mr. Donald Grant, forester to Sir 
John Stirling Maxwell on his estate of Fersit in Inverness-shire, 
sent to one of us specimens of Larix europaea with a fungus 
disease on the leaves, which, he remarked, bore a striking resem- 
blance to the pine leaf rust, Peridermium pini f. acicola. 
An examination of the specimens in the laboratory. leads 
to the conclusion that fungus present must be provisionally 
included in Peridermium, a genus of the Uredineae, consisting 
of a number of species parasitic on Gymmosperms, of which only 
the aecidial stage is known. Klebahn,* in 1898, described a 
species of this genus parasitic on the larch, which he named 
Aecidium (Peridermium) Laricis,t and, although the form 
under discussion does not agree in all respects with Klebahn’s 
description, the differences are too slight to justify the creation 
of a new species. In the same paper Klebahn shows that 
Aecidium (Peridermium) Laricts is the aecidial stage of Melamp- 
soridium betulinum. 
As the occurrence of Peridermium Laricis has not been 
previously recorded in Scotland, the following information may 
prove of value to those interested in forestry. In his observations 
* Kulturversuche mit softies Rostpilzen. Bericht vii (1898). 
Zeitschr. f. Pflanzenkr., Bd, ix, 1899, p. 1 
Arthur and Kern, in Bull. Torr. ‘hot. Club, vol, xxxiii, 1906, p. 403, 
definitely placed this species in the genus Peridermium; the fungus is therefore 
described as Peridermium Laricis (Kleb.), Arth, et Kern, by Saccardo in the 
Sylloge Fungorum, vol, xxi, 1912. 
(Notes, R.B.G., Edin., No, XXXVI, March 1913.) 
