2 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



books * devotes a chapter to the description of the canker in 

 Larch, and gives a brief account of the fungus which causes it. 



In the following paper it is intended to give an account (as 

 brief as is consistent with clearness) of the life-history of the 

 fungus causing the disease, with the effects it produces ; and at 

 the end an attempt will be made to suggest remedies, some of 

 which — since I first suggested them in a paper in the Boyal 

 Agricultural Society's Journal — have been tried with success. 

 In a paper to be read before a body of men exhibiting both 

 scientific and practical knowledge it is not necessary to note how 

 discouraging it is, after the life-history of a fungus like the Larch 

 canker fungus (Dasyscypha Willkommii) has been carefully 

 studied, observed, and described by such men as Professor 

 Willkomm, of Dresden, and Professor Hartig, of Munich, that 

 practical men still refuse to believe that the effects are produced 

 by the fungus, and attribute the canker to climate, soil, bad 

 drainage, poor seeds, and other causes, just as years ago many 

 diseases attacking mankind — the history of which is now fully 

 recognised — were attributed to such causes as climate, position, 

 and that most useful of all attributable causes, " the hand of 

 God." The canker may be found in the Larch under every 

 condition in which the tree is cultivated, and the writer has 

 observed it on high hills and low-lying land, on thin calcareous 

 soils as in Kent, as well as on the clayey loams of the West Biding 

 of Yorkshire, and with all aspects. And, this being the case, it 

 does not point to a solution of the disease — as some would have 

 it — being found in position or climate. 



Most foresters and many gardeners, unfortunately, know too 

 well the external appearance which the canker presents when 

 first observed. The deformed, flattened stem or branch is gene- 

 rally blackened, and this blackness, though it occurs almost 

 always, is not due to the canker fungus, but to a smaller fungus 

 (Antennaria pithyophila, Nees) which grows on the exuded resin 

 and does no injury to the tree. The flattened side of the tree being 

 kept under observation for a short time, round white pustules 

 will be observed to be studded all over the surface, in size from 

 that of a pin's head to a rape-seed ; these are the fruits of the 

 fungus parasite on the tree, and after a day or so they change 

 their round shape and become cup-shaped, having a centre of a 

 * " Diseases of Timber." 



