22 Disease caused hif Bulgaria Polymorpha 



Association of Bulgaria with the Disease. 



A number of specimens consisting of portions of wood and bark 

 from diseased trees were forwarded for examination. They all showed 

 a covering of gum on the surface of the bark which in most cases was 

 dead. Examination of the bark yielded no results of any value. In one 

 specimeii only, a yellow mycelium was found between the bark and the 

 wood. This was probably the mycelium of Bulgaria, but attempts to 

 cultivate it failed. (Subsequent examination of the trees from which the 

 specimens were cut, suggested that in some instances the gum on them 

 had trickled down from a diseased area higher up the trunk. Two 

 specimens were placed in a damp chamber and kept under observation 

 for about 18 months. No exudation of gum occurred from these speci- 

 mens. A few saprophytic moulds appeared at first on the gum and later 

 Sfereuni hirsutum in abundance on both specimens. In the spring of 

 1916 the examination of the infected trees was resumed and was con- 

 fined to the careful investigation of one badly diseased tree in Victoria 

 Avenue, Burnham Beeches. One of the two main branches of this 

 tree had died and had been removed in the winter of 1914-15. The 

 log showed abundance of Bulgaria fructifications during 1915. The 

 remaining branch of this tree is still living and apparently healthy, 

 but a considerable area of the bark at the base is dead and although 

 no gumming has taken place in this region, yet infection experiments 

 (described below) show that the same disease is in question. It was 

 from the base of the main trunk that the specimen, referred to above 

 as showing yellow mycelium, had been obtained. Fresh portions of 

 bark from this region, which was gumming freely, were brought into the 

 laboratory and on one of them a yellow mycelium appeared. This 

 was transferred to an artificial medium and has been kept in continuous 

 cultivation. Of the various media tried, prune agar proved to be the 

 most satisfactory. Four weeks after the material had been collected 

 a fructification of Bulgaria appeared on the bark and could be clearly 

 traced in connection with the yellow mycelium. 



Ascospores were collected on sterile cover glasses suspended over 

 the apothecium, and were transferred to various media. They ger- 

 minated readily and gave rise to a mycelium identical with that obtained 

 from the diseased bark. Other specimens of bark brought in later 

 also developed fruit bodies of the fungus, and portions of bark taken 

 from other diseased trees in every case yielded the yellow hyphae. 

 Pure cultures of the mycelium have been under observation for many 



