1T6 



A Beech Disease.— In a report on tlie Beecli Coccus puLlishcd 

 in the Kew Bulletin* in 1911, reference was made to a disease of 

 the beech, which renders the trunk liable to break off at a height 

 of from 15 to 20 feet from the ground. In trees affected in this 

 w^aj, the weakness of the stem in the region referred to is due to a 

 fungal disease of the wood, which proves to be partially decayed 

 for some distance above and below the fracture. The fructifica- 

 tions of two fungi were specially noted in the same region of 

 diseased trees which had broken in this way. These were Ncctria 

 dithsima^ Tul. and Polyporiis advstus, Fr., and the disease was 

 provisionally attributed to the Nectria. 



A paperf Las recently been published giving the results of some 

 observations and experiments in connection with this disease. The 

 conclusion arrived at in the paper is that the disease is j)robably 

 caused by Polyporus adustus. 



Spore infections have not yet been made, but infection of the 

 wood was obtained by inserting mycelium in artificial wounds 

 reaching the sap-wood. The fungus is thus shown to be capable 

 of growing as a wound-parasite.J 



Yarious cultures were made from mycelium from the diseased 

 wood of trees showing the characteristic fracture, and the cultures 

 were found to be similar to those obtained from pure Polyporus 

 adustus. A study was also made of the enzymes in mycelium 

 grown from diseased wood. Diastase, Invertase, tyrosinase and 

 emulsm were found,^ but curiously enough the presence of cytase 



could not be determined experimentally. 

 Fructifications of Polyporus 



mature 



them, 



beech were examined, but basidiospores were not found .„ , 



though some of tbese spores were seen in younff encrusting- 

 Iructihcations. 



The curious phenomenon of the snapping of the trunk at a f airl j 

 uniform height is discussed, and one of the possible explanations 

 suggested IS as follows.§ Given the tapering form of the trunk, 

 the strain on the latter, due to the action of wind on the crown, 

 might cause incomplete rupture in the form of a crack at a definite 

 height and this might lead to infection at the 

 through the crack. 



, As the disease is rather a serious one, it is desirable that further 

 investigations sbould be made, including experimental" work on 

 spore-mfection, and a study of any data which may throw light on 

 the mode and oansps rA i"r,-Pr...+,v« j b 



same 



that lunblrSr Vi.'L™'''' ^J',""'""'' ""i DalHmore (loo. cit. p. 3«) was 



the e„°"roAh1t ^r^fcl*! "'" "*"" ■"= *^ '"^■"'•y responsible for 



I 



