428 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ON A DISEASE OF THE CARNATION CAUSED BY 

 SEPTORIA DIANTHI (DESM.). 



By Professor M. C. Potter, M.A., F.L.S. 



For the past four years I have had under continuous observation a leaf 

 and stem disease of the Carnation, caused by Septoria Dianthi. As this 

 fungus has not hitherto been recorded as occurring in Britain, a short 

 note of the manner of attack would seem desirable. 



The Carnations affected by the disease were observed in an old garden 

 in one of the moated houses to be found in Warwickshire. The moat, 

 being always full of water, naturally insured a certain amount of 

 humidity in the atmosphere, and provided suitable conditions for a con. 



A B 



l 



I 



. \ 



H H ? 



Fi«. 114.— Leaves of Carnation attacked \\ i tli Septoria Dianthi. A, B, upper and 

 lower surfaces of the s;unc leaf, a, the only portion still remaining green; /'.the 

 pycnhlia. Nat. size. 



tinuance of the fungus. When I first noticed the Septoria it was 

 impossible to trace the source from which the Carnations had been 

 obtained or to gain any idea as to the length of time the disease had 

 been prevalent in the locality. Apparently its presence had not been 



noted. 



The disease may be recognised by the discoloration of the affected 

 parts, which are of a light straw colour and of a dull surface, without 

 the ordinary glaucous appearance of the leaf. The discoloration is not 

 confined to small patches, but extends from the point of attack towards 

 tli- tip, along the whole surface of the leaf. The tissues also are much 

 shrunken, and the leaf often curled longitudinally. (Fig. 111.) The 



