524 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ON THE NOMENCLATURE OF THE OEGANISM CAUSING 

 "COEKY-" OR " POWDERY-SCAB " IN THE POTATO 

 TUBER, SPONGOSPOBA SUBTERRANEA (WALLR.) 

 JOHNSON. 



By George H. Pethybridge, Ph.D., B.Sc, F.R.H.S. 



To a recent number of this Journal * a useful summary of our know- 

 ledge concerning two diseases of the potato — the Wart Disease or 

 Black Scab and the disease caused by Spongospora — was contributed 

 by Mr. A. S. Horne, who refers to them under the names of Potato 

 Tumour and Potato Canker respectively. 



An extensive bibliography is appended to the article which, how- 

 ever, at least as far as Spongospora is concerned, is not quite com- 

 plete, and for this reason, if for no other, the critical remarks offered 

 with regard to the specific name of this organism cannot be accepted 

 without demur. 



Since MasseeI has also fallen into error as regards the correct 

 name of this organism, it is necessary that any misunderstandings as 

 to its nomenclature should be cleared up, so that only the correct name 

 may be used in future. 



The history of the investigations on Spongospora is as follows : — 



Although doubtless the trouble caused by the organism had been 

 known previously (probably for some considerable time, seeing that it 

 had already obtained a trivial name, Kartoffelrdnde, among farmers 

 in Germany), the attention of scientific men was first called to it in the 

 year 1841 by W^allrotii, who sent specimens of affected tubers and 

 a communication describing the disease and its cause to a meeting 

 of savants held at Brunswick in September of that year. Since 

 Wallroth himself was not present at the meeting, his communica- 

 tion was read by Prof. Bartling, president of the botanical section. 



The official report of the meeting | was published during the follow- 

 ing year (1842) and contains the description (in Latin) above referred 

 to. The organism associated with the disease was described under the 

 name of Erysihe suhterranea v. Tuherum Solaiii tuberosi, and as having 

 very large, roundish, faintly cellular spores, at first yellowish, then 

 becoming brownish-green ; situated beneath the outer skin of the tubers 

 while they are still growing underground, the skin exhibiting dis- 

 coloured areas; then with small swellings becoming roughly slit, dis- 

 closing more or less round, hemispherical, many-spored masses, and 

 when these become dissipated, leaving bare scabs on the surface. 



* Journ. B.H.S. vol. xxxvii. 1911, p. 362. 



t Di&eases of Cultivated Plants and Trees, London, 1910, p. 528. 

 % Amilicher Bericht ilher die neunzehntc V ersammlung deutscher Naturforschtr 

 und Aerzte zu Braunschweig im September 1841 , Braunschweig, Vieweg und Sohn, 1842. 



