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XXI. 



FURTHER OBSERVATIONS ON THE CAUSE OF THE COMMON 

 DRY-ROT OF THE POTATO TUBER IN THE BRITISH ISLES. 



By GEORGE H. PETHYBRIDGE, B.Sc, Ph.D., 



Economic Botanist to the Department of Agriculture and Technical 

 Instruction for Ireland ; 



AND 



H. A. LAFFERTY, 



Associate of the Royal College of Science for Ireland, Assistant in the Seeds 

 and Plant Disease Division of the Department. 



(Plates VI.-VII.) 



[Read February 27. Published June 12, 1917.] 



I. — Introductory. 



In a previous paper communicated to this Society and published nearly nine 

 years ago 1 it was shown that the dry-rot of the potato tuber was due 

 to a parasitic species of Fusarium which was then regarded as being 

 F. Solani Sacc. 



The object of that paper was to record evidence to show that this form of 

 rot was in reality due to the Fusarium fungus, and to it alone, without the 

 co-operation or intervention of bacteria or of other micro-organisms, which 

 some previous authors held to be necessary to establish the rot. Since that 

 time there has been no more controversy on this point. 



It was assumed by the authors of that paper (as also by several previous 

 authors, including Pizzigoni and Wehmer) that Fusarium Solani Sacc. was 

 the correct name of the fungus which caused the rot. But beyond obtaining 

 pure cultures of the fungus for the purpose of inoculation, no cultural or 

 morphological studies of it were undertaken at that time, and no critical 

 attention was paid to the actual identity or nomenclature of the fungus. 



1 Pethybridge, G. H., and E. H. Bowers. Dry-rot of the Potato Tuber. Econ. Proc. 

 Roy. Dublin Soc, vol. i. Part 14, August 1908, p. 547. 



SOIENT. PROC. R.D.S., VOL. XV., NO. XXI. 2 I 



