^62 JOTTHNAI, OF THE ROYAl/ llORTTCTTljTTmAL SOCIETY . 



XIII.— ON TUMOUR AND CANKER IN POTATO. 

 By A. S. HoENE, B.Sc.(LoND.), F.G.S. 



During the period of my study of Potato disease at Armstrong College, 

 Newcastle, I became familiar with the symptoms of the form of 

 disease described by M. C. Potter* in the Journal of the Board of 

 Agri&nlture for December 1902, as a new potato disease. Each year 

 tubers were planted in the soil used in his original experiments, and 

 in each successive year diseased tubers were obtained in the yield from 

 the infected soil. The organism present in the diseased tissues 

 appeared to agree more closely with that described by Schilberszky 

 in 1906, under the name of Chrysophlyctis endohiotica, than with any 

 other known organism. At the same time there were points in 

 Schilberszky's description not strictly in accord -with my own 

 observations. 



During this period also T was shown on more than one occasion by 

 Potter misshapen tubers which he had received from T. Johnson, 

 of Dublin, affected with the disease named by Johnson corky 

 scab." The microscopic examination of these tubers, however, did not 

 enable me to form a sound judgment as to the nature of the organism 

 supposed to be present in the diseased tissue — an organism which had 

 been identified by Johnson as the parasitic Myxomycete, Spongospora 

 solani, described by BrunchorstI in 1886. 



In September 1910 my attention was drawn to a supposed outbreak 

 of "wart disease" in an allotment garden in the neighbourhood of 

 Newcastle-upon-Tyne. The garden was visited and several misshapen 

 tubers were collected and examined. It was then found that the disease 

 was not " wart disease," but equivalent to Johnson's " corky scab." 

 An organism was found in all stages of development (myxamooebae, 

 " Plasmodia," spore-balls, &c.), recalling that described by Brun- 

 chorst. Almost immediately afterwards, upon visiting some experi- 

 mental plots at Cleadon which had been planned in connexion with an 

 epidemic of Phytophthora in the previous year, I found that all the 

 experimental rows were affected with potato canker. From this 

 source the photographs | which illustrate this paper were obtained. 



Soon afterwards, owing to the kindness of Professor J. W. H. 

 Trail, of Aberdeen, and Dr. W. G. Smith, of Edinburgh, I had 

 opportunities of studying the symptoms of potato canker in several 

 localities in Scotland. 



It is stated in the Journal of the Board of Agriculture^ that " corky 

 scab " (potato canker) is well known to be of old standing in 



* M. C. Potter, Jour. Bd. Agr., ix. (1902), p. 320. 

 t J. Brunchorst, Bergens Mnseinns Aarsteretning (1886). 

 X These photographs were taken by Miss Jamieson, the librarian of Arm- 

 strong College, Newcastle. 



§ Jour. Bd. Agr., xvi. (1909), p. 642. 



