WART DISEASE OF POTATOS. 



301 



WART DISEASE OF POTATOS. 

 (Synchytrium endobioticum, Perc.) 



A Study of its History, Distribution, and the Discovery of 



Immunity. 



By Geo. C. Gough, A.R.C.Sc, B.Sc. 

 Early History. 



The early history of Wart Disease and the onset of the disease in 

 the British Isles are points which raise many interesting questions. 

 That it was introduced and is not indigenous seems probable, although 

 it is possible that the causal organism (Synchytrium endobioticum) may 

 be a parasite on some wild plant without producing any deformation 

 which would call attention to it. It should be remembered that this 

 fungus has only been found on Solarium nigrum and S. Dulcamara 

 in pot experiments (21) * and not in nature, and that even in such cases 

 its presence is not very obvious macroscopically. It is therefore 

 quite possible, although not probable, that the fungus may be 

 indigenous and has only adapted itself to the potato during the last 

 sixty years. 



If the fungus has been introduced, the question arises whence ? 

 As far as our present knowledge goes, the British Isles have more 

 of the disease than any other country. It is commonly stated in 

 certain districts that it was introduced from Germany, and it is even 

 called the German Wart in some parts. This statement has little 

 foundation, as, while it is undoubtedly spreading in Germany, and 

 the authorities there are faced by the same problems as we are 

 in Britain, there is little evidence that it was in the fields until quite 

 recently, although it is reported as having been in a field at Kronenberg 

 in 1907 (70). Luxemburg, Belgium (verbal reports), and Holland (60) 

 have it, but it is not apparently of long standing, while it has 

 been reported from Norway (75) and Sweden (24). France is said to 

 be free, although Gussow (28) some years ago incorrectly reported 

 it there. 



It could hardly have come with the original potato, as Solanum 

 Commersonii and 5. etuberosum appear to be immune, while certain 

 Chilian varieties, which Mr. Malthouse (46) of Harper Adams College 

 tested, also proved immune. If it had been so, it would have made 

 its presence felt at an earlier period. 



The earliest scientific record of the disease was made by 

 Schilberszky in Hungary (72), who named the organism causing the 

 disease Chrysophlyctis endobiotica. This was in 1896, but no informa- 



* Numbers in brackets denote the references in bibliography at the end. 



