294 Diseased " Evergood " Potatoes. [aug., 



^During the past two years diseased examples of the potato 

 known as " Evergood " have on several occasions been sub- 

 mitted to the Board of Agriculture and to 



as at present known is confined to the one variety of potato 

 mentioned above. 



" Measly " is the name used by one grower in describing the 

 appearance of the disease, and the term is certainly expressive, 

 the surface of the tuber being studded with small brownish 

 warts ; each wart is surrounded by a very slight depression as 

 shown in the accompanying illustration. If a wart is cut 

 through, its substance is found to be much firmer than that of 

 the surrounding healthy tissues, and of a brownish-green colour. 

 The diseased tissue does not penetrate very far into the flesh 

 of the tuber, and is entirely removed with a somewhat thick 

 " paring," hence the disease does not occasion much loss of 

 substance, but on the other hand the unsightly warted surface 

 very much depreciates the market value. 



When a thin section through a wart is examined under the 

 microscope the mycelium of a fungus is often to be seen in 

 considerable quantity ; this suggested the idea that the fungus 

 was the primary cause of the disease. Following this idea an 

 attempt was made to obtain pure cultures of the fungus present, 

 and determine its nature. After experimenting for a year along 

 these lines, it became obvious that the primary cause of the 

 disease was not of a fungal nature, notwithstanding the almost 

 constant presence of the fungus in the tissues forming the 

 warts. 



The culture experiments clearly proved that no one particular 

 species of fungus was constantly present in the warts, but in 

 some instances three distinct kinds of fungi were obtained from 

 different warts formed on the same tuber, in other instances two 

 different fungi were present in the same wart. Among the various 

 fungi isolated from the warts were species of Fiisarium, Verticil- 

 liicm, Spicaria^ Macrosporium, a very interesting minute species of 

 Oedomyces, apparently previously unknown, also Rhizoctonia in 

 abundance. N otwith standing the presence of an ample supply 



Diseased 

 Evergood 

 Potatoes. 



Kew for investigation. 



The disease presents very characteristic 

 and easily recognised features, and so far 



