170 THE POTATO, 



gallons per Irish acre. For further details about spraying 

 see Chapter XVII. 



Black Scab or Wart Disease This is caused by 

 a fungus scientifically known as Oedomyces leproides or 

 Chlorophylictis endobioticse. It is a comparatively new 

 disease, only having been noticed in this country during 

 the last four or five years. It first attacks the young 

 sprouts, causing them to assume a brownish tinge, this 

 being followed by the formation of small warts. In due 

 course the warts increase in size and grow into each other, 

 almost enveloping the tuber, as shown in the specimens 

 illustrated. The warts eventually become a black mass 

 owing to the presence of resting spores. This new disease, 

 which is said to have been introduced from the Continent, 

 is so distinct in character that it cannot fail to be recog- 

 nised. See illustrations on pp. 167 and 168. 



REMEDIES. All diseased tubers should be promptly 

 burnt, and in the case of any apparently healthy tubers 

 saved from an infected crop for " seed," they should, be- 

 fore storing, be well dusted with flow r ers of sulphur, taking 

 care that the latter is well dusted into the " eyes " of the 

 tuber. We think it equally advisable to be careful in the 

 use of sacks that have contained infected tubers, as it is 

 quite probable that the spores of the disease may be 

 present in them. 



Bacteriosis. A disease of bacterial origin is very pre- 

 valent in America, and may find its way here. The par- 

 ticular germ is Bacillus solanacearum, and its presence is 

 indicated by the sudden .drooping or wilting of the foliage, 

 followed by discoloration and collapse of the stem. On 

 cutting open a stem brown streaks will be seen which are 

 crowded with bacteria. The disease gradually spreads 

 downwards, till the tubers are reached, where it first forms 

 a pale zone, followed by a black one just inside. 



REMEDIES. Burning all infected foliage and tubers seems 



