AMERICAN POTATO SCAB 299 



AMERICAN POTATO SCAB 



{Oospora scabies, Thaxter.) 



This troublesome disease, although so generally dis- 

 tributed, has only quite recently been thoroughly investigated 

 by an American — Dr. Thaxter. The parasite usually attacks 

 the tubers while young, forming rough patches on the 

 surface, known as 'scab.' 



When just dug up, a very delicate greyish mould is present 

 on young diseased patches, which however soon entirely 

 dries up and disappears. Beet, swede turnips, carrots, and 

 cabbages also appear to be susceptible to the same disease, 

 and should not follow a crop of potatoes, as the germs 

 remain in the soil for some years. 



This parasite has nothing in common with potato scab, 

 as understood in Britain. 



Preventive Means. — Professor Bolley recommends the 

 following treatment : — Immerse potatoes intended for plant- 

 ing — contained in a sack of open texture — for an hour and 

 a half in a solution consisting of two and a quarter ounces 

 of corrosive sublimate (bichloride of mercury) to fifteen 

 gallons of water, after which they may be cut and planted 

 as usual after being spread out to dry. First dissolve the 

 corrosive sublimate in a few gallons of hot water, and place 

 the solution in a cask or wooden vessel, as the mixture 

 corrodes metal. The solution is poisonous, and care should 

 be used. 



It has recently been proved by Professor Arthur that 

 steeping potatoes in a solution of half a pint of formalin in 

 fifteen gallons of water for two hours is a complete specific. 



Thaxter, Ann. Rep. Con?i. Agrk. Expt. Station., 1890, 

 p. 84. 



