POTAfO. 20i 



scab fungus continues to grow on the potatoes as long as the^^ are 

 in the ground. 



I 



Treated. Figure 101— Potato Scab. Not Treated. 



Both plates grown from the same lot of scabby seed. 



Scabby potatoes may be safely used for seed provided they 

 are first treated in such a way as to destroy the germs of the 

 scab that adhere to them. There are many methods of doing 

 this but the most practical now used are as follows: 



Corrosive Sublimate Treatment. — Procure from a druggist 

 two ounces of powdered corrosive sublimate (mercuric bichlor- 

 ide) ; put this into two gallons of hot water in a wooden or 

 earthenware vessel and allow it to stand until dissolved. Place 

 thirteen gallons of water in a clean barrel, pour in the solution 

 of corrosive sublimate and allow it to stand two or three hours, 

 with frequent stirrings in order to have the solution uniform. 

 Select potatoes as nearly free from scab as can be obtained; 

 put the seed potatoes into bags, either before or after cutting 

 them, and then dip them into the corrosive sublimate solution 

 and allow them to stay in for an hour and a half. If seed pota- 

 toes are treated in this way and then planted on land free from 

 scab, the resultant crop will seldom be seriously injured by scab. 

 The expense of this treatment, including labor, should not ex- 

 ceed one dollar per acre, as the material may be used repeatedly. 



