POTATOES. 221 
charged to more favorable slope and situation, but it was 
chiefly due to the more thorough preparation of the soil by 
summer fallowing and pasturing. This piece was quite 
sandy. 
It is a great temptation to plant potatoes year after 
year, on a well prepared piece, especially in a garden, or 
when the farm is not being cleared up rapidly. But this is 
usually rendered impossible by the appearance of scab. 
Seab is never present in new soil, and is brought into it by 
the potatoes planted there. It is a microscopic plant, which 
feeds upon the potato. Its spores or seeds fill the soil, and 
when succeeding crops are planted, there is so much scab in 
the soil that the crop is completely covered and largely 
ruined. In new land the only scab present is what is on the 
seed pieces, which is not enough to affect the crop. The 
second crop on the same soil may show considerable scab, 
but not usually enough to spoilits sale. But let potatoes 
be planted a third year on this land, now thoroughly in- 
fected, and the crop will be almost worthless. If for any 
reason it is intended to use certain land for potatoes con- 
tinuously, scab may be entirely kept out if done from the 
start. The seed potatoes should be soaked every spring be- 
fore planting, unless they are absolutely clean, in a solution 
of corrosive sublimate, 2 oz. to 8 gallons water, for an hour. 
This destroys the scab on the potato and there will be none 
on the crop as none exists in the soil. This method is ineffec- 
tive, on soil already filled with scab, for one cannot soak the 
ground with sublimate. The possiblity of keeping out scab 
has been demonstrated on a plot, where potatoes so treated 
have been planted for three consecutive seasons without a 
trace of the disease appearing in the crop. But scab will 
sometimes appear in spite of these precautions. In this case 
it always comes from the manure of animals which have 
eaten scabby potatoes, or from parings or slops containing 
scab. A new piece, in potatoes the first time, for which the 
seed had been treated, was so infected in 1902 by hogs, so 
that considerable scab appeared in the crop. These facts 
are given that the nature of scab may be thoroughly under- 
stood and not as an inducement to grow potatoes continu- 
ously on the same soil. The scab itself is a protest against 
