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AGRICULTURE IN SCOTLAND. 
Agriculture in Scotlaub,—No- 4. 
The Potato Disease. —My attention has of late 
been often arrested, by accounts of the wide-spread 
and destructive ravages of the potato disease in the 
United States during the past season. I have, through 
the kindness of Professor Johnston, been favored 
with a collection of opinions on this subject, from 
various shrewd practical observers, and have person¬ 
ally attended some most interesting discussions, in 
several parts of Scotland, where every means of in¬ 
formation was brought to bear upon this mysterious 
disease, in the hope that, upon the whole collection, 
some general rule for its avoidance or cure might be 
founded. 
Cause of the Disease. —There is but one opinion as 
to the prevalence of the disease, but a wide difference 
as to the means of its cure. 
1. I have found that all consider the potato plant 
to be in a weak and sickly condition, from a long 
course of cultivation and of ill-treatment. Many 
ascribe this condition to improper stowage during the 
winter. They are generally placed in large masses, 
in pits or cellars, and as an almost inevitable conse¬ 
quence, a certain degree of heating and fermentation 
takes place, which, it is thought, destroys the vital 
principle. This opinion is probably correct, as, dur¬ 
ing fermentation, a portion of their proteine (nitroge¬ 
nous) compound, is decomposed, while at the same 
time a part of their starch is converted into water and 
carbonic acid. Now these potatoes are not rotten, 
but they will not vegetate so vigorously, and will be 
less healthy, than the unfermented or unheated seed. 
2. They should not be allowed to sprout before 
planting, so that the sprouts are likely to be broken 
off. Experiment has proved that such potatoes grow 
slowly and weakly, if at all. These sprouts contain 
a large per centage of saline matter and nitrogen, and 
when they are removed the tuber is so much poorer 
in these important ingredients. 
3. Exposure to the sun and drying wind just be¬ 
fore planting, has been spoken of as a great evil. 
4. The important fact that these failures have most 
frequently taken place on long cultivated lands, where 
some of the necessary substances may have become 
exhausted. 
The means of Cure. — 1 . All seem to agree, thatthe 
first step, in most cases, is to drain the land, and 
either by the spade, or subsoil plow, to pulverize it 
deeply and thoroughly. 
2. Many excellent farmers do not take the potatoes 
which they design for seed from the ground at all; 
they throw up over them a high, narrow ridge, and 
leave them until the time for planting arrives. Mr. 
Anderson, a manager of large estates in Ireland, takes 
them up, and places them in shallow, long pits, not 
more than 2£ feet wide at the bottom, and having the 
earth heaped over them in as steep and high a form 
as possible. Before he touches them again, the field 
where they are to be planted is ready for their recep¬ 
tion ; they are then taken out, planted, and covered, 
within half an hour. By the selection of unripe 
seed, and treating it in this way, he has had excellent 
crops, while all around have failed. 
3. Taking up the potatoes before they are ripe, is 
strongly recommended by many good observers. Ex¬ 
periments on this point have, in many instances, 
seemed to indicate that this procedure is the best. 
It is not, as might be at first supposed, contrary to 
scientific principles ; for it has been lound that those 
potatoes which most abound in starch, have in many 
instances been most liable to failure; now it is said, 
that starch is less abundant in the unripe potato. 
We know also, that, as a general rule, those pota¬ 
toes are the most hardy, and the least liable to fail¬ 
ure, which are the worst for eating; that is, which 
are poorest in starch. Thus, it would seem to indi¬ 
cate, as Professor Johnston has said, “ that whatever 
goes to increase the per centage of starch, increases 
also the risk of failure in potatoes that are to be used 
for seed.” 
4. In connection with this point, is the fact, that 
many good farmers grow their potatoes intended for 
seed upon new land, or land which has long been 
suffered to rest. Tt is asserted, that potatoes grown 
upon such land, are remarkable for their small pro¬ 
portion of starch ; and the few experiments that have 
been made, seem to favor that assertion. 
5. I have found frequently, that farmers prefer for 
seed those potatoes which have been partially out of 
the ground, and have acquired a green color They 
carefully select, and lay them in a separate pile. 
Some even dig, them up, and expose them to the sun 
and air, until they become quite green, and entirely 
unfit even for the food of animals; they are then pre¬ 
served in the usual way. Several of these persons 
say, that they have followed this method for years, 
with complete success. The little green protube¬ 
rances that grow on the stalk, just above the ground, 
are said never to fail. 
6. Whole potatoes are thought to grow more sure¬ 
ly than those which are cut, but do not yield so large 
a crop, nor generally , of so good a quality. 
7. We are not, however, always to ascribe the 
disease to the organic part of the potato. The inor¬ 
ganic part may be deficient. Where land has been 
long cultivated, some of the inorganic constituents 
; necessary to the plant may have become exhausted ; 
and though these together only amount to about eight- 
tenths of a pound in a hundred pounds of the tubers, 
the absence of any one of them is fatal to the healthy 
growth of the plant. Some very interesting experi¬ 
ments upon this point have been made by Mr. Flem¬ 
ing, of Barochan, near Paisley. Analysis has shown, 
his land to be in some degree deficient in saline sub¬ 
stances, especially salts of magnesia. Acting upon 
this, he applied top-dressings of sulphate of magne¬ 
sia, nitrate of soda, &c., to his potatoes, and found 
the effect most remarkable. One hundred pounds an 
acre, or even less, of these salts, produced an increase 
of several tons in the crop. It was found that the 
potatoes raised in this way, when planted the next 
season, came up strong and vigorous; while the same 
variety which had not been top-dressed, planted close 
beside them, and subjected to the same treatment, was 
weak and yellow. 
8 It has been stated, that plucking off the flowers, 
so as to prevent the plant from bearing seed, produces 
a marked effect; but this is now disputed by some 
good authorities. 
9. Much stress has also been laid upon raising 
new varieties from seed, and thus commencing a new, 
vigorous species. This may be in some cases suc¬ 
cessful, but in many instances it has failed, Mr. 
Fleming says that he has made many thousand trials, 
and never produced a healthy variety. 
You will, I think, be convinced by this sketch of 
