The Potato Rot.
"This affection I do not regard as a disease—but simply as a rottenness in the tuber, superinduced by the combination of a low temperature with excessive moisture, during the growing season of that sort of root, when it is most liable to be affected on account of its succulent texture.[39] A friend informs me that he remembers the same kind of rottenness seizing the potato crop of the country in the late and wet season of 1799; and, as a consequence, the seed potato for the following crop fetched as high a price as 26s. the boll of 5 cwt.[40] I am inclined to believe, however, that the effects of this rot are much exaggerated. It is, in the first place, said to be poisonous; and yet pigs, to my certain knowledge, have been fed on spoiled potatoes alone, on purpose, with impunity. There is little outcry made against rot in the dry soils of Perthshire and Forfarshire, and these are the two most extensive districts from which potatoes are shipped for London. There are farmers in various parts of the country who warrant the soundness of the potatoes they supply their customers. The accounts
of the potato crop from the Highland districts are most favourable. I believe the fact will turn out to be this, that, like corn, the potatoes will not only be a good, but a great crop, in all the true potato soils—that is, in deep dry soils on a dry subsoil, whether naturally so, or made so by draining—and that in all the heavy soils, whether rich or poor, they are rotting.
A short time will put an end to all conjecture on the state of the potato crop, and afford us facts upon which we shall be able to reason and judge aright."
As the question of seed is always a most important one, whenever a new disease or partial affection of so staple a product is discovered, it may not be useless to note down Mr Stephens' ideas, in regard to the supposed destruction of the vegetative principle in part of the affected crop—
Seed Potatoes.
"I would feel no apprehension in employing such affected potatoes for seed, next spring, as shall be preserved till that time; because I believe it to be the case that the low temperature enfeebled the vegetative powers of the plant so much as to disable it from throwing off the large quantity of moisture that was presented to it; and I therefore conclude that any rot superinduced by such causes cannot possess a character which is hereditary. There seems no reason, therefore, why the complaint should be propagated in future, in circumstances favourable to vegetation; and this opinion is the more likely to be true, that it is not inconsistent with the idea of the disease of former years having arisen from a degenerate state of the potato plant, since low temperature and excessive moisture were more likely to affect a plant in a state of degeneracy than when its vitality remains unimpaired.
There is no doubt that this affection of the potato is general, and it is quite possible that it may yet spread. This, however, is a question which cannot yet be solved, and certainly, so far as we know, the Highlands, and the Orkney and Shetland Isles, have hitherto escaped. The portion of the crop as yet actually rendered unfit for human food, does not perhaps exceed one-fourth in parts of the country whence potatoes are exported; and could the affection be stopped from spreading further than this, there would still be a sufficiency of potatoes for the consumption of human beings, as the crop is acknowledged to be a large one in the best districts. Much, however, depends upon our ability to arrest the affection, or its cessation from other causes.
It is known that rotten potatoes, like rotten turnips, when left in heaps in contact with sound ones, will cause the latter to rot. Aware of this fact, farmers have, this last year, caused the potatoes in the heaps, as soon as the lifting of the crop was over, to be individually examined, and placed the sound ones in narrow, low pits, mixed with some desiccating substance, and covered with straw and earth. When the pits were opened for examination, the rot was found to have spread very much, in consequence of the dampness and heat which was so diffused throughout the pits. This is an effect that might have been anticipated. Had the precaution been used of taking up the crop in small quantities at a time, or of spreading the potatoes on the ground when the weather was fair, or in sheds when wet—and of allowing them to be exposed to the air until they had became tolerably firm and dry; and had the sound potatoes been then selected by hand, piled together, and afterwards put into smaller pits, it is probable that a much less proportion of any crop that was taken up would have been lost. Such a plan, no doubt, would have caused a protracted potato harvest, but the loss of time at that period, in performing the necessary work of selection, is a small consideration compared with an extensive injury to the crop. It is no doubt desirable to have the potato land ploughed for wheat as soon as possible after the potatoes have been removed; but
there is no more urgency in ploughing potato than in ploughing turnip land for wheat; and, at any rate, it is better to delay the ploughing of the potato land for a few days, than run the risk of losing a whole crop of so excellent an esculent.
I may here mention an experiment in regard to the potato, which shows that a larger crop has been received by planting the sets in autumn than in spring. Those who have tried this system on a large scale say, that the increase is in the ratio of 111 to 80 bolls per acre. If this is near the truth, it would indicate, that the sets may safely be entrusted to lie in the ground all winter upon the dung; and could we be assured of their safety there in all cases, the potatoes of this year, selected in the manner above described, might be used as seed this winter and preserved as such, in the ground, in a safer state than even in the small pits. Such an experiment may be tried this winter, in dry weather, without much risk of losing the future crop; for if, on examination in spring, it should be found that all the sets have rotted in the drills, there would be plenty of time to replant the crop, in its proper season, with the sets that had survived till that time, by the means of preservation used.
I have heard of farmers in this neighbourhood who are planting their potato crop in this favourable weather; and it does seem very probable that, as each set is placed at a considerable distance from the other, and in circumstances to resist frost—namely, amongst plenty of dung and earth—the entire number may escape putrefaction."
No doubt, if the potato crop shall prove to be very generally affected, the price of corn will rise yet farther, and may be for a long time maintained. But this is a very different thing from a scarcity of that article, which we believe is merely visionary. We must be fed with corn if we cannot get the potato in its usual plenty; and it is the certainty, or rather the expectation, of this, which has raised the price of the former. In the course of last month (October) we met with an admirable article on this subject, in the columns of Bell's Weekly Messenger, which we do not hesitate to adopt, as clear in its views, hopeful in its tone, and strictly rational in its argument.