to spread a considerable quantity of rotten dung on the surface, which should be ploughed early in March, provided the weather be open; but, if it be frosty, this operation must be delayed till the end of that month, or the beginning of April. After the last ploughing, the ground ought to be levelled; the furrows drawn at the distance of three feet apart; and at the depth of about seven or eight inches. In the centre of this furrow are to be set the rind, eyes, cuttings, &c.; and then covered in with the earth. A short time before the young plants appear, it will be advisable to pass a harrow over the whole, in order to eradicate weeds, to break the clods, and to remove every obstacle to their vegetation.
Farther, as the potatoes increase, it will be proper to mould, or earth them up twice; a process, by which their growth will be greatly promoted. Mr. Turner's plough is eminently adapted to this purpose; but, having already described the implement under the article Plough, we refer the reader to p. 407, and foll. of the present volume, where the manner of employing it is concisely stated.
Beside the depredations of worms, grubs, and various oiher insects, to which potatoes are subject in common with other vegetables, there is a disease termed the curl, that peculiarly affects these roots; and for which ingenious agriculturists have endeavoured to account by various conjectures.—By some it is considered as a species of blight, but it is more generally attributed to one or more of the following causes:—1. Frost, either before, or after the sets, &c. have been planted. 2. The planting of such sets, from large or unripe potatoes. 3. From not placing them at a sufficient depth, or from putting them in exhausted lands. 4. By the first shoots of the sets having been broken off previously to planting; in consequence of which, the seminal plant is incapacitated from sending forth other shoots sufficiently vigorous to expand. 5. To a white grub, that preys upon the roots. 6. To the propagation of shoots, sets, eyes, &c. constantly from the same variety, and on the same land; so that the potatoes degenerate, and at length yield very indifferent crops.
In the 8th volume of the Transactions of the Society for the Encouragement of Arts, &c. we meet with an interesting communication on the curl, by Mr. W. Hollins, who divides the disease into three different stages, viz.
1. The Half Curl, in which the leaves of the plants are somewhat long, and slightly curled: they produce, however, tolerable crops, if the summer be not too dry; otherwise the potatoes will be small and watery.
2. The Fall Curl: in this stage the plants seldom exceed the height of six or seven inches; speedily attain to maturity, and decay. The potatoes are, in general, less than a nutmeg; of a dusky-red colour; and are extremely unwholesome as an article of food.
3. Corrupted Potatoes, the vegetative power of which is almost destroyed, never appear above the surface of the ground. The seed will be found at Michaelmas in a state, apparently as fresh as when it was first set; a few small potatoes, perhaps, growing from the parent root.
This accurate observer attributes the curl first, to late setting in
