General Cultivation.—As soon as the shaws appear the ground should be hoed between the rows, and if there is any fear of frost the shaws should be lightly moulded over. As the growth advances the crop must be earthed up, care being exercised not to earth up too much, for, taking six inches as the best average depth, the crop will be diminished by an increase beyond this depth. One urgent reason for early work between the rows is that a prosperous crop will soon put a stop to it. The moment it becomes likely that the shaws will be bruised by traffic between the rows they must be left to finish their course in their own way, because the formation of tubers below will be in the ratio of the healthy growth above ground. The Potato may be said to be manufactured out of sunshine and alkaline salts. The green leaves constitute the machinery of the manufacture, for which the solar light from above, and the potash, phosphate of lime, phosphate of magnesia, and phosphoric acid from below are the raw materials.
Change of Ground and Seed.—In common with all other crops, the Potato needs as often as possible a fresh soil, and a renewal of seed from some distant source. The need for a change of soil is made apparent by an analysis of the root, which contains large proportions of potash, phosphorus, and sulphur, with smaller proportions of magnesia and lime, without which the plant cannot prosper. A succession of heavy crops of Potatoes on the same land may be said to take from the soil its available potash and phosphates, and this crop will not, like some others, take soda instead of potash when the last-named alkali runs short. Here then is a chemical reason for change of soil. Another reason is found in the history of the species of fungi that prey on the Potato when its growth is checked by heavy rains and a low temperature. These leave their spores in the soil, like wolves hiding in ambush, to destroy the next crop. They are powerless to attack any other crop; therefore a suitable rotation gives them time to die out and leave the land clean as regards the Phytophthora and other parasites that destroy Potato crops. The necessity for an occasional change of seed rests on old experience, and should scarcely need enforcing. One word may be said here by way of explanation, and it is this: the seed house that aims to put a good article in the market adopts measures which altogether differ from those followed by the majority of persons who have not been trained to the business. It is a common experience to find that those who save their own seed from year to year have as a result a constantly declining strain, so that every year the growth is weaker, less true, and less profitable. It is so all through, but is especially the case with Potatoes. We do not say that all who save their own seed act unwisely, for some are most expert in the business. But we do say that seed saving is not learned in a day, and many who think they save shillings when they save seeds, actually lose pounds by burdening themselves with a bad article. The art of ‘roguing’—the elimination of plants which are untrue to type—is but one part of the seed-saving process. There is the proper storing, the selecting and sorting operations, to which eyes and hands must be trained, and there must be no scruple about the sacrifice of false, immature or diseased samples. The point we have in view is to advise the Potato grower to be sure of his seed, and when a doubt arises as to the purity and healthiness of the sample at command, it may be remembered that the seed merchant practises methods of purgation for insuring perfectly true stocks, while by growing in many different districts, and on diverse soils, he can furnish an admirable change of seed for any description of land.
The Potato Disease.—The culture of Potatoes cannot be dismissed without allusion to the destructive fungus which is never absent in dry seasons, and in wet summers does its deadly work on a vast scale. Scientific men have acquainted us with the history of the Potato fungus, and this may eventually result in as efficient a remedy as that which renewed the vineyards of France. Such a remedy for the Potato murrain has yet to be discovered. Meanwhile, we must continue to resist the foe with the plough, spade, draining tool, and above all with a wise selection of sorts. It is an acknowledged fact that many Potatoes that have been cultivated for a long time appear to have lost their vigour, and are liable to succumb to the disease; but several kinds that have been raised from seed in recent years possess a constitution which almost defies the virulent assaults of the Phytophthora infestans. Since the introduction of Sutton’s Magnum Bonum Potato there has been a disposition to believe in ‘Disease-proof Potatoes.’ There is no such thing absolutely, and perhaps there never will be, any more than there is a disease-proof wheat, or dog, or horse, or man. But some varieties of Potatoes are known to be more susceptible to the ravages of disease than others, and it has been one of our aims to secure seedlings which combine the highest cropping and table qualities with the least tendency to succumb in seasons when conditions favour the spread of the fungus. Scientific men have not yet explained why the varieties differ in this respect, but practical men have discovered that initial vigour of growth is the main defence against the plague, and as the growing of a good Potato costs no more than the growing of a poor variety, the cultivator should bestow his care on the very best he can obtain. A little extra cost for seed in the first instance is as nothing to the multiplied chances of success a good variety carries with it. To sum up this subject, then, we say that disease may be avoided in the early crops by cultivating sorts which may be lifted before the plague generally appears; and on soils which will not produce an early crop, only such varieties should be grown for the main crops as have been proved to be most capable of standing uninjured until late in the season. Let there be a dry, warm bed, sufficient food, the fullest exposure to the life-giving powers of light, and conditions favourable to early ripening.
The Wart Disease (Black Scab) of Potatoes (Synchytrium endobioticum, Percival) is dealt with in the chapter on ‘The Fungus Pests of certain Garden Plants.’
PUMPKIN—see GOURD, page 63
RADISH
Raphanus sativus
The Radish is often badly grown through being sown too thickly, or on lumpy ground, or in places not favourable to quick vegetation. Radishes grown slowly become tough, pungent and worthless. On the other hand, those which are grown quickly on rich, mellow ground are attractive in appearance, delicate in flavour, and as digestible as any salad in common use. It should be understood that earliness is of the very first importance, and that large Radishes are never wanted. To insure a quick growth and a handsome sample the ground must not only be good, but finely broken up.
Frame Culture.—For the earliest crops it is advisable to make a semi-hot-bed, by removing a portion of the surface soil, and laying down about two-feet depth of half-rotten stable manure, on which spread four inches of fine earth, and then cover with frames. Sow the seed thinly, and put on the lights. When the plants appear, give air at every opportunity to keep the growth dwarf, and cover with mats during frost, always taking care to uncover as often as possible to give light, for if the tops are drawn the roots will be of little account. Where the plants are crowded, thin them, allowing every plant just room enough to spread out its top without overlapping its neighbour. Sowings made in this way in December, January, and February will supply an abundance of beautiful Radishes in early spring, when they are greatly valued. To follow the outdoor crops frame culture will again be necessary in autumn.
Outdoor Culture.—The second crop (which in many gardens will be the first) may be sown on warm, dry borders in February. Within a few days after sowing, collect a quantity of dry litter, and lay it up in a shed ready for use. It happens often that we have warm, bright weather in February, and the Radishes start quickly and make good progress, and then may come a severe frost, when the litter must be spread as lightly as possible, three or four inches thick. These open-ground sowings will bear cold well, but they should not be allowed to get frozen, and therefore semi-hot-beds may be employed. If time and materials appear excessive for such a purpose, it should be remembered that this is a capital way of preparing for the next crop, whatever it may be, and is a particularly good method of preparing for Peas that are to be sown in the month of April, by which time the earliest sown Radishes will be off the ground. Successive sowings should be made from March to September in the coolest place that can be found for them, and the usual practice of four-feet beds will answer very well. In many gardens sufficient supplies of Radishes are obtained by sowing in the alleys between seed-beds, but care must be taken that this plan does not interfere with the proper work of hoeing, weeding, thinning, &c. When seed is sown on light soils a moderate firming with the back of the spade may be desirable, but generally speaking it is sufficient to cover the seed lightly, and so leave it. To thin the crop early is, however, of great importance, no matter how wasteful the process may seem, for wherever the plants are crowded they will make large useless tops, and small worthless roots, and prove altogether unprofitable. For the earliest sowings we have choice of many sorts, round, oval, and long; but the long Radishes are not well adapted for late sowing, whereas the round and oval sorts stand pretty well in hot weather, if on good ground in a cool situation, with the help of a slight amount of shade. As the year advances we return to the practice recommended for the earliest crops.