POTATO

A few early potatoes can be grown on an exhausted hotbed. A covering of light soil must be given before putting a frame over them, and they must be carefully protected from frost. If started in the middle of January, the potatoes will be ready for use well ahead of the usual time .

Potatoes require rather deep, light to medium well-drained soil. Avoid shade as this encourages attacks of potato blight. It is best to plant them in ground that has been double dug, and well manured or used for a green crop the previous year. They are a good first crop, too, on virgin soil. Where ground has had a root crop the previous season it is well to apply a complete fertiliser before planting.

Sprouting a month or so before planting ensures stronger plants, also an earlier and probably heavier crop. Tubers are placed in shallow wooden trays or boxes, the end with the greatest number of eyes being uppermost. A light, frostproof shed (temperature 45 degrees F.) is ideal. Higher temperatures produce drawn weakly sprouts. If the tuber is planted so as to avoid damage to these tender green shoots, leaving the tip of it just level with the surface soil, the young potato plant will start into growth almost at once and much time can be saved. Some growers cut the tuber into two vertically so that each piece of the potato has one or two eyes. Plant for earlies, in March or April in rows 2 ft. apart, 12—15 in. distant in the row and about 4 in. deep in trenches or holes dug with a spade.

Make further plantings till early May, distances for the maincrops being increased by, say, 6 in. Local conditions often decide which varieties to grow. A list of recommended varieties is given later in this entry. As the leaves grow upwards, and the haulm begins to show, place short, twiggy pea-sticks along both sides of the row, to keep in position some clean, dry straw loosely twisted around each plant. Earth up as soon as growth is about 6 in. high. Not only does it help on the growth in the early stages, but when the tubers begin to swell, and those on the top rise through the soil, this prevents them becoming greened and spoilt in flavour.

See that earthing up has been properly attended to. Often several earthings are necessary between the first and when the plant begins to flower. The best way of earthing is to draw up the soil around the leaves with a hoe or spade, not higher than 6 in. If the soil is in a heavy, sticky condition, mix up a light compost with silver sand, and use 2 or 3 handfuls of this around each young plant, forming a little mound to protect them from the frost. Do not leave a little furrow at top of ridge, for it may harbour insect pests.

When lifting potatoes (usually when the haulm has died down), first let them dry for an hour or so in the sun. When in doubt, lift 2 or 3 tubers and if the skins will not rub off without pressure, you can start lifting. First reject any obviously diseased tubers, I.e. those with brown blotches or similar markings. Then pile them on the ground and cover with earth and straw. The clamp, as this is called, is made by piling potatoes pyramid fashion on a layer of straw and covering with a 6 in. layer of straw over which is a similar layer of earth. Straws are placed vertically from the heap through coverings to allow the tubers to sweat off and left in air to provide ventilation. The clamp should have a trench all round for drainage, and whenever opened it should be at the same end, and closed after supplies are taken. A clamp can be any length. Where no facilities exist for making a clamp, it is best to keep potatoes in a dark place, preferably in any frostproof shed or cellar, heaped up and covered with straw.

Potatoes can be lifted with a special fork having 4 prongs, which are flat and broad on the surface and grooved on the under side.

Amateurs are often puzzled about the insistence on an annual change of ‘seed’ as far as potatoes are concerned. Is Scotch ‘seed’ really better than the English counterpart? Not necessarily, but the chief reason for deterioration in stocks of individual varieties is attacks by virus diseases such as leaf curl (leaf roll), mosaic etc. These viruses pass into the new tubers once the plants are infected. Infection is transmitted by aphids. These pests are, however, less abundant in areas which are exposed and windy and with fairly high elevations, e.g. in Scotland and Ireland. Hence the Scotch and Irish stocks of seed potatoes which are offered by all seedsmen.

Choice of Varieties:. It is always advisable to ascertain which varieties thrive in your neighbourhood, especially on similar soils. Note that many varieties have their preferences. For example, Majestic and Ulster Prince prefer a light, warm soil as does the incomparable Golden Wonder, whereas King Edward VII is happiest on medium to heavy land. Kerr’s Pink does especially well in the north and Scotland, Arran Pilot crops more heavily south of the Trent, and so on.

Note that maincrops are heavier croppers than the earlies. The term Immune at the end of most varieties refers to immunity from wart disease — see Diseases, below.

First Early Varieties.

Arran Pilot: a very popular variety, despite the rather soapy flavour.

An extra heavy cropper in the south, especially in light soils. Tolerates drought. Immune.

Duke of York (Midlothian Early): some people are put off by the yellow flesh, but the quality is still good, although this variety is nearly 70 years old. Does well on heavy soils.

Home Guard: thoroughly reliable and appears to flourish on most soils.

Immune.

S/iarpe’s Express: although said to crop best on medium to heavy soils, can also be recommended for light land. Liable to dry rot.

Sutton’s Epicure: still popular in the north and Scotland. Should always be dug as a new potato, since the flavour deteriorates as the tubers age.

Resistant to late spring frosts and dry rot.

Ulster Chieftain: an extra early variety which can usually be lifted in 13 weeks (should not be left too long in the ground as the tubers tend to become coarse). Immune.

Ulster Prince: some consider this newcomer may replace Arran Pilot as it has a better flavour with really firm flesh. Does best on light, warm soils. Like Ulster Chieftain it is very early. The tubers are very large and the crop is consequently smaller than with many varieties. Immune.

Second Early Varieties.

Arran Banner: a heavy cropper which can also be grown as a maincrop and lifted in September. Immune.

Arran Comrade: a good variety for exhibitors but there is some wastage in cooking. Immune.

Craig’s Royal: a promising newcomer with red colouring around the eyes. Immune.

Dunbar Rover: recommended for light, dry soils. Does well in Scotland.

Immune.

Maincrop Varieties.

Arran Chief: recommended for light, dry soils.

Arran Victory: another variety for dry soils. Late maturing and an excellent keeper. Tubers purple and flavour first-rate. Immune.

Golden Wonder: outstanding for its chestnut flavour, and a very long keeper. Usually at its best in the New Year. Not a heavy cropper and prefers a light, warm, sandy soil, liberally enriched with manure or compost. Immune.

Great Scot: an extra heavy cropper ms to do well on most soils, even in very dry weather. Immune.

Kerr’s Pink: does well in wet districts and on heavy land. Popular in the north and Scotland. Immune.

King Edward VII: a very long keeper often into early spring, but also grown as a second early for lifting in August. Tubers very large. Probably at its best on a medium loam. Very liable to potato blight. Beginners would be well advised to substitute one of the more recent varieties such as Arran Victory and Ulster Supreme.

Majestic: the most popular variety at the present time. Very large tubers.

Excellent for making chips. Prefers a dry season. Immune.

Redskin: excellent flavour, almost equal to Golden Wonder. Pinky-red tubers which are sometimes difficult to detect when lifting. Immune.

Ulster Supreme: needs a long season of growth and should be planted early. Heavier cropper than Majestic in most districts.

Potato Diseases. There are many diseases which can attack the haulm and/or the tubers but the amateur should not be frightened, as in the average garden or allotment only the following are likely to give real trouble. Potato blight is dealt with in some detail as amateurs are often uncertain how to tackle this disease.

Potato blight. In cool, dry seasons this disease is rarely a menace but warm, moist conditions are definitely favourable. It occurs earlier and is more serious in the south-west, Ireland and Wales, than in the drier Eastern Counties.

Symptoms: The first signs of damage are fairly large brown or blackish-brown blotches and spots on the foliage, especially near the edges and tips. (Damage is, in fact, very similar to tomato blight symptoms.) On damp, dewy mornings these blotches have a white fringe on the undersides of the leaves (this comprises the fungus spores). It is certainly possible for potato leaves to exhibit dead brownish patches unconnected with blight and in dry, sunny weather when the typical colour and white fringe are absent one cannot be certain whether this disease is really present. However, if blight is responsible, these patches will increase rapidly in damp, muggy weather.

Unless blight is checked, all leaves and stems can be destroyed and tubers rot in the soil or soon after being stored. The spores are spread by wind and rain and are also washed down through the soil to the tubers, although they are protected to some extent by the covering of soil — shallow planting should always be avoided as the surface of the tubers is then more exposed with a greater risk of infection. Diseased tubers show dark, almost sunken areas on the surface. The ‘foxy’ reddish-brown patches in the actual flesh are unmistakable. Treatment: Earthing up helps to prevent infection of both haulm and tubers. Never store infected tubers, but consign them to the bonfire. Where there are blight markings on the leaves, lift the potatoes about 14 days after the tops have completely died down. If the tops show no signs of the disease and remain green late in the season, cut them off about 14 days before lifting.

Blight does not infect dry tubers, so always lift in dry weather — never store damp tubers, even if they appear healthy, as infection develops chiefly in a moist atmosphere and they may show the tell-tale patches if examined several weeks later.

Spraying with a Bordeaux mixture or a proprietary copper fungicide is the best means of preventing blight attacks, this treatment being preventive rather than curative. The object is to retain the haulm sufficiently long to enable the plant to produce a good crop of tubers. Generally speaking, an increase of life of 3 to 4 weeks is achieved by spraying, which is obviously of tremendous value as blight attacks just when tuber production is at its peak. Early potatoes are generally lifted before blight appears and need not be sprayed. Maincrops are best sprayed several times, beginning just before the foliage has closed over the drills. In the south-west the first spraying is usually given in mid-June and later in other parts of the country. Spray in the early morning or evening, never in very sunny weather or when raining. Sprays are more effective than dusts.

Dry Rot. This is a disease of stored potatoes which appears in winter, especially when tubers are being sprouted. Earlies such as Arran Pilot, Duke of York and Sharpens Express are particularly liable to attack. Maincrops are seldom badly infected, although Majestic may suffer on occasion. Attacked tubers decay and shrink, finally turning hard and dry. They often die after planting. The disease often arises from bruising, so always handle potatoes very carefully. Storage boxes can be washed down with a solution of copper sulphate (I lb. to 5 gallons of water). Always burn infected tubers.

Common Scab. This is rarely a serious trouble, although it irritates the housewife by reason of wastage in peeling and affects keeping qualities. It is very common on light, sandy soils with a high lime content, especially in dry seasons. Grass cuttings applied before the tubers are planted usually keep down this disease to a minimum, but make sure they are free from weeds. Do not lime land intended for potatoes. Virus Diseases are distributed in the sap through the entire plant, the tubers carrying diseases from one year to another. There are several distinct virus diseases which can usually be recognised by leaf distortion (curling, rolling etc.), mottling and discoloration, stunted growth and premature defoliation. Sometimes the entire top collapses. Once potatoes are affected by a virus, no curative treatment is possible and they should be destroyed to prevent the trouble spreading. Certified Scotch or Irish seed should always be planted.

Wart Disease. This is not very common nowadays, but when it occurs is certainly the most serious potato disease. Warty or cauliflower-like growths may be found near the eyes on the tubers (hence the old name cauliflower disease). Sometimes die entire tuber is a shapeless mass of warts. At first the colour resembles the tuber, subsequently turning black. The fungus spores can remain in the soil for at least 10 years and the Ministry of Agriculture must be notified immediately. Fortunately most present day potato varieties are immune and such varieties have been noted in the list of recommended varieties .

Pests Affecting Potatoes:

Wireworm frequently attacks potato tubers, especially on land recently broken up from grass. An aldrin dust can be applied to the ground before planting, working into the top 4 in. of soil. Colorado beetle is a notifiable pest which has reached Britain several times but on each occasion prompt action by the Ministry of Agriculture prevented it gaining a foothold. The bright red beetle is about 3/8 in. long with black stripes on its back and the larvae reddish-yellow with black spots. Both beetles and larvae eat down the haulm very quickly. Contact the police immediately should you discover any suspected beetles in your garden or allotment. Note that the beetles are about twice the size of a ladybird.

Potato root eelworm is estimated to cause an annual loss of £2,000,000 in this country. Potatoes affected by this pest have a sickly, dwarfed appearance and loss of their lower leaves. Tubers are smaller and fewer. If an injured plant is lifted and the root system examined numerous dead rootlets with minute white balls or cysts will be found. These cysts subsequently turn brown. Each cyst contains several hundred eggs which may hatch out over a number of years. If no suitable food is present, the eggs can remain within the cysts for as long as 10 years before hatching into young eelworms. At present no safe, economic method of controlling potato root eelworm has been found but research continues. Meanwhile, the only practicable treatment is to allow at least 5 years between successive crops. Plantains are host plants for this pest and should, of course, be destroyed wherever seen.

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