How to Grow Red and White Currants

Cultivation, care and harvesting 

Immediately after planting, spread a 5 cm (2”) deep mulch of well rotted farmyard, manure garden compost, or moist peat over the root area to prevent evaporation from the soil if the spring and early summer prove to be dry. Water when the weather is particularly dry. However, red and white currants are not as absolutely dependent on constant watering as blackcurrants, so, if your water supply is limited and you are growing blackcurrants as well, the blackcurrants should be given watering priority.

Keep the area around the bushes weed free. Remember though that red and white currant bushes are very shallow rooted, and over-exuberant hoeing can wreck the root system. Mulching or chemical weed killers are probably safer methods of keeping weeds down.

Dress annually in late spring, with well rotted farmyard manure. Keep the manure well away from the main stem, or ‘leg’, when mulching, otherwise the leg may throw out unwanted sideshoots. A layer of straw on top of this will keep weeds down for the summer, and may be removed in autumn, before the autumn crop of weeds gets going.

In very light or other soils deficient in potash, apply sulphate of potash at the rate of 15 g per sq m in late winter. Bonfire ash can be applied instead of sulphate of potash at up to 240 g per sq m (8 oz per sq yd) depending on the percentage of wood burnt. Where farmyard manure is unobtainable, you can give a proprietary general compound fertilizer according to the manufacturer’s instructions, but do not use fertilizers excessively rich in nitrogen, or unhealthy, lush and sappy growth may result.

English: Red currants Français : Groseilles rouges

English: Red currants Français : Groseilles rouges (Photo credit: Wikipedia)

Harvesting

The first small crop can be taken in the second summer after planting, but it is better to remove the flowers in spring and wait another year, to let the bush strengthen. Picking can start in early summer, and can continue through to late summer, according to the variety planted. Bushes grown on north-facing walls will come into harvest later, ripening from late summer onwards. Do not be in a hurry to pick your crop; red currants are slower to ripen fully than their rapid colouration suggests. Because the fruit does not ripen all at the same time, inspect your bushes every few days, even daily in fine weather, to harvest the ripe berries.

Pick the fruits of both red and white currants in complete little bunches, or strigs, and not individually. Ideally, picking should be done when the fruit is dry. Any currants picked in rainy weather should be used quickly, as wet currants rapidly deteriorate. You can either use scissors to cut them or nip off the strig stalk at the top between your fingernails. Do not tear them off, as this damages the wood. Berries on strigs should keep a few days longer than those off strigs.

Propagation

New red or white currant bushes can easily be obtained from cuttings taken in early to mid-autumn from the current year’s growth. Rivers’ Late Red is somewhat slower than other varieties to take root, but should eventually be successful. Whatever the variety, though, there is little point in propagating from diseased or infested bushes, as the new plants will be doomed from the start.

Unlike blackcurrants, red and white currants are usually grown on a clear stem, or leg; for this reason cuttings have to be longer than those for blackcurrants. Well ripened shoots about 37.5 cm (15”) should be adequate. In order to ensure that you get a good clean stem, without sideshoots or suckers below ground, rub out all but the top three or four buds. At the same time cut off the unripened wood at the tip, about 7.5 or 10 cm (3 or 4”) long, as it would wilt and probably die back before new roots have formed.

Insert the cuttings into a 15 cm (6”) deep slit trench, spacing them 20 cm (8”) apart. To ensure a quick, smooth operation, dig and prepare the trench before taking cuttings. Unless your soil is very sandy, it helps encourage rooting if you first sprinkle a little river sand along the bottom of the trench. Return the soil to the trench and press firmly around the cuttings. It is unlikely that you will need more than one row for cuttings, but if you do, space them at least 75 cm (2’6”) apart.

During the winter, check that none of the cuttings have been lifted by frost; firm any down which have been lifted. See that the cuttings never lack water during the following spring and summer, and that weeds have no chance to choke them. A mulch of garden compost is useful in that it keeps weeds down and also helps conserve soil moisture. By the winter of the next year, the cuttings should have rooted, produced shoots and be ready for transferring to their permanent positions. If the plants look at all weak or thin, however, it is best to leave them in the nursery bed for another season before transplanting.

If the plants are to be grown as bushes, prune all the one-year-old branches back by half; for single cordons cut back sideshoots to two buds and the main leading shoot back by one-third. For a U-cordon, choose two opposite sideshoots to form the base of the U, and to which you then cut back the central stem; let uprights develop at suitable places.

Exhibition tips 

Exhibiting red or white currants is fairly straightforward; they are shown in exactly the same way as blackcurrants. Blackcurrants, however, can be awarded a maximum of twelve points, according to the Royal Horticultural Show Handbook, while red and white currants have a maximum of eight points.

No more than 0.5 kg (1 lb) in weight of red or white currants may be shown; these should of course be of the same variety. When picking for the show, select double this weight, so that you have reserves in case you need them at the show bench. Choose the longest strigs having the largest, fully ripe berries; the judges will look for bunches with large, ripe and uniform berries on fresh stalks. Bunches with berries obviously missing, or with small, overripe, under-ripe or unevenly ripened berries will not win prizes, nor will those which have shrivelled stalks.

Currants are normally displayed on a plate, with the strigs laid out parallel to one another; the bottoms of the strigs should point towards the front of the exhibit. To get the best visual effect, it is a good idea to fill the well of the plate with soft white tissue paper, covered with a single piece of paper with ends tucked under the plate; the mounded up berries will be more attractive.

Varieties:

REDCURRANTS

Early varieties

Jonkheer Van test: medium-sized berries, deep red colour, slightly acid flavour; heavy cropper; bush moderately vigorous and upright in growth.

Laxton’s No. 1: large, bright red fruits borne on medium-sized compact bush; last to crop of the earlies and can be mid-season according to site and soil; very popular variety, highly recommended for general use; do not plant on sites exposed to wind as the shoots blow out easily; berries with superb flavour; best type for jam-making. Earliest of Four lands: first early variety; bright red berries in long bunches; strong growing bush, needs plenty of space; reliable cropper. Fay’s Prolific: very attractive scarlet berries carried in loose sprays: very sweet flavoured; heavy crops borne on small, compact bush; best variety for northern gardens.

Mid-season varieties

Laxton’s Perfection: largest berries of all red currants, carried in long bunches; bush large and strong growing, but is not suitable for northern or exposed gardens and will not do well there.

Red Lake: American variety, heavy cropper, producing long strigs of dark red berries; bunches hang clear of foliage, so easily picked; bush strong growing and upright; popular variety for commercial growers.

Raby Castle: medium-sized berries; heavy cropper on large, upright bush; subject to American gooseberry mildew; largely superceded by more recent introductions. Last of the mid-season kinds, and may be late.

Late varieties

Wilson’s Long Bunch: heavy crops borne very late in season in long bunches: fruit medium sized; bush sprawling, very suitable for fan training against a north wall; widely grown commercially.

WHITECURRANTS

White Dutch (White Grape, White Pearl): very pale, milky white fruit carried in short bunches; good flavour and reliable cropper; fruits can be eaten raw.

White Versailles: early ripening fruit, large and yellow, very sweet tasting; bush large and upright; heavy cropper; most popular white variety.

Pests and Diseases Affecting Red and White Currants

Do not be discouraged by the following list of pests and diseases. Although theoretically red and white currants are vulnerable to attack by all of the pests and diseases listed, it is very unlikely, as long as your plants are in good health, that you will encounter more than one or two of these problems. Should any symptoms appear, identify the cause and take corrective measures as soon as possible, before the infection or infestation has time to do serious damage.

Birds: the ripe fruits are very attractive to birds, particularly pigeons and blackbirds; in bad years the entire crop can be quickly stripped. Although bird scarers provide temporary protection, the most effective method of protection is to net the bushes or grow them in a fruit cage. Remember also that dormant buds may be picked out by bullfinches in winter, and protection from late autumn may be necessary. If your bushes are not grown in cages, and are continually subject to bird damage during the winter, delay pruning until bud-break in early spring. Those branches which have been largely stripped of buds will then be obvious. These should be cut back to a strong, healthy bud near the base, as the wood stripped of buds would remain permanently bare and never crop.

Aphids: as with blackcurrants, the first sign to look for is stunted, curled leaf growth, followed by honeydew and sometimes sooty mould on the leaves and developing berries. A commonly found aphid on red currants is red currant blister aphid, which feeds mainly on the leaves, to produce very marked reddish blisters on the leaves. Although disfiguring, damage is mild, compared to that of other aphids, whose feeding stunts the new shoots. White, cotton woo1-1ike patches on the surface roots of infected plants conceal the young stages of currant root aphids, but this trouble very rarely occurs, and then chiefly on plants in the nursery or on rooted cuttings before planting out. To control above-ground aphids, spray in mid-winter, while the plants are dormant, with a 5”, tar oil wash to kill the winter eggs. Alternatively, in spring, when the first leaves open, spray with derris or malathion, thoroughly wetting the under-sides of the leaves, and repeating as necessary at about ten-day intervals (not at flowering).

Caterpillars (sawfly and magpie moth): the caterpillars of the gooseberry sawfly also attack red and white currant bushes. There can be up to three generations of sawfly in one season and the green and black caterpillars will quickly strip the plant of foliage. The worst damage is done on the underside or in the centre of the bush. Pick off the caterpillars by hand in mild infestations; in severe cases, spray with derris, malathion or fenitrothion. Caterpillars of the magpie moth can also attack red and white currant bushes; the treatment is the same as for sawfly caterpillar.

Capsids: the overwintering eggs of capsids, laid on the bark of the shoots, hatch out in mid-spring. The emergent young capsid sucks the sap from the growing shoots tips; scars and pinholes are formed and later the leaves become puckered and distorted. A spray of malathion as the leaves unfold and again ten days later (if not flowering) will give some measure of control; remember to spray the ground round the plants also.

Coral spot: this fungus usually grows on dead shoots, but occasionally it attacks living wood, particularly on old red currant bushes. It enters living wood usually through a pruning wound or snag. Whole branches will die back; if the infection is not checked, the bush may be killed. The main symptom is the many pink or red spores pustules which appear on the stems when they have been killed; from here the spores quickly spread to other bushes. Another symptom of coral spot is the sudden wilting of the leaves of whole branches in spring or summer, or even entire bushes. This is due to the infection entering the branch or central stem of the plant. Old and weak plants are most vulnerable, so the best preventive measure is to keep your bushes healthy and well cultivated. Cut off and burn any infected branches back to healthy growth, and paint over the wound with a protective paint. If the whole bush is infected, it is best to grub it up and burn it, as it will never recover.

Botrytis cinerea (grey mould): this fungal infection attacks many varieties of fruit and ornamental trees and shrubs; the main above-ground symptom is a sudden wilting of entire branches, often in full leaf. If the fungus attacks the main stem, as with coral spot, the whole plant will die but, unlike coral spot, there will not be any development of red pustules later on the dead parts. The infection usually enters the bush through a wound or pruning snag, so careful cultivation and pruning are the best preventive measures; always paint over large wounds with a fungicidal paint. Plants grown too close together, or whose branches are crowded, are more likely to be infected, especially in cool, wet seasons. Moderately infected bushes can be saved by cutting back into living wood; badly infected bushes should be dug up and burned.

Cluster cup rust: although this is more common on gooseberries, red and white currant bushes are occasionally infected by this fungal disease. The main symptom is bright red or orange patches on the leaves, stems and fruits. Towards the end of summer, tiny cup-like growths develop from these red patches. Because cluster cup is most likely to occur where bushes are grown in wet or overcrowded conditions, correcting any drainage problems before planting, and siting the bushes where plenty of air can circulate around them are the best preventive measures. If your bushes have been infected with cluster cup rust before, spray them with Bordeaux mixture a fortnight before flowering. All infected leaves, fruits and shoots should be burned, and not left lying around in the garden.

Leaf spot: this is another disease which affects both gooseberries and currants. The main symptoms are small, black dot-like spots; if the infection is severe, the spots will eventually join up, the leaves will turn yellow and wither, and then fall prematurely. Rake up and burn all fallen leaves and remove infected leaves from the bushes. If the attack is severe, spray with zineb after removing infected leaves and again two weeks later, and follow the manufacturer’s directions with regard to precautions.

The variety Fay’s Prolific is very susceptible, but Earliest of Fourlands is amongst the most resistant. Black pustule disease: this fungal infection attacks gooseberry and blackcurrant bushes also, although red currant bushes seem to be the most vulnerable. The infection usually enters the bush through a pruning wound and the symptoms are oval, dark wart-like pustules which appear on infected branches. If the whole bush is infected, it will die; mild infections can be dealt with by cutting off and burning the infected branches. Always cover large wounds or pruning cuts with a coat of protective sealer.

Gooseberry mildew: American and European gooseberry mildew occasionally attack currant bushes. The symptoms of American gooseberry mildew are white powdery patches on the young leaves, and on fruits and shoots. In summer and autumn, the patches become brown and felt-like. European mildew shows itself as a delicate powdery mould on the upper sides of the leaves and, very rarely, on the berries. Control both kinds by lime and sulphur or dinocap sprays before the flowers open. Cut out and burn any diseased shoots. Fay’s Prolific is resistant to American gooseberry mildew.

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12. August 2013 by admin
Categories: Currants, Fruit Growing, Gardening | Tags: , , | Comments Off on How to Grow Red and White Currants

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