Bushes and cordons may be bought as one- or two-year-old plants. Cordons can be trained against fences or walls — on a north wall they usually crop a week or two later. Amateurs should try half-standard red currants as they fruit all the way up the main, as well as on the branches. Always stake carefully when planting.
Red currants are less fussy than the black. Nevertheless it is advisable to prepare the ground thoroughly, incorporatingand/or well-rotted manure and potash either as sulphate of potash or wood ashes. Avoid windy situations if possible, as the branches are very brittle and liable to break at the slightest provocation. Plant bushes 4—5 ft., cordons about 2 ft. and half-standards 6—7 ft. apart. At the same time both leaders and laterals should be severely pruned. Feeding requirements of red and white currants differ from those of black currants. They do not require heavy dressings of farmyard manure and can do with less nitrogen. A complete fertiliser with a high potash content broadcast in February or March would provide an excellent top dressing, to counter any potash deficiency. Bonfire ashes or sulphate of potash may also be given in November, but not muriate of potash, since this may result in severe damage to the foliage. Red and white currants bear their fruit at the base of the laterals arising from the main branches. The new shoots produced as the result of back after planting are pruned in early spring (when birds have taken their final toll of buds), the leaders being reduced to about 6—9 in. and the laterals to 1—2 in. from the base. In subsequent years leaders are pruned according to growth, being light if growth is strong, and severe should it prove weak. Remember to cut to sound buds, as with certain varieties, notably Laxton’s Perfection, some buds tend to go blind.
Red currants produce a mass of growths and any not required should be removed or else cut down to 4—5 in. from the main branches in July. This treatment will keep the centre of the bushes open, thereby facilitating picking of the berries. Do notthe leaders in summer. Suckers arising from the ground must always be removed.
Propagation of red currants is very similar to that of black currants and gooseberries except that only the topmost three or four buds are left. Shoots selected forare usually rather longer than with black currants — they should be between 12—15 in. in length, as against 10 in. for black currants.
Choice of Varieties:.
Earliest of Fourlands: ready about the same time as Laxton’s No. 1. Erect grower with stiff branches.
Laxton’s No. 1: heavy cropper. Upright habit. Widely planted on a commercial scale and is equally satisfactory in the garden.
Laxton’s Perfection: very large berries, borne on long bunches. At times buds tend to go blind and shoots are extremely brittle. Do not grow in windy situations.
Raby Castle: does well in the north of England and in exposed situations.
White Dutch or White Grape and White Versaillaise are two good varieties, both with a very sweet flavour.
Pests of Black, Red and White Currants.
Black Currant Gall Mite or ‘Big Bud’. Symptoms: By far the most serious pest of black currants, though it is not always realised that control is possible with lime-sulphur. The mite responsible for ‘big bud’ damage also appears to spread reversion. Black currants are more prone to attack than the red and white, the type of damage differing on the latter — see below.
The mite measures about one-hundredth of an inch in length. From the end of March until June it lives freely on the. In June or early July it enters the developing buds and eggs are laid. They hatch and the young mites on the inside tissues of the buds, which start to swell until by mid-August they are at least twice the usual size. During the autumn and winter they continue to reproduce themselves inside the ‘big buds’. In early spring, the new mites migrate to the foliage, entering newly-formed buds in June to lay eggs.
On red, white and flowering currants and gooseberries, buds do not become abnormally swollen, but turn brown in the centre, with the result that they eventually shrivel up.
Treatment: The mites can be controlled by applying lime-sulphur when they are migrating from infested buds to the. Application should be made when the flower spike is at the ‘grape’ stage of development and before the blossoms open. Certain black currant varieties such as Davison’s Eight, Goliath and Wellington XXX are sulphur-shy and the concentration should be reduced according to the manufacturer’s instructions. Though not giving complete control, this will assist in ‘checking’ the pest. Some scorching of the foliage may occur, but will not harm the crop.
Currant Eelworm. This pest is not widely distributed but is of major importance where it occurs (chiefly in the south-east). At present it has been recorded only on certain varieties of black currants. The first signs of attack are apparent in early spring when the leaves are develop- ‘ ing. Owing to the presence of hundreds of eelworms, infested buds fail to grow and are often killed. May be confused with ‘big bud’ caused by the black currant gall mite. Daniel’s September and Westwick Choice appear to be the most susceptible varieties. No satisfactory control has been found. Propagation from absolutely healthy stock is therefore essential.
Black Currant Leaf Curling Midge. Symptoms: The midge appears in spring. Theof the tiny white maggots distorts the growing points of the shoots, leaves being curled and twisted. Later injured leaves exhibit characteristic ragged brown edges. The growing point is often killed and secondary shoots result.
Treatment: Pyrethrin applied in early April and again 2—3 weeks after flowering. The first spray can be added to the lime-sulphur spray for controlling ‘big bud’ mite.
Aphids. Symptoms: A number ofspecies attack currants in Britain, generally causing curling in the form of characteristic blisters. The currant aphid does not cause leaf curling, but is responsible for the reddish blisters seen on the leaves. Black currants are more often attacked than the red or white.
Treatment: Tar-oil spraying in winter destroys the eggs of all currant. Care must be taken to spray the entire bush, as some species lay their eggs near soil level. If tar-oil spraying has been omitted, an emulsion may be applied in mid-April before the leaves begin to curl. Spraying once leaf curling has started is practically useless. Green Capsid Bug or Lygus Bug. Symptoms: This pest closely resembles the apple capsid bug but damages a wider range of plants, including apples, cherries, strawberries and roses. The young capsid nymph emerges in April from the egg, usually a week or two after the apple capsid bug, and starts to suck the sap from the young leaves, causing small brown markings. At the end of the month or early in May it migrates to other hosts such as strawberries, potatoes and common weeds, especially bindweed, groundsel and dandelion. Eggs are laid on these plants. When the young bugs are fully winged, they return to the currant or gooseberry and lay their winter eggs in the bark of the young twigs before dying.
Treatment: To kill the over-wintering eggs, a DNC petroleum wash should be applied not later than mid February. A Pyrethrin dust or spray may be applied when capsid damage is first noticed — this usually coincides with the flowering of Bramley’s Seedling apple. Magpie or Currant Moth. Symptoms: The looper caterpillars of the magpie Moth are black, yellow and white. Theyon the foliage from the bud-burst stage to May or June, often defoliating the branches. Spray with immediately attacks are noticed.
Diseases of black, red and white currants:
Leaf Spot. Symptoms: Small, irregular dark brown spots are found on the leaves from mid-June onwards. Early defoliation may follow, resulting in the fruit shrivelling before it becomes ripe. The bushes are weakened, with a reduction in crop the following year.
Treatment: The fungus overwinters on the fallen leaves. Spray with a copper fungicide immediately after the crop has been picked. Reversion, Nettlehead or Nettleleaj. Symptoms: Reversion is a virus disorder of major importance in black currants, red and white currants seldom being affected. Leaves of reverted bushes are darker, narrower and less serrated than those of healthy specimens, and the crop is usually of poor quality. If a normal leaf is carefully examined in June, it will be noticed that there are five or more veins spreading from the mid-rib, whereas on an ‘infected’ bush, there will be generally only four, and fewer marginal teeth. Theof healthy black currants are pale lavender, but on reverted bushes they are usually darker, being of a maroon or claret shade.
Black currants sometimes revert branch by branch. Infected branches give rise to numbers of side shoots with pointed, narrow leaves, suggesting a clump of nettles — hence the names nettlehead and nettleleaf. Control: There is no known cure. Cutting out affected branches is useless, since the disease will appear later elsewhere on the bush. Affected plants should be dug up and burned. Cuttings must be taken from completely healthy bushes. The ‘big bud’ mite appears to be a carrier of the virus, hence spraying with lime-sulphur against this pest will effect a dual control.