BLACKCURRANT PESTS AND DISEASES

APHIDS

These are small insects (commonly greenfly and blackfly) which suck the liquid out of tender new shoots. This weakens the blackcurrant bush. The aphids also create a sticky liquid which cover the leaves and attracts other insects and diseases. They rarely kill blackcurrant bushes but can seriously reduce the amount of fruit produced. See our detailed article on identifying and dealing with aphids here. A close-up picture of an aphid attack on a blackcurrant leaf can be seen below, click it to enlarge and see the full horror!

Greenfly on a blackcurrant leaf

One particular aphid can cause red blisters and marks on the surface of the leaves on all the currant bushes. It’s called the Currant Blister Aphid (Cryptomyzus ribis), see the picture below. This particular aphid tend to restrict itself only some of the leaves and although the effect looks dramatic it rarely affects the health of the plants. We simply ignore them. If you want treat it then do as described for aphids above.

Currant Blister Aphid
Red areas on currant bush leaves

Aphids, including the Currant Blister Aphid, are first seen on currant bushes from late April to mid May depending on the climate in your area. If you do intend to spray them, do it at the very first sign of damage for maximum effect.

BIG BUD MITE

Big bud mite almost exclusively affects blackcurrant bushes. In late winter, January and February time, when the buds would normally begin to form, they do so but are much larger than normal. Affected buds either fall off or produce distorted growth which fails to produce fruit.

There is no cure for big bud mite, chemical or otherwise so your best course of action is to let the plants grow throughout the season, harvest whatever fruit is produced (it is safe to eat) then dig up and burn the plant. Replace with another plant, the variety Ben Hope has good resistance to big bud mite.

REVERSION DISEASE

Reversion Disease affect blackcurrant bushes almost exclusively. It is a virus which cannot be treated and affected plants should be dug up and burnt. The variety Ben Gairn has been shown to have some resistance to Reversion Disease.

In almost all cases it follows an infection of Big Bud Mite (see above). Reversion Disease will cause the yield of your blackcurrant bush to reduce significantly to almost nothing after three years. Another sign of Reversion Disease are flowers which are malformed.

MILDEW

Mildew often affects blackcurrant bushes and it is normally preventable. The signs are a greyish powder which can appear on the fruit, leaves and in bad cases on the stem. It is unlikely to kill the bush but it will weaken it and make it more prone to other diseases. For a full description of the symptoms and treatments for Powdery mildew, .

There are chemical sprays available to help kill mildew although prevention is much better than cure. Older varieties of blackcurrants are far more susceptible to mildew so avoid growing those. The “Ben” varieties (with the exception of Ben Lomond) of blackcurrants are all resistant in some degree to mildew. The new variety (to the UK) Titania also shows significant resistance to mildew.

Pruning methods can also significantly reduce the risk of being affected by mildew. See our article of pruning blackcurrants here. If your blackcurrants are susceptible to mildew pay particular attention to keeping the central part of the bush free from congestion. Also take care to remove all crossing and touching branches. When they rub together they can open up the bark letting in infections.

FRIUTS FALL OFF BEFORE THEY ARE RIPE

The symptoms are that blackcurrant bushes form green currants normally but around mid May to mid June they fall off before they are ripe. This can be due to several causes and it is known as “run-off”. By far the most common cause is adverse weather conditions especially cold weather. Other causes can be lack of water, pests and diseases, particularly botrytis and mildew. It can occur in one year and then never appear again or can occur in several years depending on the cause.

Older varieties of blackcurrants are particularly prone to run-off and often the only solution is to plant one of the newer varieties which are more resistant. Our suggestion for a variety which rarely suffers from run-off is Ben Sarek.

LEAVES WILT AND BLACKCURRANT PLANTS DIE

If the leaves on a blackcurrant bush wilt and die, but at the same time you are sure there is no shortage of water, then the conclusion must be that, for some reason or other, the roots are not able to take up moisture and nutrients. The most common cause of this in the UK is the vine weevil. In its most damaging stage of life it eats the roots of blackcurrant bushes both in pots and the open ground. To find out how to specifically identify this pest and what can be done to eradicate it for our in depth page on vine weevils.

WOOLLY (VINE) SCALE INSECT

The symptoms are small patches of white stuff on the stems of blackcurrant bushes. They often appear on slightly weaker parts of the bark where leaves or small stems have broken off. If you prune late in the year they will also be attracted to the point at which a stem has been pruned. The picture below shows just that happening although they can just as easily appear anywhere on stems and branches.

Woolly Scale Insect (click to enlarge)

The technical name for this insect is Pulvinaria vitis. At the centre, underneath the white substance you will find a female scale insect and she has laid eggs and then created the white covering to protect the eggs. They can vary in appearance, shape and size depending on the conditions. A few of them don’t do much damage but if left they will breed and can then become a problem.

The white coating protects them from insecticides which are of little use because they just run off. If you can get the timing just correct, the time to spray with an insecticide is when the eggs hatch and the young scale insects begin moving about to a new part of the plant. In most cases, this window of opportunity is too small to be of use. The only way to get rid of them is either to squash the white blobs with your fingers (killing the eggs inside) or to use a toothbrush or similar to do the same job.

OTHER SCALE INSECTS

There are many forms of scale insects which attack a variety of plants and blackcurrants are often one of their victims. The picture below shows just how scary looking this pest is but, although serious if left to its own devices, it is not impossible to control. At maturity they look like pea-sized growths which are purple-brown on stems and young branches.

Picture of scale insects on a blackcurrant bush
(picture courtesy of Margaret L.)

First, exactly what is it? What you see in the picture above is a scale insect which feeds on the sap of a twig, branch or leaf. Their life cycle begins when the scales overwinter and then lay eggs around May time – 200 or so eggs which are beneath the parents body. In May to mid July the eggs hatch and crawl away to new parts of the tree. This is the stage at which pesticides can be effective, when the insects are moving about. When the insects find a suitable position they clamp their jaws onto the bark of tree and begin to feed on the sap of the tree without moving again.

If you can identify the period in May /June when the young scale insects are on the move spraying with an insecticide will kill them. Ask at your garden centre for an appropriate spray. In general though, sprays suitable for killing aphids will also kill moving scale insects.

If you miss this stage of their lifecycle then a plant oil winter wash treatment (again ask at your local garden centre) in December to January will effectively suffocate many of the overwintering bugs.

The easiest method, if your tree is a manageable size, is to manually remove the scale insects around May when they are clearly visible but have not yet hatched their eggs. If you are squeamish about removing them with your fingers use a toothbrush and some diluted washing up liquid to brush them off. A gentle spray after with a hose should then remove all traces of them.

CORAL SPOT

This is a fungal infection which causes yellow / orange / coral spots on the stems of blackcurrant bushes (and many other plants with woody stems such as red currants). At different stages of the disease the appearance changes slightly.

Picture of Coral Spot on a blackcurrant bush

The fungus initially attacks dead wood which, in the case of blackcurrants, is normally caused by faulty pruning techniques. It then spreads to live wood and affects the health of the bush. Small, deformed leaves are the secondary sign followed by stems which die back. In the end the plant will die if not treated.

Another picture of Coral Spot

To halt the progress of the fungus the minimum which should be done is to prune out all affected wood. Do this 15cm into good, healthy looking wood. Our personal recommendation would be to prune the entire plant back so that only 15cm remains above ground level.

This is harsh treatment and the bush is unlikely to produce fruit for two years. However it has the best chance of eradicating the fungus completely. If the bush is ten or more years old it is best to remove entirely and replace with a new plant.

To avoid this fungus follow our pruning instructions which can be found here. Use sharp implements to prune and make the cuts as clean as possible.

BLACKCURRANT SAWFLY

The key sign of this pest are simple to identify, the leaves are reduced to skeleton and look like lace. The sawfly has five distinct stages to its life cycle and the damage is done in the fourth cycle, when the pest is a caterpillar. They eat the soft parts of the leaves leaving the veins completely alone. The fruit is also untouched.

Picture courtesy of reader Peter L.

This pest should be treated in exactly the same manner as raspberry sawfly as described here.

STEMS ARE HOLLOW / HAVE BLACK CENTRES

Some observant people notice, when pruning their blackcurrant bushes, that some of the stems are either hollow or have black / brown marks in the centre. See the two pictures below which clearly show what the problem is.

Blackcurrant stem with black ring in the centre

Blackcurrant stem hollowed out in the centre

Both of these are simply stems which are past their best. The black centre in the stem occurs first and if the stem is not pruned it later becomes hollow in the centre. Neither of these stems will produce a crop of blackcurrants so the solution is to prune them away as close to the base of the plant as possible without damaging the plant.

Regular pruning as recommended here will ensure that similar branches are pruned away before they get to this stage, ensuring the maximum amount of fruit is produced each year.

CURRANT BORER

The larvae of the Currant Clearwing Moth is commonly called the Currant Borer. It’s not a common pest in the UK but does occasionally strike. The moths don’t really look like your average moth. The bodies are slim and black with two wings and two feelers clearly visible from the front of the head. Males have four yellow bands around their body, females have three.

The larvae, which do the damage are 15 to 18mm long and a cream body. Because they are concealed inside the stems they are often not noticed and cannot be treated with pesticides. An understanding of the Currant Clearwing Moth may help in preventing too much damage.

Larvae of Currant Clearwing Moth
Picture courtesy of Aubin van Berckel

APRIL TO MAY
The moths will be seen flying around the currant bushes often resting on the leaves. They lay tiny single eggs in the V between new shoots or buds. The eggs hatch after a week or two and the larvae, which are small at this stage, eat their way into the centre of a stem.

MAY TO APRIL
The larvae spend all this time feeding on the centre part of the stems and go into hibernation in winter.

APRIL TO MAY
The warmer weather re-invigorates the larvae who eat into the outer wood of the stem leaving a thin outer layer. They spin a cocoon which in a week or so pupates and then eats its way through the remaining thin bark layer and emerges as the moth. The skin of the pupa remains at the exit hole from the bark.

After reading through the lifecycle above you’ll now understand how difficult it is to treat this pest. It is possible to spray pesticide on the leaves in April to May time in an attempt to kill the moths but there is no research to understand if this is effective.

The best course of action is to prune the affected bushes to 15cm / 6in above ground level in December time and burn the prunings. This will result in a very low crop the next year but in later years the plant will fully recover.

Diseases

Currant Cane Blight or Botryosphaeria Canker (Botryosphaeria ribis): Initial symptoms appear as yellowing foliage and leaf wilting of young shoots during spring and summer. Affected shoots may resemble currant borer damage, but will have not borer larvae or exit holes. Once the cane is dead and no longer transporting nutrients, the fungus will make small (2mm in diameter) round black survival structures, stromata, which burst through the epidermis near tips of infected shoots. This disease causes canes to become extremely weak and consequently break off during high winds in the fall and subsequent winter. All currant varieties may be affected however gooseberries are not known to be affected.

Management: Watch for a rapid blight of young shoots during early fruit development, and scout mature canes for the small black survival structures prior to budbreak. Prune out and burn infected canes in spring. There are differences in resistance among cultivars, but it is variety specific and not linked to color traits.

Redcurrant Cordons & Pruning

Initial Pruning for Redcurrants

Redcurrants and whitecurrants do not need the hard pruning that is recommended for Blackcurants and a framework of growth is left in place. Initially the leaders can be shortened by up to one third to any outwardly facing bud. This has the effect of keeping the centre of the bush more open which makes the foliage less prone to disease and also makes harvesting easier. You will find the fruiting trusses in the centre of the bush will ripen more readily, and will be sweeter as a result of this type of pruning. This pruning should be done soon after planting. The following winter leading branches can further be shortened to encourage side laterals. At this stage any unwanted low branches can also be removed at their base.
By the third year you should have a well shaped and nicely branched bush. From now on the only attention is to continually shorten longer/main branches and remove any that are causing congestion, diseased, or broken.

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Cordon currants

An increasingly popular way of growing both redcurrant and white currants is as the cordon system. This saves a great deal of space in the garden as a single cordons can be planted just 15” apart, with double cordons only 18”-24” apart. A single cordon will have just one main stem with numerous short side laterals coming off it. A double cordon will have two main stems in the shape of ‘V’ so it will produce double the crop but will take more space.
Cordons are quite easy to maintain and the fruits ripen really well with the benefit of all that sunshine and air circulation. They will need some support; a good stout bamboo cane for a single cordon, and two for the double, can be sufficient if you need to grow them in the open and only want one or two specimens. But gardeners often take advantage of the modest planting distance required, two plant a row and thus incorporate more varieties. Gooseberries href=”https://www.chrisbowers.co.uk/category/redcurrants/”>Redcurrant also can be included here as well. In this case a post and wire system would be more practical, the posts need to be 48” height allowing for burial, and 1 x 1” should be satisfactory. Two straining wires, placed at 24” and 36” is adequate. The cordons themselves will grow quite tall if you let them – heights of up to 6’ are common and that is ok if you want to grow them against a wall but in an open position I would recommend tipping them at 4 or 5’. Of course the taller they are the more crop you will get.
Pruning consists of keeping the main side shoots trimmed back to 4 or 5 leaves in June OR July of each year. These shoots ripen to give fruit the following summer. The leader is left intact at this point.
After 2 or 3 years you will have an established framework which should be maintained by trimming back all laterals to 1”. The main leader can be trimmed to just above a bud as required. This type of pruning should be carried out from November to February. A second dose of pruning is then required later that summer, this time trimming back those side shoots to 4 or 5 leaves again.

Pests and diseases

With the exception of big bud mite, redcurrant and whitecurrants bushes may suffer from the same pests and problems as blackcurrants, a resume follows here.
Predation from birds cannot be underestimated and will be much more severe than it is with blackcurrants. Redcurrants in particular are one of their most favourite things and provision should be made to deter them. Growing redcurrants in a fruit cage is a very worthwhile practice to be absolutely sure you get to harvest your spoils. If this is not possible then fastidious netting – making sure there are no holes or pockets that the birds’ can gain access through, as their eyes are much sharper than ours – is the best option. This should be erected just as the very first berries start to colour up. At this point most of the crop will still be green but if you leave it too late then the majority of the berries will be taken just as they start to ‘turn’ colour.

Aphids & greenfly

Are the most commonly troublesome critters, causing soft new growth to curl and become distorted, sometimes it also become streaked with yellow. These insects overwinter on the bush so the first step to eradication is to provide a winter wash all over the bush whilst it is dormant. Insecticides are still very effective but you need to start early, soon after the first leaves emerge and repeat applications as directed by the manufacturer. If you have left it too late and your blackcurrants already show signs of heavy infestation, be prepared to snip off the ends of the new growth where the damage is worst, destroy these growths, and then spray. Unchecked greenfly populations sap the strength of the bush and they also spread diseases.

Mildew

This is a fairly commonplace problem with currants and is more troublesome with the older varieties but not exclusively so. The leaves become silvery and powdery and it can spoil the fruits too. Sometimes this fungal disease is encouraged by a lack of pruning as too much congested or soft growth encourages it. It is fairly easily dealt with by a proprietary insecticide but again prevention is better than cure so start an early spraying programme to prevent it getting a hold in the first place.

Leaf spot

Begins life as small brown spots on the leaves which gradually become larger and coalesce. Leaves fall prematurely and the resultant crop is usually affected. The disease can be controlled by the use of a broad spectrum fungicide, applied shortly after flowering. Extra feeding is usually effective to help the bushes regain vigour that has been lost.

Connecticut State The Connecticut Agricultural Experiment Station

Plant Health Problems
Diseases caused by Fungi:
Anthracnose, Pseudepeziza ribis.
The leaves are most commonly attacked although this disease can also occur on the fruit. The symptom on leaves is a scattered pattern of small red-brown to purplish spots that ooze masses of pink spores on the underside of the leaf. Red and white varieties are most susceptible.
Control can be achieved by raking and removing of infected leaves and fruit. It is also important to maintain good air circulation and maximize plant vigor. Use of fungicides is not effective or practical.
Powdery mildew, Sphaerotheca.
White powdery patches develop on leaves and shoots in early spring. These areas gradually turn a rusty brown as the spots age. Newly formed fruit are often infected and are covered with the white powdery growth characteristic of this disease. Infected fruit shrivel, crack and shatter. Species and cultivars vary in their susceptibility although European varieties are more susceptible than American ones.
Control can be achieved by pruning and removing of infected shoots. It is also important to maintain good air circulation and maximize plant vigor. Use of fungicides is not effective or practical.
Botrytis fruit rot, Botrytis cinerea.
Diagnostic symptoms appear as infected leaves and fruit are covered with a gray fuzzy mass of the fungus. This disease can result in extensive losses when wet weather occurs right before harvest.
Strategies to control this disease are aimed at methods that maximize air circulation and drying of the fruit and include pruning and thinning of the plants. When weather is favorable for disease, fungicide sprays are often necessary for effective control. Among the compounds registered for use in Connecticut is sulfur. Sprays are usually applied just before bloom and are repeated as necessary. Consult the label for dosage rates, safety precautions, and days to harvest intervals.
Cane blight, Botrysphaeria spp.
This disease occurs on the stems and can result in girdling and killing cankers. On the dead stems small, black fruiting pustules are produced and visible with a hand lens.
Pruning and removing infected canes back to healthy wood when the bark is dry is a key strategy for control. It is also helpful to maximize plant vigor by following sound cultural practices which include fertilizing, pruning, and watering.
White pine blister rust, Cronartium ribicola.
All species and varieties of currants are susceptible to one stage of the rust causing white pine blister rust. Symptoms appear as flat bright orange spots on the leaves in midsummer. Red currants are not very susceptible but black currants are very susceptible. Although this rust is of minor importance on currants, the fact that they are an alternate host for the white pine blister rust, probably the most serious disease of white pine, gives added importance to this disease on currants.
Although Connecticut no longer prohibits growing currants, many other New England states still limit their growth. Black currants (R. nigrum) are the most susceptible to this disease although hybrid, rust-resistant black currants are now available. These include Titanic, Consort, and Crusader. Chemical control is not effective.
Insect Problems:
Currant aphid, Cryptomyzus ribis.
This aphid is usually found on the underside of the tender terminal leaves which become more or less curled or blistered. Glossy black eggs on the twigs of the new growth carry the insect through the winter. These eggs hatch soon after the first leaves unfold. Many generations during the summer are born alive, most of them females without wings. When the aphids become overcrowded, winged females develop and migrate to other currant plants. The distorted and curled leaves often turn red and drop. After midsummer, the aphids become less abundant because of natural enemies, but enough females survive to lay eggs on the twigs in October.

Sprays of insecticidal soap, ultrafine horticultural oil or malathion, which are among the compounds registered for control of this pest in Connecticut, may be applied to the undersides of the leaves as soon as the aphids appear. Consult the label for dosage rates, safety precautions, and preharvest intervals.

Currant borer, Synanthedon tipuliformis.
Certain stems that appear to be unthrifty and finally die usually have the center or pith tunneled by the larva of this insect. The eggs are deposited singly on the bark. The fully grown larva is about ½” long and is white with brown head and legs. The adult is one of the clearwinged moths with a wingspread of about 3/4″. The wings are transparent with opaque purplish margins. There is one generation each year, and the moths emerge in June. Sickly canes may be cut off and burned, if allowed, before June 1.

Currant fruit fly, Epochra canadensis.
This insect often causes serious injury to currant and gooseberry. The larva or maggot infests the berries, which may hang on the bushes or drop to the ground. There is only one generation each year, and the winter is passed in the pupa stage in the ground. The adult fly is about the size of the housefly, but is pale yellowish in color with banded wings. Two or three sprays or dusts of rotenone, which is among the compounds registered for use against this pest in Connecticut, at weekly intervals, starting when the blossoms fall, should control this pest. Consult the label for dosage rates, safety precautions, and preharvest intervals.

Currant stem girdler, Janus integer.
This insect is a sawfly that lays an egg in May in the new shoot and girdles or cuts it partly off an inch or less above the egg. These tips break off or hang from the canes. On the hatching of the egg, the young larva burrows downward in the pith to a distance of not more than 6 inches. About September 1, the larva reaches maturity, cleans out the lower end of the burrow, and eats a passageway to the outer bark. It passes the winter as a larva in the burrow and pupates in the spring. There is one generation each year. The only known remedy is to clip off and burn the tips of the canes.

Fourlined plant bug, Poecilocapsus lineatus.
This bug lays eggs in the soft stems. They hatch about the middle of May and the young bugs suck the sap from the tender leaves. They molt five times and when mature, about the middle of June, they have wings and are nearly 1/3″ long. The insect body is yellow, marked lengthwise on the wings with four black stripes alternating with three green stripes. The injury to the leaves consists of sunken areas around the punctures. These areas later appear as circular transparent spots and finally as circular holes. This insect injures the new leaves of many different kinds of annual and perennial plants and shrubs. There is one generation each year. The nymphs can be managed by spraying with azadirachtin, ultrafine horticultural oil, insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut. Consult the label for dosage rates, safety precautions, and preharvest intervals.

Gooseberry spanworm, Cymatophora ribearia.
This insect occasionally feeds on gooseberry and currant. The larva is about an inch long when full-grown. It has the habit of a measuring worm and loops when it crawls. It is whitish with yellow stripes and black spots. It pupates in the ground and the moth emerges late in June. The moth has a wing spread of about 1 1/4″ and is light tan with a row of parallel gray dashes across each wing. The eggs are laid on the bark in July and hatch the following spring. Treatment is seldom needed.

Imported currantworm, Nematus ribesii.
The adult sawflies emerge when the currant leaves first unfold, and lay white elongate eggs end to end in rows along the veins on the underside of the leaves of currant and gooseberry. The eggs hatch in a week or 10 days, and the larvae feed on the leaves, becoming full grown in 2 to 3 weeks, when they are about 3/4″ long. During most of the feeding period, the larvae are grayish-green, covered with black spots but at the last molt, they lose the black spots and are a uniform green. They pupate beneath leaves or trash on the ground. A second generation begins in late June or early July. The first generation causes most of the injury; the second is of little account. Among the compounds registered for control of this pest in Connecticut, rotenone should be effective if sprayed when the first generation larvae begin to feed. If treatment seems necessary when the fruit is near maturity, pyrethrum may be used. Consult the label for dosage rates, safety precautions, and preharvest intervals.

San Jose scale, Quadraspidiotus perniciosus.
Large infestations of the San Jose scale can cause loss of vigor in currants. Partially-grown scales overwinter under their circular gray covering or scale on the twigs. They begin to feed as the sap starts to flow. When apple trees bloom, the males emerge from under their scales to mate with the immobile females. Females are circular and cone-shaped, and their circular scales are about 1/16″ in diameter, with a raised center or nipple. The males are smaller and elongate, with the nipple not centered on the scale. Females give live birth to tiny bright yellow crawlers in June, usually about 3-5 weeks after the flower petals drop. The young crawlers quickly settle, insert their long mouthparts into the twigs, and then suck sap from twigs. As they grow, the crawlers secrete a waxy filament that becomes their scale or covering. Scales apparently have 2 generations per year, with the first in June and the second in August. Scales may be controlled by applying horticultural oil, which is among the compounds registered for control of this pest in Connecticut, as either a summer or dormant spray. Consult the label for dosage rates and safety precautions. To detect the yellow crawlers, wrap black tape coated with Vaseline around small branches. Adult flights may be detected with pheromone traps.

Scurfy scale, Chionaspis furfura
These whitish or light gray scales infest pear, apple, currant, and other trees and shrubs, reducing tree vigor. Scurfy scales pass the winter as purplish eggs under the shell of their mother. In Connecticut, the yellow crawlers hatch from eggs about the last week of May. They soon settle on the bark and insert their long mouthparts to suck the sap. The adult females are pear-shaped and about 1/10″ long. The males are much smaller, long and narrow, with 3 longitudinal ridges or carinae. Dormant treatments with horticultural oil control these scales. A spray of insecticidal soap, which is among the compounds registered for control of this pest in Connecticut, early in June also will destroy the young. Consult the labels for dosage rates and safety precautions.

Twospotted spider mite, Tetranychus urticae.
This mite may be a serious problem on currants, especially if naturally occurring predators (predatory mites, six-spotted thrips, and mite destroyer ladybeetles) are disrupted with insecticides (such as rotenone). Ultrafine horticultural oil will control these mites while conserving natural predators. Consult the label for dosage rates, safety precautions, and preharvest intervals.

Learn About Currant

Common Currant Disease Problems

Anthracnose: This is a fungus disease that attacks the fruit as it is ripening. The first visible sign is a circular spot on the skin that is slightly sunken. The spots enlarge and turn black; the fruit rots. Extended periods of heat and humidity facilitate anthracnose growth. The fungus overwinters in diseased plant debris. Burpee Recommends: Plant resistant varieties, provide sufficient space between plants for good air circulation, avoid overhead watering which can spread the fungus spores, keep a clean garden, remove and discard all diseased plant material and rotate crops. Use a mulch to prevent spores from splashing from the soil onto plants.

Botrytis: This fungus causes a grey mold on flowers, leaves, stems and buds. It thrives in cool wet weather conditions. Burpee Recommends: Remove affected plant parts, avoid watering at night and getting water on the plant when watering. Make sure plants have good air circulation. Contact your Cooperative Extension Service for fungicide recommendations.

Powdery Mildew occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.

Septoria Leaf Spot: This disease causes severe losses in the Atlantic and Central states. It is most severe during rainy seasons in closely planted gardens. It usually appears when the plants begin to set fruit. Circular spots with gray centers and dark margins appear on the lower older leaves. Fungal spores are produced and darken the center of the spots. There is a progressive loss of foliage and fruits suffer from sunscald. Burpee Recommends: Remove and destroy infected plant debris. Don’t handle or brush against plants when they are wet. Rotate plantings. Remove weeds growing nearby.

White Pine Blister Rust: Small yellow spots appear on the underside of the leaves in spring. In late summer yellow to brown threadlike growths appear on or near the spots. The growths produce spores that will spread the disease to pine tree, the alternate host. Burpee Recommends: Plant resistant varieties. Do not plant near to pine trees. Avoid wetting the leaves when watering. If it is a bad infection remove and destroy plant. There are no effective pesticides to control White Pine Blister Rust.

Common Pest and Cultural Problems for Currant Plants

Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.

Currant Borer: The larva is pale yellow and wormlike. The female lays eggs on the canes in early June. The worm hatches and enters the cane and feeds all season. Larvae overwinter in the infested cane, emerging in the spring as an adult. The first symptom is yellow leaves on individual canes in late spring. Canes will die in summer. Burpee Recommends: Remove and destroy infested canes as early as possible.

Gooseberry Fruitworm or Currant Fruit Fly: Signs include hollow fruit or small maggots inside fruit. Fruit may drop early and have dark spots surrounded by red areas. Burpee Recommends: Remove all dropped fruit and destroy. Plant early-maturing varieties. Contact your local Extension Service for pesticide recommendations for your area.

Scale: Small bugs look like brown, black, gray to white bumps on the stems of plants. Scale may not have any apparent legs and may not move. Scales have a sucking mouth part. Scale may produce honeydew so leaves and stems may be sticky. Scale can weaken the plant causing it to grow very slowly and may wilt at the middle of the day. Burpee Recommends: Completely spray the stems with insecticidal soap. For a severe infestation contact your local County Extension Service for recommendation for your area.

Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.

Ministry of Agriculture, Food and Rural Affairs

Always follow manufacturer’s instructions for the application of pesticides. They are found on the container label. Apply no more than the amounts specified and at the times indicated. Be certain not to apply pesticides closer to the picking date than specified on the label.

Diseases

Powdery Mildew

Black currants and European types of gooseberries are especially susceptible. In early summer, a white powdery fungus growth appears on young leaves and tips of branches and new shoots. The fungus may spread over much of the bush and often occurs on gooseberry fruits. It seldom occurs on the berries of currants. Later, the white powdery growth becomes brown, and forms a felt-like coating over affected parts. Shoot growth is often stunted, tips may be killed, and gooseberry fruits may also be stunted. The fungus is spread by spores. Warm, humid conditions favor its development. Cut off and destroy diseased tips of shoots and branches when pruning in the winter or early spring. Provide a site with good air circulation. Control can be obtained by planting resistant varieties or with the use of fungicides.

Anthracnose (Leaf Spot)

This is a serious disease of black currants and can also cause severe injury to red currants and gooseberries. Many small, brown spots occur on leaves from mid-summer to late fall. Badly infected leaves turn yellow and drop. The main damage is the defoliation which may occur as early as the end of July. Early defoliation reduces growth and causes loss of crop the following year. Spots can also occur on young shoots, leaf petioles, fruit stems and berries. The fungus lives over winter mainly in fallen leaves. Remove and destroy fallen infected leaves in late fall or in the early spring before buds burst. Apply any new mulch after leaves drop. Fungicides also provide control.

The fungus causing this disease spends part of its life cycle on currants or gooseberries and part on white pine. The disease can cause serious problems with white (five-needle) pines. Do not plant currants or gooseberries within 300 m (1,000 ft) of susceptible pines. Black currant varieties such as Titania and Consort are resistant to rust.

Insects

Currant Borer

This insect can cause serious injury to currant, and to some extent gooseberries. The adult is a clear-winged moth similar in size and appearance to a thin housefly. Wings have black bands and the body has several narrow yellow bands. The moths appear in mid-June at Vineland and lay eggs in the axils of leaves. The young larvae bore into the pith of the shoot and feed there. The following spring, affected shoots often leaf out late, are sickly and may die. When an injured shoot is cut, a dark hole can be seen where the larva has tunneled in the pith. The yellowish-white larvae, which are about 12 mm (1/2 inch) long, may also be present. When pruning, remove and destroy branches which have dark, hollow piths. Also, remove and destroy any dying or sickly branches during the growing season. Follow recommended pruning practices and do not let shoots become too old. Keep plants growing vigorously.

Scale Insects

Several scale insects attack currants and gooseberries. The small scales (round or like any oyster shell) can easily be seen on dormant wood. These insects suck juices from the tender wood and sometimes occur on the fruit.

Aphids

Small greenish-yellow aphids feed on the under surface of young leaves at the tips of shoots. These leaves curl downward and have a blistered appearance. Red currants are particularly susceptible and affected leaves are weakened and may die.

Currant Sawfly

The larvae of this insect are smooth greenish worms with many black spots. The worms are about 20 mm (3/4 inch) long when fully grown. They feed on the edge of leaves and can strip plants of much of their foliage. When signs of feeding are noticed, usually early in the season, kill any worms present.

Currant Fruit Fly

The adult flies emerge about the time currants are in bloom. The female lays eggs in developing berries. The eggs hatch into maggots which feed inside the berries. Affected fruits of currants and gooseberries ripen prematurely and many drop to the ground before the normal harvest time. A small white maggot will be found in each fallen berry. The insect leaves the berry and spends the winter in the soil.

Premature Fruit Drop

Black currants frequently suffer from premature fruit drop several weeks after bloom. In Europe, this phenomenon is called “run-off” and is thought to be caused by lack of seed set in the fruit.

Run-off is a complex problem with a number of causes, including susceptible varieties, self-incompatibility, lack of pollination (too few pollinators or poor pollinating conditions), soil fertility levels, virus, currant fruit fly, drought, excessive moisture, Botrytis, frost or varietal intolerance of cold above 0°C temperatures.

Research at the Horticultural Research Institute found that the variety Magnus can lose 60% of its fruit if the overwintering buds are subjected to 2°C for two days when the fruit buds are at the grape stage, the period when the fruit buds are just beginning to expand (usually one or two weeks before flowering).

Many home gardeners have problems with premature fruit drop and in most cases, the variety that they are growing is susceptible to cold, above 0°C temperatures before bloom. Two varieties, Magnus and Willoughby, are particularly prone to this phenomenon. These varieties have been in widespread sale through nursery catalogues.

Growers should avoid planting these varieties. Non-fruiting, established Magnus or Willoughby bushes should be replaced by a known variety. Ben Alder and Ben Sarek produce less ethylene and are therefore less susceptible to “runoff”.

Flower:

Arching to dangling clusters of 6 to 15 stalked flowers arising from leaf axils. Flowers are about ¼ inch across, saucer-shaped with 5 inconspicuous, erect, stubby pink to purplish petals. Alternating with the petals are 5 stamens nearly as long as the petals with creamy colored, heart-shaped tips (anthers). The calyx cupping the flower is purplish or greenish, hairless and not glandular, with 5 sepal lobes that are rather petal-like, much larger and showier than the actual petals. Sepals are pink to purplish or greenish, broadly wedge-shaped and typically rolled under. Between the calyx and flower stalk is a smooth, green ovary.

At the base of the flower stalk is a short, broad bract sparsely covered in glandular hairs. Flower stalks are less than ¼ inch long, hairless or minutely hairy, with scattered short, glandular hairs.

Leaves and stems:

Leaves are 1½ to 3½ inches long, 2 to 4 inches wide, coarsely toothed, straight to heart-shaped at the base, with 3 to 5 primary lobes that may be again shallowly lobed. Veins are prominent and radiate from the base.

The upper surface is sparsely hairy, the lower variously covered in white hairs, more densely so along major veins and may become smooth with age. Leaf stalks are 1 to 2½ inches long, minutely hairy with scattered short, glandular hairs.

New twigs are green, with a mix of glandular and non-glandular hairs, becoming smooth and reddish brown, the thin outer layer peeling away. Older stems are brownish to gray and lack spines or prickles. Stems are erect, ascending, or trailing, rooting at the nodes and stem tips.

Fruit:

Fruit is a shiny, smooth, bright red berry ¼ to 3/8 inch in diameter.

Notes:

The Ribes species consist of both gooseberries and currants. Currants are distinguished by their lack of any spines, prickles or thorns on the stems, which all gooseberries have to some degree, and clusters of 6 or more flowers, where gooseberries have clusters of only 1 to 4 flowers. Most similar to Swamp Red Currant is Garden Red Currant (Ribes rubrum), which has similarly shaped flowers that are yellowish to greenish with anthers that are dumbbell-shaped, and lacks glandular hairs on flower stalks, where Swamp Red Currant has more pinkish flowers with heart-shaped anthers, and has glandular hairs on stalks. There are also subtle differences in the leaves described in some references, but we have not found them to be very reliable characteristics in the field, though we observed Swamp Red Currant leaves are hairier on the upper surface where Garden Red Currant is mostly hairless. Swamp Red Currant also tends to stay short and low to the ground where Garden Red Currant can reach 4 feet or more tall.

Red Currant

What are Red Currants?

Red currants are a member of the genus Ribes, which belong to the family of Grossulariceae, and grows in the north temperate region. It is native to the region of Europe, Germany, France, Italy and Spain. It is a deciduous shrub which produces edible bright red berries.


Picture 1 – Red Currant Picture
Source – Blogspot.com

Red Currant Definition

Red Currants are bright, red berries that grows in bunches in the deciduous red currant shrub, and can be eaten raw as a fruit, or used to prepare sauces and jellies.

Flowering Red Currants

Ribes sanguineum is a flowering Currant, or the red flowering currant, as it is also called. It is a species that is found in the region native to the North America. It is also a deciduous shrub, a very well known and beloved species of the northwest region, which has a beautiful display of the caramine red flowers.

Red currant Plants

Red currant plants are relatively low maintaining plants. They can be used for ornamentation because they are beautiful to look at and enhance the beauty of the garden. These plants can grow well in well drained soil which has a pH of about 6 to 7, and can grow into beautiful red currant trees in this soil. The plant should be kept weed free. It takes quite some time before these plants actually grow up into red currant trees.

Red Currant fruit

Red currant fruits are of translucent red color berries that grows in bunches. The plant produces numerous pendulous chains of small bright red berries. These fruits can be eaten raw, and are very delicious to taste. They are very easy to pick, as these fruits have strigs which enable the picker to hold the fruits without any problem. These berries are 8-12 mm in diameter. Approximately 3-10 berries grow on each raceme. A normal sized red currant bush can produce 3 to 4 kilos of berries in the summer season.

Red Currant flowers

The red currant flowers appear at the time of early spring. These flowers are grown and spurs on the older stems. Each of the bud opens up into a number of flowers, and they are together joined together into a delicate and drooping inch stem, which is called a strig. The numbers of flowers may fall low due to the chillness of winter. One may not be able to see an individual flower so distinctly, but when it is combined with the other flowers, they provide a lacy texture to the plant.

Growing Red Currants

Red currants are deciduous shrubs. They grow fast and into a healthy plant under optimum conditions. The roots of this plant are superficial and are prone to damage if they are cultivated quite frequently. The plant requires well drained soil for growing. They require very little space to grow. The place where the shrub is planted should be chosen in such a way that it gets enough sunlight. Clayey soil is preferable for growth.

Red Currant harvest

The cultivars hold well on the plants. Red currant bushes can be harvested from early to mid summer. While harvesting, you should always look for the plump and the rich forms. These berries can be harvested by snapping them at the top of the spring. This is a better method of picking, rather than picking individual berries.

Red currant Cuttings

The process of taking a cutting from the red currant is same as that of black currant. It involves a small little process. Never cut anything off the top of the cutting, so that the buds are intact. The buds from the bottom should be removed while cutting.

Red Currant pruning

Regular and annual pruning of the crop maintains regular yield of the plant, and keeps it manageable too. Pruning is also required so that the fruits are grown on the spurs of older woods. Regular pruning red currant bushes also maintains a supply of wood. The stems required to be pruned regularly so that the stems do not grow very scraggly. But this pruning should not be done after commencement of spring.

Red Currant Recipe


Picture 2 – Red currant Image
Source – blogspot.com

Red currant can be used to prepare a number of recipes. These dishes are very delicious to taste. It is used to prepare those dishes that are sweet in taste, as red currants have a natural sweetness in them. It can be used for the preparation of jams and jellies, tarts and cakes, some of the basic red currant recipes are:

  • Red Currant sorbet – Since the red currants are intense, they are used for the preparation of syrups and sorbets. They are almost surreal. The fruit is juiced to prepare delicious red currant sorbets.
  • Red Currant tart recipe – Red Currant tarts are not only deliciously sweet to taste, but they are also very good to look at. It is a large and spectacular one. It is made up of red currants, sugar, rhubarb, flour and eggs.
  • Red Currant jam – Red Currant jams are very easy to prepare as they require comparatively less time to be made. This jam is very sweet and yummy, and is especially liked by the children.
  • Red Currant ice cream – Like other ice creams, the red currant ice cream is also almost irresistible.

Other items that are cooked with red currants are:

  • Red Currant wine recipe
  • Red Currant muffins
  • Red Currant cake
  • Red Currant pie
  • Red Currant sauce
  • Red Currant Juice Recipe

Red Currant Nutrients Facts

Red currant is a nutritionally rich fruit. It has all the nutrients in adequate proportions. Apart from being extremely delicious, people should also consume his fruit because of its benefits and the presence of a number of essential nutrients. The amount of nutrients that is provided by a 100 gm of this fruit is as follows:

  • Total fats – 0.2 gram

Saturated fat – 0 gram

  • Total carbohydrate – 7.9 gram

Sugar 7.9 gram

  • Dietary fibers -0 3.5 gram
  • Sodium – 1.4 mg
  • Energy – 191.8 kJ
  • Vitamin C – 21 mg
  • Iron – 1.2 mg
  • Proteins – 1.3 gram

Red Currant Benefits

Red currant provides numerous benefits to the people. These are high utility plants. Not only are they delicious to taste, but the amount of benefits they provide is truly impeccable. They are used for making jams and jellies as they are rich flavored and sweet in taste.

Red currants Health Benefits

Red currants are very healthy fruits. They offer a lot of health benefits to the people. They contain vitamin c, potassium and other minerals. Some of the health benefits that they provide are as follows:

  • They aid in developing resistance power in human beings.
  • They are very effective for minor burns as they possess antiseptic properties.
  • It maintains the electrolyte balance in the body.
  • It is a good antioxidant, and is effective as it can scavenge the free radicals in the body.
  • It is rich in anthocynins and proanthocyanin.
  • These fruits are beneficial fro diabetic and heart patients.
  • It is also beneficial for heart patients.
  • It is said to have provided help in controlling menstrual flow, sweats and is a good laxative.
  • It also possesses blood cleansing properties and digestive properties.


Picture 3 – Red Currant photo
Source – wordpress.com

Red currant Tea

Tea can be extracted from the leaves of red currant plant. It is a red currant extract. This tea is very nutritious, and it can ease the harmful effects of rheumatism and gout. It can be used for compressing the wounds that do not heal fast. It can also be used as a gargling solution. This tea is also used to combat the destructive free radicals that cause aging in the body. It controls healthy degeneration of the body. It is also rich in antitoxidants.

Red currants Tomato

The red color of red currants, its round shape and it structure make red currant eh tiniest tomato on earth. These fruits are very sweet and are tiny in size, and there is less than a few ounces. They have a sweet taste and a balance3d flavor of tomato in it. This is an indeterminate crop, which gives a relatively stable supply of red currant berries throughout the year.

Red Currant Varieties

There are certain varieties of the red currant berries. Some of its well known and famous varieties are:

  • Junifer
  • Red lake
  • Jonkheer van tests
  • Rovada
  • Stanza

Rovada Red Currant

This is the best variety of red currant that is available now. It is a kind of perfect redcurrant bush. It comes in perfect long strings that enable easy picking with enormous yields. Rovada needs approximately 140 cm spacing to grow.

Red currant Extracts

Some of the things that are extracted from Red Currant are:

Red Currant Jelly

Pure red currant jelly is dark transparent red in color. It is very sweet in taste. It can be used on a toasted baguette, or can also be brushed over fruit tarts to get a glossy and a sweet sheen. It enhances the look of the food with its attractive color, sweet and delicious taste and yummy flavor.

Votivo Red Currant Diffuser

Red currant diffusers have a very good aroma. This aroma ill spread in your entire house as if it is a huge bouquet. This diffuser contains red currant fragrance blended with finest fragrant oils and aromatic diffuser in the concentrated form.

Votivo Red Currant Candles

Votive candle red currants are one of the most famous kinds of candles that are available. It is very well known throughout the world. This kind of candle has a very good fragrance owing to the red currant berries. it is the original kind of candle, with practically no substitute available. Its wax is naturally soy, the seal is hand pressed and it is hand wrapped.

Red Currant Oil

The oil extracted from red currant seeds is used for making soap, and tarts. It is fragrance oil. This oil is good for skincare and for cooking purpose as well.

Wild Red Currant

The wild red currant is atasty kind of fruit that grows wildly. It can be used to prepre a whole lot of recipes. It can be used in place of any recipe that is good for the cultivated berries. You can prepare salads or puddings using the wild red currant berries.

Substitute for Red Currant

The most common kind of substitute available for red currants is gooseberries or raspberries. The substitute for red currant jelly is grape jelly, apple jelly and Cranberry sauce.

Red Currant Diseases

There are certain diseases may affect the growth of red currants or may even be transmitted to the people eating them are:

White Pine Blister Rust

It is caused due to the fungus Cronartium ribicola. It causes some damage to the plants, is more fatal to the taller plants.

Anthracnose

This disease is caused due to the fungus Drepanopeziza. It is a very serious disease. It infects the new leaves of the plant during the rainy months. It can cause the leaves of the plant to grow irregular manner with spots on leaves.

Red currant is a very sweet and nutritious fruit. It is used for preparing a lot of dishes. You should only be careful about selecting a good breed of this fruit so that it does not create any health problem. Taste this fruit if you still have not, and take advantage of its manifold benefits and yummy flavor!

We searched around on this- it wasn’t obvious and we remain uncertain. But we can provide some information now while still soliciting advice from people in both the US and UK.
1) It could be a virus (UPDATE BELOW)
2) It could be nutrients
1) In one of your pictures (“Noticing this discoloration as well”) the veins are clearly visible. This sometimes indicates a viral infection. These would be vectored by aphids or some other sucking insect or possibly from the nursery you got them from.
The symptoms are similar to Tomato Ringspot Virus which does occur in currants http://www.ars-grin.gov/cor/ribes/rib…
See some details here on this virus https://www.eppo.int/QUARANTINE/virus…
2) Nutrients
It seems more likely that your plants are lacking certain nutrients. Currants (Ribes) have very shallow roots and if it is well drained soil they can be nutrient poor very quickly.
This is a bit on what soil they tolerate
“Currants and gooseberries are fairly tolerant of a wide range of soil conditions and less-than-perfect sites. They perform best in well-drained silt to sandy loam soils with organic matter content greater than 1 percent and good water-holding capacity. Planting in light sandy or heavy clay soils should be avoided, as well as areas in which water stands for any length of time. If the site is poorly drained, improve it by tiling or building raised beds. When using raised beds, monitor soil moisture as they can dry more quickly than level soil areas. Both heavy and light soils can be improved with the addition of organic matter. The ideal soil pH is moderately acidic, from 5.5 to 6.5. Micronutrient deficiencies may occur at an alkaline pH greater than 7.0. Saline or salty soils near coastal areas should be avoided.”
page 4 http://pubs.ext.vt.edu/438/438-107/43…
You should check your soil
“A soil test should be done to determine the soil pH and phosphorous and potassium levels and needs. These nutrients should be amended to moderate levels, with available phosphorus brought to a range of 50 to 75 pounds per acre and potassium to 150 to 200 pounds per acre. If pH levels are below 5.5, lime should be add- ed to bring the soil pH to 6.0 to 6.3. Along with lime, phosphorus can be incorporated in the fall. However, both potassium and nitrogen (25 to 35 pounds per acre) should be incorporated in the spring to avoid the loss of nutrients to leaching. Note that currants and gooseberries are sensitive to the chloride contained in muriate of potash (0-0-60) so another form of potassium, such as sulphate of potash, should be used. For smaller plantings, a general purpose fertilizer such as 10-10-10 or similar analysis can be used, and it should be broadcast and worked into the planting area, using approximately one pound of material per 100 square feet. Currants and gooseberries respond well to organic amendments, which in all soil types improves aeration and drain- age and increase water-holding capacity. Organic matter can be applied in the fall or spring before planting. Well- aged manure at four to five bushels per 100 square feet (1,750 to 2,200 bushels per acre) is a good option. Other suitable additions include finished compost, leaves, rotted hay or straw, shredded peat, or sawdust”
“When available, manure or other composted materials with significant nitrogen content (3 percent to 5 per- cent) are the best nutrient sources for ribes, which re- spond well to slowly released organic nitrogen sources.”
also http://pubs.ext.vt.edu/438/438-107/43…
So, what nutrients might you be missing? Some nutrients, such as potassium or magnesium, are highly mobile within a plant. If need be, they are quickly transported to younger parts of a plant, resulting in deficiency symptoms mainly on older leaves.
In Currants magnesium and potassium deficiency look similar. Chlorosis between veins (like the picture you showed). You can treat magnesium with dolomitic lime, which is a mixture of magnesium and calcium carbonate. Too much reduces the absorption of potassium, so be sparing at first.
Here is a great resource on what the different nutrient deficiencies look like. http://5e.plantphys.net/article.php?i…
I would suggest applying fertilizers/supplements and seeing how you get on.
It would be useful to record your progress in our plant journal (see under your profile) so we can see how you get on
UPDATE MAY 26TH
I contatced Dr Joseph Postman | Plant Pathologist – Curator
NATIONAL CLONAL GERMPLASM REPOSITORY
USDA Agricultural Research Service
33447 Peoria Road, Corvallis, Oregon USA
“The single leaf with yellow veins looks like typical symptoms of Gooseberry veinbanding virus, although aphid feeding can also induce symptoms like this, so check for presence of aphids. The general yellowing of leaves can have multiple causes. One possibility for black currants is a disorder called “Black currant yellows”. No virus or other pathogen has been associated with this disorder. It may be genetic like June Yellows in strawberry, or it may be caused by a virus that has not yet been identified, though this is unlikely as small fruit virologists have repeatedly examined affected plants. Certain black currant cultivars regularly exhibit the “yellows” symptoms in the spring, and then produce normal green growth as the season progresses. Do you know what cultivar is showing these symptons?”

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