Editing Blackcurrant (section)

==Cultivation==
{{See also|Blackcurrant production in the United States}}
[[File:Blackcurrant 1.jpg|thumb|Cultivated specimen]]

Cultivation in Europe is thought to have started around the last decades of the 17th century.<ref name=AgroAtlas>{{cite web |url=http://www.agroatlas.ru/en/content/cultural/Ribes_nigrum_K/ |title=Crops: European Black Currant |author1=Doronina, A. Ju. |author2=Terekhina, N. V. |work=Economic plants and their diseases, pests and weeds |publisher=AgroAtlas |access-date=2013-06-02}}</ref>

===Site selection and planting===

Blackcurrants can grow well on sandy or heavy loams, or forest soils, as long as their nutrient requirements are met. They prefer damp, fertile but not waterlogged ground and are intolerant of [[drought]]. Although the bushes are winter hardy, [[frost]]s during the flowering period may adversely affect the yield<ref name=AgroAtlas/> and cold winds may restrict the number of flying insects visiting and pollinating the flowers. A [[soil pH]] of about 6 is ideal for blackcurrants and the ground can be limed if the soil is too acidic. Planting is usually done in the autumn or winter to allow the plants to become established before growth starts in the spring,<ref name=Gilbert>{{cite book |title=Soft Fruit Growing |last=Gilbert |first=E. G. |year=1970 |publisher=Penguin |isbn=1445512254 |pages=101–118 }}</ref> but container-grown stock can be planted at any time of year.<ref name=RHS>{{cite web |url=https://www.rhs.org.uk/advice/grow-your-own/fruit/blackcurrants |title=Grow your own blackcurrants |publisher=Royal Horticultural Society |access-date=2016-07-14}}</ref>

Two-year-old bushes are usually planted but strong one-year-old stock can also be used. Planting certified stock avoids the risk of introducing [[Plant virus|viruses]]. On a garden scale the plants can be set at intervals of {{convert|1.5|to|1.8|m|abbr=on|frac=2|ft}} or they can be set in rows with planting intervals of {{convert|1.2|m|ft|0|abbr=on}} and row separations of {{convert|2.5|m|ft|0|abbr=on}} or more. In the UK, young bushes are generally planted deeper than their initial growing level to encourage new stems to grow from the base.<ref name=Gilbert/>

===Manures and fertilizers===
The blackcurrant requires a number of essential nutrients to thrive; [[nitrogen]] provides strong plant growth and stimulates the production of flower sprigs; [[phosphorus]] aids growth, the setting of fruit and crop yield; [[potassium]] promotes growth of individual shoots and increases the weight of individual fruits; [[magnesium]] is a constituent of [[chlorophyll]] and helps increase yields through interaction with potassium; [[calcium]] is required for cell division and enlargement and is particularly important for young plants and buds.<ref>{{cite web |url=http://www.blackcurrantfoundation.co.uk/the_blackcurrant_growing.html |title=Plant Nutrients |work=The blackcurrant |publisher=The Blackcurrant Foundation |access-date=2013-09-08 |archive-url=https://web.archive.org/web/20130917165221/http://www.blackcurrantfoundation.co.uk/the_blackcurrant_growing.html |archive-date=2013-09-17 |url-status=dead }}</ref>

An annual spring mulch of well rotted manure is ideal and poultry manure can also be used but needs prior [[compost]]ing with straw or other waste vegetable material. Spent [[mushroom compost]] can be used but care should be taken as it often contains lime and blackcurrants prefer slightly acidic soils. The blackcurrant is a gross feeder and benefits from additional nitrogen, and phosphatic and potash fertilisers should also be applied annually.<ref name=Gilbert/> A balanced [[Fertilizer|artificial fertilizer]] can be used and a 10-10-10 granular product can be spread around the bushes at the rate of {{convert|100|to|240|g|frac=4|abbr=off}} per plant.<ref>{{cite web |url=http://www.fruit.cornell.edu/mfruit/gooseberries.html |title=Minor fruits: gooseberries and currants |publisher=Department of Horticulture, Cornell University |access-date=2013-09-08}}</ref> Weed growth can be suppressed with an organic mulch such as sawdust, bark, mushroom compost or straw, heavy plastic topped with an organic mulch cover or [[landscape fabric]].<ref name=Gilbert/>

===Pruning===

Blackcurrant fruit is borne primarily on one-year-old shoots. Newly planted bushes should be pruned severely, cutting all shoots back to two buds above ground level. This gives the plant a chance to get properly established before needing to put its energy into producing fruit. The general rule when pruning is to remove all weak shoots and those growing out sideways which may get weighed down when fruiting. The remaining branches should be thinned to remove old unproductive wood and to encourage new shoots. An established bush should not be allowed to become overcrowded and should have about one third of its main branches or stems removed each year.<ref name=Gilbert/> When harvesting by machine, plants with an upright growth habit are encouraged.<ref name=acornorganic>{{cite web |url=http://www.acornorganic.org/pdf/blackcurrantmanual.pdf |archive-url=https://web.archive.org/web/20240905202013/http://www.acornorganic.org/pdf/blackcurrantmanual.pdf |url-status=dead |archive-date=5 September 2024 |title=Organic Black Currant Production Manual |publisher=PEI Horticultural Association |access-date=2013-06-02 }}</ref>

===Harvesting===
On a garden scale, the berries should be picked when dry and ripe.<ref name=Gilbert/> Commercially, most harvesting is done mechanically by straddle harvesters. These move continually down the rows, straddling a row of bushes, shaking the branches and stripping off the fruit. The blackcurrants are placed into half tonne bins and to minimise stoppage time, some machines have [[Conveyor system|cross conveyors]] which direct the fruit into continuously moving trailers in the adjoining row. A modern machine can pick up to fifty tonnes of blackcurrants in a day using only one operator and two tractor drivers.<ref name=acornorganic/> The bins should be stored in a cool place. Some fruit is still picked by hand for use in the fresh fruit market.<ref name=acornorganic/>

===Diseases and pests===

''Ribes'' plants are susceptible to several diseases and a number of insect pests. However, new varieties have been or are being developed to overcome some of these problems.<ref>{{cite web |url=http://www.blackcurrantfoundation.co.uk/the_blackcurrant_growing.html |title=Pest and Disease |work=The blackcurrant |publisher=The Blackcurrant Foundation |access-date=2013-09-08 |archive-url=https://web.archive.org/web/20130917165221/http://www.blackcurrantfoundation.co.uk/the_blackcurrant_growing.html |archive-date=2013-09-17 |url-status=dead }}</ref>

[[Cecidophyopsis ribis#Blackcurrant reversion disease|Reversion]] is a serious disease transmitted by the [[blackcurrant gall mite]] (''Cecidophyopsis ribis''). It causes a decline in yield and is quite widespread in Europe but is rarely encountered on other continents. Symptoms include a modification of leaf shape in summer and swollen buds ("big bud") in winter, each housing thousands of microscopic mites.<ref name=Hummer>{{cite web |url=http://www.ars-grin.gov/cor/ribes/ribsymp/stem6.html |title=Black Currant Gall Mite |last1=Hummer |first1=Kim |last2=Postman |first2=Joseph |date=2000-03-01 |work=Currant and Gooseberry Pests |publisher=USDA/ARS [[National Clonal Germplasm Repository]] |access-date=2013-03-09 |url-status=dead |archive-url=https://web.archive.org/web/20120926145635/http://www.ars-grin.gov/cor/ribes/ribsymp/stem6.html |archive-date=2012-09-26 }}</ref> As pest control has limited effectiveness, severely infected bushes should be destroyed. All new plants purchased should be certified as virus-free.<ref>{{cite web |url=http://www.which.co.uk/documents/pdf/blackcurrant-reversion-151472.pdf |title=Which magazine: Blackcurrant reversion |access-date=2012-06-13  |archive-date=2019-08-17  |archive-url=https://web.archive.org/web/20190817171314/https://www.which.co.uk/documents/pdf/blackcurrant-reversion-151472.pdf |url-status=dead }}</ref>

[[White pine blister rust]] (''Cronartium ribicola'') needs two alternate [[Host (biology)|hosts]] to complete its life cycle. One host is plants in the genus ''[[Ribes]]''. On the blackcurrant, it causes the leaves to become pale and later develop tiny orange pustules and sometimes a yellow filamentous coating on some leaves. The fruit crop is little affected but the leaves fall early and growth is slowed the following year. The other host is any of the [[white pine]]s, in which it causes serious disease and mortality for the North American species that have not co-evolved with the rust.<ref name=acornorganic/> As a result, the blackcurrant was [[Blackcurrant production in the United States|banned in the United States]] as a [[Vector (epidemiology)|disease vector]] for much of the 20th century, and even after the federal ban was lifted in 1966, several [[U.S. state]]s continued their own [[Ribes#United States of America|bans]], some of which remain in force as of August 2021. The effectiveness of these restrictions is questionable, since other ''Ribes'' species also host the disease, some are native to North America, and others such as [[red currant]]s and ''[[Ribes uva-crispa]]'' were never banned.{{Citation needed|reason=content needs citation for verification|date=June 2019}}

[[Podosphaera|American gooseberry mildew]] and [[powdery mildew]] can infect the leaves and shoot tips, and [[Botryotinia|botrytis]] may cause the fruit to rot in a wet season. Currant and [[gooseberry]] leaf spot (''Drepanopeziza ribis'') is another disease of blackcurrants, but it is not usually a serious problem as most cultivars now have some resistance.<ref name=Gilbert/>

The blackcurrant leaf midge can cause browning, crimping and distortion of leaves at the tips of shoots but it is seldom a serious problem. The blackcurrant sawfly (''[[Nematus ribesii]]'') lays its eggs on the underside of the leaves and the voracious larvae work their way along the shoots, stripping off leaf after leaf. In a serious attack, the bush can be denuded of leaves. Larvae of the currant borer drill their way along the centres of shoots, which wilt and die back. Other insect pests include [[scale insect]]s, [[aphid]]s and [[earwig]]s.<ref name=acornorganic/>

===Research and cultivars===
[[File:Ribes nigrum 'Vertti'.jpg|thumb|Green currant is a variant of blackcurrant cultivated in [[Finland]]; its berries lack the  dark color and strong aroma typical of blackcurrant. This particular cultivar is 'Vertti'.]]

There are many [[cultivar]]s of blackcurrant. 'Baldwin' was the mainstay of the industry for many years but it has now largely been superseded by more productive and disease-resistant varieties.<ref>{{cite book |title=The Royal Horticultural Society Encyclopedia of Gardening |editor-last=Brickell |editor-first=Christopher |year=1992 |publisher=Dorling Kindersley |isbn=9780863189791 |page=415 }}</ref><ref name=varieties>{{cite web |url=http://www.blackcurrantfoundation.co.uk/growing-blackcurrants/growing/varieties |year=2009 |title=The blackcurrant: Varieties| publisher=The Blackcurrant Foundation |access-date=2016-12-12}}</ref> During the 20th century in Europe, much hybridisation work has been carried out in order to reduce the plant's susceptibility to disease and frost and also to increase yields. This effort centered mainly in Scotland, Poland, and New Zealand.<ref name="bfhistory">{{cite web|title=A History of Blackcurrants|url=http://www.blackcurrantfoundation.co.uk/growing-blackcurrants/history/history-blackcurrants|publisher=Blackcurrant Foundation|access-date=10 December 2017|date=2017}}</ref>

In Britain the [[Scottish Crop Research Institute]] was tasked with developing new varieties suitable for growing in the north of the country. They produced new cultivars that had greater cold tolerance, especially in the spring, ripened earlier and more evenly and had greater fungal disease resistance. Frost tolerance was improved by selecting for late flowering and [[Molecular genetics|genetic research]] identified genes involved in resistance to gall mite and the blackcurrant reversion virus. 'Ben Lomond' was the first of the 'Ben' varieties and was released in 1975. This was followed by several other cultivars for the juicing industry such as 'Ben Alder' and 'Ben Tirran'. The cultivar 'Ben Hope' was released in 1998 with increased tolerance to gall mite, and in the same year, 'Ben Gairn' became available. It shows resistance to the reversion virus.<ref name=SCRI/> For gardeners and the pick-your-own market, 'Ben Sarek', 'Ben Connan' and 'Big Ben' were introduced and have large, sweet berries.<ref name=varieties/> The cultivars 'Ben Connan'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/56451/Ribes-nigrum-Ben-Connan-(B)/Details | title = ''Ribes nigrum'' 'Ben Connan' | publisher = RHS | access-date = 17 February 2021}}</ref> and 'Big Ben'<ref>{{cite web | url = https://www.rhs.org.uk/advice/profile?pid=1027 | title = Blackcurrants | publisher = RHS | access-date = 17 February 2021}}</ref> have gained the [[Royal Horticultural Society]]'s [[Award of Garden Merit]].<ref name=RHS/> and new varieties are being developed continually to improve frost tolerance, disease resistance, machine harvesting, fruit quality, nutritional content and fruit flavour.<ref name=varieties/>

Varieties producing green fruit, less strongly flavoured and sweeter than typical blackcurrants, are cultivated in [[Finland]], where they are called "greencurrants" (''viherherukka'').<ref>{{cite journal|last=Junnila|first=S.|display-authors=etal|date=1987|title=A green-fruited blackcurrant variety 'Vertti'|journal=Annales Agriculturae Fenniae|volume=26|pages=278–283}}</ref> In Poland, the Research Institute of Horticulture has done work on improving the blackcurrant with regard to disease and pest resistance, fruit quality, adaptations to local conditions and mechanical harvesting. Researchers have crossed various varieties and introduced inter-specific genetic material from the gooseberry (''[[Ribes grossularia]]''), the [[redcurrant]] (''Ribes rubrum'') and the flowering currant (''[[Ribes sanguineum]]''). The resulting offspring were further back-crossed to ''R. nigrum''. Cultivars produced include 'Tisel' and 'Tiben' in 2000 and 'Ores', 'Ruben' and 'Tines' in 2005. Further cultivars 'Polares' and 'Tihope' are being tested.<ref name=Pluta>{{cite web |url=http://www.inhort.pl/home_en.html |title=The blackcurrant breeding program in Poland, aims and recent improvements |last=Pluta |first=Stan |publisher=Research Institute of Horticulture, Skierniewice, Poland |access-date=2013-09-10 |archive-url=https://web.archive.org/web/20130917110240/http://www.inhort.pl/home_en.html |archive-date=2013-09-17 |url-status=dead }}</ref> Since 1991, New Zealand has become an important centre for research and development, as its temperate climate is particularly suitable for cultivation of the crop. Breeding programmes are concentrating on yield, large fruit size, consistency of cropping and upright habit.<ref>{{cite web |url=http://www.plantandfood.co.nz/page/news/video-index/video/blackcurrant-breeding/ |archive-url=https://web.archive.org/web/20130209071620/http://www.plantandfood.co.nz/page/news/video-index/video/blackcurrant-breeding/ |url-status=dead |archive-date=9 February 2013 |title=Blackcurrant breeding plots at Waipuna farm |author=Langford, Geoff |year=2010 |work=Plant and food research |publisher=The New Zealand Institute for Plant & Food Research |access-date=2013-06-03 }}</ref>

In North America, there is a need for this fruit to have resistance to white pine blister rust. New cultivars such as 'Crusader', 'Coronet' and 'Consort' have been developed there by crossing ''R. nigrum'' with ''[[Ribes ussuriense|R. ussuriense]]'' and these show resistance to the disease. However the quality and yield of these varieties are poor as compared to non-resistant strains and only Consort is reliably self-fertile. Back-crossing these varieties to a parent have produced new strains such as 'Titania' that have a higher yield, better disease resistance, are more tolerant of adverse weather conditions and are suitable for machine harvesting.<ref name=VCE>{{cite web |url=http://pubs.ext.vt.edu/438/438-107/438-107.html#L3 |title=Specialty Crop Profile: Ribes (Currants and Gooseberries) |author1=Bratsch, Anthony |author2=Williams, Jerry |publisher=Virginia Cooperative Extension |access-date=2013-09-08 |archive-date=2013-09-09  |archive-url=https://web.archive.org/web/20130909235035/http://pubs.ext.vt.edu/438/438-107/438-107.html#L3 |url-status=dead }}</ref> Two new releases from a black currant breeding program in British Columbia, Canada, 'Blackcomb' and 'Tahsis', were selected for their immunity to white pine blister rust and their frost tolerance.<ref>{{Cite web|url=http://www.berrycrops.net/|title=McGinnis Berry Crops|website=Berrycrops.net|access-date=2024-03-28}}</ref>