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  • Blueberries

    Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section Cyanococcus with the genus Vaccinium.[1] Commercial blueberries—both wild (lowbush) and cultivated (highbush)—are all native to North America. The highbush varieties were introduced into Europe during the 1930s.[2]

    Blueberries are usually prostrate shrubs that can vary in size from 10 centimeters (4 inches) to 4 meters (13 feet) in height. In the commercial production of blueberries, the species with small, pea-size berries growing on low-level bushes are known as “lowbush blueberries” (synonymous with “wild”), while the species with larger berries growing on taller, cultivated bushes are known as “highbush blueberries”. Canada is the leading producer of lowbush blueberries, while the United States produces some 40% of the world’s supply of highbush blueberries.

    Description

    [edit]

    Many species of blueberries grow wild in North America, including Vaccinium myrtilloidesV. angustifolium and V. corymbosum, which grow on forest floors or near swamps.[3]

    Wild blueberries reproduce by cross pollination, with each seed producing a plant with a different genetic composition, causing within the same species differences in growth, productivity, color, leaf characteristics, disease resistance, flavor, and other fruit characteristics.[3] The mother plant develops underground stems called rhizomes, allowing the plant to form a network of rhizomes creating a large patch (called a clone) which is genetically distinct.[3] Floral and leaf buds develop intermittently along the stems of the plant, with each floral bud giving rise to 5–6 flowers and the eventual fruit.[3] Wild blueberries prefer an acidic soil between 4.2 and 5.2 pH and only moderate amounts of moisture.[3] They have a hardy cold tolerance in their range in Canada and the northern United States.[3] Fruit productivity of lowbush blueberries varies by the degree of pollination, genetics of the clone, soil fertility, water availability, insect infestation, plant diseases, and local growing conditions.[3] Wild (lowbush) blueberries have an average mature weight of 0.3 grams (1128 oz).[3]

    Lowbush blueberries, sometimes called “wild blueberries”, are generally not planted by farmers, but rather are managed on berry fields called “barrens”.[4] Cultivated highbush blueberries prefer sandy or loam soils, having shallow root systems that benefit from mulch and fertilizer.[5] The leaves of highbush blueberries can be either deciduous or evergreen, ovate to lanceolate, and 1–8 cm (12–3+14 in) long and 0.5–3.5 cm (14–1+38 in) broad. The flowers are bell-shaped, white, pale pink or red, sometimes tinged greenish.

    The fruit is a berry 5–16 mm (31658 in) in diameter with a flared crown at the end; they are pale greenish at first, then reddish-purple, and finally uniformly blue when ripe.[5] They are covered in a protective coating of powdery epicuticular wax, colloquially known as the “bloom”.[3] They generally have a sweet taste when mature, with variable acidity.[3][5] Blueberry bushes typically bear fruit in the middle of the growing season: fruiting times are affected by local conditions, such as climate, altitude, and latitude, so the time of harvest in the northern hemisphere can vary from May to August.[3][5]

    Identification

    [edit]

    Commercially offered blueberries are usually from species that naturally occur only in eastern and north-central North America. Other sections in the genus are native to other parts of the world, including the Pacific Northwest and the southern United States,[6] South America, Europe and Asia. Other wild shrubs in many of these regions produce similar-looking edible berries, such as huckleberries and whortleberries (North America) and bilberries (Europe). These species are sometimes called “blueberries” and are sold as blueberry jam or other products.

    The names of blueberries in languages other than English often translate as “blueberry”, e.g. Scots blaeberry and Norwegian blåbærBlaeberryblåbær and French myrtilles usually refer to the European native V. myrtillus (bilberry), while bleuets refers to the North American blueberry.

    Cyanococcus blueberries can be distinguished from the nearly identical-looking bilberries by their flesh color when cut in half. Ripe blueberries have light green flesh, while bilberries, whortleberries, and huckleberries are red or purple throughout.

    Species

    [edit]

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    Note: habitat and range summaries are from the Flora of New Brunswick, published in 1986 by Harold R. Hinds, and Plants of the Pacific Northwest coast, published in 1994 by Pojar and MacKinnon.

    Some other blue-fruited species of Vaccinium:

    • Wild blueberry in autumn foliage, Pilot Mountain, North Carolina, in October
    • A maturing ‘Polaris’ blueberry (Vaccinium corymbosum)
    • A selection of blueberries, showing the typical sizes of the berries. The scale is marked in centimeters.

    The lowbush varieties are V. angustifoliumV. borealeV. mytilloidesV. pallidum, and V. angustifolium × V. corymbosum. They are still grown similarly to pre-Columbian semi-wild cultivation, i.e. slash and burn. The highbush varieties are darrowii and corymbosum. Rabbiteye (V. ashei/V. virgatum) differ from both high- and lowbush.[8]

    Distribution

    [edit]

    Flowers on a cultivated blueberry bush
    Fresh blueberries

    Vaccinium has a mostly circumpolar distribution, with species mainly present in North America, Europe, and Asia.[1] Many commercially available species with English common names including “blueberry” are from North America,[8] particularly Atlantic Canada and the northeastern United States for wild (lowbush) blueberries, and several US states and British Columbia for cultivated (highbush) blueberries.[4][9]

    North American native species of blueberries are grown commercially in the Southern Hemisphere in Australia, New Zealand and South American nations. Vaccinium meridionale (the Andean blueberry) is wild-harvested and commonly available locally.[10] Several other wild shrubs of the genus Vaccinium also produce commonly eaten blue berries, such as the predominantly European V. myrtillus and other bilberries, which in many languages have a name that translates to “blueberry” in English.

    Cultivation

    [edit]

    Blueberry harvester in Michigan

    Blueberries may be cultivated, or they may be picked from semiwild or wild bushes. In North America, the most common cultivated species is V. corymbosum, the northern highbush blueberry. Hybrids of this with other Vaccinium species adapted to southern U.S. climates are known collectively as southern highbush blueberries.[11] Highbush blueberries were first cultivated in New Jersey around the beginning of the 20th century.[9][8]

    So-called “wild” (lowbush) blueberries, smaller than cultivated highbush ones, have intense color. V. angustifolium (lowbush blueberry) is found from the Atlantic provinces westward to Quebec and southward to Michigan and West Virginia. In some areas, it produces natural “blueberry barrens”, where it is the dominant species covering large areas. Several First Nations communities in Ontario are involved in harvesting wild blueberries.

    “Wild” has been adopted as a marketing term for harvests of managed native stands of lowbush blueberries. The bushes are not planted or selectively bred, but they are pruned or burned over every two years, and pests are “managed”.[12]

    Numerous highbush cultivars of blueberries are available, with diversity among them, each having individual qualities. A blueberry breeding program has been established by the USDA-ARS breeding program at Beltsville, Maryland, and Chatsworth, New Jersey. This program began when Frederick Vernon Coville of the USDA-ARS collaborated with Elizabeth Coleman White of New Jersey.[13] In the early part of the 20th century, White offered pineland residents cash for wild blueberry plants with unusually large fruit.[14] After 1910 Coville began to work on blueberry, and was the first to discover the importance of soil acidity (blueberries need highly acidic soil), that blueberries do not self-pollinate, and the effects of cold on blueberries and other plants.[15] In 1911, he began a program of research in conjunction with White, daughter of the owner of the extensive cranberry bogs at Whitesbog in the New Jersey Pine Barrens. His work doubled the size of some strains’ fruit, and by 1916, he had succeeded in cultivating blueberries, making them a valuable crop in the Northeastern United States.[14][16] For this work he received the George Roberts White Medal of Honor from the Massachusetts Horticultural Society.

    The rabbiteye blueberry (Vaccinium virgatum syn. V. ashei) is a southern type of blueberry produced from the Carolinas to the Gulf Coast states. Production of rabbiteye blueberries was a focus in Texas in the early 21st century.[17] Other important species in North America include V. pallidum, the hillside or dryland blueberry. It is native to the eastern U.S., and common in the Appalachians and the Piedmont of the Southeast. Sparkleberry, V. arboreum, is a common wild species on sandy soils in the Southeast.

    Successful blueberry cultivation requires attention to soil pH (acidity) measurements in the acidic range.[18][19][20]

    Blueberry bushes often require supplemental fertilization,[19] but over-fertilization with nitrogen can damage plant health, as evidenced by nitrogen burn visible on the leaves.[18][19]

    Growing regions

    [edit]

    Worldwide highbush blueberry growing areas (data from 2008)

    Significant production of highbush blueberries occurs in British ColumbiaMarylandWestern OregonMichiganNew JerseyNorth Carolina, and Washington. The production of southern highbush varieties occurs in California, as varieties originating from University of FloridaConnecticutNew HampshireNorth Carolina State University and Maine have been introduced. Peru, Spain, and Mexico also have significant production, as of 2018 (see Production).[21]

    United States

    [edit]

    In 2018, Oregon produced the most cultivated blueberries, recording 59 million kilograms (131 million pounds), an amount slightly exceeding the production by Washington.[22] In descending order of production volume for 2017, other major producers were GeorgiaMichiganNew Jersey, California, and North Carolina.[23]

    Hammonton, New Jersey, claims to be the “Blueberry Capital of the World”,[24] with over 80% of New Jersey’s cultivated blueberries coming from this town.[25] Every year the town hosts a large festival, which draws thousands of people to celebrate the fruit.[26]

    Maine is known for its wild blueberries,[27] but the state’s lowbush (wild) and highbush blueberries combined account for 10% of all blueberries grown in North America. Some 44,000 hectares (110,000 acres) are farmed, but only half of this acreage is harvested each year due to variations in pruning practices.[28] The wild blueberry is the official fruit of Maine.[29]

    Canada

    [edit]

    Wild blueberry fields in Nova Scotia, Canada

    Canadian production of wild and cultivated blueberries in 2015 was 166,000 tonnes valued at $262 million, the largest fruit crop produced nationally accounting for 29% of all fruit value.[30]

    British Columbia was the largest Canadian producer of cultivated blueberries, yielding 70,000 tonnes in 2015,[30] the world’s largest production of blueberries by region.[31]

    Atlantic Canada contributes approximately half of the total North American wild/lowbush annual production with New Brunswick having the largest in 2015, an amount expanding in 2016.[32] Nova Scotia, Prince Edward Island and Québec are also major producers.[33] Nova Scotia recognizes the wild blueberry as its official provincial berry,[34] with the town of Oxford, Nova Scotia known as the Wild Blueberry Capital of Canada.[35]

    Québec is a major producer of wild blueberries, especially in the regions of Saguenay-Lac-Saint-Jean (where a popular name for inhabitants of the regions is bleuets, or “blueberries”) and Côte-Nord, which together provide 40% of Québec’s total provincial production. This wild blueberry commerce benefits from vertical integration of growing, processing, frozen storage, marketing, and transportation within relatively small regions of the province.[36] On average, 80% of Québec wild blueberries are harvested on farms (21 million kilograms (23,000 short tons)), the remaining 20% being harvested from public forests (5 million kilograms (5,500 short tons)).[36] Some 95% of the wild blueberry crop in Québec is frozen for export out of the province.[36]

    Vaccinium meridionale, a wild species found in the Andes[citation needed]

    Europe

    [edit]

    Highbush blueberries were first introduced to Germany, Sweden, and the Netherlands in the 1930s, and have since been spread to numerous other countries of Europe.[2] V. corymbosum only began to be cultivated in Romania in a few years leading up to 2018 and rapidly increased in production and sales in that time (as with berries in general). As of 2018 it remains relatively unmolested by pests and diseases (see Diseases below).[37]

    Southern Hemisphere

    [edit]

    In the Southern Hemisphere, Brazil, Chile, ArgentinaPeruUruguay, New Zealand, Australia, South Africa,[38] and Zimbabwe grow blueberries commercially.[39]

    In Brazil, blueberries are produced in the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and Minas Gerais.[40]

    Blueberries were first introduced to Australia in the 1950s, but the effort was unsuccessful. In the early 1970s, the Victorian Department of Agriculture imported seed from the U.S. and a selection trial was started. This work was continued into the mid-1970s when the Australian Blueberry Growers’ Association was formed.[41]

    In the 21st century, the industry grew in Argentina: “Argentine blueberry production has increased over the last three years with planted area up to 400 percent,” according to a 2005 report by the U.S. Department of Agriculture.[42] “Argentine blueberry production has thrived in four different regions: the province of Entre Rios in northeastern Argentina, the province of Tucuman, the province of Buenos Aires and the southern Patagonian valleys”, according to the report.[43] In the Bureau of International Labor Affairs report of 2014 on child labor and forced labor, blueberries were listed among the goods produced in such working conditions in Argentina.[44]

    Pests and diseases

    [edit]

    Diseases

    [edit]

    Main article: List of Vaccinium diseases

    As of 2018 V. corymbosum remains relatively unmolested by pests and diseases in Romania, with Phytophthora cinnamomiMonilinia vaccinii-corymbosiBotryosphaeria corticisGodronia cassandraePhomopsis sp., Botrytis cinereaNaohidemyces vacciniiMicrosphaera penicillata var. vaccinii, and various viruses being the most common.[37]

    Pest management

    [edit]

    Pesticides

    [edit]

    DDT began to be used in blueberry soon after its discovery in 1939, and a few years later in the mid-1940s research began into its use in North America.[8]

    Because “wild” is a marketing term generally used for all low-bush blueberries, it does not indicate that such blueberries are free from pesticides.[45]

    Insecticide modes of action must be varied to avoid encouraging resistance in the invasive pest Drosophila suzukii.[8]

    Some insecticides can be counterproductive, harming natural enemies of pests as well. For example, treatment for Illinoia pepperi can reduce populations of its predatorsKaolin clay for Rhagoletis mendax also reduced effectiveness of Diachasma alloeum, its parasitoid. The pest predator Harpalus erraticus maintains greater abundance with selective insecticides rather than broad-spectrum MoAs.[8]

    Integrated pest management

    [edit]

    Blueberries are naturally relatively unmolested by arthropod pests. Nonetheless, there are 24 insect taxa known to be pest (organism)s in North America, the worst in New Jersey, MichiganMaine, and Eastern Canada being Rhagoletis mendax. Secondary but still important are Acrobasis vacciniiGrapholita packardi, and Conotrachelus nenuphar. These four are the most common targets for the development of IPM practices. as of 2019, IPM research has also taken an interest in Drosophila suzukii and arthropods like aphids (that vector diseases such as scorch virus and shoestring virus) and cicadellids (vectoring the phytoplasma that causes blueberry stunt). Managing pests down to the cosmetic level is necessary for this fruit because they are a premium product.[8]

    Changes in locale and environment – to new geographies, and into greenhouses – have required new pest management regimes, including innovative IPM. Conversely, importing foreign potential enemies into North America may yield good results: Operophtera brumata is a pest of blueberries and birches which is successfully parasitized by Cyzenis albicans despite the lack of historical, natural contact between the two. The same results were obtained with Scirtothrips citri and Beauveria bassiana. Results are available for Choristoneura rosaceana and overwhelming numbers of Trichogramma minutum, and Cyclocephala longula overwhelmed by Steinernema scarabaei. This has also been attempted with flower thrips and potential predators but with inconclusive results.[8]

    International quarantine

    [edit]

    Rhagoletis mendax is a quarantine pest in phytosanitary regimes of some countries around the world.[8]

    Resistant cultivars

    [edit]

    Insect resistance was not a priority in breeding programs until about the year 2000 and is still not a high priority. However, it may become more common as it becomes easier, especially using marker-assisted breedingV. ashei is naturally more resistant than V. corymbosum to Scaphytopius magdalensisV. ashei is less resistant than V. darrowii to Prodiplosis vaccinia. There is variation between cultivars of V. ashei in resistance to Oberea myops. There is variation in resistance among cultivars of V. corymbosum to Acrobasis vaccinii and Popillia japonica. Wild V. spp. have greater resistance than highbush cultivars to I. pepperi. There is significant variation between highbush cultivars in the abundance of various Tephritidae, thrips, and Homalodisca vitripennis.[8]

    Production

    [edit]

    CountryProduction
    (tonnes)
     United States351,130
     Peru227,971
     Canada146,551
     Chile122,795
     Mexico66,482
     Spain61,230
    World1,113,261
    Source: FAOSTAT of the United Nations[46]

    In 2021, world production of blueberries (lowbush and highbush combined) was 1.1 million tonnes, led by the United States with 32% of global production, Peru with 20%, and Canada with 13%.[46]

    In 2019, Canada was the largest producer of wild blueberries, mainly in Quebec and the Atlantic provinces,[47] but Canadian production of wild blueberries decreased since 2017 by transitioning to the more profitable cultivated highbush blueberries.[48] British Columbia produced 93% of the Canadian highbush blueberry crop in 2019.[47]

    Regulations

    [edit]

    Canada No. 1 blueberries are all similar in size, shape, weight, and color—the total product can be no more than ten percent off-color and three percent otherwise defective.[49]

    A dish of blueberries
    Nutritional value per 100 g (3.5 oz)
    Energy240 kJ (57 kcal)
    Carbohydrates14.49 g
    Sugars9.96 g
    Dietary fiber2.4 g
    Fat0.33 g
    Protein0.74 g
    showVitamins and minerals
    Other constituentsQuantity
    Water84 g
    Link to USDA Database entry
    Percentages estimated using US recommendations for adults,[50] except for potassium, which is estimated based on expert recommendation from the National Academies.[51]

    Uses

    [edit]

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    First Nations peoples of Canada consumed wild blueberries for millennia.[4]

    Blueberries are sold fresh or are processed as individually quick frozen fruit, purée, juice, or dried or infused berries. These may then be used in a variety of consumer goods, such as jelliesjamspiesmuffins, snack foods, pancakes, or as an additive to breakfast cereals.

    Blueberry jam is made from blueberries, sugar, water, and fruit pectinBlueberry sauce is a sweet sauce prepared using blueberries as a primary ingredient.

    Blueberry wine is made from the flesh and skin of the berries, which is fermented and then matured; usually, the lowbush variety is used.

    Nutrients

    [edit]

    Blueberries consist of 14% carbohydrates, 0.7% protein, 0.3% fat, and 84% water. They contain only negligible amounts of micronutrients, with moderate levels (relative to respective Daily Values) (DV) of the essential dietary mineral manganesevitamin Cvitamin K and dietary fiber. Generally, the nutrient contents of blueberries are a low percentage of the DV. A 100-gram serving provides a relatively low amount of food energy – 240 kilojoules (57 kcal) – with a glycemic load of 6.

    Phytochemicals and research

    [edit]

    Blueberries contain anthocyanins, other polyphenols and various phytochemicals under preliminary research for their potential biological effects.[52] Most polyphenol studies have been conducted using the highbush cultivar of blueberries (V. corymbosum), while content of polyphenols and anthocyanins in lowbush (wild) blueberries (V. angustifolium) exceeds values found in highbush cultivars.[53]

    • A cut blueberry showing how, having been frozen and then thawed, the anthocyanins in the pericarp can run into the damaged cells, staining the flesh.
    • Core structure common to all anthocyanins, some of which produce the blue pigments in blueberries.[52]
  • Strawberry

    The garden strawberry (or simply strawberryFragaria × ananassa)[1] is a widely grown hybrid plant cultivated worldwide for its fruit. The genus Fragaria, the strawberries, is in the rose family, Rosaceae. The fruit is appreciated for its aroma, bright red colour, juicy texture, and sweetness. It is eaten either fresh or in prepared foods such as jamice cream, and chocolates. Artificial strawberry flavourings and aromas are widely used in commercial products. Botanically, the strawberry is not a berry, but an aggregate accessory fruit. Each apparent ‘seed’ on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.

    The garden strawberry was first bred in Brittany, France, in the 1750s via a cross of F. virginiana from eastern North America and F. chiloensis, which was brought from Chile by Amédée-François Frézier in 1714. Cultivars of F. × ananassa have replaced the woodland strawberry F. vesca in commercial production. In 2023, world production of strawberries exceeded ten million tons, led by China with 40% of the total.

    Strawberries have appeared in literature and art from Roman times; Virgil wrote about the snake lurking beneath the strawberry, an image reinterpreted by later writers including Shakespeare. Strawberries appear in Italian, Flemish, and German paintings, including Hieronymus Bosch‘s The Garden of Earthly Delights. It has been understood to symbolise the ephemerality of earthly joys or the benefit that blessed souls get from religion, or to allegorise death and resurrection. By the late 20th century, its meaning had shifted: it symbolised female sexuality.

    Evolution

    History and taxonomy

    In Europe, until the 17th century cultivated plants were obtained by transplanting strawberries from the forests; the plants were propagated asexually by pegging down the runners, allowing them to root, and then separating the new plants.[2] F. virginiana, the Virginia strawberry, was brought to Europe from eastern North America; F. chiloensis, the Chilean strawberry, was brought from Chile by Amédée-François Frézier in 1714. At first introduction to Europe, the Chilean strawberry plants grew vigorously, but produced no fruit. French gardeners in Brittany in the 1750s noticed that the Chilean plants bore only female flowers. They planted the wild woodland strawberry F. vesca among the Chilean plants to provide pollen; the Chilean strawberry plants then bore abundant fruits.[3]

    In 1759, Philip Miller recorded the ‘pine strawberry’ (F. ananassa) in Chelsea, England.[3] In the gardens of the Palace of Versailles, France, Antoine Nicolas Duchesne found in 1766 that F. ananassa was a hybrid of the recently arrived F. chiloensis and F. virginiana.[1] In 1806, Michael Keens of Isleworth, England selected the Keens Imperial cultivar from many hybrids,[4] winning the Royal Horticultural Society‘s Silver Cup.[3] Both the names ‘pine’ and ‘ananassa’ meant “pineapple”, for the fruit’s flavour.[4] Modern strawberries and both parent species are octoploid (8N, meaning they have 8 sets of 7 chromosomes).[5] The genome sequence of the garden strawberry was published in 2019.[6]

    Hybridisation and polyploidy in strawberries. Garden strawberries are octoploid (8N), like both parents, the Virginia and Chilean strawberries.

    Further breeding in the following centuries produced varieties with a longer cropping season and more fruit.[3] During the Green Revolution of the 1950s, agronomists used selective breeding to expand phenotypic diversity of the garden strawberry. Adoption of perpetual flowering hybrids not sensitive to changes in photoperiod gave higher yields and enabled production in California to expand.[1]

    Phylogeny

    The phylogeny of the cultivated strawberry within the genus Fragaria of the Rosaceae family was determined by chloroplast genomics in 2021. The polyploidy (number of sets of chromosomes) is shown as “2N” etc. by each species.[7]

    RosaceaeRosa and other genera Potentilla (cinquefoils) Fragariaat least 11 other speciesF. viridis 2N (green strawberry) F. orientalis 4N (eastern strawberry) F. moschata 6N (musk strawberry) F. mandshuricaF. vesca ssp. vesca 2N (wild strawberry) F. vesca ssp. bracteata 2NF. virginiana 8N (Virginia strawberry, parent species) F. chiloensis 8N (Chilean strawberry, parent species) F. x ananassa 8N (the hybrid garden strawberry) 

    Description

    See also: Fragaria

    Botanical structure of a strawberry, compared to a peapod. The strawberry is a swollen receptacle, covered with many small achenes, the botanical fruits.[8]

    In culinary terms, a strawberry is an edible fruit. From a botanical point of view, it is not a berry but an aggregate accessory fruit, because the fleshy part is derived from the receptacle. Each apparent seed on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.[8]

    • Leaves
    • Flower
    • Achenes (botanical fruits)
    • Growth (video)

    Composition

    Nutrition

    Nutritional value per 100 g (3.5 oz)
    Energy136 kJ (33 kcal)
    Carbohydrates7.68 g
    Sugars4.89 g
    Dietary fiber2 g
    Fat0.3 g
    Protein0.67 g
    showVitamins and minerals
    Other constituentsQuantity
    Water90.95 g
    Link to USDA Database entry
    Percentages estimated using US recommendations for adults,[9] except for potassium, which is estimated based on expert recommendation from the National Academies.[10]

    Raw strawberries are 91% water, 8% carbohydrates, 1% protein, and contain negligible fat (table). A reference amount of 100 grams (3.5 oz) supplies 33 kilocalories, is a rich source of vitamin C (65% of the Daily Value, DV), and a good source of manganese (17% DV), with no other micronutrients in significant content (table). Strawberries contain a modest amount of essential unsaturated fatty acids in the achene (seed) oil.[11]

    Phytochemicals

    Garden strawberries contain diverse phytochemicals, including the dimeric ellagitannin agrimoniin, which is an isomer of sanguiin H-6.[12][13] Other polyphenols present include flavonoids, such as anthocyaninsflavanolsflavonols and phenolic acids, such as hydroxybenzoic acid and hydroxycinnamic acid.[11] Although achenes comprise only about 1% of the total fresh weight of a strawberry, they contribute 11% of all polyphenols in the whole fruit; achene phytochemicals include ellagic acid, ellagic acid glycosides, and ellagitannins.[14]

    Pelargonidin-3-glucoside is the major anthocyanin pigment in strawberries, giving them their red colour, with cyanidin-3-glucoside in smaller amounts. Strawberries also contain purple minor pigments, such as dimeric anthocyanins.[15]

    Flavour and fragrance

    Furaneol contributes to the fragrance of strawberries.

    Sweetness, fragrance and complex flavour are important attributes of strawberries.[16] In plant breeding and farming, emphasis is placed on sugars, acids, and volatile compounds, which improve the taste and fragrance of the ripe fruit.[17] Estersterpenes, and furans are the chemical compounds having the strongest relationships to strawberry flavour, sweetness and fragrance, with a total of 31 out of some 360 volatile compounds significantly correlated to desirable flavour and fragrance.[17][18][19] In breeding strawberries for the commercial market in the United States, the volatile compounds methyl anthranilate and gamma-decalactone, prominent in aromatic wild strawberries, are especially desired for their “sweet and fruity” aroma characteristics.[18][19] As strawberry flavour and fragrance appeal to consumers,[18][19][20] they are used widely in manufacturing, including foods, beverages, perfumes and cosmetics.[21][22]

    Allergy

    Some people experience an anaphylactoid reaction to eating strawberries.[23] The most common form of this reaction is oral allergy syndrome, but symptoms may also mimic hay fever or include dermatitis or hives, and, in severe cases, may cause breathing problems.[24] Proteomic studies indicate that the allergen may be tied to a protein for the red anthocyanin biosynthesis expressed in strawberry ripening, named Fra a1 (Fragaria allergen1). White-fruited strawberry cultivars, lacking Fra a1, may be an option for people allergic to strawberries.[25] They ripen but remain pale, appearing like immature berries. A virtually allergen-free cultivar named ‘Sofar’ is available.[26][27]

    Varieties

    Further information: Breeding of strawberries

    For a more comprehensive list, see List of strawberry cultivars.

    Strawberries are often grouped according to their flowering habit.[28][29] Traditionally in the Northern Hemisphere, this has consisted of a division between “June-bearing” strawberries, which bear their fruit in the early summer and “everbearing” strawberries, which often bear several crops of fruit throughout the season.[29] One plant throughout a season may produce 50 to 60 times or roughly once every three days.[30] Strawberries occur in three basic flowering habits: short-day, long-day, and day-neutral. These describe the day-length sensitivity of the plant and the type of photoperiod that induces flower formation. Day-neutral cultivars produce flowers regardless of the photoperiod.[31] Strawberry cultivars vary widely in size, colour, flavour, shape, degree of fertility, season of ripening, liability to disease and constitution of plant.[28]

    Cultivation

    Production

     China4.21
     United States1.25
     Egypt0.73
     Turkey0.68
     Mexico0.64
     Spain0.33
    World10.49
    Source: FAOSTAT of the United Nations[32]

    In 2023, world production of strawberries was 10.5 million tonnes, led by China with 40% of the total; the United States was the main secondary producer.[32]

    For commercial production, plants can be propagated from bare root plants or plugs. One method of cultivation uses annual plasticulture;[33] another is a perennial system of matted rows or mounds which has been used in cold growing regions for many years.[34] In some areas, greenhouses are used; in principle they could provide strawberries during the off season for field crops.[35]

    In the plasticulture system, raised beds are covered with plastic to prevent weed growth and erosion. Plants are planted through holes punched in this covering. Irrigation tubing can be run underneath if necessary.[33][36]

    Another method uses a compost sock. Plants grown in compost socks have been shown to produce significantly more flavonoidsanthocyaninsfructoseglucosesucrosemalic acid, and citric acid than fruit produced in the black plastic mulch or matted row systems.[37] Similar results in an earlier study conducted by United States Department of Agriculture confirms how compost plays a role in the bioactive qualities of two strawberry cultivars.[38]

    Strawberries may be propagated by seed.[39] Strawberries can be grown indoors in pots.[40] Strawberries will not grow indoors in winter though an experiment using a combination of blue and red LED lamps shows that this could be achieved in principle.[41] In Florida, winter is the natural growing season and harvesting begins in mid-November.[30]

    • Strawberry field in North Rhine-Westphalia, Germany
    • A field using the plasticulture method

    Manuring and harvesting

    A man carries a flat of strawberries in a field
    Strawberries are usually picked and placed in shallow boxes in the field.

    Nitrogen fertiliser is often needed at the beginning of every planting year. There are normally adequate levels of phosphorus and potash when fields have been fertilised for other crops in preceding years. To provide more organic matter, a cover crop of wheat or rye can be planted in the year before planting the strawberries. Strawberries prefer a somewhat acidic pH from 5.5 to 6.5, so lime is usually not required.[42]

    To achieve top quality, berries are harvested at least every other day. The berries are picked with the caps and half the stem still attached. Strawberries need to remain on the plant until fully ripe, because they do not continue to ripen after being picked.[43] The harvesting and cleaning process has not changed substantially over time. As they are delicate, strawberries are still often harvested by hand and packed in the field.[44]

    Domestic cultivation

    Strawberries are popular in home gardens, and numerous cultivars have been selected for consumption and for exhibition purposes.[45] The following cultivars have gained the Royal Horticultural Society‘s Award of Garden Merit:

    Pests and diseases

    Over 200 species of pest arthropods attack strawberries.[52] These include mothsfruit flies, chafers, strawberry root weevils, strawberry thrips, strawberry sap beetles, strawberry crown moth, mites, and aphids. Non-arthropod pests include slugs.[52][53] Some are vectors of plant diseases; for instance, the strawberry aphid, Chaetosiphon fragaefolii,[54] can carry the strawberry mild yellow-edge virus.[55]

    Strawberry plants are subject to many diseases, especially when subjected to stress. The leaves may be infected by powdery mildewleaf spot (caused by the fungus Sphaerella fragariae), leaf blight (caused by the fungus Phomopsis obscurans), and by a variety of slime molds. The crown and roots may fall victim to red stele, verticillium wilt, black root rot, and nematodes. The fruits are subject to damage from gray mold (Botrytis cinerea), rhizopus rot, and leather rot.[56][57]

    Disease resistance and protection

    The NPR1 gene from Arabidopsis thalianaAtNPR1, confers A. thaliana‘s broad-spectrum resistance when transexpressed in F. ananassa. This includes resistance to anthracnose, powdery mildew, and angular leaf spot.[58][59]

    A 1997 study found that many wound volatiles were effective against gray mold (B. cinerea). Both Tribute and Chandler varieties benefited from the treatments, although the effects vary widely with substance and variety. Strawberry plants metabolise these volatiles, more rapidly than do either blackberry or grape.[60][61]

    Culinary use

    See also: List of strawberry dishes

    Strawberries were eaten fresh with cream in the time of Thomas Wolsey in the court of King Henry VIII.[62] Strawberries can be frozen or made into jam or preserves,[63] as well as dried and used in prepared foods, such as cereal bars.[64] In the United Kingdom, strawberries and cream is a popular dessert at the Wimbledon tennis tournament.[62] Desserts using strawberries include pavlova,[65] fraisier,[66][67] and strawberry shortcake.[68]

    In art, literature and culture

    The Roman poet Ovid wrote that in the past Golden Age, people had lived on wild fruits such as mountain strawberries.[69] Virgil wrote in his Eclogues that “Ye who cull flowers and low-growing strawberries, / Away from here lads; a chill snake lurks in the grass”, and his imagery was taken up by medieval and early modern writers, the snake beneath the strawberry standing for dangerous literature, or beautiful but unfaithful women, or eventually any risky pleasure. In this vein, Shakespeare‘s King Richard III asks for a dish of strawberries while feigning friendship to his enemy; while in OthelloIago shows Desdemona‘s handkerchief “spotted with strawberries”, implying she has been unfaithful and hinting at Iago’s own devious plans.[70]

    The strawberry is found in Italian, Flemish, and German art, and in English miniatures.[70] In medieval depictions, the strawberry often appears in the Virgin Mary‘s garden, while in the Madonna of the Strawberries, she is seated on a strawberry bed and garlanded with strawberry leaves.[70]

    In the work of the late medieval painter Hieronymus Bosch, strawberries feature in The Garden of Earthly Delights amongst “frolicking nude figures”.[69] Fray Jose de Siguenza described the painting as embodying the strawberry as a symbol of the ephemerality of earthly joys.[69] More recently, scholars have seen the symbolism entirely differently: Clément Wertheim-Aymes believed it meant the blessed souls’ benefit from religion; Pater Gerlach supposed it meant spiritual love; and Laurinda Dixon asserted it was part of an allegory of death and resurrection.[69] By the late 20th century, the strawberry (and the raspberry) had become “traditional symbols of the mouth and female sexuality”.[71]