Editing Chestnut (section)

=== Cultivation ecology ===
{{see also|Chestnut orchard}}

==== Climate and seasonal germination cycle ====
Chestnuts produce a better crop when subjected to chill temperatures during the [[dormancy|dormant]] period. [[Frost#Effect on plants|Frosts]] and snowfalls are beneficial rather than harmful to the trees.<ref name="chestnutbrook" /><ref name="laren60" /> The dormant plant is very cold-hardy in Britain,<ref name="KenFern">Ken Fern. Notes from observations, tasting, etc. at ''Plants for a Future'' and on field trips. Cited in ''Plants for a Future''</ref> to the [[Royal Horticultural Society]]'s H6 hardiness rating, to -20&nbsp;°C.<ref>{{cite web |title=Castanea sativa, sweet chestnut |url=https://www.rhs.org.uk/Plants/3191/Castanea-sativa/Details |access-date=13 August 2020 |website=Find a Plant |publisher=Royal Horticultural Society}}</ref> Chestnut is [[Hardiness zone|hardy to USDA zone 5]], which is {{cvt|-20|F|order=flip}} lower in average minimal temperature than [[London#Climate|London]] in [[Hardiness zone|zone 9]].<ref name="pfaf">[http://www.pfaf.org/database/plants.php?Castanea+sativa Castanea sativa – Mill.] in ''Plants for a Future''.</ref> The young growth in spring, even on mature plants, however, is [[frost]]-tender;<ref name="KenFern" /><ref name="pfaf" /> [[bud]]-burst is later than most other fruit trees, so late frosts can be damaging to young buds.<ref name="laren60" />

Trees can be found at altitudes between 200 and {{nowrap|1000 m}} above sea level;<ref name="laren60" /> some mention between 300 and {{nowrap|759 m}} altitude,<ref name="lille">[http://www.univ-lille1.fr/pfeda/iaal/docs/iaal2002/crem/rapport/crememarron.pdf ''Étude d'un produit régional: La crème de marrons'']. By Sabrina Derouet, Flavie Dhellemmes, Lamia Hakam, Claire Lhaoucine and Maxime Vanhoutte. EPU Lille-USTL. 2003.</ref> while the famous [[Hundred Horse Chestnut]] on [[Mount Etna]] stands at 1200 metres.<ref name="rushton">[http://digicoll.library.wisc.edu/cgi-bin/HistSciTech/HistSciTech-idx?type=turn&entity=HistSciTech001201260012&isize=text The Chestnut tree of Mount Etna]. Detailed account of the tree, its state and its surroundings, written by Wm. Rushton on June 29, 1871.</ref> They can tolerate maritime exposure, although growth is reduced.<ref name="pfaf" />

Seeds [[germination|germinate]] in late winter or early spring,<ref name="KenFern" /><ref name="pfaf" /> but the life length is short. If kept moist, they can be stored in a cool place for a few months, but must be checked regularly for signs of germination.<ref name="pfaf" /> Low temperature prolongs dormancy.<ref name="fao" /> Sowing them as soon as ripe is better, either in [[cold frame]]s or [[seedbed]]s outdoors,<ref name="sheat">''Propagation of Trees, Shrubs and Conifers.'' By W. G. Sheat. MacMillan and Co 1948. Cited in ''Plants for a Future''.</ref> where they can be left ''in situ'' for one to two years before being planted in their permanent positions,<ref name="pfaf" /> or in pots, where the plants can be put out into their permanent positions in summer or autumn. They must be protected from the cold in their first winter,<ref name="KenFern" /> and also from [[mouse|mice]] and [[squirrel]]s.<ref name="pfaf" />

Chestnuts are considered self-sterile,<ref name="pfaf" /><ref name="song">[http://www.songonline.ca/nuts/chestnut.htm Sweet Chestnut (''Castanea'' species)]. Society of Ontario Nut Growers.</ref> so at least two trees are needed for pollination.<ref name="delmarvelous" />

==== Soil requirements ====
''Castanea'' grows best in a soil with good [[Drainage system (agriculture)|drainage]] and adequate moisture.<ref name="laren60" /><ref name="delmarvelous" /> The tree prefers sloping, deep soils; it does not like shallow or heavy soils with impermeable, [[clay]] [[subsoil]]s.<ref name="laren60" /> The Chinese chestnut prefers a fertile, well-drained soil, but it grows well in fairly dry, rocky, or poor soils.<ref name="Kentuckyforestry">[http://www.forestry.ky.gov/programs/reforestation/Tree+Species+Information.htm Kentucky Division of Forestry] {{webarchive|url=https://web.archive.org/web/20080820025958/http://www.forestry.ky.gov/programs/reforestation/Tree%2BSpecies%2BInformation.htm|date=August 20, 2008}}.</ref>

Although ''Castanea'' can grow in very [[acidic]] soil,<ref name="pfaf" /> and while these soils are reasonably well tolerated, the preferred range is from pH 5.5-6.0.<ref name="laren60" /> It does not grow well on [[Alkaline#Alkaline soil|alkaline soils]], such as [[chalk]],<ref name="rhs" /><ref name="pfaf" /> but thrives on soils such as those derived from [[granite]], [[sandstone]], or [[schist]].<ref name="rhs" /> On alkaline soils, chestnut trees can be grown by [[grafting]] them onto [[oak]] rootstocks.<ref name="edlin" /> <br> Recently cleared land is best avoided to help resist the [[root rot]], ''Armillaria mellia''.<ref name="laren60" />

==== Sun exposure ====
''Castanea'' likes a full sun position.<ref name="delmarvelous" /> An experiment with ''C. dentata'' seedlings in Ohio confirmed the need for sun for optimal growth.<ref name="ohio">[http://abstracts.co.allenpress.com/pweb/esa2003/document/25264 Survival and growth in size and biomass of American Chestnut (''Castanea dentata'') seedlings under various silvicultural regimens in a mixed oak forest ecosystem.] {{Webarchive|url=https://web.archive.org/web/20080921193704/http://abstracts.co.allenpress.com/pweb/esa2003/document/25264|date=2008-09-21}} By Corinne McCament and Brian McCarthy. Ohio University, Athens, Ohio. Paper presented on 6 August 2003 at the ESA 2003 Annual Meeting.</ref> The butt of the tree is sometimes painted with white paint to protect the tree from [[sunburn]] until it has developed enough [[Canopy (forest)|canopy]].<ref name="laren60" />

Wide spacing between the trees encourages low, broad [[crown (botany)|crowns]] with maximum exposure to sunshine to increase fruit production. Where chestnut trees touch, virtually no fruit is produced. Current [[orchard|industrial planting spacings]] can range from 7 x 7 to 20 x {{nowrap|20 m}}. The closer plantings, which are more popular, mean quicker increases in short-term production, but heavy pruning or even tree removal is required later.<ref name="laren60" />

==== Watering ====
The optimum rainfall for chestnut trees is {{convert|800|mm|in|0|abbr=on}} or more, ideally in even distribution throughout the year. [[Mulch]]ing during summer is recommended. Rainfall below {{convert|700|mm|in|abbr=on}} per year needs be complemented with, for example, a [[drip irrigation]] system. This should water the soil at the outer half of the circle formed by the drip line<ref name="laren60" /> to encourage root growth.

Independently from annual rainfall, watering young trees is recommended at least during summer and early autumn.<ref name="laren60" /> Once established, they resist [[drought]]s well.<ref name="rhs" /><ref name="bean1" /><ref name="Bown">''Encyclopaedia of Herbs and their Uses''. By D. Bown. Dorling Kindersley, London. 1995 {{ISBN|0-7513-0203-1}}.</ref><ref name="chittendon">''RHS Dictionary of Plants plus Supplement''. By F. Chittendon. 1956 Oxford University Press 1951.</ref>

==== Preservation ====
In addition to being consumed fresh, chestnuts can also be canned, pureed, or preserved in sugar or syrup (''marrons glacés''). Shelled and cooked nuts should be covered, refrigerated, and used within 3–4 days. Cooked chestnuts, either whole, chopped, or pureed, may be frozen in an airtight container and held up to 9 months. Because of their high water content, [[transpiration]] rates, and consequent loss weight, the nuts react as fresh fruits (not as nuts). They should be kept cool at all times, including in shops when on display for sale.<ref name="laren60" /> To preserve their freshness for a few months with no artificial refrigeration, the chestnuts can be soaked in cold water for about 20 hours immediately after [[harvest]], after which they are dried in the shade, then layered in dry sand.<ref name="valnet" /> <br> Chestnuts behave similarly to seeds in that they produce very little [[Ethylene as a plant hormone|ethylene]], and their [[Plant respiration|respiration]] rate is low, varying between 5 and 20&nbsp;mg/(kg·h) depending on the temperature.<ref name="fao" />

==== Pests ====

===== Mammals and birds =====
* [[Grey squirrel]]s strip bark from when the tree is about eight years old and onward through the life of the tree.<ref name="laren60" />
* [[Rabbit]]s and [[wallaby|wallabies]] can do great damage to young trees, which need guarding by some fence or by wrapping the tree trunk in sisal or other appropriate material. Deer and kangaroos can also be troublesome.<ref name="laren60" />
* Cattle and horses may require temporary fencing to prevent them from damaging fallen chestnuts at harvest time.<ref name="laren60" />
* The [[sulphur-crested cockatoo]] can damage branches up to {{nowrap|10 mm}} in diameter by carrying out "beak maintenance" on young trees.<ref name="laren60" />
* [[Rosella]]s can be troublesome at harvest time.<ref name="laren60" />
* Shrews, squirrels, mice, and other critters often eat the chestnut seed after it has sprouted within the first, and even second years of growth. Some avoid this by removing the chestnut seed from the stem.<ref>Sliver, Akiva. Trees of Power. 2019. p 85.</ref>

===== Insects =====
* ''[[Dryocosmus kuriphilus]]'', the oriental chestnut gall wasp, is native to China, but is an invasive pest elsewhere. It attacks and destroys the chestnut fruit. It is considered the world's worst pest of chestnuts.<ref name="isc">CABI, 2013. [http://www.cabi.org/isc/?compid=5&dsid=20005&loadmodule=datasheet&page=481&site=144 ''Dryocosmus kuriphilus''.] In: Invasive Species Compendium. Wallingford, UK: CAB International.</ref>
* The [[larva]]e of the polyfag moth (''[[Phytomyza horticola]]'')<ref name="plantdoctor">[http://plante-doktor.dk/insektrigeteng.htm Plantedoktoren]. A gallery of plant pests.</ref> species are among those that do most damage to [[Shoot (botany)|shoot]]s and foliage.<ref name="szenti">[http://www.sarkpont.hu/webset32.cgi?Sarkpont@@EN@@21@@GOOGLEBOT ''The pest control of the Chestnut tree''] by Dr Péter Szentiványi. Chestnut – Agricultural Publisher. For Sarkpont Cc., Hungary.</ref>
* The most frequently occurring pests are the [[winter moth]] (''Operophtera brumata'') and the [[mottled umber moth]] (''Erannis defoliaria'').<ref name="szenti" />
* The [http://uk.ask.com/web?qsrc=167&o=41439048&l=dis&siteid=41439048&q=Attelabus+nitens+picture&dm=all oak roller weevil] ([[List of weevil (Curculionoidea) species recorded in Britain#Family Attelabidae|''Attelabus nitens'']]) causes relatively less damage by rolling up the leaves into a barrel shape to shelter its eggs and developing larvae. The insects swarm from the end of April to mid-June, and damage the tree's flower buds during their feeding season.<ref name="szenti" />
* The [[larva]]e of the oak-leaf-mining moth, also called the tischerid moth (''[[Tischeria ekebladella]]''), digs white, see-through mines in chestnut leaves. It lays its eggs in the leaves between May and June. The larvae cause white spots in the leaves by chewing them from the inside.<ref name="szenti" />
* The oak [[aphid]] (''[[Myzocallis castanicola]]'') sucks on the apex of young [[Shoot (botany)|shoot]]s and leaves. Native to Europe and North America, it is, for example, active in [[Hungary]]. Leaves do not roll up, but their feeding delays the growth of shoots and damages young [[Grafting|graft]]-shoot hosts. Commercial plantations and nurseries spray pesticides during the shoots' growth period to fight the damage.<ref name="szenti" /> The chestnut [[mosaic virus]] is probably transmitted by ''M. castanicola'' aphids.<ref name="ctifl">[http://cat.inist.fr/?aModele=afficheN&cpsidt=3010278 ''Chestnut mosaic virus : Transmission by the aphid Myzocallis castanicola on Chestnut tree'']. By J.-C. Desvignes and D. Cornaggia (CTIFL, Centre de Lanxade, La Force, France). In Phytoma, la défense des végétaux. 1996, no. 481, pp. 39–41 (6 ref.). {{ISSN|1164-6993}}.</ref>
* The chestnut weevil (''[[Curculio elephas]]'') most often damages the fruits. In Hungary, it swarms in chestnut [[orchard]]s around August 20, particularly strongly around noon and in sunny weather. The eggs are laid into the [[Calybium and cupule|cupule]]s or around the [[peduncle (botany)|peduncle]] joints. The larvae feed on the nuts and leave only nutchips and excrement within. While the chestnuts ripen, the larvae retreat into the ground after having chewed their way out of the nuts. The following July, they turn into [[pupa]]e. <br> The larvae of the chestnut weevil can only chew their way out of a fallen nut, so breeding occurs mostly where chestnuts lie on the ground for a sufficient length of time, or where the trees produce many small fruits which remain behind at the harvest. Timing the harvests to pick up the chestnuts as soon as they fall reduces the numbers of the [[overwinter]]ing larvae. Regular soil work is also unfavourable to its life habits. Small [[Grafting|grafts]] are sprayed with chemicals. A warm, aerosol-based protection has been developed for older trees, by Sifter and Bürgés in 1971. Planting chestnut orchards beside [[Quercus cerris|turkey oak]] forests is not advised, because both trees are susceptible to the chestnut weevil (which also uses the turkey oak acorn to develop), and the turkey oak trees can pass it on to the chestnut trees.<ref name="szenti" />
* In Hungary, the most common moth threatening chestnut trees is the [[Tortricidae|acorn moth]] (''Laspeyreisa splendana'') and its subspecies. Its grayish-yellow larvae cause similar damage to that of the chestnut weevil, but they spin characteristic webs among the nutchips and larval excrement. This moth causes about 5–41% of the damage that occurs in western Hungary's plantations. Plantations need regular protection against these moths, the occurrence of which does not decrease.<ref name="szenti" />
* In New Zealand, the grass grub beetle eats the soft, new-season foliage. They can entirely strip a young tree in the late spring, when they fly at dusk, often in huge numbers.<ref name="nzcouncil" />

==== Diseases ====
[[File:Chestnut blight.jpg|thumb|Chestnut blight]]
* [[Chestnut blight]] fungus (''Cryphonectria parasitica'') (formerly ''Endothia parasitica'') affects chestnut trees. The Eastern Asian species have coevolved with this disease and are moderately to very resistant to it, while the European and North American species, not having been exposed to it in the past, have little or no resistance.<ref name="rhs" /> Early in the 20th century, chestnut blight destroyed about four billion American chestnut trees,<ref name="acfh" /> and reduced the most important tree throughout the East Coast to an insignificant presence. The American chinkapins are also very susceptible to chestnut blight. The European and West Asian chestnuts are susceptible, but less so than the American species.<ref name="rhs" /> The resistant species (particularly Japanese and Chinese chestnut, but also Seguin's chestnut and Henry's chestnut) have been used in breeding programs in the U.S. to create [[Hybrid (biology)|hybrids]] with the American chestnut that are also disease-resistant.<ref name="rhs" /> <br>The bark miner ''Spulerina simploniella'' (Lepidoptera: Gracilariidae) was found in intensively managed chestnut [[Coppicing|coppices]] in Greece, but not in orchards. The larvae (and the rain) may be agents in the spread of the disease. They mine under the thin periderm of young trees up to 10 years old, while the stem bark is still smooth. Rain during the pupation period (around the last week of May and first two weeks of June), and the actions of the larvae, may collude for [[Conidium|conidiospores]] to come into contact with the freshly exposed [[phloem]], thus causing cankers.<ref name="nagref">[https://archive.today/20130105081641/http://www3.interscience.wiley.com/journal/118712634/abstract?CRETRY=1&SRETRY=0 ''The role of Spulerina simploniella in the spread of Chestnut blight'']. By S. Diamandis (NAGREF, Forest Research Institute, 570 06 Vassilika, Thessaloniki, Greece) and C. Perlerou. Received: 27.07.2004; accepted: 25.02.2005; editor: P. Raddi. {{doi|10.1111/j.1439-0329.2005.00413.x}}.</ref>
* Ink disease also appears in a number of other plants. The disease attacks the phloem tissue and the [[cambium (botany)|cambium]] of the [[root]]s and root collars about 10–20&nbsp;cm above ground. [[Wet rot]] settles in as a result. It was named after the ink-black color of the [[tannic acid]] becoming ([[Redox|oxidized]]) after seeping out, but that symptom is not a characteristic of only that disease. The same ink-black color can appear following other types of [[Decomposition|decays]] and mechanical injuries that make liquids seep through; these liquids can also oxidize after contact with air. Moreover, with some phytophthoric diseases, no tannic acid is generated. With the ink disease, the leaves turn yellow and later fall off; the fruits remain small, and the nuts prematurely drop out of the burrs. These dry and remain on the trees throughout winter. In acute cases, root decay makes the trees dry out and wither away.<ref name="szenti" /> It is caused by ''[[Phytophthora cambivora]]'' and ''[[Phytophthora cinnamomi]]''.<ref name="Robin">{{cite journal |last=Robin |first=Cécile |author2=Olivier Morel |author3=Anna-Maria Vettraino |author4=Charikleia Perlerou |author5=Stephanos Diamandis |author6=Andrea Vannini |date=1 May 2006 |title=Genetic variation in susceptibility to Phytophthora Cambivora in European chestnut (Castanea sativa) |journal=Forest Ecology and Management |volume=226 |issue=1–3 |pages=199–207 |doi=10.1016/j.foreco.2006.01.035}}</ref>
* ''Phytophthora'' disease is the longest-known chestnut tree disease leading to tree death. Of the two main [[pathogen]]s for this disease, the one in European chestnuts is known since 1971 to be ''[[Phytophthora cambivora]]''. ''[[Phytophthora cinnamomi]]'' was discovered in chestnut trees in the United States in 1932. Both trigger similar symptoms. Since then, it has also been shown to occur in most European chestnut-growing countries. Differentiating between the two pathogens is difficult. Chemicals seem of little effectiveness. Many countries impose strict [[Prophylaxis|prophylactic]] rules to prevent the spread of the disease.<ref name="szenti" />
* ''Melanconis modonia'' can infect trees through injuries and induce "bark death". It was first reported in Hungary by Hausz in 1972. The damage is of little consequence in older or stronger trees, but it affects sapling graftings in nurseries. ''Coryneum perniciosum'', one of the two [[conidium]]-like side forms of this fungus, occurs on all decayed, [[lignin|ligneous]] parts of a chestnut tree. The symptoms of infection on young, smooth trunks is similar to that of the chestnut blight fungus ''Cryphonectria''. For this reason, it has persistently been wrongly thought of as the pathogen for ink disease. With ''Melanconis'', the bark sinks in and takes on brownish-red tones, with black, lentil-like multicell conidium bodies and black cone-like [[Thylakoid|stromata]] breaking through the bark. Unlike with ''Cryphonectria'', though, no orange-colored fruiting bodies are seen. Prevention primarily includes keeping trees in good shape; some further protections against ''Cryphonectria'' also help prevent bark death caused by ''Melanconis''.<ref name="szenti" />
* Chestnut mosaic virus is probably transmitted by the oak aphid ''Myzocallis castanicola''.<ref name="ctifl" />
* [[Root rot]] is caused by the [[honey fungus]] ''Armillaria mellia''. When planting ''Castanea'', recently cleared land is best avoided to help resist this fungus.<ref name="laren60" /> The disease is more prevalent on heavier and poorly drained soil types.<ref name="nzcouncil" />
[[File:Chestnut plantations (10.3897-mycokeys.48.31715) Figure 1.jpg|thumb|Chestnut canker]]
* [[Leaf spot]] is the most common disease for chestnut trees (''Mycosphaerella maculiformis''). It is known as ''cylindrosporium'' leaf spot disease, after its summer conidium form ''Cylindrosporium castaneae''. The pathogens spend the winter in the white spots of the fallen leaves. At spring time, it reinfects the new leaves. In or near June, tiny white spots on the leaves appear, which grow and turn brown over time. At the end of the summer, the spots entirely cover the leaf, which turns yellow. In rainy and humid weather with large temperature fluctuation, the tree loses its leaves. If August is dry and warm, the infected leaves roll up, the arteries twist, and the dead leaves dry on the tree until defoliage. This recurs yearly, though the extent of the damage varies from year to year. Some species are more resistant than others.<ref name="szenti" />
* Oak mildew is among several foliage diseases of smaller significance for European chestnut growing. It infects the most trees (''Microsphaera alphitoides''). Younger trees suffer most; their shoots become short-jointed, growth is delayed, and they develop sensitivity to frostbite. In older trees, the fungus usually infects only the tip of the shoots. The pathogens hibernate in the shoots and infect the leaves from there. The fungus grows on the top of the leaves, with the appearance of a coating only in midsummer. The infected leaves' development slows down or stops, the distance between their [[Vascular tissue|vessels]] shrinks, and the vessels themselves become curly.<ref name="szenti" />
* In storage rot, breaking the tuft provides the most common entrance for fungal [[spore]]s during storage. ''[[Ciboria]]'', the most diffuse, turns the flesh black and spongy. Other fungi are known, such as ''Rhizopus'', ''Fusarium'', and ''[[Colletotrichum]]''.<ref name="fao" /> In chestnuts, Colletotrichum disease symptoms may also be called '''blossom end rot'''. Browning of the chestnut burs at the blossom end may be a first sign in August. At harvest time, blackening of pointed end of the chestnut shell and kernel indicates infection. The extent of blackening can vary. It can range from a barely visible black tip of the kernel to the whole nut being black. Parts of the nut kernel with no color change remain edible.<ref>Greg Miller, Blossom End Rot of Chestnut: A Small Problem Becomes a Big Problem, The Chestnut Grower, Winter 2017</ref>
* Chestnut canker can be caused by fungi of genus ''Dendrostoma''.<ref name="Jiang 2019">{{cite journal |last1=Jiang |first1=Ning |last2=Fan |first2=Xin-Lei |last3=Crous |first3=Pedro W. |last4=Tian |first4=Cheng-Ming |year=2019 |title=Species of Dendrostoma (Erythrogloeaceae, Diaporthales) associated with chestnut and oak canker diseases in China |journal=MycoKeys |issue=48 |pages=67–96 |doi=10.3897/mycokeys.48.31715 |pmc=6416227 |pmid=30881194 |doi-access=free}}</ref>