Editing Chestnut (section)

==== 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>