Jump to content

Dutch elm disease

From Wikipedia, the free encyclopedia
(Redirected fromDutch Elm Disease)
This article is about the disease affecting elm trees. For the economic phenomenon, seeDutch disease.

Dutch elm disease
On agolden elmwith characteristic leaf shedding
Common namesDED
Causal agentsOphiostoma ulmi
Ophiostoma himal-ulmi
Ophiostoma novo-ulmi
Hostselmtrees
Vectorselm bark beetle
EPPO CodeCERAUL
DistributionEurope, North America and New Zealand

Dutch elm disease(DED) is caused by a member of thesac fungi(Ascomycota) affectingelmtrees, and is spread by elmbark beetles.Believed to be originally native toAsia,the disease was accidentally introduced intoAmerica,Europe,andNew Zealand.In these regions it has devastated native populations of elms that did not have resistance to the disease. The name "Dutch elm disease" refers to its identification in 1921 and later in theNetherlandsby Dutch phytopathologistsBea SchwarzandChristine Buisman,who both worked with professorJohanna Westerdijk.[1][2]The disease affects species in the generaUlmusandZelkova,therefore it is not specific to theDutch elm hybrid.[3][4][5]

Overview

[edit]
Branch death, or flagging, at multiple locations in thecrownof a diseased elm

Dutch elm disease (DED) is caused byascomycetemicrofungi.[6]Three species are now recognized:

Beetle feeding galleries onwych elmtrunk
An infected English elm at West Point, NY, July 2010

DED is spread in North America by three species of bark beetles (Family:Curculionidae,Subfamily: Scolytinae):

In Europe, whileS. multistriatusstill acts as avectorfor infection, it is much less effective than the large elm bark beetle,S. scolytus.H. rufipescan be a vector for the disease, but is inefficient compared to the other vectors.S. schevyrewiwas found in 2003 inColoradoandUtah.

Other reported DED vectors includeScolytus sulcifrons,S. pygmaeus,S. laevis,Pteleobius vittatusandР. kraatzi.[11]Other elm bark beetle species are also likely vectors.

Field resistance

[edit]

'Field resistance' is an umbrella term covering the various factors by which some elms avoid infection in the first place, rather than survive it. A clear example would be theEuropean White Elm(Ulmus laevis) which, while having little or no genetic resistance to DED, synthesizes atriterpene,Alnulin, rendering the bark distasteful to the vector beetles, obliging them to look further afield for more suitable elms. Another would be the inability of the beetles to see elms which did not break the silhouette. 'Weeping' elms are often spared infection owing to the beetles' aversion to hanging upside-down while feeding.

Mechanism

[edit]

In an attempt to block the fungus from spreading farther, the tree reacts by plugging its ownxylem tissuewith gum andtyloses,bladder-like extensions of the xylemcell wall.As the xylem (one of the two types ofvascular tissueproduced by thevascular cambium,the other being thephloem) delivers water and nutrients to the rest of the plant, these plugs prevent them from travelling up the trunk of thetree,starving the tree of water and nutrients, which eventually kills it.

Symptoms

[edit]

The first symptom of infection is usually an upper branch of the tree with leaves starting to wither and yellow in summer, months before the normal autumnal leaf shedding. This morbidity spreads in a progressive manner throughout the tree, with further dieback of branches. Eventually, the roots die, starved of nutrients from the leaves. Often, not all the roots die: the roots of some species, especially theEnglish elm(formerlyUlmus procera), can repeatedly put up suckers, which flourish for approximately 15 years before dying off.[9]

Disease range

[edit]

Europe

[edit]

Dutch elm disease was first noticed in continental Europe in 1910, and spread slowly and eventually extended to all other countries except Greece and Finland.[12]Barendina Gerarda Spierenburgcompiled records of trees displaying symptoms from 1900 - 1905 onwards in the Netherlands and her publication[13]of this information in 1921 was one part of the start of extensive research and practical measures to try to halt the disease. In addition the fungus that caused the disease was isolated in 1921 in The Netherlands byBea Schwarz,a pioneering Dutchphytopathologist,and this discovery would lend the disease its name.[14]Following this, in the 1920s and 30sChristine Buisman,working in the Netherlands and USA, identified the sexual stage of the fungal pathogen and also developed methods for experimental infections of elm seedlings that led to selection of resistant trees.[15]

In Britain, the disease was first identified in 1927 by T R Peace on English elm in Hertfordshire.[16]This first strain was a relatively mild one, which killed only a small proportion of elms, more often just killing a few branches, and had largely died out by 1940 owing to its susceptibility to viruses.

Salisbury Cathedral from Lower Marsh Close,1820, Andrew W. Mellon Collection, National Gallery of Art, Washington, D.C.

In around 1967, a new, far morevirulent,strain arrived in Britain, apparently via east coast ports on shipments of rock elmU. thomasiilogs from Canada destined for the small-boat industry, confirmed in 1973 when another consignment was examined at Southampton Docks.[16]This strain proved both highly contagious and lethal to European elms; more than 25 million trees died in the United Kingdom alone, while France lost 97% of its elms.[17]The disease spread rapidly northwards, reaching Scotland within 10 years.[16]

By 1990, very few mature elms were left in Britain or much of continental Europe. One of the most distinctiveEnglishcountryside trees (SeeJohn Constable's paintingSalisbury Cathedral from the South-West), the English elmU. minor'Atinia',is particularly susceptible as it is the elm most favoured by the Scolytus beetles. Thirty years after the outbreak of theepidemic,nearly all these trees, which often grew to more than 45 m high, are gone. The species still survives inhedgerows,as the roots are not killed and send up root sprouts ("suckers"). These suckers rarely reach more than 5 m tall before dying off from a new attack. However, established hedges kept low by clipping have remained apparently healthy throughout the nearly 40 years since the onset of the disease in the United Kingdom.

Sign on A27, Brighton

The largest concentrations of mature elms in Europe are now inAmsterdamandThe Hague.In 2005, Amsterdam was declared the "Elm City of Europe": the city's streets and canals are lined with at least 75,000 elms, including several generations of research-elms (see below:Resistant trees).[18][19]Some 30,000 of the 100,000 mature trees inThe Hagueare elms, planted because of their tolerance of salty sea-winds. Since the 1990s, a programme of antifungal injections of the most prominent 10,000 elms, and of sanitation felling, has reduced annual elm losses in The Hague from 7% to less than 1% (see below:Preventive treatment). The losses are made up by the planting of disease-resistantcultivars.[20]The largest concentration of mature elm trees remaining in England is inBrighton and Hove,East Sussex,where of the 30,000 elms in 1983[21]15,000 still stand (2005 figures), several of which are estimated to be over 400 years old. Their survival is owing to the isolation of the area, between theEnglish Channeland theSouth Downs,and the assiduous efforts of local authorities to identify and remove infected sections of trees immediately when they show symptoms of the disease.[22]Empowered by the Dutch Elm Disease (Local Authorities) (Amendment) Order 1988,[23]local authorities may order the destruction of any infected trees or timber, although in practice they usually do it themselves, successfully reducing the numbers of elm bark beetleScolytusspp.[24]Sanitary felling has also, to date, preserved most of the 250,000 elms on theIsle of Man,[25]where average temperature and wind speed inhibit the activity of the beetles, which need a temperature of at least 20 degrees to fly and a wind speed of less than five metres per second.[26][27]

Felling a diseased elm, Edinburgh, November 2011

The largest concentration of mature elms in Scotland is inEdinburgh,where over 5,000 remained in 2009 from some 35,000 in 1976.[28]The city council gives the overall number of elms as 15,000 (2016).[29]Edinburgh'sLeith LinksandMeadowshave some of the highest concentrations of mature elms among U.K. parks (2014). A policy of sanitary felling has kept losses in the city to an average of 1,000 a year (2009).[30]Between 2013 and 2020 losses were below 1,000 a year.[31]Elm was the most common tree in Paris from the 17th century; before the 1970s there were some 30,000ormes parisiens.Today, only 1,000 mature elms survive in the city, including examples in the large avenues (Avenue d'Italie, Avenue de Choisy, Boulevard Lefebvre, Boulevard de Grenelle, Boulevard Garibaldi) and two very old specimens, one in the garden of theTuileriesin front of thel'Orangerieand another in thePlace Saint-Gervaisin front ofl'hôtel de ville de Paris.Losses are now being made up with disease-resistant cultivars, especially the Dutch-French research elm'Nanguen' (Lutèce),named for the ancient Roman name for the city: Lutetia.[32][33]

North America

[edit]
Arborist removing infected elm inSaint Paul, Minnesota

DED was first reported in theUnited Statesin 1928, with the beetles believed to have arrived in a shipment of logs from the Netherlands destined for use asveneerin theOhiofurnitureindustry. Quarantine and sanitation procedures held most cases within 150 mi (240 km) of metropolitanNew York Cityuntil 1941 when war demands began to curtail them.[34]The disease spread fromNew Englandwestward and southward, almost completely destroying the famous elms in the "Elm City" ofNew Haven, Connecticut,reaching theDetroitarea in 1950,[35]theChicagoarea by 1960, andMinneapolisby 1970. Of the estimated 77 million elms in North America in 1930, over 75% had been lost by 1989.[36]

Rows of American elm trees south of theLincoln Memorial Reflecting Poolon the National Mall in Washington, D.C. (November 11, 2006)

The disease first appeared on the planted rows ofAmerican elm trees (Ulmus americana)on theNational MallinWashington, D.C.,during the 1950s and reached a peak in the 1970s. The United StatesNational Park Service(NPS) used a number of methods to control the epidemic, includingsanitation,pruning,injecting trees withfungicideand replanting with DED-resistant American elm cultivars (seeUlmus americanacultivars). The NPS combated the disease's local insectvector,the smaller European elm bark beetle (Scolytus multistriatus), by trapping and by spraying withinsecticides.As a result, the population of American elms planted on the Mall and its surrounding areas has remained intact for more than 80 years.[37]

DED reached eastern Canada during World War II, and spread toOntarioin 1967,Manitobain 1975 andSaskatchewanin 1981. InToronto,80% of the elm trees have been lost to Dutch elm disease; many more fell victim inOttawa,Montrealand other cities during the 1970s and 1980s.Quebec Citystill has about 21,000 elms, thanks to a prevention program initiated in 1981.[38]AlbertaandBritish Columbiaare the only provinces that are currently free of Dutch elm disease, although, in an isolated case, an elm tree inWainwright, Alberta,was found diseased in June 1998 and was immediately destroyed.[39]The presence of DED was monitored in this area during subsequent years but was not seen again. Today,Albertahas the largest number of elms unaffected by Dutch elm disease in the world.[40]

The provinces of Alberta, Manitoba, andSaskatchewanall prohibit the pruning of elm trees during the middle of the year (taking effect in April, and lasting through the end of September, July, and August respectively), which they deem to be the most active time of year for bark beetles.[41][42][43]It is also illegal to use, store, sell, or transport elm firewood.[43][44][45]

The largest surviving urban forest of elm trees in North America is believed to be in the city ofWinnipeg,where close to 200,000 elms remain.[46]The city spends $3 million annually to aggressively combat the disease usingDursban Turfand the Dutch Trig vaccine.[47][48]

New Zealand

[edit]

Dutch elm disease has reachedNew Zealand.It was found inNapierwhere it was eradicated and was also found in theAuckland Regionin 1989. TheMinistry of Agriculturefunded a national management programme but it was cancelled to allow more funds to be available for pests of a higher priority.[49]A major outbreak occurred in New Zealand in July 2013, particularly at the site ofKingseat Hospital,south ofAuckland.[50]Auckland has 20,000 elms.[51]

Preventive treatment

[edit]

Mechanical

[edit]
Diseased elmringbarkedto slow down transmission before felling.

The first attempts to control Dutch elm disease consisted of pruning trees to remove and burn diseasedtimber.While this method was effective inNew York Stateand adjacent areas, its cost made it uneconomical except in large cities where elms were considered valuable attractions.

Chemical

[edit]

In the US, when Dutch elm disease spread away from the Atlantic coast, control focused on controlling the bark beetle by usinginsecticidessuch asDDTanddieldrin,which were sprayed heavily across all parts of elm trees, usually twice a year in the spring and again at a lower concentration in the summer. In its early years, it was generally thought by observers that pesticides did slow the spread of the disease across the United States[52]but as early as 1947, concern was raised that many bird species were killed in large numbers by ingesting poisoned invertebrates.[52][53]In areas sprayed during the 1950s, local people observed birds such as theAmerican woodcock,American robin,white-breasted nuthatch,brown creeperand variousPoecilespecies dying. BiologistRachel Carsonconsequently argued for improved sanitation and against spraying elms, which she saw as having been more effective in areas with earlier and greater experience countering Dutch elm disease.[54]Spraying against elm bark beetles declined very rapidly after 1962, a trend aided byfungicides.[55]

Lignasan BLP (carbendazim phosphate), introduced in the 1970s, was the first fungicide used to control Dutch elm disease. This had to be injected into the base of the tree using specialized equipment, and was never especially effective. It is still sold under the name "Elm Fungicide".

Arbotect (thiabendazole hypophosphite) became available some years later, and it has been proven effective. Arbotect must be injected every two to three years to provide ongoing control; the disease generally cannot be eradicated once a tree is infected. Arbotect is not effective on root graft infections from adjacent elm trees. It is more than 99.5% effective for three years from beetle infections, which is the primary mode of tree infection.

Alamo (propiconazole) has become available more recently, though several university studies show it to be effective only for the current season in which it is injected. Alamo is primarily recommended for treatment ofoak wilt.

Multistriatinis apheromoneproduced by female elm bark beetles, which can be produced synthetically. It has potential in being used to trap male beetles, which carry the fungus.

Biological

[edit]

Because of the ban on the use of chemicals on street and park trees in the Netherlands, theUniversity of Amsterdamdeveloped a biological vaccine by the late 1980s. Dutch Trig is nontoxic, consisting of a suspension in distilled water of spores of a strain of the fungusVerticillium albo-atrumthat has lost much of its pathogenic capabilities, injected in the elm in spring. The strain is believed to have enough pathogenicity left to induce an immune response in the elm, protecting it against DED during one growing season. This is calledinduced resistance.[56]Trials with the American elm have been successful; in a six-year experiment with the American elm in Denver, CO, annual Dutch elm disease losses declined significantly after the first year from 7 percent to between 0.4 and 0.6 percent;[48]a greater and more rapid reduction in disease incidence than the accompanying tree sanitation and plant health care programs.[57]

Preventive treatment is usually justified only when a tree has unusual symbolic value or occupies a particularly important place in the landscape.

Resistant trees

[edit]
Row ofPrinceton elmtrees atScripps CollegeinClaremont, California,resistant to Dutch elm disease[58]

Research to select resistantcultivarsand varieties began in the Netherlands in 1928, followed by the United States in 1937 (seeUlmus americanacultivars). Initial efforts in the Netherlands involved crossing varieties ofU. minorandU. glabra,but later included the Himalayan or Kashmir elmU. wallichianaas a source of antifungal genes. Early efforts in the USA involved the hybridization of the Siberian elmU. pumilawith American red elmU. rubrato produce resistant trees. Resulting cultivars lacked the traditional shape and landscape value of the American elm; few were planted.

In 2005, theNational Elm Trial(USA) began a 10-year evaluation of 19 cultivars in plantings across the United States. The trees in the trial were exclusively American developments; no European cultivars were included. Based on the trial's final ratings, the preferred cultivars of the American elm (Ulmus americana) are ‘New Harmony’ and ‘Princeton’. The preferred cultivars of Asian elms are theMorton Arboretumintroductions and ‘New Horizon’.[59]

Recent research inSwedenhas established that early-flushing clones are less susceptible to DED owing to an asynchrony between DED susceptibility and infection.[60]

Testing for disease resistance

[edit]

Elms are tested for resistance by inoculation with the fungal pathogen in late May when the tree's growth is at its annual peak. Clones raised for testing are grown to an age of 3 or 4 years. In Europe, theinoculumis introduced into the cambium by a knife wound. However this method, developed in the Netherlands, was considered too severe in America, where the principal disease vector is the bark beetleScolytus multistriatus,a far less effective vector than the larger beetleendemicto Europe,Scolytus scolytus,which is unknown in America. In the method devised by theUSDA,the inoculum is introduced to the cambium via a 2 mm-diameter hole drilled through the bark in the lower third of the tree. This method was further refined by theUniversity of Wisconsinteam, which drilled holes in the branches to simulate natural infection by the bark beetles feeding in the twig crotches, but results from this method were found to exaggerate the genetic resistance of the host. Consequently, tests were conducted on specimens in a controlled environment, either in greenhouses or customized plant chambers, facilitating more accurate evaluation of both internal and external symptoms of disease.

Another variable is the composition of the inoculum; while an inoculum strength of 106spores / ml is standard in both continents, its composition reflects the differentOphiostomaspecies, subspecies and hybrids endemic to the two continents. In Italy for example, two subspecies,americanaandnovo-ulmi,are present together with their hybrid, whereas in North America, ssp.novo-ulmiis unknown.[61]The differences in method and inocula possibly explain why the American cultivar'Princeton',displaying high resistance in the US, has often succumbed to Dutch elm disease in Europe.[62]

Hybrid cultivars

[edit]
Inoculation of virulent strains ofOphiostomain elm cambium, Dorschkamp Institute for Forestry and Landscape Planning,Wageningen,1984

Many attempts to breed disease-resistant cultivar hybrids have involved a genetic contribution from Asian elm species that are demonstrably resistant to this fungal disease. Much of the early work was undertaken in the Netherlands. The Dutch research programme began in 1928, and ended in 1992. During those 64 years, well over 1000 cultivars were raised and evaluated. Still in use are cultivars such as 'Groeneveld', 'Lobel', 'Dodoens', 'Clusius' and 'Plantijn', although the resistance levels in these trees aren't high enough to confer good protection. The programme had three major successes:'Columella','Nanguen'Lutèce,and'Wanoux'Vada,[63]all found to have an extremely high resistance to the disease when inoculated with unnaturally large doses of the fungus. Only 'Columella' was released during the Dutch programme's lifetime—-in 1987. Patents for theLutèceandVadaclones were purchased by the French Institut National de la Recherche Agronomique (INRA), which subjected the trees to 20 years of field trials in theBois de Vincennes,Paris,before releasing them to commerce—-in 2002 and 2006, respectively.

Asian species featured in the American DED research programs were the Siberian elmU. pumila,Japanese elmU. davidianavar.japonica,and the Chinese elmU. parvifolia,which gave rise to several dozen hybrid cultivars resistant not just to DED, but also to the extreme cold of Asian winters. Among the most widely planted of these, both in North America and in Europe, are'Sapporo Autumn Gold','New Horizon'and'Rebona'.Some hybrid cultivars, such as'Regal'and'Pioneer'are the product of both Dutch and American research. Hybridization experiments using the slippery (or red) elmU. rubraresulted in the release of'Coolshade'and'Rosehill'in the 1940s and 50s; the species last featured in hybridization as the female parent of'Repura'and'Revera',both patented in 1993, although neither has yet appeared in commerce.

InItaly,research was initiated at the Istituto per la Protezione delle Piante, Florence, to produce a range of disease-resistant trees adapted to the warmer Mediterranean climate, using a variety of Asiatic species crossed with the early Dutch hybrid'Plantyn'as a safeguard against any future mutation of the disease.[64]Two trees with very high levels of resistance,'San Zanobi'and'Plinio',[65]were released in 2003.'Arno'and'Fiorente'were patented in 2006 and entered commerce in 2012. All four have the Siberian elmU. pumilaas a parent, the source of disease-resistance and drought-tolerance genes.'Morfeo'was released in 2011; it arose from a crossing of the Dutch hybrid clone '405' (female parent) and theChenmou Elm,the latter a small tree from the provinces ofAnhuiandJiangsuin eastern China, The '405' clone is a crossing of an EnglishU.×hollandicaand a FrenchU. minor.

In the Netherlands a new program has been initiated. From the old proving grounds of the Dorschkamp Research Institute, 10 fourth-generation hybrids survive in a DED-ridden area. These have been tested and some have a very high level of resistance. At Noordplant Nursery new hybrids have been tested since 2013.

Species and species cultivars

[edit]

North America

[edit]
Results of artificial inoculation ofOphiostomastrains in elm cambium, Arlington Experimental Station,Wisconsin,1987

Ten resistant American elm cultivars are now in commerce in North America. No cultivar is immune to DED; even highly resistant cultivars can become infected, particularly if already stressed by drought or other environmental conditions where the disease prevalence is high. With the exception of 'Princeton', no trees have yet been grown to maturity; trees cannot be said to be mature until they have reached an age of 60 years.

Notable cultivars include:

  • 'Princeton', is a cultivar selected in 1922 byPrinceton Nurseriesfor its landscape merit. By coincidence, this cultivar was found to be highly resistant in inoculation studies carried out by theUSDAin the early 1990s. As trees planted in the 1920s still survive, the properties of the mature plant are well known. However, 'Princeton' has not proven resistant in Europe, where the main vector of the disease—the larger elm bark beetle,Scolytus scolytus—is capable of introducing far more fungal spores into the tree; many of the 50 trees planted atHighgrove Housein the south-west ofEnglandin 2006 had died from Dutch elm disease by 2011.[62]
  • 'American Liberty',is, in fact, a set of six cultivars of moderate to high resistance produced through selection over several generations starting in the 1970s. Although 'American Liberty' is marketed as a single variety, nurseries selling the "Liberty Elm" actually distribute the six cultivars at random and thus, unfortunately, the resistance of any particular tree cannot be known. One of the cultivars,'Independence',is covered by patent (U. S.Plant patent6227). The oldest 'American Liberty' elm was planted in about 1980.
  • 'Valley Forge', released in 1995, has demonstrated the highest resistance of all the clones to Dutch elm disease in controlled USDA tests.
  • 'Lewis and Clark'=Prairie Expedition TM,released in 2004 to commemorate the bicentenary of the Lewis & Clark expedition, was cloned from a tree found growing inNorth Dakotawhich had survived unscathed when all around had succumbed to disease.

In 2007, the Elm Recovery Project of theUniversity of Guelph Arboretumin Ontario, Canada, reported that cuttings from healthy surviving old elms surveyed across Ontario had been grown to produce a bank of resistant trees, isolated for selective breeding of highly resistant cultivars.[66]

The University of Minnesota USA is testing various elms, including a huge now-patented century-old survivor known as"The St. Croix Elm",which is located in a Minneapolis-St. Paul, MN suburb (Afton) in the St. Croix River valley—a designated National Scenic Riverway.

The slippery or red elmU. rubrais marginally less susceptible to Dutch elm disease than the other American species, but this quality seems to have been largely ignored in American research. No cultivars were ever selected, although the tree was used in hybridization experiments (see above).

In 1993, Mariam B. Sticklen and James L. Sherald reported the results of NPS-funded experiments conducted atMichigan State UniversityinEast Lansingthat were designed to applygenetic engineering techniquesto the development of DED-resistant strains of American elm trees.[67]In 2007, AE Newhouse and F Schrodt of theState University of New York College of Environmental Science and ForestryinSyracusereported that youngtransgenicAmerican elm trees had shown reduced DED symptoms and normalmycorrhizalcolonization.[68]By 2013, researchers in bothNew York StateandNorth Carolinawere conducting field trials ofgenetically engineeredDED-resistant American elms.

Europe

[edit]

Among European species, there is the unique example of the European white elmU. laevis,which has little innate resistance to DED, but is eschewed by the vector bark beetles and only rarely becomes infected. Recent research has indicated it is the presence of certain organic compounds, such astriterpenesandsterols,which serves to make the tree bark unattractive to the beetle species that spread the disease.[69]

In Europe the testing of clones of survivingfield elmsfor innate resistance has been carried out since the 1990s by national research institutes, with findings centrally assessed and published.[70]The first results of this ongoing project suggest that in some countries a very small number of nativefield elmgenotypes have comparatively high levels of tolerance to DED. In Spain, for example, of around 5,000 native elms evaluated to 2013, some 25 genotypes (0.5% of those tested) fall into this category; and it is now hoped that the controlled crossing of the best seven of these (genetically and aesthetically) will produceUlmus minorhybrids with effective 'field resistance' and market appeal.[71]Similar results are beginning to emerge in trials on surviving field elms in Greece.[72]

United Kingdom
[edit]

Much of the work in the United Kingdom is by the Forestry Commission's research arm, which has had Dutch elm disease on its agenda since the 1920s. In 1994 a Research Information Note (no 252) was published, written by John Gibbs, Clive Brasier and Joan Webber, and in 2010 a Pathology Advisory Note, as well as throughout the period a stream of more academic papers: notable results have been the observation that the progress of the disease through Scotland has been quite slow, and that genetic engineering has been tried to improve the resistance of theEnglish elm.

In England theConservation Foundationhad been propagating, distributing and planting clones of surviving indigenous elms, including field elms (but not the highly susceptibleEnglish elm), as part of a scheme to return elms to city and countryside.[73][74][75][76]The Foundation was running two elm programmes: the 'Great British Elm Experiment' and 'Ulmus londinium', an elm programme for London – these use saplings cultivated through micropropagation from mature parent elms found growing in the British countryside: parent trees are monitored for disease, while saplings were offered free to schools and community groups, who are asked to monitor their trees' progress on the Foundation's online elm map; in London, places with 'elm' in their name were offered a sapling – in an attempt to find out why some elms have survived while others succumbed to Dutch elm disease. Both these projects have been discontinued.

The spread of DED to Scotland has focussed attention on a small number of wych elmsU. glabrasurviving in areas of high infectivity, prompting theRoyal Botanic Garden Edinburghto begin a programme of selecting trees, with a view to determining innate resistance (2009).[77]The Garden is raising and distributing in Scotland seedlings derived from controlled crosses of rare survivors in these areas (2023).[78][79][80]

In 2001–2004, English elmU. minor'Atinia'was genetically engineered to resist disease, in experiments atAbertay University,Dundee,Scotland,by transferring antifungal genes into the elm genome using minute DNA-coated ball bearings.[81][82]However, owing to reservations to GM developments, there are no plans to release the trees into the countryside.

Spain
[edit]

In Spain, the Escuela Técnica Superior de Ingenieros de Montes,Universidad Politecnica de Madrid,charged with discovering disease-resistant elms for use in forestry, has raised and patented seven cultivars of the field elmUlmus minor,although two have subsequently been found to have Siberian elmU. pumilaDNA, the species introduced to Spain in the 16th century. Although none have been released to commerce (2020), the clone'Ademuz',pureU. minor,has been imported into the UK since 2014, and widely planted there.

Possible earlier occurrences

[edit]

The 'Elm Decline'

[edit]

From analysis of fossil pollen in peat samples, it is apparent that elms, an abundant tree in prehistoric times, all but disappeared from northwestern Europe during themid-Holoceneperiod around 4000 BC, and to a lesser extent around 1000 BC. This roughly synchronous and widespread event has come to be known as the 'Elm Decline'. When first detected in the mid-20th century, the decline was attributed to the impact of forest-clearance byNeolithicfarmers, and of elm-coppicing for animal fodder, though the numbers of settlers could not have been large. The devastation caused recently by DED has provided an alternative explanation. Examination of subfossil elm wood showing signs of the changes associated with the disease has suggested that a form of DEDmayhave been responsible. Fossil finds from this period of elm bark beetles support this theory. A consensus today is that the Elm Decline was probably driven by both factors.[83][84]

Historic period

[edit]

A less devastating form of the disease, caused by a different fungus, had possibly been present in north-west Europe for some time. DrOliver Rackhamof Cambridge University presented evidence of an outbreak of elm disease in north-west Europe, c. 1819–1867. "Indications from annual rings [a reference to the dark staining in an annual ring in infected elms] confirm that Dutch elm disease was certainly present in 1867," he wrote, quoting contemporary accounts of diseased and dying elms, including this passage inRichard Jefferies' 1883 book,Nature near London:

There is something wrong with elm trees. In the early part of this summer, not long after the leaves were fairly out upon them, here and there a branch appeared as if it had been touched with red-hot iron and burnt up, all the leaves withered and browned on the boughs. First one tree was thus affected, then another, then a third, till, looking round the fields, it seemed as if every fourth or fifth tree had thus been burnt. [...] Upon mentioning this I found that it had been noticed in elm avenues and groups a hundred miles distant, so that it is not a local circumstance.

Earlier still, Rackham noted, "The nameScolytus destructorwas given to the great bark beetle on evidence, dating from c. 1780, that it was destroying elms around Oxford. "[85]

In Belgium, elm die-back and death was observed in 1836 and 1896 inBrussels,and in 1885–1886 inGhent.In the later outbreaks the die-back was attributed to the elm bark beetle.[86]

It has been suggested that "for thousands of years elms have flourished in natural balance with thescolytidae,combating occasional infections of Dutch elm disease. "[87]

SirThomas Browne,writing in 1658, noted inThe Garden of Cyrusan elm disease that was spreading through English hedgerows, and described symptoms reminiscent of DED.[88]

See also

[edit]

References

[edit]
  1. ^Schwarz, M.B. (1922). "Das Zweigsterben der Ulmen, Trauerweiden und Pfirsichbaume".Mededelingen Phytopathologisch Laboratorium, Willie Commelin Scholten.5:1–73.
  2. ^Buisman, C. (1928). "De oorzaak van de iepenziekte".Tijdschr Ned Heidemaatsch.40:338–345.
  3. ^"Dutch elm disease in Britain".UK Forestry Commission. Archived fromthe originalon 9 March 2018.Retrieved6 June2007.
  4. ^Dutch Elm Disease.Macmillan Science Library.{{cite book}}:|work=ignored (help)
  5. ^Smalley, EB (1963). "Seasonal fluctuations in susceptibility of young elm seedlings to Dutch elm disease".Phytopathology.53(7): 846–853.
  6. ^Ascomycetes: Phylum Ascomycota,Biology of Plants, Seventh Edition,W. H. Freeman and Company, 2005.
  7. ^Clinton, G. P., McCormick, Florence A.,Dutch elm disease, Graphium ulmi;New Haven, 1936
  8. ^M.D., C.M.; Mehrotra, M.D. (1995). "Ophiostoma himal-ulmisp. nov., a new species of Dutch elm disease fungus endemic to the Himalayas ".Mycological Research.99(2): 205–215.doi:10.1016/S0953-7562(09)80887-3.ISSN0953-7562.
  9. ^abSpooner, Brian; Roberts, Peter (2010) [2005].Fungi.Collins New Naturalist Library. Vol. 96. HarperCollins. p. 235.ISBN978-0-00-740605-0.
  10. ^Johnson, O. (2011).Champion Trees of Britain and Ireland.Royal Botanic Gardens, Kew. ISBN978-1842464526
  11. ^Ижевский, С.С.; Никитский, Н.Б.; Волков, О.Г.; Долгин, М.М (2005).Иллюстрированный справочник. жуков-ксилофагов – вредителей леса и лесоматериалов Российской Федерации(PDF).Тула: Российская Академия Наук, Уральское отделение, Коми научный центр, Институт биологии. (Izhevsky, SS; et al. (2005). "An illustrated guide to the xylophagous beetles injuring forests and timber in the Russian Federation". Russian Academy of Sciences, Ural Branch, Komi Science Center, Institute of Biology. Tula). p. 165.
  12. ^Clouston, B., Stansfield, K., eds.,After the Elm(London, 1979)
  13. ^Spierenburg, Barendina (1921). "Een onbekende ziekte in de iepen (An unknown disease in elms)".European Journal of Plant Pathology.27(5).
  14. ^Holmes, Francis W.; Heybroek, H.M. (1990).Dutch elm disease: the early papers: selected works of seven Dutch women phytopathologists.APS Press.ISBN978-0-89054-110-4.
  15. ^Heybroek, H. M. and Nijboer, R. (2013).Christine Johanna Buisman in Italy.p. 4–6. Private publication, Netherlands.
  16. ^abcHarris, E. (2017). The European White Elm, Ulmus laevis Pall.Quarterly Journal of Forestry,Vol. 111, No. 4, October 2017. p.263. Royal Forestry Society.
  17. ^"Lutèce®, a resistant variety brings elms back to Paris".All The News.Nantes,France:Institut national de la recherche agronomique(INRA). 15 April 2005. Archived fromthe originalon 25 November 2006.
  18. ^"Amsterdam, City of Trees".DutchAmsterdam. 18 May 2011.
  19. ^Amsterdamse BomemArchived2011-07-24 at theWayback Machine
  20. ^"The City and its elm population".The Hague in the Netherlands.DutchTrig®. Archived fromthe originalon 29 October 2013.
  21. ^Research on Dutch Elm Disease in Europe,ed. D. A. Burdekin (London, 1983)
  22. ^Brighton and Hove Council page on the city's elm collectionArchived2011-06-14 at theWayback Machine(viewed 2 June 2010)
  23. ^"Dutch Elm Disease (DED)".Environment and Planning: Land and premises: Conservation: Trees & landscapes.Lewes District Council. 2009. Archived fromthe originalon 5 July 2009.
  24. ^Gupta, Tanya (11 November 2005)."How Brighton beat Dutch Elm menace".BBC News, South East.
  25. ^Isle of Man elms, geocomputation.org
  26. ^Coleman, M.; A’Hara, S.W.; Tomlinson, P.R.; Davey, P.J. (2016). "Elm clone identification and the conundrum of the slow spread of Dutch Elm Disease on the Isle of Man".New Journal of Botany.6(2–3): 79–89.Bibcode:2016NJBot...6...79C.doi:10.1080/20423489.2016.1271612.S2CID90001207.
  27. ^prolandscapermagazine 24 February 2017
  28. ^Coleman, Max, ed.,Wych Elm(Edinburgh 2009)
  29. ^edinburgh.gov.uk/info/20064/parks_and_green_spaces/256/trees_and_woodlands
  30. ^Coleman, Max (2009).Wych Elm.Royal Botanic Gardens Edinburgh. p. 47.ISBN978-1-906129-21-7.
  31. ^'Dutch elm disease management in Edinburgh' (2021); treecare.org.uk
  32. ^Ulmus 'Nanguen' foretpriveefrancaise
  33. ^PDFArchived24 September 2015 at theWayback Machine
  34. ^Life,11 September 1944, p. 58
  35. ^Baulch, Vivian (20 December 2001)."How Detroit lost its stately elms".Detroit News.
  36. ^New York Times, 5 December 1989, nytimes nytimes /1989/12/05/science/new-varieties-of-elm-raise-hope-of-rebirth-for-davastated-tree.html?sec=health&spon=
  37. ^Sherald, James L (December 2009).Elms for the Monumental Core: History and Management Plan(PDF).Washington, D.C.: Center for Urban Ecology, National Capital Region,National Park Service.Natural Resource Report NPS/NCR/NRR--2009/001. Archived fromthe original(PDF)on 29 November 2010.Retrieved14 October2010.
  38. ^Beaucher, Serge (Autumn 2009)."Québec, terre des ormes".Contact(in French).28(1). Laval University.
  39. ^CFIA annual pest survey report. 1999 Summary of Plant Quarantine Pest and Disease Situations in Canada (report available upon demand at the Canadian Food Inspection Agency:http://publications.gc.ca/site/eng/9.831610/publication.html)
  40. ^"Dutch Elm Disease".Alberta Agriculture and Rural Development. Archived fromthe originalon 21 May 2018.Retrieved14 December2014.
  41. ^"Hydro contractors snubbing Winnipeg elm-pruning ban, group suspects".CBC News.26 July 2017.Retrieved26 July2019.
  42. ^Agriculture, Alberta; Forestry (11 April 2018)."Elm pruning ban now in place".Alberta Farmer Express.Retrieved26 July2019.
  43. ^ab"Pruning ban on elm trees starts April 1".CTV News Regina.25 March 2019.Retrieved26 July2019.
  44. ^Semeschuk, Darci."Majestic Elms marked for removal".Souris Plaindealer.Retrieved26 July2019.
  45. ^Release, Stopded (14 November 2016)."Elm pruning ban over until March".Alberta Farmer Express.Retrieved26 July2019.
  46. ^"Winnipeg is home to the largest Urban Elm Forest in North America - Winnipeg | Globalnews.ca".Global News.Retrieved9 August2022.
  47. ^"Elm Bark Beetle Control Program"(PDF).City of Winnipeg. 2009.[permanent dead link‍]
  48. ^abRumbolt, Colin (17 November 2009)."Dutch elm vaccine tested in Winnipeg".the Manitoban.
  49. ^"Dutch Elm Disease".Biosecurity New Zealand. 26 May 2008. Archived fromthe originalon 5 December 2012.Retrieved1 October2012.
  50. ^"Elm disease strikes out south".Manukau Courier.Fairfax NZ News. 18 August 2013.
  51. ^Auckland's elms, bts.nzpcn.org.nz/bts_pdf/ABJ58(1)2003-38-45-Elms.pdf
  52. ^abBenton, Allen H. (January 1951). "Effects on Wildlife of DDT Used for Control of Dutch Elm Disease".The Journal of Wildlife Management.15(1): 20–7.doi:10.2307/3796765.JSTOR3796765.
  53. ^Dempsey, Dave (2001).Ruin & Recovery: Michigan's Rise as a Conservation Leader.University of Michigan Press. p. 126.ISBN978-0-472-06779-4.
  54. ^Carson, Rachel(2002).Silent Spring.Houghton Mifflin Harcourt. pp.105–115.ISBN978-0-618-24906-0.
  55. ^"New Fungicide Fights Dutch Elm Disease".Chem. Eng. News.42(37): 29–31. 1964.doi:10.1021/cen-v042n037.p029.
  56. ^About Dutch Trig®Archived2010-11-17 at theWayback Machine
  57. ^"Dutch Trig - United States - Distributors".Archived fromthe originalon 15 June 2013.Retrieved5 August2013.
  58. ^"Elm Tree Lawn Begins New Life".Scripps College News.Scripps College.14 April 2008.Retrieved18 February2021.
  59. ^(1)"National Elm Trial".Bioagricultural Sciences & Pest Management.Fort Collins, Colorado:Colorado State University College of Agricultural Sciences:Department of Agricultural Biology.2018. Archived fromthe originalon 30 March 2018.Retrieved23 September2021..
    (2)Griffin, Jason J.; Jacobi, E., William R.; McPherson, Gregory; Sadof, Clifford S.; et al. (2017)."Ten-Year Performance of the United States National Elm Trial"(PDF).Arboriculture & Urban Forestry.43(3).International Society of Arboriculture:107–120.doi:10.17660/ActaHortic.2018.1191.5.ISSN0567-7572.OCLC7347020445.Retrieved7 February2021.Based on the ratings, the preferred cultivars of American elm were 'New Harmony' and 'Princeton', and the preferred cultivars of Asian elm were TheMorton Arboretumintroductions and 'New Horizon'.
  60. ^Ghelardini, L. (2007)Bud Burst Phenology, Dormancy Release & Susceptibility to Dutch Elm Disease in Elms (Ulmus spp.).Doctoral Thesis No. 2007:134. Faculty of natural Resources and Agricultural Services, Swedish University of Agricultural Sciences, Uppsala, Sweden
  61. ^Mittempergher, L; Santini, A (2004)."The history of elm breeding"(PDF).Investigacion Agraria: Sistemas y Recursos Forestales.13(1): 161–177. Archived fromthe original(PDF)on 11 February 2017.Retrieved9 February2017.
  62. ^abBrookes, A.H. (2013)."Disease-resistant elm cultivars, Butterfly Conservation trials report, 3rd revision"(PDF).Lulworth UK: Butterfly Conservation. Archived fromthe original(PDF)on 29 May 2014.
  63. ^Institut National de la Recherche Agronomique. Lutèce, a resistant variety, brings elms back to Paris[1],Paris, France
  64. ^Santini, A.; Fagnani, A.; Ferrini, F.; Mittempergher, L.; Brunetti, M.; Crivellaro, A.; Macchioni, N. (2004)."Elm breeding for DED resistance, the Italian clones and their wood properties"(PDF).Invest Agrar: Sist Recur for.13(1): 179–184. Archived fromthe original(PDF)on 26 October 2007.
  65. ^Santini, A.; Fagnani, A.; Ferrini, F.; Mittempergher, L. (2002)."San Zanobi and Plinio elm trees".HortScience.37(7). American Society for Horticultural Science: 1139–41.doi:10.21273/HORTSCI.37.7.1139.
  66. ^"Elm Recovery Project".Guelph,Ontario,Canada:University of Guelph Arboretum.Archived fromthe originalon 22 November 2019.Retrieved22 November2019.
  67. ^Sticklen, Mariam B.; Sherald, James L. (1993).Chapter 13: Strategies for the Production of Disease-Resistant Elms.New York: Springer-Verlag. pp. 171–183.ISBN9781461568728.LCCN93017484.OCLC851736058.Retrieved22 November2019– viaGoogle Books.{{cite book}}:|work=ignored (help)
  68. ^Newhouse, AE; Schrodt, F; Liang, H; Maynard, CA; Powell, WA (2007). "Transgenic American elm shows reduced Dutch elm disease symptoms and normal mycorrhizal colonization".Plant Cell Rep.26(7): 977–987.doi:10.1007/s00299-007-0313-z.PMID17310333.S2CID21780088.
  69. ^Martín-Benito, D.; García-Vallejo, M.; Pajares, J.; López, D. (2005)."Triterpenes in elms in Spain"(PDF).Can. J. For. Res.35:199–205.doi:10.1139/x04-158.Archived fromthe original(PDF)on 28 June 2007.
  70. ^Screening European Elms for resistance to 'Ophiostoma novo-ulmi'(Forest Science2005) [2]
  71. ^‘Spanish Clones’ (Oct. 2013) resistantelms.co.uk
  72. ^Δoκιμή ανθεκτικότητας ελληνικών γενoτύπων πεδινής φτελιάς(Ulmus minor)κατά της Oλλανδικής ασθένειας,Σ. Διαμαντής και X. Περλέρου (:Resistance test of Greek Field Elm against Dutch Elm Disease, by S. Diamantis and H. Perlerou)[3]
  73. ^Fifteen source-trees in England cloned for the Conservation Foundation's 'Great British Elm Experiment'; conservationfoundation.co.uk
  74. ^Update on new clones in the Conservation Foundation's 'Great British Elm Experiment'; conservationfoundation.co.uk/the-great-british-elm-experiment-update
  75. ^""Super tree" from Northamptonshire helping to fight Dutch Elm Disease and repopulate woodlands ".northamptonchron.co.uk.Archived fromthe originalon 5 March 2016.
  76. ^"'Young elms return to London', conservationfoundation.co.uk ".Archived fromthe originalon 2 December 2013.Retrieved16 November2013.
  77. ^Coleman, Max, ed.:Wych Elm(Royal Botanic Gardens Edinburgh, 2009; ISBN 978-1-906129-21-7), p.76
  78. ^Russell Blackstock,The Sunday Post(Dundee), 6 August 2023, p.8
  79. ^'Scottish Plant Recovery: Next gen elms', Botanics Stories (RBGE Personal & Project Stories), stories.rbge
  80. ^Clarkson, R. & Coleman, M. (2022)'Propagating healthy mature elms that have survived in areas severely impacted by Dutch elm disease: a scoping study for a wych elm project in Scotland.' Royal Botanic Garden Edinburgh.
  81. ^'First Genetically Modified Dutch Elm Trees Grown', unisci
  82. ^resistantelms.co.uk, FAQ 'Disease Control'
  83. ^Coleman 2009,p. 17
  84. ^"The mid-Holocene Ulmus decline: a new way to evaluate the pathogen hypothesis".Archived fromthe originalon 28 September 2011.Retrieved4 November2011.
  85. ^Oliver Rackham,The History of the Countryside(London 1986), pp. 242–243, 232
  86. ^Meulemans, M.; Parmentier, C. (1983). Burdekin, D.A. (ed.)."Studies onCeratocystis ulmiin Belgium "(PDF).Forestry Commission Bulletin (Research on Dutch Elm Disease in Europe)(60). London: HMSO: 86–95. Archived fromthe original(PDF)on 15 February 2017.Retrieved15 February2017.
  87. ^Vaclav Vetvička,Trees and Shrubs(London 1985)
  88. ^Oliver Rackham,The History of the Countryside(London 1986), p.242-3

Further reading

[edit]
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Dutch_elm_disease&oldid=1249682543"