"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 who are still active in the field; 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"
"A tree at the Ryston Hall arboretum, Norfolk, listed as ""Ulmus arbusculata"" and reputedly obtained from the Späth nursery in Berlin before 1914, was killed by the earlier strain of Dutch elm disease prevalent in the 1930s. However, 'Arbuscula' or 'Arbusculata' does not appear in known Späth lists from the early 20th century. A specimen, labelled ""Ulmus arbuscula"" and described as a large tree, stood in the Nymphenburg Palace Park, Munich, in the mid-20th century. Two trees survive in eastern European arboreta (see 'Accessions'). ""U. × arbuscula"" is not known to have been introduced to North America or Australasia. ""Arbuscula"""
"is very susceptible to Dutch elm disease. The ‘Dutch’ elm quickly became popular in eighteenth-century estate plantations in England, survivors today being naturalised relics of this planting fashion; but the tree was always rare in the Netherlands, where from the eighteenth century ""hollandse iep"" (Holland elm) meant the widely planted hybrid ""Ulmus × hollandica"" Belgica (Belgian Elm). Ley (1910) noted that 'Major' could be found scattered throughout the lowlands of England and Wales, often in the company of English Elm; but, unlike the latter, extended into mountain valleys in South Wales up to 1000 feet. ‘Dutch’ elm was also planted"
"20th century. It derives its name 'Dutch' from the first description of the disease and its cause in the 1920s by the Dutch botanists Bea Schwarz and Christina Johanna Buisman. Owing to its geographical isolation and effective quarantine enforcement, Australia has so far remained unaffected by Dutch Elm Disease, as have the provinces of Alberta and British Columbia in western Canada. DED is caused by a micro-fungus transmitted by two species of ""Scolytus"" elm-bark beetle which act as vectors. The disease affects all species of elm native to North America and Europe, but many Asiatic species have evolved anti-fungal genes"
"to climatic extremes, not disease. The tree is named for Christine Buisman, the first full-time elm researcher (1927-1936) in The Netherlands, who provided the final proof that ""Graphium ulmi"" (now: ""Ophiostoma ulmi"" ) was the causal agent of Dutch elm disease. Buisman died in 1936, aged only 36. Ulmus minor 'Christine Buisman' The Field Elm cultivar Ulmus minor 'Christine Buisman' was the first cultivar released by the Dutch elm breeding programme, initiated in response to the less virulent form of Dutch elm disease (DED), ""Ophiostoma ulmi"", which afflicted Europe's elms after the First World War. 'Christine Buisman' was selected from"
"have a resistance to Dutch elm disease. With no known resistance to Dutch elm disease, the tree is now very rare in Europe. 'Lombartsii' is not known to have been introduced to North America or Australasia. A pruned tree with leaves that closely match 'Lombartsii' herbarium specimens (see 'External links') stands at the entrance to Brighton and Preston Cemetery, Hartington Road, Brighton (2016). Ulmus 'Lombartsii' The elm cultivar ""Ulmus"" 'Lombartsii' is considered ""possibly ""Ulmus × hollandica"" or ""Ulmus carpinifolia (: minor)"""" by Green (1964). The tree was raised by Lombarts Nurseries at Zundert, the Netherlands, circa 1910. The tree was"
"elm disease. However, the condition is far less serious, and afflicted trees should recover the following year. Dutch elm disease is a fungal disease that has ravaged the American elm, causing catastrophic die-offs in cities across the range. It has been estimated that only approximately 1 in 100,000 American elm trees is Dutch elm disease-tolerant, most known survivors simply having escaped exposure to the disease. However, in some areas still not infested by Dutch elm disease, the American elm continues to thrive, notably in Florida, Alberta and British Columbia. The American elm is particularly susceptible to disease because the period"
"fell victim to Dutch elm disease, as did thousands of other elms in the same district. However, 'Pitteurs' was known to have been marketed (as ""U. montana"" 'Pitteursi') in Poland in the 19th century by the Ulrich nursery, Warsaw, and so may still survive in Eastern Europe. Several trees were thought to survive in England, in the Brighton area; the only confirmed specimen, however, at the Extra Mural Cemetery in Brighton, was blown down in the Great Storm of 1987. 'Pitteurs' is not known to have been introduced to North America or Australasia. A pruned ""U. × hollandica"" with large,"
"'Vegeta'. Although resistant to the original strain of Dutch elm disease, ""Ophiostoma ulmi"" and a range of other ailments, 'Commelin' proved very susceptible to the later, aggressive strain ""Ophiostoma novo-ulmi"" subsp. ""americana"". 'Commelin' initially enjoyed considerable commercial success and over 500,000 had been sold by 1974. However, the tree had only been screened for non-aggressive or semi-aggressive isolates of the causal fungus of Dutch elm disease. When its low resistance to the new strain of the disease became apparent, sales plummeted, and only 500 were sold in 1990. However, neither 'Commelin' nor its slightly less vulnerable contemporary 'Groeneveld' had sold"
"Dutch Elm Disease whilst four others exhibited weakness at the root and fell in gales in later years. Only one tree remains (the TROBI champion); 12 m high, 26 cm d.b.h. in 1997, and that in poor health in 2008. The trees are survived by numerous root suckers however. Other plantings in Europe are few and far between; several were established in the port area of Amsterdam . The tree also featured in trials , in Canberra, Australia started in 1988 but ""has not shown promise in that environment"". 'Urban' was crossed with the Wilson's Elm (now treated as Japanese"
"25 m and was considered very elegant, although it tended to shed shoots after flowering heavily; it was felled after succumbing to Dutch elm disease. Two trees planted as part of the UK Forestry Commission's elm trials at the Westonbirt Arboretum in the 1970s also died, although the cause of death has not been recorded. Plantings elsewhere in Europe are few and far between. A line of more than 20 trees survives at Wageningen in the Netherlands, collected by Heybroek in the Himalaya in 1960. Several trees also survive in the Gijsbrecht-Amstelpark area of Amsterdam and in the port ."
"at least 30 are now probably lost to cultivation as a consequence of Dutch elm disease and/or other factors: 'Exoniensis', Exeter Elm, has traditionally been classified as a form of ""U. glabra"", but its identity is now a matter of contention. ""U. glabra"" hybridises naturally with ""U. minor"", producing elms of the ""Ulmus × hollandica"" group, from which there have arisen a number of cultivars: However, hybrids of ""U. glabra"" and ""U. pumila"", the Siberian elm, have not been observed in the field and only achieved in the laboratory, even though the ranges of the two species, the latter introduced"
"is a list of tree species that existed in Britain before 1900. The sheer number of tree species planted subsequently precludes a complete list. Most serious disease threats to British woodland involve fungus. For conifers, the greatest threat is White Rot Fungus (""Heterobasidion annosum""). Dutch Elm Disease arises from two related species of fungi in the genus ""Ophiostoma"", spread by Elm Bark Beetles and acute oak decline has a bacterial cause. Another fungus, ""Nectria coccinea"", causes Beech bark disease, as does ""Bulgaria polymorpha"". Ash canker results from ""Nectria galligena"" or ""Pseudomonas savastanoi"", and most trees are vulnerable to Honey Fungus"
"in Europe, North America, and parts of the Southern Hemisphere, notably Australasia. Some individual elms reached great size and age. However, in recent decades, most mature elms of European or North American origin have died from Dutch elm disease, caused by a microfungus dispersed by bark beetles. In response, disease-resistant cultivars have been developed, capable of restoring the elm to forestry and landscaping. There are about 30 to 40 species of ""Ulmus"" (elm); the ambiguity in number results from difficulty in delineating species, owing to the ease of hybridization between them and the development of local seed-sterile vegetatively propagated microspecies"
"was severely damaged by bombing in 1940, many of the graves were also transferred to Crooswijk. The cemetery is laid out as a park. The cemetery is a general (non-denominational) cemetery. There are sections for casualties of wars, the resistance in the Second World War. There is also a fast-growing Islamic section. Many of the trees symbolise grief such as Weeping Beech, Silver Birch (Betula pendula var. ""Tristis"", which in Dutch is known as the Weeping Birch), Dutch Elm (in Dutch known as Weeping Elm) and Weeping Willow. The cemetery is a national heritage site (Rijksmonument) in the Netherlands, as"
"ecologist George Peterken, it was found that tree growth led to a decline in tree numbers, through increasing shade and browsing by deer, and, over time, disturbances such as Dutch elm disease in the 1970s, and a late snowfall in 1983 had increasingly disproportionate impacts on the woodland. It was found that ""there was no single natural composition; rather, the natural mixture would fluctuate between beech dominance and ash-lime dominance according to the chance impacts of various disturbances."" In recent years the woodland has become overrun by fallow deer and grey squirrels — both non-native species — affecting the regrowth"
"mm) petiole, greater foliar asymmetry, and more extensive axillary tufts on the lower surface of the lamina. Richens did not investigate the flowers and fruit. The tree is very susceptible to Dutch elm disease. The current status of the tree in the Channel Islands following the introduction of Dutch elm disease is not (2015) recorded. Ulmus × hollandica var. insularum Ulmus × hollandica var. insularum was recognized as a biometrically distinct population of ""U. × hollandica"" endemic to all the Channel Islands and the Cotentin peninsula of France by Richens and Jeffers in 1975. The tree had been treated within"
"1948. Nevertheless, its moderate resistance to Dutch elm disease saw it, or its selfed progeny, successfully used in later Dutch hybridizations, notably 'Nanguen' =. The largest known examples in the UK grow along Crespin Way, Hollingdean, Brighton; planted in 1964, they measured 19 m high by 50 cm d.b.h. in 2009. The tree is named for Bea Schwarz, the Dutch phytopathologist who identified Dutch elm disease in the 1920s. Ulmus × hollandica 'Bea Schwarz' The elm cultivar Ulmus × hollandica 'Bea Schwarz' was cloned (as No. 62) at Wageningen in the Netherlands, by the elm disease committee, ostensibly from a"
"to Dutch elm disease, it is not favoured by the vector bark beetles and thus only becomes colonized and infected when there are no other choices, a rare situation in western Europe. Research in Spain has suggested that it may be the presence of a triterpene, alnulin, which makes the tree bark unattractive to the beetle species that spread the disease. However this possibility has not been conclusively proven. More recently, Field Elms ""Ulmus minor"" highly resistant to DED have been discovered in Spain, and form the basis of a major breeding programme. Owing to their innate resistance to Dutch"
"Ulmus × hollandica 'Bea Schwarz' The elm cultivar Ulmus × hollandica 'Bea Schwarz' was cloned (as No. 62) at Wageningen in the Netherlands, by the elm disease committee, ostensibly from a selection of ""Ulmus minor"" found in France in 1939. However, specimens of the tree grown in the UK and the United States are treated as Ulmus × hollandica (after Fontaine ). The tree was considered of poor growth and shape. Moderately resistant to Dutch elm disease, and more resistant to Coral Spot fungus ""Nectria cinnabarina"" than its forebear 'Christine Buisman'. Commercial production was discontinued soon after its release in"
"very high resistance to Dutch elm disease; in trials in Italy, it sustained only 2.8% defoliation and 1.2% dieback when inoculated with unnaturally high concentrations of the fungal pathogen. The cultivar also has a tolerance of ""Verticillium"" wilt. The tree's foliage was adjudged 'resistant' to black spot by the Plant Diagnostic Clinic of the University of Missouri , however it can be severely damaged by the elm leaf beetle (""Xanthogaleruca luteola"") in the United States Several mature specimens near the Hampshire coast in England have become (2014) afflicted by Dryad's saddle fungus (""Polyporus squamosus""). In favorable conditions; notably a moist,"
"Dutch elm disease. Research in Spain has indicated that it is the presence of an antifeedant triterpene, alnulin, at a concentration of 200 μg/g {dried bark} which renders the tree unattractive to the beetles. Ergo: the tree's decline in western Europe is chiefly owing to woodland clearance in river valleys, and river management systems eliminating flooding, not disease. It was noted by Jouin at Metz, and a century later by Mittempergher and Santini in Italy, that ""U. laevis"" had a very low susceptibility to the elm leaf beetle ""Xanthogaleruca luteola"". Research in Germany has established that the tree is also"
"which reaches the seed. Like other European elms, natural populations of the European white elm have little innate resistance to Dutch elm disease, although research by Irstea has isolated clones able to survive inoculation with the causal fungus, initially losing < 70% of their foliage, but regenerating strongly the following year. Moreover, the tree is not favoured by the vector bark beetles, which colonize it only when there are no other elm alternatives available, an uncommon situation in western Europe. Indeed, in a study of elm in Flanders, not one example of ""U. laevis"" was found to be afflicted by"
"cuttings come from, on the 'stock' on which it is grafted, and on possible continuing mutation. Specimens may therefore vary in appearance. Grown in lower latitudes like Victoria, Australia, the tree can attain a height and spread of over 13 m. 'Camperdownii' is susceptible to Dutch elm disease, however, there are still many examples to be found in parks and gardens across the British Isles as it often avoids detection by the ""Scolytae"" beetle (a major vector of Dutch elm disease) because of its diminutive height. In North America it often escapes infection possibly because the American vectors of the"
"groundnut ""Arachis hypogaea"" at the agricultural research station in Bogor. The elm tree Ulmus × hollandica 'Bea Schwarz' was named after her in recognition of her research into the cause of Dutch elm disease. Marrying in 1926, she retired from research to raise a family. When the East Indies were invaded by the Japanese army in 1942, Schwarz and her husband were interned in separate camps, her husband dying soon afterwards. After liberation, Schwarz and her two sons returned to the Netherlands, where she joined the Centraal Bureau voor Schimmelcultures (Central Bureau for Fungus Cultures) in Baarn, studying various fungi"
"Pa have died or have been removed due to elm yellows. Elm malls across the US are at risk of being destroyed by elm yellows. Cornell University, for example, had a large elm collection which was being managed for Dutch elm disease, much like Penn State, but once elm yellows had spread to the campus, all of the elms were destroyed within a matter of years. In North America the disease is transmitted from infected to healthy trees by the whitebanded elm leafhopper (""Scaphoideus luteolus"" ), the meadow spittlebug (""Philaenus spurarius"") and by another leafhopper (""Allygus atomarius""), although other insects"
"stock, which would not produce suckers, whilst others simply rooted the cuttings, which would. A comparatively high percentage of the seed is usually viable. The tree was one of four European cultivars found by researchers in The Netherlands to be resistant to the initial strain of Dutch elm disease, ""Ophiostoma ulmi"", prevalent in the 1920s and '30s, the others being 'Monumentalis' , 'Berardii' and 'Exoniensis'. The four were rated less resistant than ""U. foliacea"" clone 23, from Spain, later cultivated as 'Christine Buisman'. 'Vegeta' has, however, only a marginal resistance to the later, three times more lethal strain, ""Ophiostoma novo-ulmi""."
"Plot's Elms or 'Plot-type' elms are classified as ""Ulmus"" aff. 'Plotii'. These are very close to Plot's Elm and have a number of characteristics of the type, but their crowns are too broad and regular to match ""true Plot"". Melville himself, from the 1940s, had used the name ""Ulmus"" aff. ""plotii"" for elms close to Plot but outside the range of his variable species. An uncommon tree even before Dutch elm disease, 'Plotii' has also been affected by the destruction of hedgerows and by urban development within its limited range. No mature 'type' trees are known to survive. One of"
"to Westbury. There have been several white trees at the junction, either a silver birch or a tree with a trunk painted white. One white tree was demolished to make way for the roundabout. Another white tree was cut down during the 1970s outbreak of Dutch elm disease. The ""Seven Sisters"" are a group of pine trees on Durdham Down. A number of the trees have been lost over the years - notably in the 1990 Burns' Day storm - leaving three survivors. Replacement trees in the group have been vandalised, so an entirely new group of seven has been"
"of Dutch elm disease, 'Vegeta' was planted in large numbers across Amsterdam after the Second World War as a replacement for 'Belgica' (Belgian Elm), but was itself eventually replaced by the Dutch cultivar 'Dodoens' following the arrival of the more lethal strain of DED in the early 1970s. The UK TROBI Champion grew at Higham Ferrers in Northamptonshire, measuring 28 m high by 167 cm d.b.h. in 1999 but was felled in 2014; another at Courteenhall in the same county measured 166 cm d.b.h.. In London, many examples still survive, notably around the Millfields Recreation Ground, the largest measuring 31"
"elm was felled in 1977 after it had succumbed to Dutch elm disease. Cuttings were taken in 1915, although all but one of the resultant trees have also died, the survivor still thrives (2006) at Barclay Beach. Moreover, a specimen raised from seed survives on Founder's Green, Haverford College, and is perpetuated by selfed seedlings gathered by the arboretum staff in autumn. The tree is not known to be in cultivation beyond North America, nor is it in commerce. None known. Ulmus americana 'Penn Treaty' The American Elm cultivar Ulmus americana 'Penn Treaty' was raised by the Plant Sciences Data"
"The outbreak of the new, three times more virulent, strain of Dutch elm disease ""Ophiostoma novo-ulmi"" in the late 1960s brought the tree to its nadir. Since circa 1990 the elm has enjoyed a renaissance through the successful development in North America and Europe of cultivars highly resistant to the new disease. Consequently, the total number of named cultivars, ancient and modern, now exceeds 300, although many of the older clones, possibly over 120, have been lost to cultivation. Some of the latter, however, were by today's standards inadequately described or illustrated before the pandemic, and it is possible that"
"of the group, the tree suckers very freely, though it is often base-grafted on wych elm to prevent suckering. The tree often develops highly distinctive cancerous burls on its branches or trunk. Guernsey Elm is very susceptible to Dutch elm disease. With its light, upcurving branches, Guernsey Elm never became a danger, unlike English Elm, which sometimes shed heavy lateral boughs. This fact, and its compact form, made it ideal for street planting. The tree was popular in Britain, where it was widely cultivated. Dutch elm disease has, however, now destroyed nearly all the mature trees in England save a"