Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus", a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of Ascomycota are asexual and thus do not form asci or ascospores. Familiar examples of sac fungi include morels, truffles, brewers' and bakers' yeast, dead man's fingers, and cup fungi. The fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota.
Elms are deciduous and semi-deciduous trees comprising the genus Ulmus in the family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North America and Eurasia, presently ranging southward in the Middle East to Lebanon and Israel, and across the Equator in the Far East into Indonesia.
Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Believed to be originally native to Asia, the disease was accidentally introduced into America, Europe, and New 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 the Netherlands by Dutch phytopathologists Bea Schwarz and Christine Buisman, who both worked with professor Johanna Westerdijk. The disease affects species in the genera Ulmus and Zelkova, therefore it is not specific to the Dutch elm hybrid.
Ulmus 'Lobel' is a Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, from a crossing of clone '202' with '336'. 'Lobel' was cloned in 1962 and released for sale in 1973.
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 a batch of 390 seedlings grown from seed collected in the Parque de la Quinta de la Fuente del Berro, Madrid, by Mrs Van Eeghen, a friend of elm researcher Johanna Westerdijk, in 1929 and named for the elm disease researcher Christine Buisman. Originally identified as Ulmus foliacea, it was later treated as Ulmus × hollandica by Melville. However, more recent research in Belgium using DNA markers has reaffirmed 'Christine Buisman' as a clone of U. minor.
Ophiostoma ulmi is a species of fungus in the family Ophiostomataceae. It is one of the causative agents of Dutch elm disease. It was first described under the name Graphium ulmi, and later transferred to the genus Ophiostoma.
Ophiostoma novo-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the key causative agents associated with Dutch Elm Disease (DED), along with Ophiostoma ulmi and Ophiostoma himal-ulmi.
Dothiorella aromatica is a fungal plant pathogen that causes fruit rot of avocado.
Dothiorella dominicana is a fungal plant pathogen that infects Mangifera indica, the mango tree. In South Africa, it is known as blossom blight. Infection with D. dominicana causes rapid drying and partial or complete death of the inflorescense, and can also cause branch die-back.
The elm Ulmus wallichiana subsp. xanthoderma was identified by Melville and Heybroek after the latter's expedition to the Himalaya in 1960. The tree is of more western distribution than subsp. wallichiana, ranging from Afghanistan to Kashmir.
Ulmus wallichiana subsp. wallichiana was identified by Melville and Heybroek after the latter's expedition to the Himalaya in 1960.
Ulmus wallichiana var. tomentosa was identified by Melville & Heybroek after the latter's expedition to the Himalaya in 1960.
Platychora ulmi is a plant pathogen infecting elms.
A wilt disease is any number of diseases that affect the vascular system of plants. Attacks by fungi, bacteria, and nematodes can cause rapid killing of plants, large tree branches or even entire trees.
Christine Johanna Buisman was a Dutch phytopathologist who dedicated her short career to the research of Dutch elm disease and the selection of resistant elm seedlings. In 1927, Buisman provided the final proof that Graphium ulmi was the causal agent of the disease, concluding the controversy which had raged among Dutch and German scientists since 1922.
Ophiostoma himal-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the causative agents of Dutch elm disease. It was first isolated around breeding galleries of scolytid beetles in the bark of Ulmus wallichiana. This, together with the fact that it is endemic to the Himalayas, is the reason it is named himal-ulmi.
Johanna Westerdijk was a Dutch plant pathologist and the first female professor in the Netherlands.
Dothiorella moneti is an endophytic fungus that might be a canker pathogen, specifically for Eucalyptus gomphocephala. It was isolated from said trees in Western Australia.
Dothiorella santali is an endophytic fungus that might be a canker pathogen, specifically for Eucalyptus gomphocephala. It was isolated from said trees in Western Australia.
Scolytus schevyrewi, the banded elm bark beetle, is a 3–4 mm long elm bark beetle species in the genus Scolytus native from Asia and accidentally introduced to North America. It is a vector of the Dutch elm disease, caused by the Ascomycota Ophiostoma ulmi and Ophiostoma novo-ulmi. In North America, it is displacing both the native elm bark beetle and the previously introduced smaller European elm bark beetle, which are becoming less common in their range with the expansion of S. schevyrewi.
