The American Elm
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
''Ulmus americana'' 'Iowa State' was cloned in the 1980s from a tree discovered by Professor Alexander (Sandy) McNabb of
Iowa State University
Iowa State University of Science and Technology (Iowa State University, Iowa State, or ISU) is a public land-grant research university in Ames, Iowa. Founded in 1858 as the Iowa Agricultural College and Model Farm, Iowa State became one of the ...
as the sole survivor in of diseased elm at
Burlington.
Description
The tree is possessed of a fastigiate, thickly-branched habit, but has relatively weak branch unions owing to acute angles of attachment leading to bark inclusions.
Pests and diseases
'Iowa State' was reported in the ''American Horticulturist'' News Edition, 63(5):4, 1984, as "a natural selection from southeastern Iowa, highly resistant to
Dutch elm disease
Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into America, Europe, ...
when inoculated". The species as a whole is highly susceptible to
Elm Yellows
Elm yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts."Elm Yellows." Elmcare.Com. 19 Mar. 2008 . Elm yellows, also known as elm phloem necrosis, is very aggressive, with no known cure. Elm yellows occurs in t ...
; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle ''
Xanthogaleruca luteola
''Xanthogaleruca luteola'', commonly known as the elm-leaf beetle, is a beetle species in the family Chrysomelidae that is native to Europe but invasive in other parts of the world.http://cisr.ucr.edu/elm_leaf_beetle.html - Center for Invasive Sp ...
'',
and highly preferred for feeding by the Japanese Beetle ''
Popillia japonica
The Japanese beetle (''Popillia japonica'') is a species of scarab beetle. The adult measures in length and in width, has iridescent copper-colored elytra and a green thorax and head. It is not very destructive in Japan (where it is controll ...
''
in the United States. ''U. americana'' is also the most susceptible of all the elms to
verticillium wilt
Verticillium wilt is a wilt disease affecting over 350 species of eudicot plants. It is caused by six species of ''Verticillium'' fungi: ''V. dahliae'', ''V. albo-atrum'', ''V. longisporum'', ''V. nubilum'', ''V. theobromae'' and ''V. tricorpus ...
.
[Pegg, G. F. & Brady, B. L. (2002). ''Verticillium Wilts''. CABI Publishing. ]
Cultivation
The cultivar was trialed in Minneapolis.
[ One of the original plantings (1978) in the Dean Park area of Minneapolis had to be felled in 2012, 34 years later, after serious defects developed.][Blair, (2013). Goodbye to 'Iowa State'. ''Elm Archives - Trees''. University of Minnesota]
/ref>
References
{{Elm species, varieties, hybrids, hybrid cultivars and species cultivars , state=collapsed
American elm cultivar
Ulmus
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