The American Elm

American Elm

Ulmus americana, generally known as the American Elm or, less commonly, as the White Elm or Water Elm, is a species native to eastern North America, occurring from Nova Scotia west to Alberta and Montana, and south to Florida and central Texas. The American elm is an extremely hardy tree that can...

 Ulmus americana cultivar 'St. Croix' is a recent (2008) selection cloned from a huge tree, growing at Afton, St. Paul, which has displayed an apparently high resistance to Dutch elm disease

Dutch elm disease

Dutch elm disease is a disease caused by a member of the sac fungi category, affecting elm trees which is spread by the elm bark beetle. Although believed to be originally native to Asia, the disease has been accidentally introduced into America and Europe, where it has devastated native...

 (DED) . A U S patent was granted in 2009.

Description

'St. Croix' is typical of the species. The parent tree at Afton had a d.b.h.

Diameter at breast height

Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements....

 of 1.9 m when measured in 2008.

Pests and diseases

Resistance to Dutch elm disease is still being determined. The species as a whole is susceptible to Elm Yellows

Elm Yellows

Elm Yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts. Elm Yellows, also known as Elm Phloem Necrosis, is very aggressive, with no known cure. Elm Yellows occurs in the Eastern United States and southern Ontario in Canada. It is caused by phytoplasmas which...

; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle Xanthogaleruca luteola

Xanthogaleruca luteola

Xanthogaleruca luteola, commonly known as the Elm Leaf Beetle, is a serious pest of the elm. Indigenous to Europe, it was accidentally introduced to North America. Both the imagines and larvae feed on the emergent leaves of the elm...

http://www.bioone.org/doi/full/10.1603/0022-0493%282001%29094%5B0162%3AROTCEU%5D2.0.CO%3B2, and highly preferred for feeding by the Japanese Beetle Popillia japonica http://www.bioone.org/doi/full/10.1603/0022-0493%282001%29094%5B0445%3APOTCEU%5D2.0.CO%3B2 http://www.sunshinenursery.com/survey.htm in the USA.
U. americana is also the most susceptible of all the elms to verticillium wilt

Verticillium wilt

Verticillium Wilt is a wilt disease of over 300 species of eudicot plants caused by one of two species of Verticillium fungus, V. dahliae and V. albo-atrum. Many economically important plants are susceptible including cotton, tomatoes, potatoes, eggplants, peppers and ornamentals, as well as others...

 .

Cultivation

'St. Croix' is currently undergoing further tests for DED resistance at the University of Minnesota

University of Minnesota

The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...

. Should the results prove satisfactory, the tree will be produced and marketed by Bailey Nurseries http://www.baileynurseries.com/, of Newport

Newport, Minnesota

Newport is a city in Washington County, Minnesota, United States. The population was 3,435 at the 2010 census.-Geography:According to the United States Census Bureau, the city has a total area of , of which, of it is land and of it is water....

, Minnesota.