Elms

Elm Selections

	Ulmus americana 'Valley Forge' 'Valley Forge' has an upright, arching, broadly vase-shaped branching structure with a full, dense canopy of leaves. It will grow very rapidly once established. In adaptability trials, 'Valley Forge' has performed well in Ohio, Maryland, D.C., and Oklahoma and can be considered adaptable from USDA zones 5-7. This selection has proved to be the most DED tolerant American elm identified out of thousands screened in fungal inoculation trials in Ohio and Maryland. It will make an excellent choice for urban and suburban sites, large yards, recreational and industrial parks, and for street trees. American elms are adaptable to a wide variety of soil conditions, tolerate deicing salts, air pollution, drought, and a range of soil pH. They have yellow fall color.
	U. americana 'New Harmony' The parent tree of 'New Harmony' is 68 feet tall with a crown spread of 72 feet. It has a broad vase shaped crown with the main trunk dividing about 30 feet from the ground into several erect limbs which are strongly arched above and which terminate in numerous slender, often drooping branchlets. It has grown well in Georgia, Maryland, Minnesota, New Jersey, Ohio, Pennsylvania, and Tennessee and can be considered adaptable from zones 5 - 7 with possible cold hardiness to zone 4. 'New Harmony' ranked a close second behind 'Valley Forge' in DED tolerance trials.
	Ulmus americana 'Jefferson' (may be a hybrid between tetraploid U. americana and an unknown diploid species) 'Jefferson' is a National Park Service introduction, a hybrid of unknown origin with triploid chromosome levels. It has a vase shape with arching limbs to 50' height and 50' spread, Zone 4. It has shown good resistance to DED.
	U. wilsoniana 'Prospector' 'Prospector' was developed from selected seedlings of U. wilsoniana, an Asian elm. This tree has shown resistance to elm yellows disease and to the elm leaf beetle. It has a vase shape similar to that of the American elm, but its branches droop lower. The tree grows from 35-45 feet tall and has yellow fall color.
	**Ulmus x 'Frontier' (Ulmus parvifolia x Ulmus carpinifolia)** 'Frontier' was developed in 1971 when U. parvifolia was crossed with a European species, U. carpinifolia. It has proven to be resistant to elm yellows disease (phloem necrosis) but only moderately resistant to the elm leaf beetle. It has a pyramid shape growing to a height of 35-45 feet and has red fall color.
	Ulmus x 'Patriot' (Ulmus x 'Urban' x U. wilsoniana 'Prospector') Patriot elm resulted from a a controlled pollination made in 1980 between 'Urban' elm and U. wilsoniana 'Prospector'. When grown for 11 years among hundreds of infected American elms in Delaware, OH, Patriot showed no signs of susceptibility to elm yellows. It has proven to have a very high level of DED resistance and moderate elm leaf beetle resistance. It has an upsweeping crown developing into a vase shape. At 13 years from seed, the parent tree in Ohio was 43' tall and showed a crown spread of 25'. Autumn color is yellow. It is considered cold hardy to zone 4. It does best when grown in a well-drained, moist soil, but adapts well to all soils.

Other Elm Species

In addition to the selections listed above, many others species of elms perform extremely well in the western plains.

U. parvifolia (Lacebark Elm)
U. parvifolia is a handsome tree with small, thick, glossy, leathery leaves. It displays great variation of form and branching patterns, some resembling American elm although smaller. The bark of the tree is peeling and gives a beautiful mottled look to the trunk and branches. This "lacebark" effect varies considerably from tree to tree. Selections are being made for attractive bark, desirable shape, winter hardiness, leaf characteristics and color, fall color, and resistance to bacterial leaf spot.

U. davidiana (David Elm)
U. davidiana is native to Manchuria and other areas of northern China. These trees resemble American elm, but are much smaller reaching 25 feet in height. Foliage has a deep green color with impressive glossiness. They appear to be a good tree for planting in adverse urban conditions, and their size, form and toughness make them a promising tree for use under power lines.

Ulmus glaucescens
U. glaucescens is a small tree of northern China, from dry regions, growing to 30'. Good drought tolerance and high resistance to elm leaf beetle makes it useful in the Great Plains.

Ulmus japonica
U. japonica grows with a somewhat dominant central trunk as a tall tree to 60 to 75'. It appears to appreciate good drainage, as clay soils slow the growth. It has good resistance to elm leaf beetle.

Ulmus lamellosa
U. lamellosa has a rounded crown supported by a slender trunk and slender branches. Attaining a height of 30 to 40', it appears suitable for parks, open areas, and possibly street use. It has flaking mottled bark and fall color is a rich golden yellow. It has good resistance to elm leaf beetle.

U. macrocarpa
U. macrocarpa has a form similar to that of American elm and grows to a height of 30 to 40 feet. It grows in generally adverse situations in the mountains of northern China, it likes well-drained soils. It has good resistance to elm leaf beetle.

Ulmus propinqua
U. propinqua is a small tree 25 to 30' that appears to tolerate a wide range of soil conditions. The branches are often corky, the leaves are medium green and resist elm beetle feeding.

U. szechuanica
U. szechuanica reaches 25 feet in height and spreads its branches into an umbrella-like canopy. The emerging foliage in the spring is red for several weeks and it has subdued purplish-red fall color. It resists elm leaf beetle feeding. Growing best in well-drained soil, it tolerates somewhat adverse sites. Zone 6

Elm Leaf Beetle Survey Results

We are currently evaluating over 100 different elm trees on the grounds of our arboretum for resistance to elm leaf beetle feeding. The results of the 1999 and 2000 surveys are here. Data for 2001 is not available because there was no beetle population that year.