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Trees to Choose From

Hybrid Elms

Ulmus hybrids
Height: 50' to 80' (45' at age 30)
Width: 30' to 80' (30' at age 30)
Hardiness Zone: depends on the cultivar
Crown: depends on the cultivar
Foliage: green to dark green, turning yellow to golden in fall
Flowers: inconspicuous
Fruit: 1/2 ", disc-shaped, mature in the spring
Description: Elm breeders in the U.S. and Europe have succeeded in creating cultivars that have useful levels of resistance to Dutch elm disease (DED). Several European and Asiatic species have been hybridized, and therefore their crown forms differ from the idealized vase-shape of American elm.
Advantages: Elms have very high tolerance of urban and seacoast environments. Pest-resistant cultivars can have special appeal to those who are nostalgic for those over-arching trees that graced the streets of small town America.
Limitations: Cultivars with high resistance to DED are not immune, and may fall victim to the more virulent strains of the pathogen. Phloem necrosis (elm yellows), Nectria canker, and elm leaf beetles are other serious pest problems. Availability is limited.
Site and Culture: Hybrid elms respond well to transplanting and grow vigorously. They are adaptable to a wide range of urban environments. They tolerate compacted, wet, or droughty acid to alkaline soils, salt, and pollution. Plants propagated on their own roots are preferred. Cultivars- Recent Dutch releases such as 'Groeneveld' (has heavy seed crops), 'Dodoens', 'Lobel', and 'Plantyn' have good resistance to DED, but their crown form is not vase-shaped and their winter hardiness has not been widely tested in the U.S.
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Baumann Horsechestnut "Aesculus hippocastanum 'Baumannii'"

Height: 60' to 70' (40' at age 30)
Width: 45' to 55' (35' at age 30)
Hardiness Zone: 4 to 8
Crown: ovate, upright, medium-coarse texture
Foliage: palmately compound with 4" to 10" leaflets, typically scorched in late summer, yellow in fall
Flowers: white, 9" double flowers in tight clusters, showy and long lasting in spring
Fruit: fruitless
Description: Known since 1822, it was discovered in Switzerland as a branch sport of the common horsechestnut. The species is native to Greece and Albania, and is widely planted in Europe as a specimen tree in parks and spacious public places. Growth rate is slow.
Advantages: Long-lasting, showy flowers, and tolerant of urban conditions.
Limitations: Nearly always has leaf scorch in late summer under stressful conditions. Susceptible also to leaf blotch, powdery mildew, anthracnose, cankers, leaf spot, mealy bug, Japanese beetle, scale insects, and Tussock moth. Availability may be a problem.
Site and Culture: Transplant B&B into moist, well drained soil. Adaptable to a range of pH, prefers full sun.
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Ivory Silk Japanese Tree Lilac "Syringa Reticulata 'Ivory Silk' Tree Form"

Height: 20' to 30' (25' at age 30)
Width: 15' to 20' (15' at age 30)
Hardiness Zone: 3 to 8
Crown: ovate, medium texture
Foliage: dark green, without notable fall color
Flowers: in late spring bears large creamy-white flower clusters at an early age
Fruit: clusters of capsules, turning from green to brown
Description: A small tree with stiff branches that is native to Japan. It has a reddish brown, cherry-like bark that becomes gray and scaly with age. Growth rate is medium. "Ivory Silk" was introduced in Ontario, Canada, about 1975. It is a vigorous, sturdy, upright tree with a straight trunk.
Advantages: Superior to trees grown from seed. The small size, upright habit, and attractive flowers, fruit, and bark make it a versatile tree well suited for use along streets. It is relatively pest-free. Good for planting under utility lines or in planters. Grows faster than "Summer Snow."
Limitations: Susceptible to powdery mildew and lilac borer, but much less than common lilac.
Site and Culture: Transplants readily. Prefers full sun, well drained soil, pH 6.5 to 8.0.
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Bloodgood London Planetree "Platanus x acerifolia 'Bloodgood'"

Height: 70' to 80' (50' at age 30)
Width: 55' to 65' (40' at age 30)
Hardiness Zone: 5 to 9
Crown: broadly ovate, course texture
Foliage: 6" to 9," yellow-brown in fall
Flowers: inconspicuous
Fruit: usually two or three 1" balls per stem, persist into winter
Description: The London plane is a cross between the eastern American sycamore and the Oriental plane that originated in England. The 'Bloodgood' cultivar was probably first propagated by rooted cuttings in Pennsylvania about 1900, before it had been named. It grows rapidly into a very large tree. The patchy olive-green, creamy gray, and brown bark is its most distinctive feature.
Advantages: A large, durable tree suited to city conditions where there is ample space. It tolerates compacted soils, drought, and seacost environments. Resistance to anthracnose is high; some contrary reports involve uncertain identity of the cultivar.
Limitations: Bark, leaf, and fruit litter may be a nuisance. The hybrid is susceptible to serious and geographically pervasive damage by cankerstain disease; also to cankers, mildew, lacebugs, aphids, frost cracks, and winter injury. Despite ozone sensitivity in laboratory tests, pollution tolerance is quite good. Will heave sidewalks.
Site and Culture: Transplants readily, and is adaptable to a wide range of sites, but needs a wide tree lawn. Plants propagated on their own roots are preferable.
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