Discovery Elm (Ulmus davidiana var. japonica 'Discovery')

'Discovery' is a Japanese elm cultivar developed in Manitoba, Canada by Wilbert Ronald and Jeffries Nurseries. It is among the most cold-hardy DED-resistant elm cultivars in commercial production, suitable for USDA zone 3 plantings where most other resistant cultivars are marginal.

Origin

'Discovery' was selected by Canadian plantsman Wilbert Ronald from Japanese elm seedlings grown at Jeffries Nurseries in Portage la Prairie, Manitoba, in the 1980s. The selection emphasized cold-hardiness, vigor, and disease resistance for the harsh prairie climate. The original parent material was Ulmus davidiana var. japonica — the same species that contributes resistance to many North American elm hybrids.

Commercial release followed in the early 1990s, with the cultivar gradually distributed through specialty and prairie-adapted nursery networks.

Identification

• Form: Broad oval to vase-shaped crown
• Mature size: 50–55 feet tall, 35–45 foot crown spread
• Leaves: Glossy dark green, oval with double-serrated margins, asymmetric base; 2–4 inches
• Fall color: Yellow
• Bark: Gray-brown, becoming furrowed with age
• Growth rate: Moderate to fast

Hardiness and adaptability

• USDA hardiness zones: 3–7 (exceptional cold-hardiness)
• Site preferences: Adaptable; tolerates clay soils and the alkaline conditions common in prairie sites
• Stress tolerance: Drought-tolerant; well-adapted to wind exposure and temperature extremes

Dutch Elm Disease resistance

'Discovery' demonstrates high DED resistance derived from its Japanese elm parentage. The cultivar has performed strongly in Canadian prairie trials and Manitoba municipal plantings.

The cultivar is also resistant to elm yellows phytoplasma, a feature shared with most Asian-derived elms.

Landscape uses

• Street trees throughout the Canadian prairies and northern US plains
• Municipal canopy restoration in cities like Winnipeg, where DED has been a major historical issue
• Mixed plantings with Prairie Expedition™ and other cold-hardy resistant cultivars
• Shelter and farmstead plantings

Limitations

• Availability outside Canada and the northern US is limited
• Asian elm aesthetics differ from American elm; less suited to plantings explicitly seeking the historic American canopy form
• Mature size is smaller than top-tier American elm cultivars
• Performance in hot southern climates (zone 7+) is variable; better-suited cultivars exist for those regions

Similar cultivars

• Prairie Expedition™ — American elm cold-hardy companion
• Accolade™ — Japanese × Wilson's elm hybrid for slightly milder climates
• Triumph™ — Asian elm hybrid with glossy foliage

Related pages

• What Cultivars Are Resistant to Dutch Elm Disease?
• Disease-Resistant Varieties Guide
• Elm Species: A Complete Guide

References

• Ronald, W. G. (1991). "Tree breeding at the Morden Research Station, 1968–1990." Canadian Journal of Plant Science, 71(4), 1241–1249.
• Griffin, J. J., Jacobi, W. R., McPherson, E. G., et al. (2017). "Ten-year performance of the United States National Elm Trial." Arboriculture & Urban Forestry, 43(3), 107–120.
• Agriculture and Agri-Food Canada. Prairie tree improvement program records.