Cultivar Selection

Resistant Elm Cultivars for Urban Street Planting

Decades of breeding work have produced elm cultivars that survive in disease-pressure environments. Their suitability for Polish street conditions depends on several factors beyond disease resistance alone.

Published: May 2026 · Updated: June 5, 2026

Mature elm tree with characteristic bark pattern showing resilient growth

The effort to develop elm cultivars tolerant to Dutch elm disease began in the Netherlands in the 1920s and has continued in various forms through European and North American research institutions to the present. The primary goals have been high levels of resistance to Ophiostoma novo-ulmi, combined with acceptable urban form, cold hardiness, and tolerance of compacted or disturbed soils.

No cultivar currently available is described as fully immune in all conditions. The terminology used in cultivar registrations and trial reports distinguishes between "resistant" (surviving infection with minimal crown loss under high disease pressure) and "tolerant" (showing delayed or reduced symptom progression). The practical difference for urban forestry decisions is significant.

Dutch breeding program cultivars

The Netherlands has maintained the longest continuous elm breeding program, operated through what is now the Dutch Elm Disease Research Group and associated with Wageningen University. The program has released a succession of cultivars, with the most widely planted being Ulmus 'Lobel', 'Dodoens', and 'Plantijn'. These were developed through crossing European field elms (Ulmus minor) with Asian elm species known for resistance.

Cultivar Resistance level Form Notes
Ulmus 'Lobel' High Columnar-upright Widely planted in Dutch cities; narrow form limits use on wide boulevards
Ulmus 'Dodoens' High Broad crown Greater canopy spread than 'Lobel'; used in park and boulevard settings
Ulmus 'Plantijn' High Semi-broad Intermediate form; considered adaptable for varied urban contexts
Ulmus 'Columella' Moderate–high Columnar Dutch origin; used in restricted spaces

British and American program cultivars

The United States developed several resistant cultivars through work at the Elm Research Institute in New Hampshire and at the USDA Forest Service. The cultivar 'New Harmony' (a Ulmus americana selection) and 'Princeton' have been evaluated in European conditions with variable results — North American elm species often show different cold hardiness profiles and soil adaptation compared to European-origin cultivars.

The British program, associated with the University of Horticulture at East Malling and later with other institutions, produced Ulmus 'Sapporo Autumn Gold', which has some European distribution. The UK Forestry Commission has evaluated several cultivars in urban trial plots, with trial data published through Forest Research.

Elm tree avenue on a street in Germany showing characteristic elm canopy form
Elm avenue planting on an urban street in Germany. Photo: Wikimedia Commons (CC BY-SA 3.0).

Performance in Polish conditions

Poland spans a range of climatic conditions from the milder oceanic-influenced west to the more continental east, where winter temperatures can reach levels that stress cultivars developed primarily for Atlantic European conditions. Published trial data specific to Polish urban environments is limited, but the cultivars 'Lobel', 'Dodoens', and 'New Horizon' (a hybrid developed in the Netherlands from Ulmus pumila × Ulmus japonica parentage) have been included in some municipal plantings in Warsaw and Poznań.

Soil considerations: Street tree sites in Polish cities typically involve compacted mineral soils, often with variable drainage and pH. Elm cultivars from European field elm (Ulmus minor) parentage tend to show better tolerance of these conditions than cultivars with significant Ulmus pumila content, which may perform poorly in heavy clay or alkaline soils.

Growth rate and canopy development

Resistant elm cultivars vary considerably in growth rate. 'Lobel' establishes relatively quickly and achieves structural form within ten to fifteen years in favorable urban conditions. Cultivars with broader canopy targets such as 'Dodoens' require more establishment time and more space between trees to develop without interference. The choice of cultivar in a street planting project is partly a function of the time horizon the municipality is planning for: a narrow columnar form provides earlier visual impact in tight street profiles, while broader forms offer more shade and canopy continuity in the longer term.

Procurement availability in Poland

Nursery availability of resistant elm cultivars in Poland has increased over the past decade. Major wholesale nurseries in the Warmia-Mazury, Mazovia, and Greater Poland (Wielkopolska) regions list several cultivars including 'Lobel' and 'New Horizon' in standard sizes (12–14 cm and 14–16 cm trunk girth). Larger specification material (20+ cm) is available on special order with lead times of two to three years.

Important limitations

Resistance in cultivar trials is assessed under controlled or semi-controlled conditions. Performance in actual urban environments involves additional stressors — drought, soil compaction, air pollution, road salt — that can reduce a tree's capacity to mount effective defensive responses. A cultivar that demonstrates high resistance in a trial may show greater susceptibility when planted on a heavily trafficked city street with poor rooting volume.

Cultivar diversity in new plantings is generally recommended to reduce the risk of a single pathogen or pest eliminating a large proportion of a city's tree canopy. Planting a street entirely with one cultivar reconstructs the monoculture conditions that made the original elm losses so severe.

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