USDA searches for best urban landscape trees

Power Trees Project from USDA’s Agricultural Research Service is testing trees for urban landscapes. Lead researcher John Hammond’s wish list includes trees that can survive years of service shading city sidewalks or traffic median strips.

Poorly chosen specimens often outgrow the confines of streets, which leads to severe pruning or removal by utility companies, he said. Hammond heads the ARS Floral and Nursery Plants Research Unit in Beltsville, Md.

“It’s really a shame to see trees that have been unwisely planted having to be aggressively trimmed because of their interference with utility lines and other structures,” he said.

Hammond’s team has identified some good street tree candidates for two zones -- within 30 feet of power lines and some 30 feet away from power lines. Acer rubrum ‘Brandywine,’ A. rubrum ‘Somerset,’ A. rubrum ‘Sun Valley,’ Lagerstroemia ‘Natchez,’ Malus ‘Adirondack’ and Prunus ‘Dream Catcher’ are good choices near power lines. Ulmus ‘Frontier’ works best at least 30 feet away from power lines.

The ultimate street tree is small- to medium-sized, tolerant to environmental extremes and pest resistant.

Hammond also is testing how production techniques affect a tree’s street survival. To date, container trees have outperformed field-grown trees. Tests will continue for several years at nine trial locations.

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For more: John Hammond, ARS Floral and Nursery Plants Research Unit, (301) 504-5313; john.hammond@ars.usda.gov.