By Mary Yurlina

Autumn olive (Elaeagnus umbellata) is a deciduous shrub or small tree that can grow up to 20 feet tall and 30 feet across. It has a rounded, dense form with alternate, lanceolate leaves, two to four inches long, which have silvery undersides. It may bear thorns. Fragrant, cream-colored flowers appear in late May. Flowers are ½ inch long and tubular, unlike the flowers of shrubby native willows, with which it may be confused.

In September, it produces abundant red-orange fruits speckled with tiny scales that are widely dispersed by birds and mammals. The shrubs mature rapidly and begin flowering by age three. A single shrub can produce over 50,000 seeds. A native of East Asia, autumn olive hosts nitrogen-fixing bacteria on its roots, like legumes, and was widely planted here to revegetate disturbed sites.

Although only moderately shade tolerant, autumn olive is otherwise quite versatile, growing in a wide range of soil conditions, including drought, salt and low pH, and its nitrogen-fixing ability gives it a “root” up on sites with poor soils. In Maine, it commonly occurs along roadsides, but can also be found in meadows, field edges, open woodlands, coastal shrublands and in forest canopy openings. In native communities, it interferes with existing plants and their regeneration by rapidly colonizing gaps and disturbances and changing soil nitrogen availability.

Manually pulling up the entire plant is a control option for small infestations. Cutting or brush hogging only stimulates vigorous resprouting and is not recommended without followup treatments. Treat before fruits are formed and be sure to let the roots dry out before piling. Goats and sheep will readily graze it, and can be used as a control method if repeated over a number of years. If you choose a herbicide treatment, a low concentration of glyphosate or triclopyr is effective as a foliar spray. Do not remove the plant until the herbicide has killed the entire plant, including the roots, which may take several weeks. More concentrated solutions of glyphosate or triclopyr (20-25%) can be applied to cut stems; avoid spring sap flow. Basal bark treatment is another herbicide option (25% triclopyr and penetrating oil). Follow all herbicide label instructions. If you have a large infestation, consider hiring a professional.

To see distribution maps and track your treatments, visit www.imapinvasives.org Mary Yurlina is the Maine Natural Areas Program’s invasive plant biology intern for 2016. MNAP’s work on invasive plants is supported by the U.S. EPA, Maine Outdoor Heritage Fund, and USDA – NRCS.

Invasive Plants 101: Autumn Olive