Not the Great Bird Plant People Used to Think It Was
Autumn olive was widely planted by farmers and homeowners to attract birds and provide cover for wildlife, but is it really a great wildlife plant? Many resident birds like robins and mockingbirds eat the sugary fruits, but because autumn olive tends to push out native plant species, it lowers the diversity of foods available. Migratory songbirds need high fat fruits provided by native shrubs such as viburnums and spicebush. Birds also need many insects for protein and to feed to their young. Autumn olive supports very few insects compared to a diverse planting of native shrubs.
Photo courtesy of James R. Allison, Georgia Department of Natural Resources, Bugwood.org
How to Identify Autumn Olive
Autumn olive grows as a large shrub in open areas and along forest edges. It has light green leaves that are silvery underneath. Small fragrant clusters of pale yellow flowers bloom in spring. The fruits mature in late summer turning bright red with silver dots. The fruits are edible and are high in lycopene, the same anti-oxidant found in tomatoes.
Photo courtesy of Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org
Being a Nitrogen-Fixer Is Not Always Helpful
Autumn olive can also change soil nutrient conditions because bacteria associated with its roots turn nitrogen from the atmosphere into organic nitrogen in the soil. Often we think of more nutrient-rich soils as being a benefit, but many native plant species are adapted to low-nutrient soils and invasive exotic species out-compete them in enriched soils.
Photo courtesy of Chris Evans, River to River CWMA, Bugwood.org
How to Control Unwanted Autumn Olive Shrubs
Seedlings of autumn olive can be hand-pulled, particularly in moist soils. For large shrubs, cut the trunk as close to the ground as you can. Within 2 minutes of cutting, drive 4 or 5 holes into the stump and pour concentrated herbicide containing glyphosate, such as Roundup® Weed & Grass Killer Concentrate Plus, into the holes. This treatment is most effective in late summer when the shrubs are beginning to move carbohydrates back down into the roots for winter storage. Shrubs can also be sprayed with a product like Roundup® Ready-to-Use Poison Ivy Plus Tough Brush Killer, following the instructions on the label.
Autumn Olive's Relatives
Closely related to autumn olive is Russian olive, a small tree with dry yellow fruits. Russian olive (shown) is seldom planted in the eastern U.S. but is a problem plant in the western U.S.. Farmers grow sea buckthorn shrubs, a thorny relative of autumn olive, commercially in Canada for the vitamin-rich fruits, and it is promoted as an ornamental shrub in coastal communities. It has become invasive in Canadian prairies along floodplains.
Great Alternatives to Autumn Olive
You can choose among many great shrubs to replace autumn olive. Bayberry (shown in photo) and southern wax myrtle will have about the same height and shape as autumn olive. Nannyberry viburnum has glossy leaves and colorful fruits that birds love and that people can eat too. Maple leaf viburnum, also called highbush cranberry, has bright red, edible fruits.
Find out about another problem shrub, multifora rose