Autumn olive’s invasiveness may outweigh benefits

The brilliant crimson berries of the autumn olive grow clustered together along the slender, dull-gray stems of the plant. When one walks past the thorny bushes in autumn, songbirds scatter from the branches in haste, returning to their meal when danger has passed. The feathered creatures feast on the fruits of the weedy roadside shrub until not a berry remains.

The luscious density of the fruits is perhaps what first attracted our neighbor to the berries. He stopped one day to ask what type of plant the 10-foot-tall shrub might be and whether the berries are edible. One thing led to another and, the next thing we knew, jam arrived on our countertop along with a host of information about the nutritious qualities of the autumn olive fruits.

Turns out this rather ordinary shrub is quite extraordinary.

According to an article in HortScience, a publication geared toward scientists engaged in the study of commercial and home horticulture, laboratory scientists at the U.S. Department of Agriculture Research Service have discovered that autumn olive berries have high levels of an antioxidant called lycopene. Previous research has revealed these chemical compounds – which tend to be found in brilliantly colored foods – may deter some cancers and heart disease. Their study showed that the shrub’s berries have up to 17 times more lycopene than a tomato, which has accounted for up to 90 percent of Americans’ consumption of the nutrient.

While the fruits may be eaten fresh, in jam or used to make wine, this positive aspect of the plant may not totally offset the fact that it can be invasive. Botanically known as Elaeagnus umbellate, the shrub is native to China, Korea and Japan and was introduced to the United States for cultivation in 1830. It has been used widely in conservation plantings as a shrub used for wildlife fodder and for offering quick-growing vegetative cover on disturbed sites. Today it occurs from Maine south to New Jersey and Pennsylvania and west to Wisconsin, Illinois and Missouri.

Reaching up to 20 feet in height, autumn olive grows well in a variety of soils but prefers acidic soil. The plant produces attractive, silvery-green foliage and thrives in the infertile soils of roadside ditches, as it is equipped with nitrogen-fixing nodules on its roots.

Although autumn olive tolerates shady conditions, it prefers full sun and produces more abundant fruits under sunny growing conditions. Those fruits harbor seeds which have a high rate of germination, contributing to the plant’s ability to reproduce with ease. The tasty fruits also are distributed by the birds that feed upon them, increasing the natural range of the plant.

Although the plant offers some utility, controlling it and keeping it out of ecologically sensitive areas has become quite troublesome. Once the plant has established, it is difficult to eradicate. Autumn olive tends to be highly competitive against native species and sprouts robustly after burning or cutting the stems to the ground.

Nutrition aside, this plant is one we should think twice about as we select plants for our landscape next spring. For a free publication from the University of Maine Cooperative Extension called “Gardening to Conserve Maine’s Landscape: Plants to Use and Plants to Avoid,” call your local Extension office or view the publication online at: http://www.umext.maine.edu/onlinepubs/htmpubs/2500.htm.