Autumn Olive (Elaeagnus umbellata Thunb.)
DESCRIPTION
Autumn olive is a medium to large shrub, often reaching heights
of 20 feet. The leaves, borne alternately on the stems, are generally
oval in shape, approximately 1-3 inches (2.5 - 7.5 cm.) long,
and lack teeth. The upper surface of leaves is dark green to
grayish-green in color, while the lower surface is covered with
silvery white scales, a conspicuous characteristic that can be
seen from a distance. The small light yellow flowers, borne along
twigs, bloom in late April
and May. The small (less than one-quarter inch) fleshy fruits
range in color from pink to red, are finely dotted with pale
scales, and are produced in abundance each year.
SIMILAR SPECIES
Autumn olive is distinguished from other shrubs by the silvery white scales covering the lower leaf surface and by its elliptical or ovate leaves that often have a slightly wavy margin. Autumn olive resembles Russian olive (Elaeagnus angustifolia), another exotic shrub to small tree, in that leaves of both species appear silvery on the lower surface. However, Russian olive has narrower leaves that are lance-shaped. Elaeagnus commutata Bernh. E. multiflora Thunb. are other cultivated species that may escape cultivation to become established in more natural settings. Autumn olive should be accurately identified before attempting any control measures. If identification of the species is in doubt, the plant's identity should be confirmed by a knowledgeable individual, and by consulting appropriate books.
DISTRIBUTION
Autumn olive was introduced into U.S. cultivation in 1830 from its native range in China, Japan, and Korea. In Japan, this species is common and variable, occurring in thickets and thin woods in both lowlands and uplands. In the U.S., autumn olive has long been promoted by state and federal agencies. The species was studied in the 1940s by the Soil Conservation Service and the strain 'Cardinal' was released in 1963 for commercial propagation. In the eastern and central United States, autumn olive has been planted primarily to provide food and cover for wildlife but also as screens, windbreaks, and barriers along highways, to stabilize and revegetate road banks, and to reclaim mine spoil. The first documented collections from non-cultivated material in Missouri were made in Shannon and Warren counties in 1989 and 1988 respectively. However, due to extensive planting in the state, the species is probably now naturalized in most Missouri counties.
HABITAT
Autumn olive occurs in disturbed areas, successional fields, pastures, and roadsides, where it has been widely planted. It has been noted from prairies, open woodlands, and forest edges. Autumn olive rarely is encountered in dense forests or in very wet sites.
LIFE HISTORY
Autumn olive is a non-leguminous, nitrogen-fixing woody shrub. Plants flower and develop fruits annually after reaching 3 years of age, although 2 year old plants have been known to flower. An individual plant can produce up to 8 pounds of fruit. Seed dispersal appears to be mainly by falling fruit and birds. Birds seem to be the primary vector for dispersal, although raccoons, skunks, and opossums are known to feed on the fruit. Once established, this species is highly invasive and difficult to control. Burned, mowed, or cut plants will resprout vigorously.
CURRENT STATUS
Autumn olive is no longer grown for distribution by the George O. White State Forest Nursery, but it is available from private nurseries where its sale is not restricted. It is sometimes planted in black walnut plantations because of its nitrogen-fixing capability and because its brushy growth form reduces predation on walnut saplings.
Control Recommendations
Recommended Practices in Natural Communities of High Quality
Treatment approach can be either a selective or non-selective method depending upon site quality. Young seedlings and sprouts can be hand pulled in early spring when adequate ground moisture is present to allow removal of the root system along with above-ground growth. Autumn olive is easily seen in early spring because its leaves appear while most native vegetation is still dormant.
A combination of mechanical and chemical treatment appears to be the most successful. Cutting the plant off at the main stem and applying herbicide to the stump has been effective in killing root systems and preventing resprouting. Herbicides recommended include glyphosate, triclopyr and picloram. Roundup herbicide (a formulation of glyphosate) has been effective in controlling autumn olive when used as a 10-20% solution and applied directly to the cut stump. Although the Roundup label specifies a higher concentration for cut-stump application (50-100%), this lower concentration has proven effective. Roundup can be applied either by spraying individual stumps with a low pressure hand-held sprayer or else by wiping each stump using a sponge applicator (sponge-type paint applicators can be used). With cut-stump treatment, herbicide is applied specifically to the target plant, reducing the possibilities of damaging nearby, desirable vegetation. Cut-stump treatment is particularly effective late in the growing season (July-September), but is also effective during the dormant season. Treatment of cut stumps should be done as soon as possible after cutting, i.e. within a few minutes. Glyphosate is a nonselective herbicide, so care should be taken to avoid contacting nontarget species. Time of treatment should be planned so that glyphosate is not applied when rain is forecast within 6 to 8 hours. By law, herbicides only may be applied according to label directions.
Recommended Practices on Lands Other Than High-Quality Natural Areas
Same as above for high-quality natural communities. In addition, the following treatments are effective.
Thin-line basal bark treatments with triclopyr herbicide (tradename: Garlon) have demonstrated 95% kill. Undiluted Garlon 4 (or Garlon 4 diluted 50:50 with diesel fuel) should be applied in a thin, pencil-point line around the base of the plant 6-12 inches (15-30 cm.) above the ground. Application can be made with a hand-held plant sprayer and should be performed during the dormant season to minimize risk to nontarget species. A narrow band of Garlon 4 encircling the stem is needed to be effective.
Great care should be exercised to avoid getting any of the mixtures on the ground near the target plant since some nontarget species may be harmed. This method should not be used in high quality natural areas because the diesel fuel may kill vegetation around the tree. Avoid using Triclopyr if rain is forecast for the following 1-4 days; otherwise runoff can harm nontarget species. Foliar application of dicamba herbicides (available under the tradename Banvel) and 2,4-D herbicides (available under a variety of brand names, including Crossbow) can provide total kill with little or no regrowth the following year. Banvel is mixed at the rate of 1 oz. per gallon of water plus one-half oz. of surfactant. The 2,4-D herbicide should be mixed according to label instructions. One hundred percent coverage of foliage should be achieved during the growing season (April-September). Therefore, this control application can be done any time during the growing season: summer application (July-August) is especially effective. Banvel and 2,4-D are selective against broadleaf plants, so care must be taken to avoid contacting desirable, broadleaf vegetation. Do not spray so heavily that herbicide drips off the target species. Foliar spray of herbicides should only be used in less sensitive areas because of problems with contacting nontarget species. The herbicide should be applied while backing away from treated areas to avoid walking through the wet herbicide.
Although glyphosate (Roundup) is an effective foliar spray when applied during the growing season, it is not recommended because it is nonselective. Use of this herbicide as a foliar spray can result in unnecessary damage to nontarget species.
Failed or Ineffective Practices
Repeated pruning of established plants to ground level without subsequent herbicide application is not effective for autumn olive control. Each regrowth results in a thicker stem base and denser branches.
Prescribed burning has not proven effective in controlling established autumn olive.
Adapted from the script written for the Illinois Nature Preserves Commission by: Bob Szafoni Illinois Department of Conservation R.R. 2, Box 108 Charleston, Illinois 61920
