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Autumn Olive

Elaeagnus umbellata

Summary 8

Elaeagnus umbellata, is known as Japanese silverberry,umbellata oleaster,autumn-olive,autumn elaeagnus, or spreading oleaster. The species is indigenous to eastern Asia and ranges from the Himalayas eastwards to Japan. Because it fixes atmospheric nitrogen in its roots, it often grows vigorously and competitively in infertile soils.

As an Ecological Threat in the United States 9

More info for the terms: invasive species, natural

Autumn-olive is ranked as a "severe threat" (exotic plant species that possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation) by the Tennessee Exotic Pest Plant Council [54]. It is also ranked as a "severe threat" (exotic plant species which possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation; includes species which are or could become widespread in Kentucky) by the Kentucky Exotic Pest Plant Council [30].

Autumn-olive is listed among the top 10 exotic pest plants in Georgia [17], and among "highly invasive species" (species that may disrupt ecosystem processes and cause major alterations in plant community composition and structure and that establish readily in natural systems and spread rapidly) by the Virginia Department of Conservation and Recreation [69].  It is listed as a Category II exotic plant species (considered to have the potential to displace native plants either on a localized or widespread scale) by the Vermont Agency of Natural Resources and The Nature Conservancy of Vermont [68], and as a noxious weed in several West Virginia counties [64].

U.S. Forest Service Region 8 (Southern Region) lists autumn-olive as a category 1 weed (exotic plant species that are known to be invasive and persistent throughout all or most of their range within the Southern Region and that can spread into and persist in native plant communities and displace native plant species and therefore pose a demonstrable threat to the integrity of the natural plant communities in the Region). The introduction of Category 1 Species is prohibited on National Forest System Lands [65].

Habitat characteristics 10

More info for the terms: mesic, natural

Autumn-olive has been planted throughout much of eastern North America for various purposes (Management Considerations), and has subsequently escaped into a variety of natural and seminatural habitats [4,10,40,71]. For example, Invasive Plant Atlas of New England [37] lists the following general habitats where autumn-olive may be found in New England: abandoned field, abandoned gravel pit, early-successional forest, edge, pasture, planted forest, railroad right-of-way, roadside, utility right-of-way, vacant lot, yard, or garden. It is probably most prolific on disturbed or ruderal sites [5,8,26,40,77].

Autumn-olive grows best on deep, relatively coarse-textured soils that are moderately-well to well drained [1,65]. It does less well on very dry soil and usually fails on very shallow, poorly drained, or excessively wet soil. Autumn-olive does not require highly fertile soil, and it appears to thrive equally well on soils ranging from "moderately acid to moderately alkaline" [1]. In Ontario, escaped autumn-olive is found in a variety of dry to mesic sandy, forested and open to sparsely shaded habitats, with soil pH from 5-7. It is most invasive in areas of dry sandy soils. Although it has been cultivated on fine-textured, periodically wet soils, it is generally not invasive on such sites in southern Ontario [4].

Impacts and control 11

More info for the terms: fire management, natural, shrubs

Impacts: In general, invasive autumn-olive impacts native biotic communities in eastern North America by displacing native plants. Invasive populations can supplant native habitat, sometimes forming dense thickets. Prodigious seed production and widespread seed dispersal by frugivorous birds probably contribute to its invasiveness [55]. An Illinois study reported autumn-olive concentrations of 5,225 stems per hectare in a pine plantation, 27,500 stems per hectare in a grazed upland woods, and 33,975 stems per hectare in hardwood-dominated ravines [10]. Autumn-olive densities of 125,000 plants hectare were recorded in the understory of a yellow-poplar-sweetgum plantation in southwestern Indiana in 2000. This population was established from nearby plantings in the early 1970's. Although 90% of these individuals were 2 feet (0.6 m) or less in height, they formed "a nearly impenetrable thicket" and were "commonly the only understory species present" [11].

Nestleroad and others [40] have suggested that impacts of invasive autumn-olive may be greatest in communities adapted to infertile soils, where its nitrogen-fixing capabilities might confer substantial competitive advantage against native species. It is conceivable that autumn-olive could alter the nitrogen cycle in "infertility-dependent" natural communities, shifting the potential native community on these sites. Nestleroad and others [40] expressed concern that natural communities of sandy, infertile habitats in southern and eastern Ontario, and throughout the Great Lakes region, are already seriously impacted by other pressures.

Control: Controlling invasive autumn-olive may require frequent monitoring and repeated treatments to achieve success. Because seeds can be dispersed long distances by birds, it is helpful to eradicate autumn-olive populations in areas surrounding the threatened area, when possible. If the infested area is large, or if eradication of surrounding populations is not feasible, land managers may wish to focus control efforts in the most ecologically significant and/or least invaded areas first. In closed-canopy forests, control can likely be achieved through routine monitoring and eradication of new individuals by hand pulling or spot-spraying with herbicide [11].

Prevention: Where appropriate, maintaining dense, frequently mowed grass or other dense native vegetation can help prevent establishment of autumn-olive seedlings [40].

Integrated management: No information

Physical/mechanical: Hand pulling young seedlings and sprouts can be effective, particularly from moist soil [53,59]. Seedlings are easiest to identify in early spring because autumn-olive produces leaves earlier than most native shrubs [55,59]. Mowed or cut plants reportedly "resprout vigorously" [53,59], so these methods alone will probably not effectively control mature plants. Even repeated cutting is apparently ineffective without treating stumps and/or resprouts with herbicide [53]. Treating cut surfaces with glyphosate is an effective control measure and can minimize negative impacts on native vegetation when carefully applied (see Chemical control) [53,59].

Fire: See Fire Management Considerations.

Biological: No information

Chemical: Several herbicides have been used alone or in combination to provide effective control of autumn-olive, including glyphosate, triclopyr, 2,4-D, and dicamba. This is not intended as an exhaustive review of chemical control methods. For more information regarding appropriate use of herbicides against invasive plant species in natural areas, see The Nature Conservancy's Weed control methods handbook. For more information specific to herbicide use against autumn-olive, see The Nature Conservancy's Element Stewardship abstract of autumn-olive and the Connecticut Invasive Plant Working Group (CIPWG) and Illinois Nature Preserves Commission websites.

Dicamba and 2,4-D have been used as a foliar application to effectively control autumn-olive [35,53,59]. Triclopyr has also been used effectively on resprouts following cutting [53]. Because this method is conducted during the growing season, and because 100% coverage of foliage is recommended for most effective control, Szafoni [59] suggests that foliar application is best suited to shorter plants.

For larger plants, basal-bark application of triclopyr or 2,4-D can control invasive autumn-olive [11,35,53]. Basal-bark treatment is the application of herbicide solution directly to the bark the lower portion of woody plants. Herbicide then penetrates the bark and is absorbed by the plant [53]. Rather than a broad band application, a thin line of herbicide applied around the entire circumference of the stem 6-12 inches (15-30 cm) above the ground is sufficient, and less likely to harm nearby, desirable plants [53,59].

Direct application of glyphosate to cut stumps can also be effective, particularly late in the growing season (July-September) [53,59]. According to Szafoni [59], reduced application rates of 10-20% solution (compared with 50-100% recommended on some glyphosate product labels) are sufficient for effective treatment of cut stems. Careful application of herbicide directly to target plants can reduce damage to nearby, desirable vegetation [59].

Multiple herbicide treatments may be required to completely kill all plants. Edgin and Ebinger [11] describe treating an invasive population of autumn-olive in Illinois with basal-bark applications of triclopyr during springs of 1996 and 1997. A subsequent search in early summer 1997 yielded no evidence of live autumn-olive in treated areas. But by 2000, autumn-olive had re-established within these same treated areas. Because a dense population of well-established autumn-olive remained in an area adjacent to treatment plots, many of the newly established plants were assumed to have originated from the seed bank or from seeds transported into the plots by birds after herbicide treatments. But nearly 11% of the larger stems (2.6 to 4.9 feet (80-150 cm) tall) had an "enlarged basal caudex" and were considered to be resprouts that were only top-killed by the herbicide treatment.

Cultural: No information

Sources and Credits

  1. (c) Dan Nydick, some rights reserved (CC BY-NC), https://www.flickr.com/photos/66842577@N08/20398722704/
  2. (c) Doug Raybuck, some rights reserved (CC BY-NC), uploaded by Doug Raybuck
  3. (c) Tom Potterfield, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/tgpotterfield/9080925210/
  4. (c) Dan Nydick, some rights reserved (CC BY-NC), https://www.flickr.com/photos/66842577@N08/9704019309/
  5. (c) Fluffymuppet, some rights reserved (CC BY-NC), https://www.flickr.com/photos/fluffymuppet/7439275444/
  6. (c) Wendell Smith, some rights reserved (CC BY), https://www.flickr.com/photos/wendellsmith/9052980210/
  7. (c) Wendell Smith, some rights reserved (CC BY), https://www.flickr.com/photos/wendellsmith/9052914894/
  8. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Elaeagnus_umbellata
  9. Adapted by Kate Wagner from a work by Public Domain, http://eol.org/data_objects/24635892
  10. Public Domain, http://eol.org/data_objects/24635901
  11. Public Domain, http://eol.org/data_objects/24635908

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