Elaeagnus umbellata

Family: Oleaster
Native Range: East Asia, China, Japan, Himalayas
Invasive Range: Woodlands Eastern USA from Maine to Virginia and west to Wisconsin

Overview

Autumn olive is a large deciduous shrub with multiple trunks and dense branching. It can grow to 15 feet tall and wide. You can easily identify autumn olive in spring because it leafs out before most native vegetation, and its new leaves are bright silver.

This plant was introduced into North America in the 1830s. It was used extensively to revegetate strip mines and to create shelterbelts because it thrives in poor soil. Because it fruits heavily, autumn olive was recommended for creating wildlife habitat. Unlike many
nonnative plants, native birds and animals do eat its ripe fruits. The sugary fruits are junk food for wildlife, especially for migrating birds. Birds need high-fat and high-protein foods, not sugary sweets, to fuel their flights. Poor nutrition slows migration and makes birds vulnerable to other risks.

As Autumn olive leafs out early and retains its leaves into late fall, it kills desirable plants with its shade. The shrub then gets a further competitive edge by adapting to a wide range of soil and light conditions, and its deep tap root makes it drought tolerant.

Any attempt at cutting down autumn olive without applying herbicide only increases the number of stems that sprout from its crown and roots.

Habitat

Autumn Olive thrives in poor disturbed sites, and can quickly form a monoculture in sunny fields and roadsides. It can also spread into open forests from infested fields. It does well in nutrient-poor soils, sand or clay, moist or dry. In all of these sites, it displaces desirable plants and reduces species diversity. Because its roots can fix nitrogen, this fast-growing invasive shrub alters soil fertility and changes the habitat. It increases nitrate levels and thus pollutes streams and rivers. The increased soil nitrogen promotes the spread of weedy species in favor of the natives adapted to the site.

This shrub is a serious threat to fragile native plant communities such as rocky barrens and prairies. Autumn olive infests fields and woodlands in most of the eastern U.S., from Maine to Virginia and west to Wisconsin.

Description

Autumn olive is a large shrub with multiple trunks and dense branching. It can grow to 15 feet tall and wide. You can easily identify autumn olive in spring because it leafs out before most native vegetation, and its new leaves are bright silver.

Fruit & Flowers

• 

• 

The small, fragrant, tubular-shaped flowers have four petals and are creamy to pale yellow. They bloom in profusion in spring, along with silvery new leaves. The oval-shaped, single-seeded fruits, (drupe) are 1/4 to 1/3 inch long and ripen in August and September. They are dull to bright red and are dotted with tiny silvery speckles. Inside is a single seed.

Mature plants can produce up to 30 pounds of fruit each autumn, which yields about 65,000 seeds. Because the seeds have extremely high germination rates, a population explosion then occurs. Since the fruits can linger on branches well into winter, they provide a food source when native fruits are scarce. This ensures seeds are carried far and wide.

Leaves

New leaves are densely covered in silvery-white scales on both surfaces, the upper surface becoming bright to dull green and appearing dotted, the lower remaining silvery often with scattered brown scales mixed with the white. Leaves mature to olive-green with silvery undersides. (Other invasive shrubs such as bush honeysuckle, multiflora rose, and Chinese privet also leaf out early, but their leaves are bright green.)

Autumn olive’s leaves are alternate on the stems and vary from narrow to wide ovals – up to 1 inch wide. The leaf undersides are densely covered with silver scales, as may be the tops of immature leaves.

Stems / Bark

Young twig tips may be silvery and scaly. Older stems have brown to yellowish-brown, smooth bark, which becomes scaly with age. Small thorns often occur on the twigs. Stems are multiple from the base or sometimes a single, central trunk with gray bark that is split and furrowed. A mature shrub is heavily branched with ascending branches and is about as broad as tall.

Lifespan

This shrub will bear fruit in approx 3-6 years and it’s productive lifespan is 30-40 years. Cold stratification improves germination. The growth rate is approximately 1 ft per year.

Ecological Impacts

Autumn olive threatens native ecosystems by out-competing and displacing native plant species, creating dense shade and interfering with natural plant succession and nutrient cycling.

Fruits not eaten drop to the ground, where the seeds plant themselves, germinate, and quickly grow into a thicket. The seed bank in the soil is quickly depleted. However, because autumn olive begins to heavily flower and fruit when only three to five years old, the seed bank is easily replenished. The growth of new plants gets out of hand so quickly that it is almost impossible to eradicate all the invading plants.

As the climate warms, resilient invasive species like Autumn olive can gain even more of a foothold over native plants.

How it Spreads

Fruits not eaten drop to the ground, where the seeds plant themselves and germinate. The seeds have over a 90% germination rate and are also spreads via birds and small mammals. There can be some vegetative propagation also occursUnfortunately, deer do not eat this plant.

Control Methods

Biological

An effective and sustainable strategy to manage autumn olive is to graze goats along with cattle on the affected pasture. Goats prefer brushes such as multiflora rose and autumn olive, especially when they are young, over other forage. They can defoliate areas infested with brushes that offer limited access to humans. They must be grazed for several years to kill the shrubs, but be aware that they browse indiscriminately. Such targeted grazing by goats contained using a solar-powered temporary step-in fence has proven to be effective, especially to control smaller brushes. Various types of fencing materials, such as poly-wire, electric-tape, and electric-netting, are available on the market. Once the brush is under control, create and maintain a dense canopy of forage and employ rotational grazing. These help the forage out-compete new autumn olive seedlings and prevent the shrub’s reestablishment.

Livestock tend to trample and forage on brushes when their grazing is confined to a tighter area.

Mechanical & Manual

Seedlings and young autumn olive shrubs can be hand-pulled or dug if the population is not extensive. Digging larger plants is problematic because they resprout from any roots left behind. Repeatedly cutting back established shrubs to ground level without applying herbicide will not control autumn olive, because stems regrow thicker and denser than before.

Tools such as the Weed Wrench® or Root Talon® offer more leverage than a shovel, allowing removal of plants with stems up to 3 inches across. In low-quality, heavily invaded fields, you can pull large autumn olive shrubs with a chain or a tractor bucket. Treat resprouts with herbicide. Regular repeat mowing can prevent seedlings from establishing.

Burning

Prescribed burning does not control established autumn olive because it does not kill the root system, which resprouts vigorously. Two to three additional burns with sufficient fuel may ignite the dead stems and kill the roots. Prescribed burning can kill autumn olive seedlings when adequate fuel is present. Burning can be combined effectively with foliar spraying. Burn to kill the tops of the plants, then use a recommended foliar herbicide on the resprouts.

Herbicides

If applying herbicides to treat autumn olive, always read the entire pesticide label carefully, follow all mixing and application instructions, and wear all recommended personal protective gear and clothing. The label is the law. Always ensure you apply the minimum amount of herbicide needed and only to the target plant. Take care to protect native plants.

Cut Stump – Autumn olive can be controlled at any time of year, except during spring growth, by cut-stumping. Cut or saw all stems to several inches from the ground and immediately spray cuts with a concentrated recommended herbicide or a ready-to-use stump killer. Watch for resprouts; cut and treat all new stems or apply a foliar herbicide spray to the new foliage.

Basal Bark – Concentrated herbicide applied to autumn olive stems of 6 inches or less in diameter is effective. Use a concentrated herbicide in a horticultural or vegetable oil. Spray or paint all stems from ground level up to about 10 inches. This is most effective in January and February or from May to October.

Foliar Spray – A higher concentration of foliar herbicide than is effective on most other plants is needed to control autumn olive. Be sure to add a surfactant if the product you use does not contain it. Treat any time after autumn olive leafs out until just before its leaves change color in fall. Because it greens up earlier and remains green later than many plants, early spring or late fall treatment reduces collateral damage. Use foliar sprays in summer only where there are few desirable plants nearby.

Lookalikes

Two other species of Elaeagnus are also seriously invasive but are less common in the Blue Ridge. Russian olive (Elaeagnus
angustifolia) has invaded Warren County. It is a 30-foot-tall tree with one to several trunks. Its leaves are much narrower and are
very silvery on both sides; thorns are sometimes present. Silver scales coat the fruits.

Thorny olive (Elaeagnus pungens) has leathery, evergreen leaves that are egg-shaped with wavy margins. The leaf tops are shiny green without silvery scales, and the undersides are covered with dull white scales and light brown dots. Large thorns arm the branches.

Several species of bush honeysuckle (Lonicera sp.) are invasive in the Blue Ridge and might be mistaken for autumn olive because they have red berries. They are easily told apart. Bush honeysuckles have green, opposite leaves without any silvery scales.