Invasive Autumn and Russian Olives
Native to Europe and Asia, autumn olive (Elaeagnus umbellata) and Russian olive (Elaeagnus angustifolia) are multi-stemmed, deciduous, woody plants that were brought to the United States in the mid-1880s. Imported originally as ornamental landscape plants, they were desirable for their narrow, willow-like, silvery leaves, fragrant, tubular flowers, and colorful fruit. Fast-growing and requiring little maintenance, more uses were quickly discovered, including erosion control, forest restoration, strip mine reclamation, highway beautification, and use in windbreaks and wildlife plots.
As members of the oleaster family (Elaeagnaceae), Russian and autumn olive are similar in size and form, growing over 20 feet tall. With a loose, irregular form, they naturally grow as shrubs. However, they may be grown as small trees by pruning a leader and major branches and shaping them accordingly. As they grow, their thorny stems and branches are covered with silvery scales that turn brown as they mature. Russian and autumn olives produce yellow and white flowers, respectively, that bloom in spring to early summer. Edible, silvery green to yellow fruits follow the flowers and ripen to red in the fall. Both are prolific fruit producers and while each fruit only contains one seed, a mature autumn olive plant produces 80 pounds of fruit. Ironically, while the shrubs were once planted in wildlife food plots for their plentiful berries, these fruits are quite low in nutrients, making them a poor food choice for our native birds.
These plants quickly escaped the confines of the areas where they were originally planted and have spread aggressively. Russian and autumn olives now grow along streams, rivers, roadsides, forest edges, disturbed sites, and open areas. Their profuse seed production aids in their spread as the fruit is eaten by wildlife and transferred to other locations through their droppings. They spread by root suckers and self-seeding. Tolerant of drought and poor soil, their fast growth rate allows them to establish dense thickets quickly, crowding out native plants. Increasing their capability to grow in poor soil is their ability to fix nitrogen, thus changing the mineral makeup of the soil. Unfortunately, that same nitrogen-fixing capability may negatively affect the nitrogen cycle of the native plants growing in that area, leading to their decline.
Once established, Russian and autumn olives are difficult to eradicate. Pull young plants and small infestations by hand or digging, but ensure complete root system removal to prevent the plant from resprouting. This is best done after rain when the ground is soft and moist. Larger plants or infestations may require chemical control. Cutting alone is ineffective, as vigorous resprouting may result in even denser growth. Combine cutting with applying a systemic herbicide to the stump immediately after cutting to prevent regeneration. This is most effective in July through September or when the plant is dormant. Whenever using chemical herbicides, follow all the instructions on the label. For additional information, the Pennsylvania Department of Conservation and Natural Resources (DCNR) provides fact sheets for all plants on the state's invasive species list.
