Partners Work to Curb Fast-Spreading Invasive Plant

Leola, SD—A $25,000 grant from the U.S. Fish and Wildlife Service will support the partnership efforts to stem the spread of yellow toadflax, an aggressive, fast-growing invasive plant that cannot be controlled through prescribed fire and grazing methods. The partners in the Leola Hills region are looking at alternative methods to control the plant, including chemical and bio-control insects and grazing with goats. The partners include Ducks Unlimited, County Weed Boards, private landowners, U.S. Fish and Wildlife Service, the U.S. Department of Agriculture and The Nature Conservancy.

"Invasive plant species of all kinds are collectively squeezing out native plants from grassland ecosystems resulting in decreased wildlife production and diversity," said Jay Peterson. “Yellow toadflax has spread at alarming rates in 2005. Not only are wildlife species being negatively impacted but beef production will likely be reduced as well if this plant is left uncontrolled and becomes established throughout area grasslands.”

The partnership effort is based on an integrated approach using different types of control measures for the plant. Goats are being used to selectively remove toadflax plants following a grazing or haying treatment. Biological control insects have been released at three locations and herbicides are being applied. Because little is known about this invasive plant, the partners are seeking to learn which control practices work the best at reducing yellow toadflax.

“Yellow toadflax was documented in the area over 20 years ago in small isolated patches,” said Randy Meidinger, Manager of Conservation Programs for Ducks Unlimited in South Dakota. “Over the past few decades this invasive plant has significantly increased its range and also increased in density on the acres already infested. From the results of this project we hope to learn which treatment or combination of treatments will be most effective in controlling this problematic species.”

Yellow toadflax (Linaria vulgaris) is a perennial with narrow, nearly opposite, 2-inch long leaves. Stems are smooth, generally unbranched and up to 3 feet tall. The showy snapdragon-like flowers are about 1 inch long, yellow with an orange throat and are borne in midsummer and fall. Seed is produced in brown, globe-shaped capsules. Seeds are round and dark colored with notched, papery collars that act as wings in spreading the seed.

Brought to the United States as an ornamental in the 1800’s, it spreads both by seed and roots and grows under a wide range of environmental conditions. The plant contains a poisonous glucoside that may be harmful to some livestock. It is now an agricultural pest and is rapidly invading our grasslands. New plants develop from root buds and from seed. Seed remain viable in the soil for up to 10 years and a single stem may contain over 5,000 seeds. The plant is adapted to fire and grazing so typical land management practices used to maintain healthy prairie (grazing and fire) do not curb its spread, rather disturbance of the plant may cause an increase by promoting vegetative reproduction.

“The partners in this project will be working together to map the current toadflax infestation across a large portion of the landscape” said Mary Miller, The Nature Conservancy’s Ordway Prairie Preserve Manager. “The data will be used to assess the rate at which the plant is spreading and which areas are at high risk of invasion. This information will give us a better understanding of the problem and help us respond more effectively.”

At the Conservancy’s Ordway Prairie, yellow toadflax is pushing out native plants. In 2001, the U.S. Department of Agriculture mapped the toadflax infestations on the preserve. From that data, it was estimated that 4 percent of the preserve was impacted by the plant. That estimate has grown at least 8 to 10 percent of the preserve.

On September 7, the partners plan to present information about yellow toadflax and the work being accomplished through this project. Supper will also be provided. Please contact Jay Peterson (605-885-6320), Mary Miller (605-439-3475) or Randy Meidinger (605-439-3329) to RSVP or for more information.