Are noxious weeds a problem for you? Let Upper Loup NRD help.
The legal description of a noxious weed is any plant designated by a Federal, State or county government as injurious to public health, agriculture, recreation, wildlife or property. More commonly they are defined as a plant that grows out of place and is competitive, persistent, and pernicious.
Regardless of which weed you are trying to manage it’s important to continue yearly management as skipping a year can cause the noxious weed to re-infest rapidly. Persistence is the key to any successful weed control program.
In Nebraska you are legally required to control noxious weeds on your property. The common noxious weeds on the Nebraska State list include: plumeless thistle, musk thistle, diffuse knapweed, spotted knapweed, Canada thistle, leafy spurge, purple loosestrife and saltcedar. Fortunately, not all of these weeds are found in our District. To help with the battle those found in our area (leafy spurge, Canada thistle, musk thistle) the Upper Loup Natural Resources District provides cost share funds for BOTH fall and spring treatment to landowners in the NRD area. Funds are available to cover 45% of the cost of approved chemicals up to $400 per landowner.
Not sure if you have noxious weeds on your property? Read on to learn more about them.
Leafy spurge is an invasive, herbaceous perennial weed that infests more than five million acres of land in 35 states and the prairie provinces of Canada. In Nebraska alone the direct loss in forage value attributed to leafy spurge has been estimated at more than 2 million dollars. It causes significant problems by invading grazing lands for cattle and horses, reducing rangeland productivity and cattle carrying capacity by 50-75 percent, decreasing plant diversity, degrading wildlife habitat, displacing sensitive species and drastically reducing land values.
Leafy spurge is an erect plant that grows 1 to 3 feet tall. Leaves are bluish-green with smooth margins, 0.25 inch to 0.5-inch-wide, and 1 inch to 4 inches long. Shoot emergence begins in early March in Nebraska and increases until early summer. Umbel flowers are surrounded by heart-shaped, showy, yellow-green bracts. An umbel looks like the stays of an umbrella if it is held upside down. Flowers occur in many clusters toward the top of the plant and are most conspicuous from mid-May to mid-June. Seeds are round to oblong, about 1/12 inch long, gray or mottled brown with a dark line on one side. Seeds are dispersed by birds, wildlife, humans, and in rivers and streams. Leafy spurge contains white milky latex in all plant parts. This latex is poisonous to some animals and can cause blistering and irritation on skin. The digestive tract is similarly affected when this plant is eaten by humans and some animals. In cattle it causes scours and weakness; when ingested in larger amounts it can cause death. Cattle usually refuse to eat leafy spurge unless it is given to them in dry, weedy hay or when better forage is not available.
Canada Thistle is another weed that poses a threat to the economic, social and aesthetic well-being of Nebraska residents. It is probably the most widespread of all thistle species and in Nebraska is estimated to infest 375,000 acres and causes over 3 million dollars in lost production each year. Canada thistle differs from musk thistle in that it is an aggressive weed in tilled cropland, range, pasture, and non-cropland areas. The other thistles are not considered problem weeds in tilled cropland. Canada thistle also harbors insects and is an alternative host for some diseases. It can release toxic substances into the soil from both live and decaying plants, inhibiting the growth of some plants.
Canada thistle is a member of the sunflower family. It is a perennial that reproduces from seed and by extensive horizontal roots from which arise aerial shoots. Once it becomes established, plants can live and reproduce for many years. Horizontal roots spread rapidly and in a single season may grow 9 to 18 feet laterally and 6 to 9 feet deep. Tillage through these patches can cut roots; however, root segments as small as 1 inch can survive and produce new plants, spreading the original infestation.
In the seedling stage, Canada thistle cotyledons are oblong and fleshy. The first true leaves are obovate and do not have a petiole (stalk that attaches the leaf blade to the stem). Leaf margins have regularly spaced, coarse, marginal hairs that resemble the spines of later-developing leaves. Canada thistle usually grows to 2 to 3 feet tall with alternate, dark green leaves that vary in length from 2 to 7 inches and in width from 0.5 to 2.5 inches. Leaves are oblong or lanceolate, usually with crinkled edges and spiny-toothed margins. The underside of leaves may be hairy or hairless when mature. Stems are erect, branching, grooved, and without hair above and below. Flowering heads form in clusters on the ends of branches. Heads are about 0.5 inch in diameter and flowers are usually pink to purple but may be white. Seeds or achenes are smooth, light brown to straw colored, and 0.1 to 0.2 inches long. Seeds are dispersed by wind (up to half a mile), irrigation water, humans (contaminant in crop seed or hay), and in rivers and streams. Seeds may germinate once they have left the seed head or they may remain dormant in the soil for up to 20 years.
Musk Thistle can invade all lands in Nebraska. Typical cropland weed control methods are very effective against them; however, land with permanent cover such as pasture, range, and roadway ditches that is not managed to prevent bare ground is more likely to develop a serious infestation. In pasture and rangelands thistles compete for the moisture, sunlight, and nutrients needed to produce forage for livestock. Musk thistle is not a poisonous plant; however, livestock will refuse to enter heavily infested areas and will not graze close to the spiny plants. On roadways and wastelands musk thistle does not provide sufficient protection against soil erosion, crowds out desirable vegetation, is unsightly, hinders movement of people and wildlife, and produces seed that infests surrounding areas.
Although classified as a biennial plant musk thistle can behave as an annual or a winter annual depending on the growing conditions. Musk thistle seedlings can emerge anytime during the growing season. Leaves of both rosettes and bolted plants are deeply cut (segmented) and dark green with a light green midrib. There is a grayish-green area at the outer edge of each spine-tipped leaf segment. Each lobe has three to five points that end in a white or yellowish spine. The leaves extend onto the stem, giving it a winged or frilled appearance The leaves and stem are relatively free of hair. Seedlings emerge with two cotyledon leaves, then add other leaves one leaf at a time to develop into a rosette that can reach over 2 feet in diameter. Mature plant heights are typically 5 to 7 feet with a long, fleshy taproot. Musk thistle has deep reddish purple flowers that are large (up to 3 inches in diameter) and attractive. The head is solitary on the end of the stem and nods or hangs down as it grows in size. Seeds are dispersed by wind, small mammals, birds, and water and may be viable in the soil more than 10 years.