A native of Eurasia, where it is controlled by natural enemies, Leafy Spurge readily adapts to a variety of situations. It infests, and if not aggressively managed, can dominate landscapes ranging from open prairie and hillsides to riparian areas and lowlands. The deep-rooted and prolific perennial has doubled in acreage every 10 years since the early 1900s, and is expanding beyond its foothold in the western United States.
Pictured above is dryland alfalfa at the old Jensen farm, run by Robert Roberts, on the south edge of Pineview Reservoir. Roberts has had some success holding back the spurge from his hay with timely swathing. The UDOT Right-of-Way here is very wide and they do not get it covered at herbicide application time.
Below is a photo just across the State road where Roberts is not so fortunate. Here the alfalfa is infested with Leafy Spurge He uses it only for his own stock so we have been hesitant in forcing him to rehabilitate the field. Even so, there is a trail of Leafy Spurge all the way to his farm that we deal with every year.
Leafy Spurge is a long-lived herbaceous perennial plant. Buds initiate elongation during the fall but remain below the soil surface throughout the winter. Bud elongation resumes in early spring and the above ground portions of the plant (shoots) become apparent in April or May, depending on location. Vegetative shoots develop rapidly and reach their full height in June or July. Mature stem heights are variable, depending on soil and weather conditions, but generally range from 0.25 to 1.5 m. Stems may be branched or unbranched. Leafy Spurge leaves are usually green or grayish-green in color, linear or lanceolate in shape, and from 2-8 cm long and 2-10 mm wide. Leaves are arranged alternately along the stem. Leafy Spurge possesses specialized, unisexual flowers in a compound umbellate arrangement (see photo below).
Because of the sticky pollen, the fact that the male flowers do not mature in sync with adjacent female flowers, and the presence of nectaries, Leafy Spurge appears to be pollinated mostly by insects. Seeds develop and mature from July through September, and are then explosively expelled up to 5 m from the parent plant; generally, from 30-150 seeds are produced by each flowering shoot. Leafy Spurge seeds may be dispersed over longer distances by flowing water, birds or grazing mammals. Spurge seeds are also transported by humans in gravel, soil, hay and farm equipment. It is farm equipment that has spread the Leafy Spurge found in Weber County.
The Economic impact of Leafy Spurge is staggering. Infestations in the Dakotas, Montana and Wyoming alone are estimated to cost agricultural producers and taxpayers $144 million a year in production losses, control expenses and other impacts to the economy. Every AUM (the amount of grazing required to sustain a cow/calf pair, or six sheep, for one month) lost to Leafy Spurge infestations costs $167 in lost economic activity. Leafy Spurge has literally forced some ranchers out of business.
Control of Leafy Spurge needs to be a collective and integrated effort to be successful. We are again fortunate in Weber County that this invader caused no where near the monitory impact that it imposes on our neighbors to the north. We have very good herbicides that are used on the infestations as they spread out on to public Rights-of-Way. See the control pages for our recommendations. The biological control community is very active with host-specific insects on Leafy Spurge, and Weber County has several of them working in our behalf near the weed populations pictured above.
Team Leafy Spurge is a USDA-ARS research and demonstration program focused on the Little Missouri River and associated watersheds in Wyoming, Montana, North Dakota and South Dakota. We appreciate their input on the information found on this web page.