Leafy spurge, first identified in North Dakota along a Fargo street in 1909, has become one of the most difficult noxious weeds to control. Leafy spurge infestations may have more than 200 stems per square yard in sandy soil and higher densities in heavy clay soils. Patches of leafy spurge usually spread vegetatively from 1 to 3 feet per year and form dense stands that crowd out other plants by shading competing for moisture and nutrients. Forage production may be reduced to 20 percent or more and most native plants are eliminated because they cannot out-compete this weed.
Leafy spurge contains a toxic substance that, when consumed by livestock, is an irritant, emetic and purgative.; It causes scours and weakness in cattle and may result in death. The toxin has produced inflammation and loss of hair on the feet of horses. However, sheep and goats will graze leafy spurge as a portion of their diet and can be used as a form of cultural control.
Leafy spurge is a long-lived perennial that normally grows 2 to 3 feet tall. The plant bears numerous linear-shaped leaves with smooth margins. Growth begins in early spring giving it a completive advantage over native grasses and forbs. Leafy spurge produces a flat-topped cluster of yellowish-green petal-like structures called bracts, which surround the true flowers. The bracts appear in early June but the true flowers emerge in mid-June. Seeds are borne in pods which when mature may burst explosively and throw seeds up to 15 feet. Seed may remain viable for up to 8 years. The root system is extensive and consists of numerous coarse and fine roots that occupy a large volume of soil. Roots can extend to a depth of 15 feet or more, are woody and durable in structure, and with numerous buds capable of producing new shoots. The root system contains a large nutrient reserve capable of sustaining the plant for years.
Control on non-crop lands:
Controlling Leafy spurge must be considered a long-term management program. Research at North Dakota State University has shown that a combination of control measures , biological, chemical or cultural, provides greater destruction of the root system than any single control measure.
Chemical: Proper timing is essential for good leafy spurge control. Leafy spurge is most susceptible to chemical control when the true flowers and seeds are developing in June or after the stems have developed new fall regrowth in early to mid-September. Spraying late June and July will also provide good control. Tordon plus Overdrive and Plateau herbicides are among the most effective and also qualify for the Landowner Assistance reimbursement