With so much at stake, it is little wonder that the people of central North Dakota have declared war on leafy spurge. They spray it with herbicides. They spread foreign beetles to eat it. They organize spurge tours, like the one that ended at Rognlien's ranch. But they know they'll never beat it completely.
Eradication works only if the new population is caught before it gets too big.
Leafy spurge, which has steadily spread west across the country since the 19th century, may have been brought here as seed in soil that was used as ballast on sailing ships. With about 1 million acres of this noxious weed, North Dakota has more leafy spurge than any other state. Until recently, leafy spurge doubled its acreage every 10 years. As an alternative, the state's ranchers and weed agents are using forms of biocontrol - that is, recruiting an insect or other animal in their battle with leafy spurge. So far, Rognlien is the only rancher using sheep.