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- - "- 0.. a <: '< t '" "- Russian 'llive often grows along rivers belween the water's edge and cottonwood trees. It eventually prevents the regeneration of cot tor'woods. In the euphorbia family and therefore related to the poinsettia, leafy spurge probably came to North America in food and bedding hay used for livestock being transported from Caucasus Asia. The first specimen was documented in 1827 in Massachusetts. Leafy spurge now grows all across the northern states and southern Canada. In North Dakota mortgage compa- nies will not lend on agricultural prop- erty infested with leafy spurge. On a per-acre basis, spurge control can exceed crop productivity. People have walked away from farms because they could neither afford spurge control nor sell the land. Leafy spurge produces enormous quantities of seeds which remain viable for years - sometimes decades - even when wet. The plant also develops a vigorous underground network of stems which produce new shoots. Plant phys- iologists also suspect that leafy spurge releases a chemical which prevents other plants from growing. All this allows the spurge to expand rapidly. And being displaced from another continent, leafy spurge does not support the array of herbivores it does back in Asia. Native North American insects, rodents, rab- bits and deer won't eat leafy spurge 12 seeds or vegetation. The plant literally grows unopposed, and the consequence is devastating. Probably no one in Colorado under- stands the leafy spL,lrge problem more thoroughly than Ron Broda, now weed and pest supervisor for Weld County. Broda spent several years assessing for the Bureau of Land Management the extent of Wyoming's range deterioration caused by leafy spurge. "You just can't believe it," Broda laments. "Thousands of acres where the only thing that grows is leafy spurge. Sheep and goats will eat a little of it, but cattle and deer and pronghorn won't. " This makes sense. The ancestral stock of domestic sheep and goats evolved in Asia. For thousands of years, these animals have grazed where leafy spurge grows natively. When cattle on impoverished range eat too much spurge, they develop blisters in their throats. Caustic chemicals in leafy spurge can likewise cause dermatitis problems for cattle and even people. "If you go down to a river where leafy spurge grows," Broda continues, "you're not going to find voles in the grasses because you won't have the grasses. And of course, when the mice move out, the hawks and other small predators go, too." Leafy spurge has thoroughly estab- lished itself in Larimer and Weld coun- ties and is moving south. Weed scientists predict that by the end of the decade it will be a dominant upland and lowland plant throughout the northern foothills and plains. Thinking about it, Broda just shakes his head. Leafy spurge is only one plant in the exotic species problem. "People just don't understand," he sighs. "A hunting club out of Denver owns more than 200 acres on the South Platte River south of Greeley. It's cot- tonwood riparian forest, but almost all the ground cover is either leafy spurge or tall whitetop." A member of the mustard family and another exotic, tall whitetop grows to six feet tall and quickly takes over. "I got a hold of the club officers and two of them came out, " Broda explains. "One of them seemed to understand what I was saying, but the other guy sawall the greenery and presumed it was good cover. "But you know, " adds Broda, "in the two hours or so that we walked their property, we didn't see one deer, not one rabbit. We didn't see or hear a single Colorado Outdoors