Posted on Fri, Sep. 05, 2003   Charlotte Observer

Eurasian spotted knapweed, a thistle-studded thug that has overtaken grazing pastures in the West, wages war by injecting a toxin into soil to kill competing plants, researchers report in today's issue of the journal Science.

Because the weed is immune to its own poison, the research project leader at Colorado State University hopes those protective genes can be engineered into other plants so they're better armed for the plant warfare.

The finding has immediate value for ranchers and land managers who try to control the weed with herbicide and reseed with a beneficial plant, said Jorge Vivanco, an assistant professor in CSU's department of horticulture and landscape architecture: "What they've seen is 99 percent of these plants don't grow. Now we know why. You have a toxic compound in the soil."

Spotted knapweed releases catechin to disrupt the chemistry of would-be neighbors.