Weed produces "safe" poison.

• Position: Herbicides

Scientists have speculated for decades that spotted knapweed is able to spread over large areas because of a secret weapon--an ability to release a chemical that kills surrounding plants. Until now, they have never been able to put their thumb on the phenomenon, but Jorge Vivanco, assistant professor of horticultural biotechnology, Colorado State University, Ft. Collins, has identified and isolated the chemical for the first time. What's more, it is being used as a completely natural and environmentally friendly herbicide to kill other weeds.

The discovery and isolation of the chemical catechin within spotted knapweed may revolutionize the war against weeds for homeowners and farmers. "For years, scientists have talked about spotted knapweed releasing this chemical, but they couldn't find it in the soil because it was almost impossible to separate from all the other compounds that naturally occur in soil," explains Vivanco. "We looked for it in the plant. Spotted knapweed releases catechin into the soil through its roots."

Now that catechin has been identified and isolated, and scientists can capture the chemical in the laboratory, Vivanco and a team of researchers are investigating a wealth of applications for the chemical. They have discovered that the weed produces two types of catechin that are the same chemical compound, but the mirror image of each other in...