Razorooter II root-control herbicide from Duke’s Root Control contains the active ingredient diquat dibromide, and is registered with the U.S. Environmental Protection Agency for controlling nuisance tree roots in sanitary sewer line collection systems. Crews insert a hose from manhole to manhole, preparing to fill the affected sewer pipe with foam. Once released, the foam compresses against pipe surfaces, penetrating cracks, joints and connecting sewers. Roots are killed on contact, decay naturally and slough away. Applications prevent root-related stoppages for two to three years. 800/447-6687; www.dukes.com.