Roundup Extended Control Weed and Grass Killer Plus Weed Preventer’s dual-action formula kills existing weeds and prevents new ones from growing for up to 4 months. Kills weeds to the root, guaranteed. Use on driveways, sidewalks, and patios; along fences, foundations, curbs, retaining walls and edge of lawns, as well as on decorative rock or gravel areas. Rainproof in 10 minutes. Visible results in 3 hours. Active ingredients Ready-to-Use: 1% Glyphosate, 2% Pelargonic acid and related fatty acids, 0.017% Imazapic. Active ingredients concentrate: 18% Glyphosate, 0.73% Diquat, 0.3% Imazapic.