Or, try sabadilla, rotenone or diazinon. Used properly, herbicides are safe and effective tools, says Danny Barney, University of Idaho extension horticulturist. But homeowners who misuse them can inadvertently damage or kill desirable plants. Phenoxy herbicides like 2,4-D and MCP can harm both broadleaf and conifer plants through direct contact with spray or granules, through drifting mist or vapors and through the roots, Barney says. Injured plants will have small, deformed and puckered leaves or twisted and deformed shoots.
Grapes are especially sensitive.
Glyphosate products like Roundup and Kleenup can kill both grass and broadleaf plants. Damaged plants show stunted and deformed leaves and may develop yellowish or brown discoloration, while those that die outright usually turn brown without deformities or twisting. To protect your desirable plants from contact with glyphosate, keep your sprayer pressure low and use a nozzle setting that produces a coarse spray rather than a fine, drift-prone mist. Water can carry it onto adjacent lawns and kill the grass. Symptoms include bark cankers near the ground on woody plants and brown, dead grass downslope of the application zone.