How long after spraying Round-Up on a plant before I can cut the plant off and still have the roots die? I sprayed some shrubs I wish to be gone. They easily come back from bits of root in the ground. It will take a long time before the plants look dead, but I would like to have them gone now. Will the plants have absorbed enough Round-Up to kill them in 4 or 5 days so that I can cut off the tops now? Or do I have to wait till the plants look dead?
If digging them up is a problem, another way for Roundup (glyphosate) to be effective is to cut the shrub down to within 2 or 3 inches of the ground and paint concentrated Roundup on the freshly-cut trunk. If it begins to regrow, you can cut again a little below the original cut and reapply. This is the only effective way I know to eliminate shrubs like established Scot's Broom (Cytisus scoparius) and Spurge Laurel (Daphne laureola) which are next-to-impossible to dig up especially if there a big rocks in the ground.
Thanks Margot. Is painting the fresh cut more effective than spraying the whole plant and cutting it off 3 or 4 days later?
I don't know if any research has been done to compare methods of application. Perhaps a better word would be 'efficient'. From a subjective point of view, I would rather use less product in a controlled way. Spraying something as large as a shrub risks damaging other, desirable, plants and the possibility of the applicator breathing in the mist.
A used and cleaned out plastic bleach bottle can be modified to become a spray drift barrier when attached to a pump sprayer nozzle.
