I need to kill horseradish in my landscape; tried Roundup Pro twice now to no avail, the tops die but the root sends up new ones a few weeks later. It was in a container sunk in the ground and evidently the roots went down. When the container was removed the plant really began to flourish. What can I use to kill the plant?
Multnomah County Oregon
Getting the upper hand over horseradish is a sort of good-news-bad-news story: You can win, but it will require repeated effort. Your goal is to starve the roots which, as you know, can be sizable This is *not* a once-and-done action.
An effective strategy requires muscle power and herbicide. This is what you need to do:
1. Moisten the soil well, then dig out as much as possible; the deeper you go, the better.
2. Fill the hole with the original soil and wait.
3. When new sprouts appear, apply herbicide. (Pour a small amount of the undiluted material into a container, then paint the leaves with a small disposable brush or dribble the herbicide into the center of the greens.
- Wait until new growth appears, then repeat from #2. Continue as needed, possibly for the next several years or for as long as it takes.
What type of herbicide is recommended? Roundup, Crossbow, or any others that work? Thank you for your help.
You need to use an herbicide that works against broadleaved plants. Both of the products you mentioned will do so.
The potential problem with glyphosate (the active ingredient in Roundup) is that it will kill all plants, both broadleaved and narrow leaved, that receive an adequate dose. Crossbow combines two active ingredients (2,4-D and triclopyr) which only act against broadleaved plants. That said, a paint-on application is much safer than a spray.
Know that you could avoid using herbicides if you simply remove the new sprouts whenever they show above ground. Doing that will get rid of the horseradish in the same time period as if you use chemicals. In fact, hand removal of the greens is likely to be easier than dragging out the herbicides.