Cannot be killed

Asked May 16, 2019, 7:52 PM EDT

I live in a condominium community in Bethesda MD where there Has been a 4 year effort to eradicate a 4 to 6 foot shrub ( when full-grown) Without success. It spreads by roots underground and appears to like a more watery environment. Efforts to dig it up, pull it out, and poison it have failed. If you cut it down to soil level it just sprouts again. Very young sprouts have red/rosy tinge to center vein, underside. Just found only in one area of the property and no one knows how it got there. The pictures you see here are of it sprouting again after Another failed effort to remove it in the fall.I have seen it full-grown but I have not seen flowers or berries. It does not climb. If we can only identify it, I feel we have a better chance of knowing how to exterminate it! Help!

Montgomery County Maryland japanese knotweed invasive

3 Responses

This is Japanese knotweed, one of the worst non-native Invasive plants.It is difficult, but not impossible, to kill.

Here is our page on Japanese knotweed: https://extension.umd.edu/hgic/topics/japanese-knotweed
The link to Weeds Gone Wild has management practices you will need. See the Chemical options.

Actually you have made good progress weakening the knotweed. Note that the herbicide is 2%. Look for that. Also, note that it should be sprayed--but not so heavily that it drips off. And be sure to mix in a surfactant (also known as sprayer-sticker), which will make the herbicide stick to the slick leaves.

The herbicde is a last resort but necessary because the knotweed stores up huge amounts of energy in its roots so it can resprout. Glyphosate is a "systemic" which will go down to kill those roots. Don't let sprouts survive long (spray--let it absorb the herbicide--before you cut it back).

For many plants, fall is especially good time to kill roots with systemics because plants are naturally transporting energy down to their roots that time of year.

Ellen

This is Japanese knotweed, one of the worst non-native Invasive plants.It is difficult, but not impossible, to kill.

Here is our page on Japanese knotweed: https://extension.umd.edu/hgic/topics/japanese-knotweed
The link to Weeds Gone Wild has management practices you will need. See the Chemical options.

Actually you have made good progress weakening the knotweed. Note that the herbicide is 2%. Look for that. Also, note that it should be sprayed--but not so heavily that it drips off. And be sure to mix in a surfactant (also known as sprayer-sticker), which will make the herbicide stick to the slick leaves.

The herbicde is a last resort but necessary because the knotweed stores up huge amounts of energy in its roots so it can resprout. Glyphosate is a "systemic" which will go down to kill those roots. Don't let sprouts survive long (spray--let it absorb the herbicide--before you cut it back).

For many plants, fall is especially good time to kill roots with systemics because plants are naturally transporting energy down to their roots that time of year.

Ellen