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Comment by exDM69 | Hacker News Reader

Previous owner of my property planted this damn plant here in two separate patches.

I'm on year four trying to get rid of it and it's still showing signs of vitality. If I let my guard down, it's gonna be back with a vengeance in a year or two.

I dug out about 600 kg of roots from about 6 square meter area and have culled every shoot every day from the patch almost every day for four years.

The other patch was first treated with herbicide and then covered it with a light blocking tarp made for this purpose. It's still going after 4 years in the dark.

Please do not pick it up or mess with it. It is a terrible plant and destroys everything around it.

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I believe cutting every day is counter-productive because it causes it to spread. I’m in Massachusetts. The strategy we’re using is cutting once in early summer. Then we let it grow (completely undisturbed) until right after it flowers in early fall. At that point we cut and inject concentrated glyphosate into the stumps. The idea is to inject the herbicide right as the plant is drawing stuff back into its root system for the winter.

I've read about this strategy and am giving it a shot this year.

If I understand it correctly, the reasoning is that until the late summer, the underground root system is putting its energy towards growing the stalks and leaves, so you _want_ it to grow as much as possible. If you trim daily, you'll never let it get into the rapid growth stage where it's really depleting its energy reserves. In other words if you trimmed daily or monthly til the end of time, eventually you'd kill the plant, but it might ironically die more quickly if you trimmed monthly.

It's a bummer knowing that it'll be hard to fully eradicate it given how widespread it is in the area (I'm also in Massachusetts), but I guess there aren't really any permanent victories in life when you think about it.

I do not cut it. I dig out any shoots and as much root as I can as soon as they appear above ground.

For the other patch, I did just what you say, cut, herbicide and then covered it.

> I do not cut it. I dig out any shoots and as much root as I can as soon as they appear above ground.

That's a lot of digging!

Cutting vs digging shouldn't make much of a different in terms of the plant's response to damage (aggressive spreading). It'll spread when it gets hurt either way. Also, knotweed's root system goes down down 4-12 feet so usually removing the roots isn't feasible. Frequently digging it out or cutting it will hurt the plant but it's going to be a very slow and labor intensive way to eradicate it.

Yeah, it is a lot of digging. I already dug out all of the roots I could, which meant digging a waist deep hole and taking half a ton of the root stuff to the recycling center (to be burned). But now I'm dealing with the remaining roots trying to spread.

When I dig out the shoots, I always try to get more than this year's growth, and hope that laws of thermodynamics will eventually prevail.

The damn thing is almost dead by now. I get a dozen shoots a week or so.

Wonder if this plant would be helpful for greening up deserts or converting co2 to biomass. Apparently it doesn't even need light!

I always see it growing on wet/damp soils near canals.

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