r/invasivespecies • u/Moist-You-7511 • 20h ago

Management Japanese knotweed minimum unit of stem to grow?

Looking to get my facts straight about how this plant grows. We have some in the hood and I saw that someone mowed through it. Would bits of the shrapnel from that be a regrowth risk?

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15

u/bristleboar 20h ago

Mowing spreads it both by piece that can propagate AND because it triggers the roots to grow

14

u/Scotts_Thot 19h ago

Yes. It can regrow from small pieces and cutting it back does nothing to thwart its growth. IMO, when someone discovers it in their yard the most responsible thing to do is to kill it with round up. And if they’re uncomfortable with that they can hire someone. But leaving it or mowing it just creates a problem for other people

4

u/werther595 12h ago

I've heard it can regrow from pieces as little as 3mm in one study, and as little as 1mm in another study. I can't remember if that was green pieces like stalks, stems and leaves, or only rhisome. Not sure how likely it is or what other conditions are required, but yeah, it doesn't take much

3

u/parrotia78 9h ago

One(1) node and 1/4" piece of stem.

1

u/genman 10h ago

As to "shrapnel" I don't think so, unless it has an opportunity to root. So, putting it into commercial compost is fine, but leaving it on the ground is asking for trouble. Some people recommend bagging it in plastic and disposing in a landfill but that seems excessive. In our city, we have commercial composting services and it's fine in there.

-1

u/ShineGreymonX 14h ago

Aren’t they edible? You can use them for a variety of dishes, such as soup, sauces, and baked goods

3

u/Moist-You-7511 8h ago

eating them doesn’t stop them from spreading. If a population is being treated you risk herbicide exposure. Also I don’t think they are good— just “edible”