Fallopia Japonica (also known as Japanese Knotweed), is currently causing a huge issue in the English countryside where it was introduced. This is due to the fact that it spreads and grows rather quickly, its roots go roughly about 3m into the ground and are quite hard to dig up as there are so many of them interconnected and they are so firm. The only really absolute way of getting rid of them is chemical treatment for the soil which is obviously not so good for the environment nor that soil. This treatment is necessary due to the fact that even if one is to leave a very small amount of the root there, the plant is likely to still grow back quickly. All roots have to be fully removed for it to go.
However, in Japan, to where it is native, there is no such issue as there is in England and other countries where is it causing a mass problem.
This is probably due to the fact that the ecosystem is different and thus it will be balanced out and controlled by other plants in the ecosystem which aren't present here.
However, I have not yet come across proper research on this matter, so I was wondering if it is known why it isn't such a problem in Japan and how it is controlled and balanced out by what is naturally there, but isn't in the countries where it is causing an issue? Is there a specific plant which controls it? Perhaps an animal that eats it?