Knotweed on the garden fence.
We live in Bavaria. Our neighbor has had a strip of about one meter wide with dense growth of Japanese knotweed, which is considered an extremely invasive weed, right next to our shared border fence (chain link fence) on his side for years.
He allows this strip, which is now not only overgrown with knotweed but also with wild blackberries, field bindweed, and other weeds, to grow freely through the fence onto our side. He regularly mows the rest of his lawn but just as consistently leaves this strip standing by his fence. Our request to kindly mow there as well, since the knotweed is now almost two meters high and, like the other weeds, grows through the fence and overgrows our plantings/hornbeams, was rigorously rejected.
He does not see it as his summer hobby to mow there regularly, and it should be enough for us if he mows once a year after the weed growth period, so in the fall.
To our surprise, he recently, for the first time, referred to us as the cause of his problem with the knotweed flourishing on his side. He refers to the fact that over twenty years ago, during the construction of our hillside house, we built a stone staircase right next to the border fence. His fence had to be removed for this. With the condition to rebuild everything and reset the fence, he gave his consent. This we also complied with.
Now he claims that during the dismantling and an alleged backfilling twenty years ago by us, soil contaminated with knotweed was brought onto the property boundary, and now he calls us the actual cause of his problem. After this long time has passed since the house was built, we can no longer remember specifically, but we believe that during the excavation for the staircase, there was already enough soil and there was no reason for additional backfilling with soil. In the long time that has passed since the construction of the house, it would also be difficult to blame either side for the introduction of allegedly contaminated soil. We will also refute his blame.
Additionally, he now also believes that we cannot ask him to remove the knotweed anymore, as he now refers to the knotweed not as a weed, but as a perennial plant, and perennials are generally exempt from distance restrictions according to the law.
So, there seems to be no way to ask the neighbor to remove the knotweed on his side by regularly mowing it.
However, we believe that the overhang and the wild growth through the fence with knotweed/perennials/other weeds, which are now more than two meters high and overgrown our plants, must be removed by the neighbor.
Our neighbor disagrees with this. We also do not have the right to demand removal.
He claims that he would rather have a claim against us, as we caused the problem and the damage that occurred and continues to exist on his side.
Can the neighbor hold us liable according to the principle of causation if contaminated soil was unknowingly brought in by us twenty years ago?
Do we have a legal right to demand the neighbor to cease and remove the growth from his side?
Can we ask him to trim back everything on his side that grows higher than two meters?
Can we ask him to remove and eliminate everything that grows from his side through the fence to our side and set a deadline for this?
