Japanese Knotweed

The Problem

Photograph by Philip Precey


Japanese Knotweed (Fallopia japonica) was again introduced as an ornamental garden species in the 19th century. The species is now found across the UK and can be spread through rhizomes and stem fragments. As well as out competing native plant species, on river banks Japanese Knotweed can increase erosion. The plant also causes structural damage to buildings and roads due to its ability to grow through tarmac and foundations.

What Are We Doing?

We have identified Japanese Knotweed on our Portrack Marsh reserve. Control of the species begins in May when the plant has reached roughly 90cm. We treat the plant by spraying with Glysophate. In summer when regrowth occurs this is treated via stem injection again with Glysophate, with additional spraying if required in September.