Japanese Knotweed Removal   contact us 

Greentree Ltd. is an approved contractor for Japanese Knotweed removal for Sheffield City Council, and has a steadily expanding client list across the public and private sector. We have established an enviable reputation for dealing with knotweed, and specialise in environmentally sensitive and difficult to access sites. We have been contracted to work in Sites of Special Scientific Interest (SSSI's), local nature reserves, public parks and along river corridors, where consideration for the surrounding environment has been a paramount concern.

 Japanese Knotweed - the problem

Japanese Knotweed is a highly invasive non-native species (INNS) that is becoming an increasingly serious problem across the UK. It out competes our native plant species in the wild, so reducing bio-diversity, but is also able to grow through tarmac and building foundations, so is very damaging to property.

Knotweed is extremely effective in propagating itself, and will re-grow aggressively through its crown, rhizome (underground stem) and stem segments, though thankfully its seeds are not viable. The weed can grow a metre in a month and can cause heave below concrete and tarmac, coming up through the resulting cracks and damaging buildings and roads. Studies have shown that a 1cm section of rhizome can produce a new plant in 10 days. Rhizome segments can remain dormant in soil for twenty years before producing new plants.

The Solution

Stem injection is however, a successful and cost effective solution to this damaging problem. We use the latest industry standard stem injection equipment, coupled with the most effective herbicides on the market today. Our application technique has proved itself to be highly effective with around 95% of plants killed on first treatment, with a follow on treatment seeing the remaining 5% killed.

Japanese Knotweed near water

If a site runs close to a watercourse this can be another challenge. The chemicals used to kill Japanese Knotweed are highly toxic to aquatic life, so Environment Agency approval is a legal requirement in all cases if a water course is within 5m of the treatment area. Greentree are experienced in liaising with the Environment Agency to gain this necessary approval to get the job done.

We have successfully completed projects throughout the River Don catchment region, eradicating knotweed on numerous sites on the river Don itself, its tributaries; the Sheaf, Porter and Loxley as well as a number of smaller becks feeding into the river system. The shot below shows a large stand of knotweed right to the waters edge on the River Sheaf. This was treated in late summer of 2015 and it will be interesting to see the results of stem injection next year.

Japanese Knotweed is one of only two terrestrial plants listed by the UK Wildlife and Countryside Act as illegal to cause it to grow in the wild.

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