Japanese Knotweed Survey
Japanese Knotweed Photo


Japanese Knotweed Survey

>contact us > terms & conditions
>home > sample report

Japanese knotweed controlled by chemical application

Treated Japanese knotweed


Japanese Knotweed Chemical Control  

tel: 0333 456 7070
mob: 07950 259 905



The only herbicide approved for use in or near water which controls japanese knotweed is Glyphosate. For maximum effect, the plant should be sprayed at 6 l/ha from late summer onwards. Maximum effect is best when the plant is sprayed during the flowering period. Control is usually improved if the herbicide is applied to both the topside and the underside of the leaves. A nozzle that creates a 360 degree swath can be used to flood the leaves. The best method is to walk into the stand, start spraying and walk backwards away from the sprayed material. Large areas can be divided up by cutting pathways into the stand at 3-5 m intervals. Re-growth the following year will be much easier to treat.

Herbicides containing Picloram (Tordon 22K), Imazapyr (Arsenal) and Triclopyr (Garlon 4)can only be used away from the waters edge. Regular inspections, preferably in May and August, of treated sites are recommended for at least two years with spot treatments on any surviving plants.

Stem Injection

Unlike traditional Japanese knotweed herbicidal treatment methods, which are applied to the surface of the leaves of the plant, stem injection targets the application of a controlled quantity of herbicide directly into the core of the plant. This direct targeting of the herbicidal application enables stem injection to be the least insidious method of eradication of Japanese knotweed.

Stem injection is not weather dependant - traditional spraying methods are severely compromised by weather conditions and cannot be applied during heavy winds or rain. Stem injection can 100% be safely applied in an area where TPOs (Tree Preservation Orders) have been issued and traditional spraying and mechanical removal methods are not suitable, or will result in severe damage to other vegetation.

Stem injection has no impact on any surrounding vegetation or wildlife. Traditional spraying methods can cause damage to any surrounding vegetation and can cause harm to local wildlife. Stem injection is accepted and authorised by the Environment Agency for use on organic approved farms, without causing the loss of their organic status. Due to the labour intensiveness of stem injecting it is really on used on smaller sites or sites that carry environmental issues for example watercourses and TPO's.

In August to late September, the knotweed is cut immediately below the first node (approximately 8-15 cm above ground level) using a pair of loppers. The cut stems and leaves are usually stacked on polythene to prevent propagation (as new plants may arise even from small stem fragments scattered on the ground), allowed to dry and burned. A Glyphosate (Round-up Pro-biactive) mixture, ten times greater than the foliar spray recommendation i.e. 5:1 instead of 50:1, is injected into the hollow stem using a spot gun applicator. The solution can be coloured with dyes to enable identification of treated stems.

Additional to Round-up Probiactive, other chemicals considered potentially effective and tested at various concentrations are: Dormone 2,4 D Amine (2,4 D Amine), Garlon 4 (Triclopyr), Tordon 22K (Picloram), Reglone (Diquat), Arsenal (Imazapyr) and Asulox (Sodium Salt of Asulam).Only Glyphosate, Diquat and 2,4D Amine are licensed to use near water courses, where many of the infestations occur. Picloram and Imazapyr can be persistent and damage neighbouring trees and broad-leaved herbs.

> Identification Service

Not sure if it is Japanese knotweed? Email photographs for our surveyor's expert opinion.

We can also send a surveyor's letter identifying the plant in the photographs if required.
*fees and conditions apply

more info >>

> Japanese knotweed survey

Approval has been given for an insect to be released to control the invasive Japanese knotweed in the North East.

The rampant plant, which was introdu ...

> Japanese knotweed survey

A homeowner who tried to remortgage his £400,000 property had his application refused because of Japanese knotweed in his garden.

Dave Williams, 42, w ...

> A formidable problem

You should aim to completely eradicate the knotweed before any construction works commence, unless you want to incur delays and major expense at a later stage ...


Company’s Registered Office Address: 597 Etruria Rd, Basford, Stoke On Trent, Staffordshire. ST4 6HP.
Japanese Knotweed Survey © Copyright 2011

Japanese knotweed survey, management, control, eradication & land remediation relief.
Areas include Staffordshire, Cheshire, West Midlands, Manchester, Birmingham & Stoke On Trent.

Hosted by Square-Sun Web DesignSquare-Sun Web Design logo