Japanese Knotweed

 An information guide about Japanese Knotweed

Description

Japanese Knotweed was originally a plant found in volcanic regions of Japan and surrounding areas. It was introduced into this country as an ornamental plant and eventually found its way into the wild. The plant itself is a perennial plant meaning that it does not just last for one year but normally will attempt to return the next year. It thrives via a stem system underground. This underground stem system is why Japanese Knotweed is such a problem. It uses the stem system to grow in different places. These stems (called Rhizomes) can grow underground up to 7 metres from the original plant and then surface as new growth.

The plant can spread under walls, pavements, patios or most other objects which would restrict normal plant growth. On the surface the plant looks like a 2-3 metre tall green leafed plant with cane like stems and white/creamy flower.

During the winter the surface plant dies back leaving a woody like stem growth behind and then will re-emerge the following spring. Japanese Knotweed grows particularly well in fertile soils such as gardens. The plant itself has no natural predators in this country which, is one of the reasons it spreads and grows so well.

                          

Control – Domestic Sites & Council Owned Land  

Note: Developers need to seek separate advice)

Control of Japanese Knotweed is not as simple as cutting the plant down or spraying it with weed killer. Be prepared to repeat the control each year for up to 3 years to successfully control the plant. The problem lies in 2 areas:–

1. The plant above ground
2. The plant below ground

1. The plant above ground
In September cut the plant back. To do this you will need a set of secatures or other cutting tool.

Cut the base of the plant approximately 150mm (6 inches) from ground level. Remove the arisings leaving the base of the stems sticking out the ground. Remove the cut stems to a safe and secure place where they can be dried off naturally. Then burn them. They should not leave your site

Into the cut stems remaining in the ground apply weed killer containing Glyphosate (Glyphosate is the active ingredient which kills the plant. If in doubt ask at a garden centre for advice when buying Glyphosate).

Wear rubber gloves and eye protectors. Always follow the instructions on the label.


Apply the weed killer directly into the cut stem, ensure you treat all the stems – the stems tend to be hollow. Watch for any re-growth the following spring and treat again the following September

2. The plant below ground
Direct application of weed killer to the stem of the plant will allow absorption of the weed killer into the root system. Pulling or digging up the plant is very difficult for 3 reasons:-

1. The root system can be very extensive and far reaching.
2. Any small broken pieces of Japanese Knotweed left in the ground or in the removed soil can grow into new plants.
3. The disposal of the plant once dug up is difficult and care must be taken not to spread the plant further.

If you try to pull or dig up the rhizomes and roots they should be removed and dried out which helps kill them and then if possible they should be burnt in a safe manner.

Do’s & Dont's

Do

• Take action and treat the plant where it is
• Seek advice from your local authority if in any doubt
• Seek advice from garden centre staff and horticultural stockists regarding Glyphosate products

Do Not

• Ignore it, it will only get worse
• Do not permit the plant or parts of it to leave your garden or site
• Do not put any part of the plant into brown waste disposal bins
• Do not try to take it to a domestic landfill site such as Foxhall tip. They will not accept it. You need to treat it where it grows.

Legal Status

Most of the legal rules and regulations concerning Japanese Knotweed are related to its disposal and the soil from which it is removed. Following is a summary of the legal implications regarding Japanese knotweed and its handling:-

• Soil excavated from a Japanese Knotweed site must be disposed of in a licensed landfill site.
• You can not reuse contaminated soil in other building or landscaping developments
• Landfill operators must be made aware of the Japanese knotweed in any soil of which they are to dispose
• Contaminated soil must be buried to a depth of at least 5 metres.
• A written description of the waste (soil) and any properties harmful or otherwise it may have (Japanese Knotweed) must be given to the site operator prior to disposal – see section 34 of the Environment Protection Act 1990
• It is illegal to spread Japanese Knotweed as outlined in the 1981 Wildlife and Countryside Act
• The 1990 Environmental Protection Act classes Japanese Knotweed material as “controlled waste” to which a duty of care is applied

For further information about these regulations please see the links below:-

The 1990 Environmental Protection Act
http://www.opsi.gov.uk/acts/acts1990/Ukpga_19900043_en_1.htm

The 1981 Wildlife and Countryside Act
http://www.jncc.gov.uk/page-3614

Japanese Knotweed Tips

Here are a few tips regarding Japanese Knotweed

If you think you have it in your garden or property

• Try to identify it
• If you can’t identify it yourself or are still not sure if you have it then seek advice from a horticulturist
• Do not dispose of suspect plants until you are sure they are not Japanese Knotweed

If you spot Japanese Knotweed within the Ipswich town area

• If it is on public land do not try and treat it yourself
• Inform the property owner if it is on a residential area or private grounds
• If the weed is in an adjoining property to your home or garden inform the property owner, the weed could spread to your property via its rhizome system under the ground.

If you would like to treat the weed yourself
Follow our guide to controlling the plant
Only treat the weed if it is on your property

If you are in the Ipswich Borough area and would like to get help treating the weed

• Contact us telephone no. 01473 433000
• Ask the advice of any local horticulturist, you can enquire at places such as garden centres and other related stores

Where is it in Ipswich?

Treatment has already started at Council owned sites:-

There are also reports of Japanese Knotweed on non-council land at:-

printable :  Information Guide about Japanese Knotweed (202KB).pdf
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