HEC Associates
Japanese Knotweed
For more information please contact us on
0114 272 4227 or e-mail info@hallamec.plus.com
UKEconet > HEC Associates > Japanese Knotweed
-
About
-
Control
-
The Law
<
>
About Japanese Knotweed
Japanese Knotweed (Fallopia japonica) was introduced into Britain in the 1850s as a decorative shrub from Japan via Holland. The invasive nature of the plant is due to the absence of control organisms such as fungi and bacteria that maintain it to its natural extent in japan. Furthermore, it rarely reproduces by producing seed (all the plants you see are female) but more frequently reproduces vegetatively by means of new underground stems called Rhizomes. These rhizomes will spread into any kind of habitat as well as into services, drains, brickwork foundations, walls and other building structures if left unchecked. It only takes about 10 mm of rhizome to create a new plant.
Its normal growing season is from March, when the early growth appears, through the spring and summer to August when the canes are at their highest (up to 3 m) and the creamy-wh9ite sterile flowers are in full bloom. The majority of the canes come from a large crown although new canes will appear from new rhizomes and later develop into a large crown. The canes dry, go brown and die back over winter when they may get trampled or cut back. At this stage, they look harmless but new canes will grow again the spring.
The rapid growth of the plant causes major shading problems for other species which the die out due to the intense competition. It can also cause obstruction to pathways and streams; along roadways it can obscure signs and entrances to side roads and driveways. More importantly, it can cause damage to buildings, pathways and roads as the shoots push through any small gaps available.
Its normal growing season is from March, when the early growth appears, through the spring and summer to August when the canes are at their highest (up to 3 m) and the creamy-wh9ite sterile flowers are in full bloom. The majority of the canes come from a large crown although new canes will appear from new rhizomes and later develop into a large crown. The canes dry, go brown and die back over winter when they may get trampled or cut back. At this stage, they look harmless but new canes will grow again the spring.
The rapid growth of the plant causes major shading problems for other species which the die out due to the intense competition. It can also cause obstruction to pathways and streams; along roadways it can obscure signs and entrances to side roads and driveways. More importantly, it can cause damage to buildings, pathways and roads as the shoots push through any small gaps available.
Controlling Japanese Knotweed
Because of its ecology Japanese Knotweed cannot be quickly and easily removed. It has to be dug out to a depth of 6 m and a width of 14 m to ensure all fragments of rhizomes will be removed. If you dig it out when you have the major problem of disposing of the plant material and the soil it is growing as Controlled Waste. That means it has to be taken to a landfill site licensed to take it, carried by a Licensed Waste Management operator in order to prevent contravening the law. That costs a lot of money!!
Can We Burn It?
The canes can be left until late autumn when they are dry and brown in colour and then they can be cut at a level of 150-200 mm above the ground. They must not be pulled out by hand, as this may cause fragments of rhizome to break off. The cut material must be put into secure plastic bags and left on the site to dry out completely in preparation for burning.
The permission to burn is at the discretion of the Local Environmental health Authority and/or Fire Service. If permission is granted then it comes under the control of Paragraph 30, Schedule 3 of the Waste Management Licensing regulations 1994.
Can We Dig It Up?
Most of the rhizomes of the Japanese Knotweed are to be found in the top 0.5 m of the soil. An excavator can be used to remove the surface crowns and rhizomes, then cultivated at the lower depth so that any new growth can be sprayed with herbicide in the next growing season. To prevent spreading, the removed topsoil can be placed in a secure compound, on site, and again, any new growth can be treated with herbicide early in the next growing season. Any stockpiled material must not be used until all the knotweed material is confirmed unviable by a qualified person.
Care is needed to prevent spreading infected material.
Can It Be Sprayed With Herbicide?
If the site is not to be dug over then spraying with herbicide mix is permissible.
The most effective time to spray the knotweed is when the canes are about 1 m tall, usually between April and July although spraying could continue into September.
For large areas of infestation the spraying should be left to licensed operators. For small crowns and single regenerated stems the use of small garden spray can be successful, even though it might take up to 3 years to eradicate it from a garden site.
There are several herbicides available but the selection is normally controlled by the environment in which the plant is growing. Some herbicides reside in the soil for a long time while others become ineffective in the soil within a very short time period from application. The close proximity of water (ponds, lakes, streams, etc.) also dictates which herbicide should be used.
Can We Burn It?
The canes can be left until late autumn when they are dry and brown in colour and then they can be cut at a level of 150-200 mm above the ground. They must not be pulled out by hand, as this may cause fragments of rhizome to break off. The cut material must be put into secure plastic bags and left on the site to dry out completely in preparation for burning.
The permission to burn is at the discretion of the Local Environmental health Authority and/or Fire Service. If permission is granted then it comes under the control of Paragraph 30, Schedule 3 of the Waste Management Licensing regulations 1994.
Can We Dig It Up?
Most of the rhizomes of the Japanese Knotweed are to be found in the top 0.5 m of the soil. An excavator can be used to remove the surface crowns and rhizomes, then cultivated at the lower depth so that any new growth can be sprayed with herbicide in the next growing season. To prevent spreading, the removed topsoil can be placed in a secure compound, on site, and again, any new growth can be treated with herbicide early in the next growing season. Any stockpiled material must not be used until all the knotweed material is confirmed unviable by a qualified person.
Care is needed to prevent spreading infected material.
Can It Be Sprayed With Herbicide?
If the site is not to be dug over then spraying with herbicide mix is permissible.
The most effective time to spray the knotweed is when the canes are about 1 m tall, usually between April and July although spraying could continue into September.
For large areas of infestation the spraying should be left to licensed operators. For small crowns and single regenerated stems the use of small garden spray can be successful, even though it might take up to 3 years to eradicate it from a garden site.
There are several herbicides available but the selection is normally controlled by the environment in which the plant is growing. Some herbicides reside in the soil for a long time while others become ineffective in the soil within a very short time period from application. The close proximity of water (ponds, lakes, streams, etc.) also dictates which herbicide should be used.
Japanese Knotweed and the Law
Knotweed and the Law
Japanese Knotweed (Fallopia japonica) is such an invasive and damaging plant it is controlled by law:
Japanese Knotweed (Fallopia japonica) is such an invasive and damaging plant it is controlled by law:
- The Wildlife & Countryside Act 1981: It is an offence to plant or otherwise cause the plant to grow in the wild.
- Environmental protection Act 1990, Duty of Care Regulations 1991: Cut Japanese knotweed material and soil containing rhizomes MUST be disposed of as Controlled waste, if they are to be removed from their site of origin.
- Third-party litigation: You can be sued for costs and damages if you allow the spread of the plant from your property on to that of a neighbour.
To obtain further information, or if you need help with your knotweed problem, please contact us. Details at top of page.
Background image: japaneseknotweed.com
