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Japanese Knotweed is a highly invasive, non-native plant and is considered one of the most problematic plant species in the UK and Ireland. Japanese knotweed is extremely hardy and can cope under stressful conditions, where other species would not. This being the case, Japanese Knotweed does not give up easily and killing it can be something that is best left to the professionals!

The only way to eradicate Japanese Knotweed is to completely remove the plant and its rhizomes from the ground and disposing of in a licenced landfill. Some believe that if they remove the above-ground growth, then the plant will die. This is not the case. The above-ground growth of Japanese Knotweed can be removed and incinerated at a licenced facility, however, this will not kill the plants underground growth and the plant will continue to grow. Japanese Knotweed has an extensive underground rhizome system that can spread up to 7 metres horizontally and 3 metres deep, this can make it extremely hard to kill on site.

After establishing that the only way to ‘kill’ Japanese Knotweed is to completely remove all of the infested soil and take it off-site to a licensed landfill, what else can be done to control Japanese Knotweed? The most popular and cost-effective method of dealing with Japanese Knotweed is to control its growth through persistent but monitored herbicide application. Herbicide application is a good way to control the plant and place it into a forced dormancy underground – stopping it from growing and spreading. Applying herbicide to the leaves of the plant at specific times of the year and by a trained professional, allows the herbicide to travel to the root of the plant via photosynthesis.

Japanese Knotweed certified surveyors will be able to determine the amount of chemical to use depending on the maturity and extent of the growth. This will ensure that the growth does not get ‘flooded’ with chemical and receives the correct amount to have the greatest long-term effect. If the chemical is over-applied to the leaves of the Japanese Knotweed plant, an adverse effect can happen which affects our ability to control the growth. If over application occurs, the plant will have an adverse reaction, but not one you want to see! You will see the plant begin to form smaller, triangular-shaped leaves and in much greater numbers than before. These new leaves have a much smaller percentage of coverage compared to healthy leaves, therefore, we can get far less herbicide onto the leaves and gaining control is very difficult, sometimes impossible. This type of growth is called ‘Bonsai growth’ and herbicide control is difficult, sometimes impossible and would require full removal.

We would suggest that Japanese Knotweed treatment is completed by a certified professional for best results and would never advise anyone to attempt themselves. It is important to instruct a PCA Accredited company such as CYB Environmental to put an herbicide treatment programme in place and ensure that the growth is treated properly, professionally and with the potential of providing an Insurance Backed Guarantee for lending purposes in the future.

For any queries on the above or if you would like a free identification of a potential Japanese Knotweed plant, please contact us at info@cyb-environmental.com

Japanese Knotweed is an invasive non-native plant pest and is considered one of the most problematic plant species in the UK and Ireland. This is mainly due to its highly invasive nature and its extremely rapid growth rate. The species was introduced to Britain in mid-19th century as an ornamental plant for large gardens, prized due to its imposing size and sprays of creamy white flowers.

Japanese Knotweed plants have a Creamy white colour, 0.5cm wide. It forms clustered panicles that can grow to 10cm and bloom in the very late summer around August/September time. The stem of the plant grows in zig-zag pattern, with green, purple and red speckles visible on the cane itself. The cane is hollow and grows to 2-3 metres in height. Can Grow up to 2cm a day. Japanese Knotweed leaves are a light green with red or purple flecks. Heart or shovel-shaped with a pointed tip and shoots out from nodes in a zig-zag pattern. New leaves are rolled up with dark red veins, mature leaves can grow up to 20cm. Japanese Knotweed can grow up to 10cm per day during late spring / early summer, with the plant typically growing up to 2.1m (7ft) but can grow up to 3m (9.8ft).

Japanese Knotweed is a self-propagating plant, meaning that it spreads and grows from fragments of the plant itself. Japanese Knotweed has an extensive underground rhizome system and if you were to snap a piece of the rhizome you would see that inside of Japanese Knotweed rhizome is a bright orange colour and this is how we are able to determine whether plant is in fact Japanese Knotweed.

Dead canes of Japanese Knotweed can also be mistaken for doc plants and vice versa, with the dead cane looking woody. Mature canes of Japanese Knotweed are thick and strong like bamboo.

For any queries on the above or if you would like a free identification of a potential Japanese Knotweed plant, please contact us at info@cyb-environmental.com

Japanese Knotweed is an invasive non-native plant pest and is considered one of the most problematic plant species in the UK and Ireland. This is mainly due to its highly invasive nature and its extremely rapid growth rate. The species was introduced to Britain in mid-19th century as an ornamental plant for large gardens, prized due to its imposing size and sprays of creamy white flowers.

During the spring and summer months, Japanese knotweed has been reported to grow as quickly as 10cm a day. However, there is no research to support how fast it spreads underneath the ground. Japanese Knotweed has an extensive underground rhizome system that can spread up to 7 metres horizontally and 3 metres deep. However, from experience, underground rhizome growths reach approximately 2m in depth and width. Japanese Knotweed can grow up to 0.3 – 0.4 metres per week, meaning that in just 10 weeks a cane of the plant can reach up to 3-4 metres.

The spread of Japanese knotweed can be increased by the breakage or disturbance of the ground. This is why it is important to underline the future plans of a site and to establish what method of treatment should be put in place prior to works. Laws are in place to prevent the spread of the highly invasive plant: Wildlife and Countryside Act 1981 – “You must not facilitate the spread of Japanese Knotweed in the wild.” Failure to comply with the act could result in large fines.

Japanese Knotweed is a self-propagating plant, meaning that it spreads and grows from fragments of the plant itself. A common mistake is to trim the plant once it is overgrown and put the fragments in common waste. Japanese Knotweed plants must be taken to a licensed landfill or licensed incineration centre, once removed from a site.

Please see the relevant law put in place to ensure the appropriate care is taken when disposing of the plant: Environmental Protection Act 1990 – “Waste containing Japanese Knotweed is classified as ‘controlled waste’. As such, you must observe the appropriate duty of care for its proper handling and disposal“.

It is important to note that when applying herbicide to the plant, it is the leaves that will hold the herbicide prior to photosynthesis that allows the herbicide to travel to the root structure of the plant and cause it to lie dormant underground. If disturbed, we may see new growths and the treatment programme will have to re-start.

If undisturbed and untreated Japanese Knotweed plants will continue to grow rapidly and thrive in damp and non-resistant areas. Causing external and internal damage to boundary walls of properties, gardens and outer buildings.

For any queries on the above or if you would like a free identification of a potential Japanese Knotweed plant, please contact us at info@cyb-environmental.com