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Is Japanese Knotweed Really A Problem?

Japanese Knotweed (knotweed) is increasingly becoming a scourge throughout Ireland and be found in all counties. The problem is also being compounded by confusion and lack of knowledge by land and property owners.

Knotweed can cause damage to infrastructure as it can export the smallest flaw in concrete and tarmac and gradually push its way through just about any building material.

Knotweed also damages ecosystems and biodiversity as it grows fast and shades out other native species.

Knotweed myths and facts and fiction: -

Q. Can knotweed grow through concrete?

A. The simple answer is no!

Knotweed will not grow through well laid concrete, but it will exploit weaknesses and grow through cracks caused by frost damage or where there is a join between concrete slabs.

Knotweed will grow through tarmac, and mortar between bricks.

Knotweed Breaking Through Brick Wall

Q. Can I dig knotweed up to get rid of it?

A. Knotweed likes being disturbed. It is known to be able to remain dormant for over 20 years in undisturbed ground, only to regenerate with a vengeance upon ground disturbance. The likelihood of removing all viable vector material through digging is very slim!

And remember, it is not unusual for knotweed to grow 7 metres laterally in all directions from the surface growth and up to 2 metres in depth. If you have a well established stand, be prepared for a very large hole! You'll need to apply a specialist root barrier when all the digging is done.

Professional knotweed removal companies will normally use soil sifting machinery to minimise soil waste.

Remember, it is a criminal offence to depose knotweed waste anywhere other than a licensed facility.

Early Knotweed Shoots

Effective control and management of knotweed is a difficult job, as it can grow from small fragments which can be easily dispersed through watercourses, by foraging animals and on roadsides from traffic movement.

Knotweed and its close relatives are very competitive weeds. it can grow extremely fast, with new plants able to grow in just a few days from small pieces of a rhizome, stem or crown fragments.

Knotweed grows faster than most native species and can grow in almost any environmental conditions. In its native habitat through south east Asia, it is now to happily grow on the sides of volcanos!

Knotweed has an extensive underground root system, the root system and rhizomes can withstand extremes in temperature.

One of the main reasons for its success is that none of its natural enemies, which keep it under control in its native habitat, exist in Europe.

Here at Ecoweed Control we have developed several effective methods of control for all varieties of knotweed species including herbicide spaying, direct stem injection, cut stem, electricide (Rootwave), specialised root barrier, bunding and full excavation. for some knotweed infestations, a combination of herbicide treatments applied during flowering seasons, together with other methods may be necessary.

Herbicide treatment will require 3 – 4 years to control and restrict the spread of Japanese knotweed.

Electricide treatments are normally applied at the start middle and end of growth seasons for at least 2 years, and have the advantage of being chemical free. This means surrounding vegetation is not affected.

Excavation, Dig & Dump solutions tend to be expensive due to amount of material that is likely to be moved. However, it is instant and is normally the preferred method for property developers due to timescale constraints with alternative methods.

Checkout for more information on knotweed removal methods.

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