Japanese Knotweed Treatment & Eradication

What Is Japanese Knotweed

Japanese knotweed while a very attractive ornamental plant when at it’s flowering stage is as devasting to your property and financialy to to your pocket as Foot & Mount disease is to a herd of cattle and to their owners pocket .
Japanese Knotweed is the most invasive plant known in Ireland & Britain today. The plant originated in Japan where it thrives on disturbed ground. It was introduced to the UK in the early 19th Century as an ornamental plant also being used as a feed crop for cattle. The Victorian Horticulturalist who introduced the plant cannot have envisaged the devastating impact Japanese Knotweed would have.

It is effectively a giant herbaceous perennial which grows at an alarming rate of up to 10cm per day in any type of soil. It forms dense clumps of up to 3m (10ft) in height. Japanese Knotweed thrives on disturbance and spreads by natural means and by human activity. Very small fragments of rhizome (underground stems), as little as 0.7g - approximately the size of a fingernail - can produce fresh new plants. But it is below ground where this invader causes the biggest problems, as each stand creates a rhizome network that can extend to 3m in depth and 7m in all directions. This makes it a serious threat to construction where it can have devastating consequences damaging foundations, drains and other underground services.

Why is Japanese Knotweed A Problem
In Japan, Japanese knotweed is controlled naturally by a combination of fungus and insects. However, in the UK & Ireland , there are no natural enemies for Japanese Knotweed and it outcompetes all our native species for light, water and nutrients.
The speed at which Japanese Knotweed has spread throughout Britain has been nothing less than spectacular. The damage it has already caused to commercial and domestic sites is practically unquantifiable and it now occupies a site in every 10km_ of England and Wales and is also present to a lesser extent in Scotland, however insidence are now becoming more frequent here now in Ireland .
The aggressive growth pattern is capable of exposing weaknesses in hard engineered structures such as concrete, tarmac, brick walls and foundations.
See below where a new infestation has spread from a near by ajacent property on the Southern side of Cork City from one commercial property to another . The under ground “rhizomes” of the invasive plants have traveled 7 meters under ground til they identified weak areas in a new tarmac surface in a car park and developed up through the tarmac surface reaching 1.5 meters in height in 6 weeks .
These plants will now continue to re infect the currant area and travel in many directions under the surface finding more weak surface areas to penetrate next season thus causing thousands of Euro damage to the nearby buildings if not treated professionaly .

The aggressive growing Japanese Knotweed plants growing up through tarmac on the south side of Cork City .

It is now classed as "controlled waste" under the Environmental Protection Act 1990 in the UK and requires disposal at licensed landfill sites. It should never be included in normal household waste and in England it is listed under Schedule 9 of the Wildlife and Countryside Act 1981, making it an offence to cause or allow the plant to spread in the wild. In Ireland no such classification is put on it here yet , mainly due to authorities turning a blind eye to it . In Japan, Japanese knotweed is controlled naturally by a combination of fungus and insects. However, in the UK, there are no natural enemies for Japanese Knotweed and it outcompetes all our native species for light, water and nutrients.

It Pays To Be Proactive ; Not Reactive
The majority of our work still comes from customers who have either under estimated the problem , were not aware of what they were dealing with , or availed of the cheasest possible quote which resulted in either a further spread or no net result at all or indeed at worst tackled the problem them selves , by cutting or strimming the aggressive invasive plant .
In The case of Japanese Knotweed , it is certainly a situition where you get exactly what you pay for  


Japanese Knotweed Growing Up Through A Floor Of A Living Room In a Dwelling House

Under Standing The Growth Cycle & Survival Skills Of Japanese Knotweed

Japanese Knotweed has the ability to out live , out preform , and out grow any other vegetative plant due to it’s unique vascular system & under ground rhizome system .

Unlike our common plants & grasses that we are all familiar with , Japanese Knotweed has a very vigorus growing under ground rhizome system and a seasonal direction of flow vascular system .

Normal plants within their vascular system have both directional movement in the phloem and xylum . Nutritients are transported one direction to the leaves from the roots while by products of respiration are transported the other direction in the plant’s vascular system at any one time .

Japanese Knotweed likes to be unique from other plants .
Over winter the Japanese Knotweed plant remains dormant under ground where its large rhizome net work can extend up to 7 meters in any or many directions from the parent plant , and also up to 3 meters down wards , thus creating a far greater level of infestation under ground than one would quantify being in existance from what is just visable above ground . During winter the plants store food in the form of carbohydrate within their mass rhizome net work . This gives the plant an huge ability to survive harsh winters up to and below -20 .

In early spring above ground shoots begin appearing

and quickly the plant beging to grow at an enmorus rate.

All food movement is one direction in the plants vascular system heading up wards to the leaves where “Photosynthesis” is taking place .

During the active growing period of the plant’s life up til complete dy back caused by winter frost , all parts of the viable plant tissue are highly productive to re infest an area.

A particle of plant tissue as small as your small finger nail is more than enogh to start & cause a serious infestation else where .

By Late Summer or early autumn the plants reach flowering  as below

As soon as the plants reach flowing stage , food movement within the plant’s vascular system changes direction and now food sugars are transported from the leaves down to the under ground plant rhizomes where they will be stored for the winter , thus giving the plant the ability to survive over winter .

People’s Natural Reaction & Actions  

Upon finding this terrible invasive plant growing in your property people tend to either cut it , strip it or even spray it .
Japanese Knotweed has the ability to fight most herbicides , what is worse is that plants treated non proffessionaly with day to day available herbicides and weed killers tend to die back just for a little while and then fight the chemical and grow back much better and stronger than near by un treated infestations . This is why you should never attempt to treat the infestation your self.

Strimming and cutting is one of the major causes of spread in Ireland .

Many contractors working for Irish Local Authorities have no knowledge of or about Japanese Knotweed and during there contract cut or trim many infestations along Irish roads . This inturn makes the cut infestation more vigorous to grow even more , but worse is that the viable debry cut of with the hedge cutters now blows away in the wind to reinfect nearby public or even private properties .


Japanese Knotweed Half cut with a fail head hedge cutter by a contractor along a main road in County Wexford  

One small particle blowing away in the wind or carried by a vehicle or a pedrestrian is enough to create a new infestation .
Wind , Water , Birds , Footwear , Soil and vehicles including lawn mowers  traveling on infected areas are the most common to spread the invasive plant .

Recently a new form of infestation spread is coming to light . Importing infected top soil from a site with Japanese Knotweed has fatal consequences .
While not visable during certail times of year , soil brough in around a house to extend a garden or to creat a new lawn can contain viable rhizomes . The consequences can be horrific with a major financial cost for rectification .

The photo below shows a mature Japanes rhizome crown growing out through a quay wall in Cork City centre .

The following photo showes these crowns being initalt professional treated by O’Donovan Agri Environmental Services

Control Methods

Never ever attempt to control japanese knotweed your self , seek proffessional advise first .

We Are The Number  One Company In Ireland For Providing Treatment – Control & Eradication Solutions for Japanese Knotweed .

We Provide A Comprehensive Site Survey Service And A Menu Option For treatments To Suit Your Budget
Utilizing A Professional Service From Us Is Always Value For Money For Long Term Benefits .

We use a number of different of control methods or in some situations a combination of a number of processes depending on the location , age of infestation , source of spread etc .

For further information please contact us directly or visit our dedicated web site to Japanese Knotweed control . www.japaneseknotweed.com