How to Identify , What To Do & What Not To Do
Japanese knotweed is a fast-growing, robust plant that rapidly produces dense and extensive vegetation stands. In Ireland, Japanese knotweed has no natural predators or pathogens; therefore, it has the ability to outcompete native vegetation and threaten biodiversity. It is currently one of the most widespread invasive species in Ireland.
In the last number of years Japanese Knotweed has been spotted all around our town & it continues to spread. Local estimates put the amount at approx 16,000 metres in the town. This compares to a recent survey by Cork County Council they carried out for the expansion of the city limits late last year , which put recorded sightings for the newly expanded city limits at approx 10,000 meteres.
In spring, the plant produces new shoots (tinged with red/purple) from the rhizome (underground stem) on a dense underground crown. As the shoots grow, they extend to produce upright, hollow, bamboo-like green canes which can grow up to 3m high and achieve a diameter of 4 cm in a single season. The plant flowers between August and October, producing clusters of small creamy-white flowers. These dense stands of vegetation that the plant forms can block sight-lines and signage, having major safety implications on our road network.
What does Japanese Knotweed look like
Negative Economic Impacts of Japanese Knotweed
- Damage to property
Japanese Knotweed can grow through tarmac, concrete, brick walls and foundations – putting your property at risk.
- Mortgage refusal
Should you have any Japanese Knotweed on your property and are looking to sell – potential buyers may not be able to get a mortgage to purchase.
- Planning permission
Planning may have conditions attached which can impact on loan approval.
- Land Price
The price of your land or property may be greatly affected if it is proven that you have Japanese Knotweed. Some Dublin properties have gone to market at €50,000 to €100,000 less than market value because of the discovery of Japanese Knotweed on their property.
- Neighbouring Land
If you have Japanese Knotweed spreading onto your neighbour’s property and cannot come to an amicable solution, you could be liable to have legal proceeding taken against you.
- Aggressive growth
If you don’t control it, it will soon control you – Japanese Knotweed can spread from a single piece of its stem and grow up to 4 inches per day.
- Impact on the Environment
Because of the vigorous growth of the Japanese Knotweed, it outcompetes all other native plants not allowing them to grow.
- Legal responsibilities
Under the Wildlife and Countryside Act it is illegal to “plant or cause to grow” Japanese Knotweed in the wild.
Rhizome material may remain dormant for long periods, possibly as long as 20 years, and may regrow when disturbed. Cut fresh stems will produce shoots and roots from nodes when buried in soil or immersed in water. Dispersal typically occurs through rhizome fragments being transported in soil by humans or to a lesser extent, through passive mechanical means such as in floodwaters and large vehicles along roads.
- The plant is usually found on waste ground, beside streams, on roadside ditches and in places where soil has been brought in.
- It can penetrate surfaces as hard as concrete and tarmac, as well as threatening native plants and animals by forming dense thickets.
- Once established, it can be hard to control. Along rivers, it also damages flood defence structures &can lead to bank erosion.
- Red/purple shoots, which can look like asparagus, appear in early spring. The mature canes are like bamboo and have a characteristic pattern of purple speckles. The plant can grow to over three metres in height.
- Flowering occurs in late July and August, with small, creamy white flowers. During the winter, the leaves die back and reveal orange/brown, woody erect stems.
- The root-like stems can extend up to seven metres from the parent plant and up to three metres in depth.
Should you find this invader on your property the first thing you will probably do is to try to find out how to get rid of or kill Japanese Knotweed because the sight of it on your property is enough to strike dread into the heart of any property owner.
Japanese Knotweed is not an easy plant to control and trying to get rid of or kill Japanese Knotweed yourself is not easy and takes patience! The most common method is to use a glyphosate herbicide but this will require a high dosage and it will not be eradicated after just one dose, it will require repeated doses to completely rid your property of Japanese Knotweed and may take a few seasons.
As from 26th November 2015 anyone who purchases herbicides/pesticides authorised for professional use must ensure that the intended end user holds the relevant specified certificate(s). (Section 9 (5), The Plant Protection Products (Sustainable Use) Regulations 2012) & (Part III of the Food and Environment Protection Act 1985, and related Codes of Practice).
- Regulations 49 and 50 of the European Communities (Birds and Natural Habitats) Regulations 2011 make it an offence to plant, disperse, allow dispersal or cause the spread of Japanese knotweed.
- Keep the plant in possession for purpose of sale, breeding, reproduction, propagation, distribution, introduction or release.
- • keep anything from which the plant can be reproduced or propagated from without a granted licence.
- • keep any vector material, in this case soil or spoil taken from Japanese knotweed, for the purposes of breeding, distribution, introduction or release.
- Regulations 49 and 50 of the European Communities (Birds and Natural Habitats) Regulations 2011 make it an offence to
- plant, disperse, allow dispersal or cause the spread of Japanese knotweed.
- keep the plant in possession for purpose of sale, breeding, reproduction, propagation, distribution, introduction or release.
- keep anything from which the plant can be reproduced or propagated from without a granted licence.
- keep any vector material, in this case soil or spoil taken from Japanese knotweed, for the purposes of breeding, distribution, introduction or release
In Ireland Japanese Knotweed is classed as a ‘controlled waste’ under the Environmental Protection Act. This requires disposal at licenced landfill sites.Remember new legislation now makes it an offence if you cause Japanese knotweed to spread from your property either intentionally or unintentionally.
Things to Know about Japanese Knotweed
- Do not attempt to dig out Japanese Knotweed, this can actually encourage the plant into growing faster, therefore colonising an area more aggressively
- Do not move or dump soil which may contain plant material as this may also add to its spread.
- Do not attempt to pull the plant out of the ground, as this can expose part of the infectious crowns, stimulating growth
- Do not use unlicensed herbicides close to any watercourses, plants or wildlife
- Do not compost any part of the plant as due to the resilient nature of knotweed it could survive and grow on when the compost is ready for use
- Do not dispose of Japanese Knotweed in garden waste allotments as this just transport the plant to new locations
- Do not spread any soil that has been contaminated with Japanese Knotweed rhizome as new plants will sprout
- Do not do break the law – Remember it is an offence if you cause the spread of Japanese Knotweed either intentionally or unintentionally.
- If you find Japanese Knotweed on your property it needs to be dealt with as soon as possible, if it is ignored and stands of Japanese Knotweed become established it can become very difficult to control.
- For instance if a herbicide spraying programme is not carried out correctly – depending on the level of infestation, it may need to be applied over a number of years – then the plant may be put into a dormant state, meaning that it will not actively grow for a time, but after which it will re-grow.
- Proper treatment by a professional takes 3 years – Typical treatment results in 97% success year 1 , 2% year 2 & 1% year 3 – years 2 & 3 are typically to observe that none of the plants have survived.
- Use of the wrong herbicide increases this risk and makes the spraying a waste of money and your time. The dormancy may last for a couple of seasons but will regrow with as much strength and force as before.
- If you have Japanese Knotweed on your property & wish to find out how if can be eradicated please feel free to contact us at firstname.lastname@example.org & we will give you as help as we can.