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What Kills Japanese Knotweed Permanently

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  • 20-07-2022
What Kills Japanese Knotweed Permanently

What kills Japanese Knotweed permanently? We look at what methods kill Japanese Knotweed and which ones do not. Find out more about killing Japanese Knotweed.

How do I permanently get rid of Japanese Knotweed?

Tackling Japanese Knotweed is challenging, with it being one of the most invasive plants on the planet. Considered controlled waste, with specific removal methods used to eradicate Japanese Knotweed, getting rid of it permanently can be tough. To completely eradicate Japanese Knotweed, there are some things you can do. 

  • Correctly identify it. Knotweed is sometimes confused with Giant Hogweed, which is dangerous for different reasons. The sooner you can identify Japanese Knotweed, the sooner you are likely to remove it.
  • Cut canes to the ground. Cutting Japanese Knotweed is not an easy task and, when done incorrectly, can cause further spread of the plant. For this, you can be fined. Take great care when cutting down the bamboo-like canes, and remove them from your soil immediately afterwards.
  • Use a Glyphosate-based weed killer. To kill Japanese Knotweed, only apply the weed killer to the cut canes and avoid contact with other plants, as they will suffer. 

From there, you should be cutting the plants weekly, ensuring you do not leave any stems lying on the grass. Killing Japanese Knotweed takes time and precision, as the weed killer will not destroy them in one. You should also give the herbicide time to work, as applying too much will not achieve results.

If the plants continue to irritate, we advise you to contact professional help as soon as possible, and they can provide services or information on glyphosate-based weedkillers. Identifying the weed is essential because Knotweed is commonly confused with Russian vines and Himalayan honeysuckles, both of which present their own set of issues. 

Do These Methods Kill Japanese Knotweed?

The reason why it's so hard to remove Japanese Knotweed is because of the plant's rhizomes (roots) which work underground to spread quickly. Invasive non-native plants like Japanese Knotweed grows between 10-20cm per day because of the roots burrowing deep and wide from the visible plant.

How Do I Permanently Get Rid Of Knotweed?

Many websites will tell you the best method for Japanese Knotweed eradication is herbicide application, but this is not a long-lasting method and will not completely eradicate the invasive weed. 

Herbicide Treatment Programs (HTP) are effective in limiting Japanese Knotweed growth, but herbicide treatments cannot remove the rhizomes from the ground - which is crucial in controlling the weed.

Here are some common eradication methods you will find online, and if they really work. 

A popular means of removing Japanese Knotweed is using diesel. If you or neighbouring gardens are suffering from a Knotweed problem, you must treat the plants immediately. 

Diesel may look like it is controlling Japanese Knotweed, attacking the tall stems and hindering the top growth; it is doing nothing for the underground rhizome system.

All the dead Knotweed on top of the soil will not prevent more from growing back, and the diesel will actually potentially harm other plants in the surrounding areas. 

If the soil in your garden becomes infected with diesel, this is toxic to humans, children and pets. Using diesel in Japanese Knotweed removal is incredibly unethical because of this reason and, in some instances, can be illegal. 

Bleach is another common method used to control Japanese Knotweed due to its corrosive chemicals. Cutting the bamboo-like stems and pouring bleach down may remove top growth but, much like diesel, will not affect the rhizomes underground.

The stem growth may be halted by bleach, but the plant will continue to grow even after treatment. Bleach is also incredibly toxic to aquatic life and small animals, meaning if it makes its way to a pond or nearby soil, it can cause serious harm. 

When you burn Japanese Knotweed, the top growth will be affected, and you will effectively remove all stems from the above soil. However, the Knotweed will return in due course unless you remove rhizomes from underground.

Local council bylaws will outline burning laws and regulations, but burning Knotweed is a common practice among professional services. You should remain cautious when burning Knotweed, as you can leave a black patch on your land without removing the weed itself. 

Using vinegar to smother Japanese Knotweed and hopefully kill it will not yield the desired results. Many home gardeners use vinegar in multiple attacks on Knotweed, but new growth will continue.

No professional company or governmental guidance recommends using vinegar on Knotweed. While vinegar, dish soap and a spray bottle can provide effective control against common weeds when applied correctly, it is not recommended to use. It can cause skin irritation and kill surrounding flowers and plants. 

Pulling Knotweed stems from the ground seems like the sensible solution to your weed problem, but unless you follow specific instructions, you will not likely eradicate the weed. 

Creating Knotweed waste goes against the Environmental Protection Act (Duty of Care) Regulations 1991, and you can be fined if you do not dispose of this correctly.

You should not throw Knotweed stems onto your compost as it can cause further spread and should be disposed of by a professional company accredited by the Environment Agency. 

If you are concerned, hire a waste removal business for your property, and they will ensure rhizomes are removed from the soil and Knotweed infestations are a thing of the past. 

While mowing the Knotweed is being done in your best interest of clearing the garden, it can promote the plant's growth and break regulations outlined by the Wildlife and Countryside Act 1980.

Not only are you incredibly unlikely to completely kill the weed by mowing or strimming it, but you will also probably spread or disperse the plant around your property further by disturbing it. 

Having a proper management plan is vital, and you must dispose of it correctly, using a licensed landfill site and not throwing it in with your normal rubbish. 

Glyphosate-based herbicides have been found to help control the spread of Knotweed but will not lead to the complete eradication of the weed at your property. The best time to apply such products is in early Autumn when the heart-shaped leaves can absorb more. 

Glyphosate-treated Knotweed can stop growing for a time, appearing dormant, but further growth is possible if the herbicide has not attacked all the underground rhizomes.

Since Knotweed grows the fastest between Spring and Summer, you should apply all herbicide products during that time, and if the weed is growing near a fence, ask to use it near neighbouring land also. 

Glyphosate works by being absorbed by the weed and translocating throughout the entire thing. To remain safe, apply this to the cut canes or a foliar spray.

Regardless of what chemical controls you choose, you should apply them sparingly so as not to damage the surrounding areas. Wildlife and plants around you may be protected, and you should prioritise nature's health around the weed.

Due to the alkaline qualities, some homeowners have used lime as a natural remedy for removing Knotweed. This can neutralise acidity levels in the soil but can be dangerous for humans and animals on skin contact. Minimising risks to yourself and the plant's further growth should be your main priority. 

What is the problem with Japanese Knotweed?

Japanese Knotweed (fallopia japonica or polygonum cuspidatum) is one of the UK's worst invasive weeds, taking over entire areas with underground roots and spreading incredibly quickly throughout early Summer. 

It is extremely difficult to remove this non-native weed as it can span neighbouring properties, and most other methods used against weeds are futile.

The weed will bloom creamy-white flowers throughout late Summer and continue growth throughout Autumn, seeming to die out in the following Spring. This is a facade, and the roots are still alive underground for this cycle to repeat. The rhizomes can spread over 2 metres from the visible plant, meaning you can have a bigger problem on your hands than seen.

Knotweed was introduced to the UK as an ornamental garden plant, with the female being the only thing to be introduced. Due to this, the weed cannot seed as other plants do, relying on the roots and human disruption to spread further. Fly-tipping is the main contributor to Japanese Knotweed as the shoots can spread throughout ground-level disturbance.

While Knotweed is not poisonous or harmful to humans or pets, it can cause severe structural damage to property foundations and riverbeds, causing flooding and expensive fixes. Livestock can eat this plant, but this is not a permanent solution to removing the weed. 

Buying And Selling Property Where Japanese Knotweed Is Present 

There are, of course, complications with buying and selling property where Knotweed is found. All sellers must inform future buyers and estate agents when Knotweed is on their property, which is done through a TA6 form. Solicitors and Conveyancers can provide more legal advice and information, but you are required to make the presence of this weed apparent.

Some mortgage lenders will refuse a property outright when they know Knotweed is on the site, so you must provide information about it when selling. 

A TA6 form outlines your management plan for eradication and which trade body or professional company you're using to remove it safely from the site. Always look for someone accredited with the property care association (PCA) and with experience in removing invasive weeds.

While it is not illegal to have the weed on your property (as outlined in the Anti-social Behaviour, Crime and Policing Act 2014), you should be taking care to manage it so as not to spread it further. If you aid the spread of such a weed, you can be fined £2000 and spend up to 2 years in prison. 

This should be taken into account if you plan to sell your house in the near future. If your neighbour is threatening litigation against you for spreading the weed, you must defend yourself and leave it to the professionals.

While dealing with this weed is time-consuming, you should not leave it unattended as it will only worsen. Few other weeds can lay dormant over several seasons, but Japanese Knotweed can sprout when you're least expecting it and cause high disposal costs. 

By using a professional company such as our own, you receive insurance-backed guarantees we will remove it safely from your site, only performing work we deem safe. Please get in touch if you are suffering from an invasive weed issue at your residential property.

Do you have a Japanese Knotweed problem? If you require Japanese Knotweed Removal in Essex or throughout the UK, contact our expert today.