Confused about Japanese knotweed treatment options? We’re here to help

If you discover Japanese knotweed on your property, pick up the phone, not a spade, weed-killer or can of petrol.

The Royal Horticultural Society recently changed its official advice on Japanese knotweed from suggesting individuals can attempt to treat it themselves, to advising that professional help is sought. 

Quite simply, most DIY attempts at treating knotweed fail. It’s not possible to burn it and it’s extremely unlikely that any DIY attempt at digging it out will be successful as the plant can regrow from a tiny piece of rhizome as small as a fingernail. In fact, you are more likely to unwittingly spread the knotweed than to get rid of it.

There are three treatment options available to you. The first is herbicide. The plant will be sprayed during two annual growing seasons (April to September), with a monitoring visit in the third and fourth year to check for any regrowth. Any small re-growth shoots that emerge can then be dug out or be resprayed. This is the cheapest method, but as the plant can only be treated while it is in leaf, it takes two to three years to complete. It’s also difficult to say for certain that the plant is dead  as it can lie dormant in the ground for many years.

The second option, which is much quicker and more environmentally friendly and offers absolute certainty, is to excavate the Japanese knotweed using our Resi-Dig-Out™ method, digging up the soil and sifting through it to remove every tiny piece of knotweed rhizome, piece by piece. The rhizome is disposed of in accordance with the Environmental Protection Act 1990 and the clean soil is returned to the ground. The Japanese knotweed will be completely removed within a matter of days and the treatment can be carried out at any time of year.

The third option is our DART™ method, a half-way house between herbicide and Resi-Dig-Out™ in terms of time taken, cost and result. The majority of the rhizome system is physically removed followed by a herbicide treatment programme on any knotweed that remains. The excavation process breaks any dormancy encouraging any remaining rhizome to grow, thereby making any follow –up herbicide treatment much more effective.

Resi-Dig-Out™ and DART™ are proving to be the only realistic options where previous botched attempts with herbicide have been made.

Over a quarter (27%) of our clients now opt for Resi-Dig-Out™ or DART™ attracted by the ‘quick fix’ and certainty even though the costs are higher. Both treatment methods come with an insurance backed guarantee which is underwritten by a syndicate at Lloyd’s for up to ten years. Should any regrowth be experienced, further treatment would be carried out under the guarantee at no extra cost.

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