Ben Lindley, Company Director at Japanese Knotweed Ltd. Last reviewed on 25th November .
Japanese knotweed remains one of the most challenging invasive plants in the UK, and the well established methods of herbicide treatment, excavation and careful on site management are still the main options that we uphold as the best in market. However, as research continues to move forward, and a new generation of control methods and detection technologies is beginning to take shape, we explore what alternative options could look like in the future, and their potential effectiveness:
- Experimental physical control techniques
- Biological control using a specialist insect
- New ways of detecting and mapping knotweed using drones, satellites and artificial intelligence
Researchers are still looking for new answers for knotweed control
Integrated Weed Management (IWM) is nothing new but remains a hot topic with a lot of sectors. Japanese knotweed is resilient, long lived and difficult to remove completely. Rhizomes can survive at depth, regrow from small fragments and persist on disturbed ground. For large infrastructure projects, commercial sites and complex mixed use developments, this can mean:
- Extended treatment timelines
- Constraints on excavation and movement of soil
- Long term monitoring obligations
- Ongoing legal and reputational risk if infestations are not managed correctly
For these reasons, researchers are interested in ideas and methods that can either weaken knotweed, potentially in ways different to current methods, or find infestations earlier and more accurately. Below, we highlight several lines of work that are currently under investigation and ask the question – is any of it effective enough to consider?
Experimental physical control methods
Traditional control relies heavily on herbicides and excavation. New research has begun to explore how heat and energy can be applied directly to rhizomes in the soil – though there is currently no reportable substantial evidence that these methods are effective for long-term removal.
Microwave treatment of knotweed rhizomes
One recent peer-reviewed study investigated the use of microwave energy to control Japanese knotweed. In this field research, cut knotweed stems were exposed to microwave treatment at a frequency commonly used in industrial heating, for different time periods. The scientists recorded severe damage to the rhizomes and a marked reduction in regrowth after treatment.
The key findings were:
- Longer exposure times produced greater damage to rhizomes
- Above ground regrowth was significantly reduced when compared with untreated plots
- The authors stressed the need to assess wider environmental effects and practical costs before large scale use
Conclusion: Microwave control is best viewed as an emerging technology still to be fully tested. It shows that knotweed rhizomes can be targeted with energy in ways that may complement existing techniques, particularly in tightly constrained areas where excavation is difficult. It’s important to note its limitations and potential cost, and at this stage remains a specialist research tool rather than an off the shelf commercially viable solution.
Biological control with a specialist insect
Alongside physical methods, there has been some progress in the biological control of Japanese knotweed using a tiny sap feeding insect called a psyllid. This insect feeds specifically on knotweed and related plants in its native range. Introducing a specialist natural enemy is a long term approach that aims to reduce the vigour and spread of the weed over many years rather than remove it instantly.
Early work with one strain of the psyllid did not result in reliable long term establishment in the UK climate. More recently, attention has turned to a different strain collected from a cooler region that more closely matches British conditions. Monitoring reports for this strain have documented:
- Successful overwintering at certain test sites
- Multiple insect generations over the growing season
- Characteristic leaf curling and stunting on knotweed plants
- Evidence that heavy feeding can inhibit growth on some hybrid knotweed populations
Conclusion: It is important to emphasise that this work is still tightly regulated and carried out under official approval. Biological control for Japanese knotweed is not a quick fix and is not yet a routine option for individual properties. Instead, it is best understood as a potential background pressure on wider populations over a long period, particularly in riparian and semi natural habitats where large scale spraying or excavation may be challenging.
New ways to find and map Japanese knotweed
Invasive plants are much easier to manage when they are detected early and mapped accurately. That is why a growing body of research is focusing on remote sensing and artificial intelligence. These tools aim to identify knotweed from above, using patterns in light, colour and growth that are difficult to distinguish with the naked eye.
Drones and deep learning models
Several studies have now shown that drones equipped with suitable cameras can capture detailed images of invasive knotweeds from the air. When these images are processed with deep learning models, the software can be trained to recognise knotweed patches with a high degree of accuracy.
In one 2024 study, researchers flew drones over test sites that contained Japanese knotweed and other vegetation. They then trained convolutional neural networks and other machine learning models to distinguish knotweed from surrounding plants. The researchers reported strong performance in both detection and multi class classification.
For land managers and developers, this kind of technology could in time assist with:
- Surveying large or difficult to access areas more quickly
- Identifying patches that might be missed from ground level due to challenging access or terrain
- Tracking changes in the extent of infestations between seasons
Conclusion: These methods still require professional interpretation and on the ground verification from professional surveyors. However, they hint at a future where drone surveys form part of a wider toolkit for early detection and monitoring.
Satellite imagery and large scale mapping
While drones are suited to detailed local surveys, satellites can help at a broader scale. Research using freely available multispectral satellite imagery has demonstrated that Japanese knotweed can be mapped over larger urban and peri urban areas by analysing its distinctive spectral signature across the growing season.
One study used multi temporal satellite data and machine learning classifiers to detect knotweed patches in complex urban landscapes. The authors found that, when supported by reliable ground truth data, satellite based models could identify many medium to large stands of knotweed. Smaller patches remained harder to capture, which is one of the reasons drone and ground based surveys will continue to be important.
Conclusion: We often use this tech as additional resource for identifying areas of knotweed, as part of our overall surveying strategy. As satellite sensors improve and more archives of imagery become available, this type of approach may help contractors as well as clients understand how knotweed populations change over time, and where resources should be focused – but as the study reports state – it’s a tool to support ‘feet on the ground’.
Artificial intelligence as a decision support tool
Across both drone and satellite work, artificial intelligence is being used as a decision support tool rather than as a replacement for professional judgement. Machine learning models can highlight areas of concern and flag potential knotweed stands.
In practical terms, future workflows may look like this:
- Remote sensing tools identify candidate locations where knotweed is likely
- Surveyors ground truth those locations and confirm infestations
- Specialists prepare site specific management plans using proven control methods
- Remote sensing is used again to monitor progress over time
Conclusion: This integrated approach would combine the speed of modern technology with the reliability of established survey practice. They do not remove the need for qualified surveyors who understand the plant, the site and the legal context.
What this means for property owners and developers
For most homeowners, commercial property owners and developers, the current position is clear. The main methods of herbicide treatment, controlled excavation and careful management of soils and waste – when carried out by experienced contractors remain the best and most effective options. The emerging technologies described above are promising, but they are either in early research stages or used only in specialist contexts – or cannot be quantifiably conclusive in their effectiveness.
Key takeout’s from this ongoing research:
- Japanese knotweed is taken seriously enough to attract ongoing scientific study, which reinforces the need for proper management
- Future tools/methods are likely to focus on improving detection and weakening infestations rather than offering a complete solution
- Current identification, control and removal methods combined with long term monitoring will remain the safest and most effective approach
Conclusion: For large and complex sites in particular, it is important to work with a team that stays informed about developments in the field, understands how to interpret new research, and can explain clearly what is available now and what remains experimental. Here at Japanese Knotweed Ltd you can trust we’re up to speed!
How Japanese Knotweed Ltd stays informed
As a specialist contractor, we monitor developments in research, guidance and regulation so that we can give clients accurate, up to date advice. Where new methods show promise, we assess them carefully against practical considerations such as safety, cost, deliverability regulatory approval and long term effectiveness.
Our priority is to provide management plans that are robust, evidence based and suitable for the site in front of us. While the future of knotweed control may well involve advanced technologies and biological tools, the foundation remains clear reporting, sound risk management and experienced on site delivery.
If you have Japanese knotweed on your land, or you are planning works on a site where it may be present, our team can provide surveys, management plans and treatment programmes tailored to your situation.