Weed Control Update: Reintroduction of Glyphosate Treatment

Hounslow Highways, on behalf of the London Borough of Hounslow (the Authority), is responsible for delivering weed control services across all adopted streets where the borough acts as the Highway Authority.

Our aim is to ensure that weed control maintains an adequate level of amenity for all users of the borough’s adopted streets. This means ensuring that weeds do not impair safety, cause damage, or become a nuisance. Weed management is carried out on hard surfaces such as carriageways, footways, and footpaths, and where appropriate, in grassed areas, hedge bases, and shrub or rose beds.

Service Delivery Approach

In 2019, the use of chemical weed treatments was halted in support of the Authority’s ambition for a cleaner, greener borough that promotes biodiversity and encourages wildlife. Since then, weed removal has been carried out manually.

However, manual removal is labour-intensive and has proven less effective, particularly against persistent and deep-rooted species. Invasive weeds such as Japanese knotweed (a notifiable species under the Wildlife and Countryside Act 1981) and Mare’s Tail (also known as horsetail) present significant challenges due to their aggressive root systems. These species often require targeted herbicide treatment and, in some cases, excavation.

Why Glyphosate Is Being Reintroduced

Following extensive discussions with the Authority, it has been agreed that glyphosate-based treatments will be reintroduced for the 2025 season. This decision will be reviewed again next year.

The reintroduction is necessary due to:

• The increasing prevalence and density of weed growth
• The impact of weeds on road and footpath safety and infrastructure
• The limited effectiveness of manual removal alone

How the Programme Will Work

• Treatment Schedule: A borough-wide programme has been developed, prioritising wards based on need. You can download the weeding ward programme here Spraying Dates 2025 Map Version.
• Two Spray Cycles: Glyphosate will be applied in two treatment cycles across the borough.
• Effectiveness Monitoring: Inspections will be carried out to assess the success of the treatment.
• Manual Support: Our teams will continue to manually remove weeds from strategic routes and areas where chemical treatment is less effective.

Important Considerations

• Weather Sensitivity: Glyphosate application is weather-dependent. High temperatures can cause the spray to evaporate, while rain can wash it away, reducing its effectiveness.
• Persistent Growth: Due to several years of unchecked growth, some weeds may not be fully eradicated even with chemical treatment.
• No Weed, No Spray: Streets without visible weed growth will not be treated. If you wish to remove the weeds in your road before our teams arrive, then we will not spray where there is no weed.
• Obstructions : Spray treatment cannot be applied where weeds in channels are obstructed by parked cars.

Please click here for further guidance from the London Borough of Hounslow.

We remain committed to maintaining safe, accessible, and pleasant public spaces while balancing environmental responsibility. Thank you for your continued support and understanding.

FAQ

• Can we remove all the weeds on the public roads and footpaths?

No, our focus is weed control rather than weed eradication. The spray will help us manage the excessive weed growth, however we will not be able to spray every road or remove every weed manually.

• Do you manage weeds on TfL roads?

No. TFL arrange for the spraying and treatment of the weeds on their own network.

• Can I ‘opt’ out of having my road sprayed?

No.  There is no opt-out option. However, if you wish to remove the weeds in your road, and there are no weeds present when our teams visit, as per the programme, then they will not spray.

If you notice weeds that could impair safety, cause damage, or become a nuisance, please submit an enquiry online via FixMyStreet, and the location will be inspected.

• Why weeds cause such a problem that a toxic chemical must be used to manage them, when after all they are natural harmless things?

Unmanaged weeds on adopted footways/ carriageways can cause hazards to pedestrians by obstructing the footway, obscuring defects and causing hazards that could result in injuries through trips and falls. As well as being unsightly and giving the impression of neglect (if unmanaged) weeds will cause defects by creating gaps, asphalt breakdown and pushing up/ out slabs and kerbstones overtime. When left to grow and then being removed their extraction can also breakaway asphalt and filaments on the highway. Over longer periods this will require repairs and resurfacing which is more costly to the Authority in terms of financial costs and carbon outputs. Therefore, although weeds encourage biodiversity, they do need to be removed to protect the integrity of the footways and carriageways.

• What have you tried in the past to manage weeds?

Since ending the use of glyphosate on adopted highways in 2019, except use for hazardous weeds (Japanese Knotweed, bamboo, Giant hogweed), we investigated alternative treatments such as vinegar, hot water, non-glyphosate-based chemicals. The methods trialled included the use of Foamstream, heat lances, electric lancers, mechanical weed brushes (on mechanical sweepers, edging machines and strimmers). We found none of these have proved as effective as applying a treatment in a managed way, in large part due to the constraints on removing weeds in an urban environment with parked cars obstructing the deployment of heavy equipment in a safe manner.

As much as possible, since 2019, we have been removing weeds using manual removal with operatives supported by mechanical sweepers, however, this is a very labour-intensive process, and manually removed weeds re-grow faster and more aggressively. Hence, the main benefit of a chemical treatment such as glyphosate is that it can be deployed effectively and economically at a rate that reduces the germination and future growth of weeds, and so prevents deterioration of the highway’s assets.

• Precisely what effects are going to be monitored in the future, and how will you do this monitoring? 

Many UK councils have taken it upon themselves to go pesticide-free, but there is no national ban on using pesticides in our urban areas. Glyphosate remains approved for use until at least the end of 2025. The concentration of Glyphosate in weed sprays for the highway is low. Weed spray is applied during calm, dry weather, as windy, wet weather will render the spray non-effective.

The Council will be promoting a Natural Summer where sections of grass in parks will be left to grow for the Summer. A number of large highway verges will also be left to grow for the month of May, as well as approximately 30 wildflower highway sites have been planted throughout the borough to encourage biodiversity.

Reviews will be conducted throughout the period of usage to determine the effectiveness of the treatment before we commit to a longer period of less frequent use, as we used to prior to 2019. As we have not treated weeds for five years, the first year will be quite intensive, but this will revert to standard use over time in line with accepted industry standards used across the Country by many other Councils.