The catchment wide approach to Invasive non-native species

Logo: Medway valley Countryside Partnership

In the summer of 1999, the Medway Valley Countryside Partnership (MVCP) began working to control hotspots of the invasive non-native species giant hogweed (Heracleum mantegazzianum). This programme eventually grew to become the “Medway Catchment and River Cray Giant Hogweed and Non Native Flora Control Programme”, covering almost 200km of riparian land and including additional species.

The decision to begin treatment was a response to the problems caused by the plant and the lack of any existing coordinated effort to control it. Giant hogweed is covered under Section 14(2) of the Wildlife and Countryside Act, 1981, which effectively places the responsibility for control with the landowner.

However, with no single authority responsible for its control there had often only been limited action to reduce the spread of Giant Hogweed. In response to the hazards it posed and the lack of a coordinated approach, the treatment initiative was created to co-ordinate and support action taken by landowners to control giant hogweed.

Initial efforts targeted known hotspots which were causing a serious public health hazard, previously identified in the National River Authority’s 1995 River Corridor Survey and which had become more extensive in the years following.

The logistics of control in inaccessible locations can be challenging (MVCP)
The logistics of control in inaccessible locations can be challenging (MVCP)

MVCP adopted a partnership approach with the support of the Environment Agency, local borough councils, farming and conservation agencies and users’ groups. Links were built with landowners along the target sections of the Medway to coordinate treatment.

The methodology has remained similar over the years. The catchment wide approach, whereby landowners are actively involved and contribute to the scheme via MVCP, works well in ensuring that as much land as possible is treated, where required.

Glyphosate is applied by specialist contractors. This was chosen because it is an effective systemic herbicide, cost effective in large quantities and is approved for use near watercourses under the control of Pesticides Regulations (1986). Treatment is organised systematically each year with access either by land or by boat.  

Earlier in the programme MVCP staff carried out surveying but this proved to be logistically difficult and time consuming. In more recent years the contractor uses GPS to log locations and numbers of plants treated. The information is then stored and analysed using GIS.

The spray programme takes place during spring and early summer; after the new plants have germinated but before flowering. As the plant is usually a biennial any new growth that is missed or that appears after the treatment can be treated in the following year without risk of seed production. Later spot treatments can be organised if necessary to tackle any newly identified areas or subsequent growth which is a hazard to the public.

The landowners are contacted each year to raise awareness of giant hogweed and of their responsibilities. Each is offered the opportunity to join or continue the spray treatment programme, which we can offer cheaply due to subsidisation funding from partners and economies of scale. Participating landowners sign a consent form, which includes a payment agreement.

Communication is crucial to maintaining awareness and engagement. To this end MVCP produces up to 3 newsletters each year to update participants and interested parties as well as taking opportunities to promote the scheme in the press and at talks about MVCP’s work.

The majority of landowners have welcomed the scheme and taken up the offer of treatment, with a minority electing to carry out their own control. Due to a viable seed bank and some issues with landowner consent and therefore untreated stands, complete eradication has not been a feasible target over the last decade, but substantial reductions have taken place. MVCP continue to work towards filling any gaps in landowner knowledge so more plants can be treated, therefore the overall long term aim is the eradication of the plant in this catchment area.

Floating pennywort grows rapidly and even a small untreated area can cause new outbreaks each year (MVCP)
Floating pennywort grows rapidly and even a small untreated area can cause new outbreaks each year (MVCP)

Thegreatest threat to the success of the programme is non co-operative landowners who do not issue consent and non co-operative landowners who claim to carry out their own control but do not. Other significant issues include finding a low cost method of sourcing landowner data and access issues, which make treatment difficult.

The project is now a much bigger task since the time of its inception and involves almost 300 landowners. Despite its growth in size and the greater management required the project’s catchment scale methodology, involving landowner consent and greater blanket control, proves successful.

More recently the programme has been expanded to include additional invasive non native species with some areas of riparian Japanese knotweed (Fallopia japonica) Himalayan balsam (Impatiens gladulifera) and floating pennywort (Hydrocotyle ranunculoides) addressed. Each species presents its own control challenges and although economies of scale are helpful, the lifecycles often mean that treatments for different species cannot be performed at the same time.

With the catchment wide approach having proved largely successful, the focus is now on the next five years and how to transition to a model which is sustainable without much of the funding the scheme currently receives. The issue of non-compliant landowners will have to be tackled by working with organisations such as the EA, Police, neighbours and users. More partnerships will be needed with local communities to help with swift identification and treatment of fast spreading species such as floating pennywort.

With the widespread use of smartphones, new tools are becoming available to help identify and report invasive non native species. The PlantTracker app ( enables the user to submit geo-located photos and the information can then be shared with those operating control programmes.

Whatever tools are used, the lesson from our experience are that a partnership approach, drawing together support from all relevant agencies and all those affected, is essential.

You can contact Andrea Griffiths, Senior Partnership Officer / Medway Valley Countryside Partnership 

3 Lock Cottages, Lock Lane, Sandling, Maidstone, Kent, ME14 3AU

Tel: 03000 414795 /   /

First published in CJS Focus on Volunteering in association with GB Non-Native Species Secretariat on 2 December 2013