AUNE CONSERVATION ASSOCIATION

'Conserving the Devonshire Avon from source to sea'

A REQUEST FOR HELP WITH CONTROL OF INVASIVE WEEDS IN SOUTH DEVON

The problem of non-native plant species such as Japanese Knotweed and Himalayan Balsam is widely recognised in South Devon. These plants were first introduced to this country as novel, ornamental garden varieties but have since escaped into the general environment.

Knotweed is of particular concern. Whilst it is not an offence to have knotweed growing on one's own property, it is a potentially expensive liability for land- and property-owners for the reasons given below.

• Damage to paving and tarmac areas
• Damage to flood defence structures
• Damage to archaeological sites
• Reduction of biodiversity through out-shading native vegetation
• Restriction of access to riverbanks for anglers, bank inspection and amenity use
• Increased erosion when the bare ground is exposed in the winter
• Obstructed visibility and access on roads and paths
• Reduction in land values
• Increased risk of flooding through dead stems washed into river and stream channels
• Increased risk of soil erosion and bank instability following removal of established stands in riparian areas
• Accumulation of litter in well established stands
• Aesthetically unsightly appearance
• Expensive treatment regimes (e.g. £1/sq.m for a spraying regime over 3 years not including re-landscaping)

Clearance needs to be dealt with very carefully to avoid spreading the weed further and waste containing knotweed fragments can only be moved under strict regulations to authorised disposal sites. Unfortunately, rivers provide a very effective means of dispersal for cut stem or rhizome fragments of these plants and frequently are the basis of new infestations - the Avon is no exception!

Japanese Knotweed

Active control work is being undertaken by a variety of organisations and landowners across the South Devon area. However, this investment in a knotweed-free future is being placed at risk by inaction on other knotweed sites. Any untreated location provides the source material for the plant to spread back to treated areas at a later date. Obviously, the cooperation of landowners is paramount in weed management but the development of effective control strategies depends upon the collaboration of numerous interest groups Specifically, the Aune Conservation Association (ACA) can help in the identification of infestation sites because of our strong local membership and our combined knowledge of the Avon's catchment.

The first step in any eradication programme is to establish the extent of the problem. Although the Devon Biodiversity Records Centre (DBRC) has reports of over 150 knotweed sites in South Devon, this record is probably a gross underestimate for various reasons. Frequently, landowners/ householders will ignore these weeds because the costs of a) regular chemical control b) careful removal and c) transport of controlled waste are perceived to be too high when weighed against the other option of letting Nature take its course. Unfortunately, the option of doing nothing is exactly what allows the progressive spread of these invaders to previously unaffected areas. Other reasons for under-reporting of knotweed include ignorance of the problem by landowners/ householders and difficulties in identification of the plant.

HOW CAN YOU AND THE ACA HELP?

The ACA has held preliminary discussions with Roger English from the South Devon AONB Unit about the possibility of establishing an area-wide eradication programme for knotweed based on information about infestation sites provided by our members and the general public. Affected areas would be treated by registered contractors at no cost to individual landowners/ householders. We would hope that by joining such a project, owners could be relieved of any financial and legal burdens associated with eliminating this invader. Similar community projects have been successful in North Devon.

If you have seen any knotweed anywhere around the Avon or, indeed, anywhere in South Devon when out and about walking, bird-watching, angling or picnicking, etc., on public or private land, please let us know by contacting
either
Roger at Roger.English@southhams.gov.uk
or
me at chairman@auneconservation.org.uk
We need to know what you saw, together with where and when you saw it - as with all recording the more detailed your information, the more useful it becomes.
You can also obtain a reporting form for knotweed from the following source:
http://www.devon.gov.uk/japanese_knotweed_recording_form.pdf
or I can provide a copy.
If we can build a comprehensive picture of the current situation in our river catchment area, we can help to plan a fund-raising and eradication strategy with AONB staff.

Himalayan Balsam

Although Himalayan Balsam is not in the same league of problems as the knotweeds, it is a highly invasive annual which is spread very effectively by seed dispersal. The plant is rife in many of the side streams around our estuary. It reduces biodiversity by competition for space and nutrients, and its vigorous success is adding to the problem of progressive siltation of our waterways. We plan to organise some seasonal working parties before the flowering season next year to limit the spread of this invader and you could help by volunteering!

FURTHER INFORMATION

1. For help with identifying Japanese knotweed and other knotweeds found in the South West:
   see http://www.devon.gov.uk/knotweedbooklet.pdf
    
2. For help with identifying balsam see pages 14 & 15 of:
   http://www.environment-agency.gov.uk/static/documents/Leisure/GEHO0307BLZO-e-e(1).pdf
    
3. The Aune Conservation Association (ACA) has been in existence for about 30 years but it was only in April 2007 that it became a bona fide environmental conservation charity with the main objective of promoting the conservation, protection and improvement of the physical and natural environment of the river Avon for public benefit. Much of this work goes on behind the scenes but involves extensive liaison with various bodies and official government agencies about a range of issues including water quality, safe navigation, ecology, planning and research. In a more obvious way, we work hard to keep the river clean, which is important for biodiversity, tourism and human health. We also organise public lectures on topics of relevance to the wellbeing of the river. These efforts and our communications with around 300 members, mostly living around the Avon, depend entirely upon volunteers.

Stuart Watts - October 2009