Knotweed is best dealt with via spraying and/or stem injection as is Hogweed, you are correct it can cause serious rashes. All these species were initially imported by the victorians for ornamental gardens, over the years they have escaped and spread, hence the problem now.
Here is an article i wrote whilst working in scotland as part of our then Biosecurity plan sorry if its long winded, applies to all of Uk not just Scotland.
Invasive Non Native Species
Cleaning our own doorstep
There are approximately 1000 non native species present in Scotland, the majority exist in small populations with little or no impact on the native flora and fauna. There is however a small, significant proportion that are deemed invasive non native species (INNS) - species that have been transported outside of their natural range and that damage our environment, the economy and the way we live. These are seen as the second greatest threat to biodiversity and can rapidly colonise a wide range of habitats pushing out native species.
Over the last 400 years INNS have contributed to 40% of animal extinctions where the cause of extinction is known. Water acts as an excellent transport medium for the dispersal of many of these species, rivers, lochs and shorelines are the most vulnerable areas to introduction. Already threatened species are at further risk from INNS as are the natural productivity and amenity value of waterbodies.
The threat is increasing rapidly aided by climate change, pollution and habitat disturbance with many countries including Scotland facing complex and costly problems associated with INNS. For example:
DEFRA have estimated that INNS cost the UK economy at least £2 billion per year
In the UK Japanese Knotweed is thought to affect an area roughly the size of London and report of the Review of Non-Native Species Policy 2003 has estimated the total cost of its removal using current techniques at £1.56 billion.
A Scottish Govt report estimated the potential Net economic value loss to Scotland of the introduction of Gyrodactylus salaris at £633 million with severe consequences to rural communities.
Estimated cost of clearing Rhodedendrum ponticum from Loch Lomond and Trossachs national park is £25 million.
Invasive species have already changed the character of iconic landscapes and waterbodies in Scotland reducing the amenity value in those areas.
There is also a growing recognition of translocated species. These are native species that have been transported outside their natural range and can also have severe ecological impacts. It is important to note that once a species gains a foothold then it can be very difficult and expensive to eradicate.
At the moment there are approximately 20 biosecurity plans being drawn up and implemented through the Rivers and Fisheries Trusts of Scotland
( RAFTS) as part of a national programme of action with support from the Scottish Government, Scottish Natural Heritage, Scottish Environment Protection Agency and the Esmee Fairburn Foundation.
The vision is
“ To establish a sustainable framework leading to the prevention, detection, control and eradication of Invasive non-native species within the Fisheries Trust region. This will be undertaken through the
application of appropriate management activities, data collection, liason, education and legislation.”
There are three main objectives in the realisation of this vision and are in accordance with established protocols for fish diseases and with the three key elements of the GB Invasive Non Native species Framework Strategy;
1) Prevention - Prevent introduction and spread of new INNS and fish diseases.
2) Early detection, surveillance, monitoring and rapid response - Establish optimum surveillance and monitoring and rapid response mechanisms for identified INNS and fish diseases which pose significant threats to local biodiversity and economy.
3) Mitigation, control and eradication - Effective control and eradication programmes for existing INNS and fish diseases.
The plans will describe the biosecurity issues of each Fisheries Trust area and will present the actions agreed with the stakeholders for the prevention, early detection and eradication of selected INNS. Key stakeholders include AAG ( Invasive species forum) Catchment groups, SNH, SEPA, District Salmon Fishery Boards and local councils ( Local biodiversity Action Forums)The aims and objectives of the plan will be achieved through a partnership approach in order to implement any actions. Ultimately the key to the effectiveness of the plan will be the building of local awareness, capacity and partnerships so as to ensure the success and long term sustainability of the presented actions. The implementation of this plan will bring many benefits to the local area:
Conservation and enhancement of local biodiversity
Protection of genetically distinct fish species
Restoration and improvement to aquatic habitats for a wide range of flora and fauna
Increased contribution of fisheries to the local economy.
In addition the plan will build on existing local plans:
Fisheries Trust Management Plan
River basin district management plans
Catchment management plans
Local Biodiversity Action plans
Conservation objectives of Special areas of conservation, sites of special scientific interest and special protection areas.
Current threats.
There are a number of species already gaining a foothold in Scotland, some of these have been recorded, due to location and terrain it would be easy for many species to go unnoticed, it is therefore essential that if any of the following species are discovered anywhere then they should be reported to your local SNH,SEPA or Fisheries Trust office.
Hymalayan Balsam
Japanese Knotweed
American Signal Crayfish
American Mink
Giant Hogweed
Gyrodactylus Salaris
A monogenean parasite belonging to the family Gyrodactylidae. G. salaris is a freshwater parasite of Atlantic salmon. Since first observed in Norway in 1975 it has had devastating effects on Norwegian Salmon rivers.It has never been recorded in the Uk and is a category 1 notifiable disease.
G. salaris requires only a single host and is viviparous ( gives birth to live young) and can produce 1000’s of offspring. The lack of immunity in Norwegian Salmon parr stocks led to devastating mortalities. Since first observed there has been an estimated loss of over 300 tonnes of fish. Within 10 years it had spread to 28 rivers and 11 hatcheries. Salmon parr populations in rivers reduced by 50% within two years and by 96% in five years. Affected rivers were treated with Rotenone killing all fish in the river. In some cases the fauna has re-established and stocks recovered, not all treatments have been successful and re-infection has occurred.
Stocking of infected fish is the most likely means of transfer. The parasite can be transferred in water, equipment or by other aquatic animals. It is therefore of utmost importance that all water users Ie Anglers and canoeists thoroughly disinfect all equipment when moving between not only countries but also catchments. Further information is available via the leaflet “ Keep Gyrodactylus salaris out of Scottish rivers” published by the Scottish office.
The species described above are just a very small selection of the current threats, more information can be found at
www.nonnativespecies.org along with descriptors and information sheets.
The threat is real and needs to be addressed locally, we need to clean our own doorstep, if all user groups, stakeholders and the general public pull together and are aware we can and will end this threat to our local environment, economy and lifestyle. Anglers can help in a big way, by observing the need for disinfection between catchments and acting as “eyes” they can report any unusual observations. If in doubt contact your nearest fisheries trust office or Sepa. If these species gain a foothold our sport, economy and lifestyle could be affected.
Knotweed
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