The foreigners who are destroying the Wild Atlantic Way
Published 10/08/2015 | 02:30
It was a Dutch explorer, Philipp von Siebold, who first introduced the problem that would cost Europe hundreds of millions of euro. He returned to the Netherlands with his samples from the slopes of a Japanese volcano in 1847 and then posted a cutting to Kew Gardens in 1850. The rest is geography.
Gertrude Jekyll helped bring the foreigner to Ireland. She collaborated with Edwin Lutyens and designed the gardens at Lambay Island for Lord Revelstoke (founder of Baring's Bank). In a 1900 edition of 'Home and Garden' she extolled the plant's utility: "We ought not forget the quick growing ways of the great Japan knotweeds growing fast and tall".
This week, Kerry County Councillor Michael Gleeson described the weed as an unmanageable monster that is the country's biggest environmental threat. Citizens are spreading the problem by hedge-cutting and disposing of the weed in local dumps. You could be prosecuted if you do this, as fragments can continue to propagate.
Not as obvious as giant rhubarb (Gunnera tinctoria) or rhododendron, Japanese knotweed has white flowers and heart-shaped leaves.
It is the asbestos of the landscape and it is flowering now. Dry rot in your house would be preferable to Fallopia Japonica in your garden.
Its extensive underground root system (rhizomes) can extend to seven metres wide and three metres deep, making excavation very difficult. It thrives on disturbance; a fragment the size of a nail tip can propagate a new plant.
The recession has created bumper growth, with unfinished building sites, rubble heaps and budget cutbacks in local authorities. It is their responsibility to ensure the weed is not spread through hedge-cutting, movement of soil or road maintenance.
A practical way of dealing with roadside growth would be to include weed management in the road maintenance budget.
Besides its disruptive impact on biodiversity - preventing growth of native plants and disturbing natural habitats - the knotweed can seriously damage house foundations - it eats tarmac and will grow through concrete.
In the UK, several mortgage companies have refused loans on properties where knotweed was identified.
One couple paid over €3,000 to eradicate the weed on a site before they would be granted planning permission to build.
An experiment in the UK is under way since 2010 and the results should be quantified this year. Researchers at the Central Agricultural Bioscience International have identified a psyllid bug, Aphalara Itadori, that only eats Japanese knotweed. This month, the post-flowering stage, is the best time to apply specialist herbicides.
Deep excavation and burial is more complex and requires professional attention.
In Ireland, the weed is particularly robust on river and canal banks, where it has caused damage to flood defences.
When it dies back in winter, river banks will erode and there is subsequent spoiling of fish spawning areas.
The problem with our watercourses is that the maintenance budgets fall between Inland Fisheries Ireland and the local authority. Ireland has adopted the EC (Birds and Natural Habitats) Regulations 2011, which contains provisions to address the problem. Regulations 49 and 50 prohibit the introduction and dealing in certain species of non-native plants (35) and animals (41).
However, according to BioDiversity Ireland, the Government has not yet given effect to Regulation 50, which makes it an offence to import, buy, sell or breed all listed invasive plants and species. Regulation 50 specifies two vector materials as the most threatening, the first is blue mussel seed (a threat to oyster fishing) and the other is the contaminated soil of Japanese knotweed. In essence this allows local authorities to delay implementing an efficient eradication programme.
The longer the delay, the greater the national cost to deal with the damage to fisheries and floodplains.
Delays in eradication also arise where there is multi-agency involvement. A Special Area of Conservation could require input from the OPW, Waterways Ireland, Inland Fisheries, Coillte, EPA, National Parks and Wildlife Service, Fáilte Ireland, Teagasc, NRA, Bord na Mona and, of course, Environment Minister Alan Kelly TD.
We do not need another quango to deal with this, simply better institutional integration, raising public awareness and use of existing resources to address the problem, which is fast overtaking our wild Atlantic roadsides.
Deirdre Conroy is a conservation specialist