'Reckless': Farmers warned over 'underestimated' problem of Japanese Knotweed

A notice warns of knotweed spraying in Wexford town.
A notice warns of knotweed spraying in Wexford town.

Ralph Riegel

Farmers and gardeners have been warned that accidentally planting or recklessly allowing Japanese Knotweed to spread to another property could result in a prosecution.

The warning came as experts stressed that the scale of the national problem posed by the invasive species has been underestimated.

Japanese Knotweed remains a problem in gardens, ditches, wasteland and even woodland nationwide despite an expensive campaign by local authorities over recent years to eradicate it.

The Asian plant, scientifically known as Fallopia Japonica, was introduced to Ireland by landscape gardeners in the 1850s when its full characteristics were not understood.

Japanese Knotweed infestation on the Coomnahorna River in Caherdaniel, Co Kerry Photo: Japanese Knotweed Company.com
Japanese Knotweed infestation on the Coomnahorna River in Caherdaniel, Co Kerry Photo: Japanese Knotweed Company.com

It is so aggressive that, once established, it spreads to dominate entire areas, forcing out native plant species.

Because the plant lacks natural predators in Ireland, it spreads at a remarkable rate.

Its extensive root network also makes it exceptionally difficult to remove - cutting it back merely results in the root network re-establishing the plant.

Only special weedkillers applied over repeated treatments helps eradicate the entire stand of Japanese Knotweed by destroying the root network.

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Councils nationwide now place warning signs on confirmed Japanese Knotweed growths by roadsides - and then order multiple chemical treatments to kill it off, particularly along roadsides.

Because the root network is so persistent, it can even cause damage to walls and structures over time.

The National Biodiversity Data Centre stressed that the Asian plant is a strictly regulated species.

"Under Regulation 49(2) any person who plants, disperses, allows or causes to disperse, spreads or otherwise causes to grow Japanese knotweed or any of the other invasive plants listed in the Third Schedule of the European Communities (Birds and Natural Habitats) Regulations, 2011 shall be guilty of an offence."

"Furthermore, Sections 52(7) and (8) of the Wildlife Act, 1976, as amended, make it an offence to plant or otherwise cause to grow in a wild state exotic species of plants."

In the UK, owners who have uncontrolled Japanese Knotweed growth within seven metres of a property they are trying to sell must offer a detailed eradication programme or else face significant losses on the value of their property.

The UK introduced a special code to deal with the plant's spread.

Two years ago, respected botanist Dr Frances Giaquinto stressed that Japanese Knotweed was now a threat in every single Irish county.

Dr Giaquinto, who also works as an ecologist, said she had examined dozens of Japanese Knotweed growths in the gardens of private properties around Dublin.

These were noted in both urban and rural locations.

Online Editors


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