COMHAIRLE CONTAE ÁTHA CLIATH THEAS
SOUTH DUBLIN COUNTY COUNCIL

South Dublin County Council Crest

MEETING OF SOUTH DUBLIN COUNTY COUNCIL

Monday, February 08, 2021

QUESTION NO. 1

QUESTION: Councillor Carly Bailey

To ask the Chief Executive for a report on the existence and management of invasive species such as Japanese Knotweed across the county. To ask where such species are located and how such species are managed and how successful this management is.

REPLY:

The Council's management programme to survey, map and treat locations of invasive species commenced in 2017 and continues to date. This involves the identification of locations where invasive species are present and then putting in place the surveying, mapping and treatment at the location concerned on an annual basis until such time as treatment is no longer required and monitoring can take over. Two staff members are assigned full time to the identification and treatment of invasive species.

The species identified include Japanese Knotweed, Giant Hogweed, Himalayan Balsam and Gunnera and there have been more than one of these invasive plant species found in some locations. Locations identified throughout the county include along rivers and streams, on public lands and in public parks, on roadside verges and in private property.

Control methods

Japanese Knotweed – foliar herbicide spray with follow up treatment until no regrowth is observed. Herbicide stem injection is used where plants are identified close to watercourses, next to private properties or where the growth is very well established.  Treatment by stem injection uses higher concentrations of the active ingredient than is used in foliar applications.  The Council’s interdepartmental approach attempts to curb the spread of Japanese Knotweed in particular, roadside verges are surveyed for presence of invasive species prior to the verge cutting programme taking place.

Giant Hogweed is harmful to human health as it produces sap that causes severe burns – in many instances safe removal of this plant type is the preferred control option, it is essential to remove the flower and seed heads in a safe manner and to avoid spread.  In some instances treatment by foliar herbicide spray is appropriate.

Himalayan Balsam – control is by hand pulling or strimming.

Gunnera – mainly found in wet, water logged areas. Control is by removal or foliar herbicide spray.