Castleisland – A Microcosm of Japanese Knotweed Infestation

Maps of Ireland and the UK showing the progress of of Japanese Knotweed from 1940 to 1980 to 2016.


Dan Casey’s photograph of the infested site beside Castleisland Rugby Club is typical of so many sites in the area.
The distinctive, red stemmed Japanese Knotweed pictured after recent hedge cutting on the Tralee Road in Ballymacelligott. ©Photograph: John Reidy

If you were to take Castleisland as a microcosm of the Japanese Knotweed problem you could easily see why and conclude that its rampant march throughout Ireland and the UK looks unstoppable.

The countryside around here is now paying the price of years of neglect of the progress of the seemingly indestructible weed as it took root at will where ever it wanted to.

Problems Greatly Exacerbated

Years of hedge cutting without knowledge or recognition of the problem the weed was posing has greatly exacerbated the now obvious problem around here – and everywhere else by the looks of the map.

Realisation that the countryside was under threat from the invasive species dawned only when signs began to appear on the grass margins of our country roads in the area.

Con Houlihan’s Old Home

When Con Houlihan’s old home in Reineen was being looked at a couple of years ago as a possible restoration project it was found to be smothered in knot-weed.

Look at Castleisland Rugby Club Chairman, Dan Casey’s photograph of a site beside the club on Rice’s Height and you’ll get an idea of the scale of the problem.

In spite of this, the annual and sometimes more frequent, roadside grass and hedge cutting sprees totally ignored these signs until recent years.

Contractors With Local Knowledge

Up to this year, hedge cutting contractors with local knowledge tended to avoid stretches of roadway where the knotweed dominated the growth.

However, this year was different as Kerry County Council’s procurement process ruled out all the local hedge-cutting contractors in favour of a hugely under-cutting tender from a company in Co. Louth.

County Council Accused of Hypocrisy

That company then approached several or all of the Kerry based contractors offering a price so low that most of them couldn’t afford to take on the work under the time pressures allotted.

The loss of that local knowledge led to huge swathes of knotweed being cut down with everything else and all the consequences.

One local contractor, reacting to the parachuting in of the Co. Louth involvement, accused the council of hypocrisy when it launched its ‘Shop Local’ campaign in September.

A Cure for Knotweed

It was also said by someone locally that the people in Duhallow IRD had ‘a cure’ for the knotweed.

That’s partly true but less a cure than an educated, sustained and systematic approach to its eradication.

Nuala Riordan is a Tús Supervisor with the EU Life Project in the Duhallow IRD area.

Over the past five years she has been deeply involved in a face-to-face confrontation with the dreaded knotweed problem.

Closely Controlled and Monitored

The River Blackwater and its many tributaries are within her area of care where chemical control of the plant in hedgerows and water courses has had to be closely controlled and monitored.

“We keep spraying and chemical use to a minimum and we found that picking our time carefully at the fall of the year when the flowers are dying back is the best time to deal with it,” said Nuala.

“We found that by applying a chemical just when the flowers were beginning to fade that the plant took it down to the roots and we began to see results.

Perfect Timing and Vigilance

“Vigilance is vital in the fight against knotweed and while the temptation to spray it into submission is there we found that the perfect timing approach and vigilance work best.”

Nuala’s area of responsibility stretches over to Doctors Hill on the Cork / Kerry border.  It is here that the North, East and West Kerry Development (NE&WKD) area begins and sweeps down to Castleisland.

Seán Linnane of NEWKD said that the company has been involved in a few successful multi agency pilot schemes in the West Kerry area and in Lyreacrompane in particular and he agreed that Castleisland, where the knotweed problem can be held up as a microcosm of the situation on this and the neighbouring islands,is a case that needs to be looked at in more detail.

Specialist Knotweed Company

There is a specialist knotweed company in Kerry: The Japanese Knotweed Company, Meanus, Killorglin, Co. Kerry.
066 97 9 6612, 087 664 7695

Click on the link here for more information:

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