Kilcullen scientist's Skunk Cabbage programme 'very successful'

Skunk Cabbage on the Liffeyside in Kilcullen.

A programme to control the incidence of the invasive species Skunk Cabbage along the Liffey is working out very successfully, and at the same time providing important new knowledge in how to deal with it, writes Brian Byrne.

Kilcullen resident and ecologist Dr Jan Baars is leading the programme, which is part of a research initiative at the Invasive Ecology Lab in the UCD School of Biology & Environmental Science, where he works.

This summer marks the third year of the Liffey programme, which was kicked off when Jan Baars did an initial kayak survey of a 20km stretch of the Liffey, mapping out incidences of the bright yellow plant, escaped from ornamental ponds in gardens.

Jan Baars talking about life in the river to Scoil Bhride pupils last week.

Skunk Cabbage is originally from Alaska, and gives off a distinctive odour that gets it its name. It was brought to these islands in the early 1900s as an ornamental plant, and over the last century escaped into the wild, growing in wet and marshy areas. It was classified as an invasive species by the EU in 2018.

Dr Baars found one of the biggest populations of the species in Ireland was in Kilcullen itself, some 5,600 plants on the wetland area just across from Kilcullen Town Hall. As there was little guidance available on how to control or eliminate it, he set up a specific scheme on the Liffey to try out different ways of doing so. With the help of graduate students from UCD, the programme now has developed an important data base from which a number of publications have already been made. The work has been part-funded by grants from Kildare County Council and the National Parks & Wildlife Service.

With almost a hundred sites along the Liffey now included in the project, the experience gained in bringing them under control has found that a mix of spraying and manually pulling up young plants works well. But because seeds can live in the sites for up to eight years, it is necessary to go back at least every two years to deal with recurrent infestations. 

"It has to be continued, or what we have done to date will have gone to waste," Jan Baars told the Diary last week. "Adult plants take four years to flower, and we're now at the point where we can go back and pick up all the new juvenile plants, which are easier to find than seedlings." He says the numbers of plants they are now finding on the Liffey sites 'are reducing hugely'.

Dr Baars (right) working at the Kilcullen Skunk Cabbage site in 2021 with team members Matthew Curtis and Oscar Flynn.

In addition to the Liffey project, the Invasive Ecology Lab team are controlling sites for Dun Laoghaire County Council, at Blackwater in Co Clare, and in the Killarney National Park where there are some infestations through plants originating at Muckross House.

The control projects are very labour-intensive, as manual control with some spraying has worked out to be the most consistently successful. "The key thing is getting helpers who really pay attention, because every seedling has to come out. You need to be very systematic, with a team that cares very much about what they are doing."

Since Skunk Cabbage is an issue for many Irish waterways, in the end there will likely need to be a state-funded programme to try and  fully eradicate it, but for the moment Jan Baars is very appreciative of the cooperation of landowners in allowing access to sites, and support for the pilot project provided by Bridget Loughlin, Heritage Officer with Kildare County Council; and Eileen Canny, Divisional Ecologist at the National Parks and Wildlife Service.

"It doesn't cover our full costs, but the work is giving our staff valuable experience in dealing with invasive species." 

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