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Providing evidence to improve practice

Action: Skunk cabbage: Physical removal Control of Freshwater Invasive Species

Key messages

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  • A study in Switzerland found that annual physical removal of recently established skunk cabbage plants over five years removed the entire stock.
  • A study in the Netherlands found that manual removal of mature skunk cabbage plants was effective for a small outbreak of a small-growing plant.
  • A study in Germany reported that after the first four years of a twice yearly full removal programme of skunk cabbage, a large number of plants still needed to be removed each year.

Supporting evidence from individual studies

1 

A study in 2003-2008 in Switzerland (Buholzer pers. comm. (2009) In European and Mediterranean Plant Protection Organization 2009) found that annual physical removal of recently established skunk cabbage Lysichiton americanus plants over five years removed the entire stock. One hundred plants were removed in 2003, compared with 20 plants in 2004, and only a few individual plants in each of 2007 and 2008.  In 2007 and 2008, no more plants had germinated.  From 2003 to 2006, two people removed the plants by hand on an annual basis following which a monitoring programme was put in place to check for regrowth every second year.  Total costs to 2009 were reportedly around €1000, declining from €500 in 2003, to just monitoring costs from 2008 onwards.

2 

A study in 2005-2008 in the Netherlands (Rotteveel 2007) found that manual removal of mature skunk cabbage Lysichiton americanus was effective for a small outbreak of a small-growing plant.  In 2008, two plants of over one year old, and dozens of new seedlings were found and subsequently removed by volunteers.  This followed an annual inspection and removal programme which started in December 2005.  Following removal, skunk cabbage plants were dug up, and then buried deep in the ground.  No further information was available.

3 

A study in 2004-2008 in the Taunus region in Germany (Fuchs et al. 2003) reports that manually removing mature skunk cabbage Lysichiton americanus was not effective as plants build up a seed bank which lasts for at least eight years.  After the first four years of a twice yearly total removal programme, plants with leaf length in excess of 80cm were no longer found.  However, a large number of plants still needed to be removed each year.  In 2008, at least 3,773 skunk cabbage plants were removed in the Taunus region. The programme involved removal of all skunk cabbage stands twice each year.  No further information was available.

Referenced papers

Please cite as:

Aldridge, D., Ockendon, N., Rocha, R., Smith, R.K. & Sutherland, W.J. (2019) Some aspects of control of freshwater invasive species. Pages 569-602 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.