Curly waterweed (2020) – steam treatment

Dead and gone: Steam exposure kills layered clumps of invasive curly waterweed Lagarosiphon major

© Rose Muir

This study assessed how effective steam treatments were on layered clumps of curly waterweed (Lagarosiphon major).

Mature L. major stems were placed in mesh bags, and were stacked three high on a mesh sheet. The bags were divided into nine squares and were treated with steam for 5-120 seconds. After the steam treatment, each bag was allowed to cool for 15 minutes and then transferred to a water-filled tank. The L. major in each bag was examined for tissue degradation and new growth at seven days post-steam exposure.

Across all three layers, significant degradation of L. major occurred after steam exposure of 30 seconds and longer.

This study suggested that steam treatment could be implemented at designated biosecurity stations as an effective method for invasive non-native species control.


Coughlan, N.E., Armstrong, F., Cuthbert, R.N., Eagling, L.E., Kregting, L., Dick, J.T.A., MacIsaac, H.J. and Crane, K. (2020). Dead and gone: Steam exposure kills layered clumps of invasive curly waterweed Lagarosiphon major. Aquatic Botany, 162, 103204.

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Invasive Species Ireland

Invasive Species Ireland