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Providing evidence to improve practice

Action: Floating pennywort: Chemical control using herbicides Control of Freshwater Invasive Species

Key messages

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  • A controlled, replicated study in the UK found that the herbicide 2,4-D amine applied at 4.2 kg/ha achieved near to 100% mortality, compared with the herbicide glyphosate applied at 2.2 kg active ingredient/ha (without an adjuvant) which achieved  negligible mortality.

Supporting evidence from individual studies

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A controlled, replicated field experiment in 1997 in the Addlestone Bourne flood relief channel England, UK (Newman & Dawson 1999) found that the herbicide 2,4-D amine achieved near to 100% mortality, compared with the herbicide glyphosate which achieved  negligible mortality. The chemical 2,4-D amine applied at 4.2 kg/ha achieved 76% decrease in floating pennywort Hydrocotyle ranunculoides biomass and almost 100% mortality over the first four weeks of treatment.  In comparison, treatment with glyphosate applied at 2.2 kg/ha (without an adjuvant) resulted in a 20% decrease in biomass over the first four weeks and negligible mortality.  Two trial plots in a 65m section of the channel were marked out and subdivided into six treatment blocks.  Two blocks were sprayed in 2,4-D amine, two in glyphosate, and two were left untreated in control plots. Wet weight of root and shoot material/m2 was taken before treatment, and each week after treatment for four weeks following herbicide application. Percentage cover measurements were made each week until nine weeks after spraying.

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.