Floating pennywort: Chemical control using herbicides

Overall effectiveness category Beneficial
Number of studies: 1
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How is the evidence assessed?

Effectiveness

80%
Certainty

70%
Harms

not assessed

Calculating overall effectiveness category

Background information and definitions

Application of chemical herbicides may offer a localised tool for management of floating pennywort Hydrocotyle ranunculoides provided regulatory approvals are in place. It is possible that efficacy will be enhanced by use of agents called adjuvants to bond the herbicide to the leaf surface, and the most effective adjuvants may show seasonality. For example, an information sheetpublished in the UK suggests that applications of 4-6 L/ha in 200 L water with an adjuvant called TopFilm at 1.2 L/ha work up to the middle of July whereas applications of 4–6 L/ha with a Codacide Oil adjuvant work from July onwards (Newman & Duenas 2010).

Newman J.R. & Duenas M.A. (2010) Information sheet: control of floating pennywort (Hydrocotyle ranunculoides). Centre for Ecology & Hydrology, Wallingford, UK. 3pp.

Study locations

Key messages

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.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

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.
Study and other actions tested
Referenced paper
Newman J.R. & Dawson F.H. (1999) Ecology, distribution and chemical control of Hydrocotyle ranunculoides in the U.K. Hydrobiologia, 415, 295-298.

Please cite as:

Aldridge, D., Ockendon, N., Rocha, R., Smith, R.K. & Sutherland, W.J. (2020) Some Aspects of Control of Freshwater Invasive Species. Pages 555-87 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Control of Freshwater Invasive Species

Related Actions

Actions	Effectiveness	Studies	Category
Floating pennywort: Public education Action Link	No evidence found (no assessment)	0	Synopsis Link
Floating pennywort: Physical removal Action Link	Likely to be beneficial	2	Synopsis Link
Floating pennywort: Environmental control (e.g. shading, reduced flow, reduction of rooting depth, or dredging) Action Link	No evidence found (no assessment)	0	Synopsis Link