Water primrose: Physical removal

Overall effectiveness category Unlikely to be beneficial
Number of studies: 1
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How is the evidence assessed?

Effectiveness

30%
Certainty

50%
Harms

not assessed

Calculating overall effectiveness category

Background information and definitions

Manual or mechanical removal of water primrose Ludwigia spp. with manual removal of any visible remaining fragments may offer a tool for localised population eradication.

However, it has been shown that water primrose demonstrates high regeneration capacity, and an ability to regenerate from small shoot fragments with a node with or without leaves (Hussner 2008). Therefore, it is important to carefully manage any mechanical removal program to prevent regenerative fragments from spreading to new locations.

Manual or mechanical removal programmes have been met with mixed success. For example, a review reports that effective management of large-flower primrose-willow Ludwigia grandiflora for eradication is relatively difficult, and mechanical removal tends to create viable fragments which can spread to new areas or recolonise existing managed sites (Plant Protection Service et al. 2011). A study found that mechanical harvesting, followed by several manual finishes over a two year period, eradicated large-flower primrose-willow. It was noted that ground realities, including inaccessible sites for heavy equipment, and difficulty observing the species, can strongly affect the feasibility (Legrand 2002). One study reported that in the early stages of water primrose Ludwigia spp. colonisation, removal by hand is usually possible, and that mechanised removal is only necessary when the plant has become well established (Thiébaut 2007).

Hussner, A. (2008) Ökologische und ökophysiologische Charakteristika aquatischer Neophyten in NordrheinWestfalen. Ph.D. Dissertation, Heinrich-Heine-Universität Düsseldorf, 192 pp.

Plant Protection Service, Plant Research International Wageningen UR, Aquatic Ecology and Water Quality Management Group & Centre for Ecology and Hydrology Wallingford (2011) EUPHRESCO DeCLAIM Final report A State of the art June 2011. Ludwigia grandiflora (Michx.) Greuter & Burdet. 63pp.

Legrand C., 2002. Guide technique : pour contrôler la prolifération des jussies (Ludwigia spp.) des zones humides méditerranéennes. Agence Méditerranéenne de l’Environnement, Montpellier, France. 68pp.

Thiébaut, G. (2007) Non-indigenous aquatic and semiaquatic plant species in France. In: Gherardi, F. (Ed.) Biological invaders in inland waters: profiles, distribution and threats. Springer, Dordrecht, pp. 209–229.

Study locations

Key messages

A study in the USA found that hand pulling and raking water primrose failed to reduce its abundance, whereas hand-pulling from the margins of a pond eradicated a smaller population of water primrose.

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 study in 2005 in a managed wetland in the Laguna de Santa Rosa, California, USA (Sears et al. 2006) found that hand pulling and raking water primrose Ludwigia sp. failed to reduce its abundance, whereas hand-pulling from the margins of a pond in the Laguna Wetland Preserve Sebastopol successfully eradicated a smaller population of water primrose. Attempts to reduce the coverage of primrose in the Laguna de Santa Rosa, California, were wholly unsuccessful and by the end of the season water primrose covered 100% of the pond. Hand pulling and raking were carried out for 2-6 person hours/week. Workers in the Laguna Wetland Preserve at Sebastopol spent approximately 150 person hours of effort hand-pulling water primrose from pond margins.
Study and other actions tested
Referenced paper
Sears A.L.W., Meisler J. & Verdone L.N. (2006) Invasive Ludwigia management plan. Sonoma State University and Marin/Sonoma Mosquito and Vector Control District, Sonoma, California report.

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

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Control of Freshwater Invasive Species

Related Actions

Actions	Effectiveness	Studies	Category
Water primrose: Public education Action Link	No evidence found (no assessment)	0	Synopsis Link
Water primrose: Chemical control using herbicides Action Link	Likely to be beneficial	3	Synopsis Link
Water primrose: Environmental control (e.g shading, altered flow, altered rooting depth, or dredging) Action Link	No evidence found (no assessment)	0	Synopsis Link