Parrot’s feather: Use of herbicides - endohall

How is the evidence assessed?
  • Effectiveness
    50%
  • Certainty
    40%
  • Harms
    0%

Study locations

Key messages

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

  1. A small, replicated, controlled, laboratory study conducted between 1999 and 2000 in New Zealand (Hofstra et al. 2006) found that the herbicide endothall reduced the growth of parrot’s feather Myriophyllum aquaticum. After 17 weeks, plants treated with endothall had a lower dry weight (29–57 g) than that of untreated plants (274 g). Plants were grown for approximately two months prior to herbicide application in 60 l plastic tubs. Endothall was sprayed onto plants in three tubs at a concentration of 9 and 15 kg/ha and plants in four tubs were left untreated.

    Study and other actions tested
  2. A replicated, controlled field study conducted between 2001 and 2002 in a wetland in the Northern Island of New Zealand (Hofstra et al. 2006) reported that treatment with the herbicide endothall reduced vegetation cover of parrot’s feather Myriophyllum aquaticum plants soon after application, but after 28 weeks cover was similar to pre-treatment levels. Results were not subject to statistical tests. After 10 weeks and following a second herbicide application, vegetation cover of treated plants was lower (2%) than untreated plants (47%). However, after 28 weeks, vegetation cover of treated plants (93%) was similar to that of untreated plants (97%). Authors reported that the increase in vegetation cover resulted from the encroachment of plants from outside sprayed areas rather than due to regrowth in treated plots. Endothall was applied at concentrations of 8.8 and 14.8 kg/ha. Each herbicide concentration was sprayed into three 5 x 5 m plots and three plots were left untreated. Herbicides were applied in early summer (December). A second application took place 51 days after the initial treatment.

    Study and other actions tested
  3. A small, replicated, controlled, laboratory study conducted between 2007 and 2008 in the USA (Wersal & Madsen et al. 2010), found that the application of the herbicide endothall above a certain concentration reduced the growth of parrot’s feather Myriophyllum aquaticum. After six weeks, the dry weight of parrot’s feather plants treated with endothall at a concentration of 5 mg/l was lower than that of untreated plants (12 vs 18 g/pot) but the dry weight of plants treated with endothall at a concentration of 2.5 mg/l did not differ from untreated plants (17 vs 18 g/pot). Visual assessment revealed no reduction in vegetation by endothall at either concentration six weeks after herbicide application (0% change relative to untreated plants). Parrot’s feather shoots were propagated in 3.78 l pots and placed inside 246 l containers filled with water. Each herbicide rate was applied to four 246 l containers, each holding four plants. Number of plants used as control is not presented. Visual assessments were expressed in percentage, with 0% corresponding to no control and 100% to complete control.

    Study and other actions tested
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

Control of Freshwater Invasive Species

This Action forms part of the Action Synopsis:

Control of Freshwater Invasive Species
Control of Freshwater Invasive Species

Control of Freshwater Invasive Species - Published 2017

Control of Freshwater Invasive Species Synopsis

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust