Parrot’s feather: Use of herbicides - carfentrazone-ethyl

Overall effectiveness category Likely to be beneficial
Number of studies: 5
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How is the evidence assessed?

Effectiveness

50%
Certainty

40%
Harms

5%

Calculating overall effectiveness category

Background information and definitions

Chemical herbicides have been used for the localized control of parrot’s feather (e.g. Morreira et al. 1999). Herbicides licensed for use around the world use a wide diversity of different active ingredients (e.g. 2,4-D, imazapyr, carfentrazone-ethyl, diquat). However, herbicide control of aquatic vegetation is prohibited in numerous countries (e.g. no herbicides are approved for submerged species in Europe) (De Winton et al. 2013; Hussner et al. 2017). Therefore it is important to consider local regulations before using herbicide control. Legislative restrictions may be lifted for herbicides under particular conditions (Hussner et al. 2017). Impacts on non-target species should be considered prior to herbicide use.

Emerged and submerged vegetation may require different herbicides, and adjuvants may increase the efficacy of the treatment. More than one application of the herbicide is often required. The use of fungal-based herbicides to control parrot’s feather is discussed under the intervention ‘Biological control using fungal-based herbicides’.

De Winton M., Jones H., Edwards T., Özkundakci D., Wells R., McBride C., Rowe D., Hamilton D., Clayton J., Champion P. & Hofstra D. (2013) Review of Best Management Practices for Aquatic Vegetation Control in Stormwater Ponds, Wetlands, and Lakes. Auckland Council technical report, TR2013/026.

Hussner A., Stiers I., Verhofstad M.J.J.M., Bakker E.S., Grutters B.M.C., Haury J., van Valkenburg J.L.C.H., Brundu G., Newman J., Clayton J.S. & Anderson L.W.J. (2017) Management and control methods of invasive alien freshwater aquatic plants: A review. Aquatic Botany, 136, 112-137.

Moreira I., Ferreira T., Monteiro A., Catarino L. & Vasconcelos T. (1999) Aquatic weeds and their management in Portugal: insights and the international context. Hydrobiologia 415, 229–234.

Study locations

Key messages

Five laboratory studies (including one replicated, controlled, before-and-after study) in the USAfound that carfentrazone-ethyl reduced growth in parrot’s feather.

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 small, replicated, controlled, before-and-after, laboratory study conducted in 2003 in the USA (Glomski et al. 2006), found that the application of the herbicide carfentrazone-ethyl reduced growth in parrot’s feather Myriophyllum aquaticum but did not lead to plant death. After 28 days, the biomass of parrot’s feather shoots treated with carfentrazone-ethyl was 29.5–54% lower than untreated plants. However, emerged and submerged foliage remained viable. The study was carried out using 12 1,600 l containers filled with water, each of which contained eight 5 l containers with three 15 cm parrot’s feather stems. Each of the three tested herbicide rates (50, 100 and 200 μg/l) was applied to three 1600 l containers, and plants in three containers were left untreated. Plants from four of the eight 5 l plastic containers placed inside each 1600 l container were harvested, dried and weighed before herbicide application, and the remaining plants were harvested, dried and weighed 28 days after herbicide application.
Study and other actions tested
Referenced paper
Glomski L., Poovey A. & Getsinger K. (2006) Effect of carfentrazone-ethyl on three aquatic macrophytes. Journal of Aquatic Plant Management, 44, 67-69.
A small, replicated, randomized, controlled, laboratory study conducted in 2004 in the USA (Gray et al. 2007), found that the herbicide carfentrazone-ethyl reduced growth in parrot’s feather Myriophyllum aquaticum. After three weeks, young parrot’s feather plants treated with carfentrazone-ethyl had a lower dry weight (1.8–2.4 g/pot) than untreated plants (6.4–10 g/pot). Parrot’s feather shoots were propagated in 3.9 l plastic containers. Carfentrazone-ethyl application rate ranged between 100 and 200 μg/l and each herbicide rate was applied to three plants.
Study and other actions tested
Referenced paper
Gray C., Madsen J., Wersal R. & Getsinger K. (2007) Eurasian watermilfoil and parrotfeather control using carfentrazone-ethyl. Journal of Aquatic Plant Management, 45, 43-46.
A small, replicated, controlled, laboratory study conducted in the USA (Richardson et al. 2008), found that the herbicide carfentrazone-ethyl reduced growth in parrot’s feather Myriophyllum aquaticum. Parrot’s feather plants treated with carfentrazone-ethyl had a lower dry weight (0.55–0.88 g) than untreated plants (1.43 g). Parrot’s feather shoot tips (5–10 cm) were transplanted into 9 cm² pots. Carfentrazone-ethyl application rate ranged between 56 and 224 g/ha and each herbicide rate was applied to pots with three plants and plants in one pot were left unsprayed. Dates of the studies are not presented.
Study and other actions tested
Referenced paper
Richardson R.J., Roten R., West A., True S. & Gardner A. (2008) Response of selected aquatic invasive weeds to flumioxazin and carfentrazone-ethyl. Journal of Aquatic Plant Management, 46, 154-158.
A small, replicated, randomized, controlled, laboratory study conducted in 2006 in the USA (Wersal et al. 2010), found that the application of the herbicide carfentrazone-ethyl reduced growth in parrot’s feather Myriophyllum aquaticum. After four weeks, the dry weight of parrot’s feather plants treated with carfentrazone-ethyl was lower than untreated plants (1–2.1 vs 4.6 g/pot). Daytime and night-time application of the herbicide resulted in similar results. Parrot’s feather shoots were propagated in 3.78 l pots and placed inside 246 l containers filled with water. Each herbicide rate (0.1 and 0.2 mg/l) was applied to three plants.
Study and other actions tested
Referenced paper
Wersal R.M., Madsen J., Massey J., Robles W. & Cheshier J. (2010) Comparison of daytime and night-time applications of diquat and carfentrazone-ethyl for control of parrotfeather and Eurasian watermilfoil. Journal of Aquatic Management, 48, 56-58.
A small, replicated, controlled, laboratory study conducted between 2007 and 2008 in the USA (Wersal & Madsen 2010) found that the application of the herbicide carfentrazone-ethyl reduced growth of parrot’s feather Myriophyllum aquaticum. After six weeks, the dry weight of parrot’s feather plants treated with carfentrazone-ethyl was lower (10–12 g/pot) than that of untreated plants (18 g/pot). Six weeks after application, plants treated with carfentrazone-ethyl were reduced by 0–15% (visual assessment with 0% corresponding to no reduction in cover relative to untreated plans and 100% to complete elimination). Parrot’s feather shoots were propagated in 3.78 l pots and placed inside 246 l containers filled with water. Each herbicide rate (0.1 and 0.2 mg/l) was applied to four 246 l containers, each holding four plants. Number of plants used as control is not presented.
Study and other actions tested
Referenced paper
Wersal R.M. & Madsen J.D. (2010) Comparison of subsurface and foliar herbicide applications for control of parrotfeather (Myriophyllum aquaticum). Invasive Plant Science and Management, 3, 262-267.

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
Parrot’s feather: Biological control using herbivores Action Link	Trade-off between benefit and harms	4	Synopsis Link
Parrot’s feather: Biological control using plant pathogens Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Parrot’s feather: Mechanical harvesting and cutting Action Link	No evidence found (no assessment)	0	Synopsis Link