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Providing evidence to improve practice

Action: Parrot’s feather: Use of herbicides - 2,4-D Control of Freshwater Invasive Species

Key messages

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  • Three laboratory studies (including two replicated, controlled studies and one randomized, controlled study) in the USA and Brazil found that the herbicide 2,4-D reduced the growth of parrot’s feather.
  • One replicated, controlled laboratory study in Brazil found that 2,4-D led to a greater reduction in growth of parrot’s feather than the herbicides diquat, glyphosate or imazapyr.
  • One replicated, randomized, controlled field study in Portugal found that 2,4-D amine reduced the biomass of parrot’s feather.
  • One randomized, controlled field study in Portugal found that the combined application of 2,4-D and MCPA completely eliminated parrot’s feather.
  • One randomized, controlled laboratory study in the USA found that the combined application of 2,4-D and carfentrazone-ethyl led to a higher reduction in the cover of parrot’s feather than the application of the herbicide dichlobenil eight days after treatment but not 45 days after treatment.

Supporting evidence from individual studies

1 

A replicated, randomized, controlled, field study conducted in summer 1986 in Portugal (Moreira et al. 1999) found that the application of the herbicide 2,4-D amine reduced the biomass of parrot’s feather Myriophyllum aquaticum. For three out of three comparisons, the fresh weight of parrot’s feather plants treated with 2,4-D amine was lower relative to untreated plants (2–9 vs 22–26 kg/m2). Additionally, four and a half months after treatment, the biomass of plants treated with 2,4-D amine (2.2 kg/m2) was significantly lower than that of plants treated with diquat (18 kg/m2), gluphosinate-ammonium (14–15 kg/m2) and glyphosate (13 kg/m2). Parrot’s feather biomass was assessed in 20 x 7 m plots and each herbicide rate was tested in four replicates. Herbicide rates were 6.5 kg/ha for 2,4-D amine, 2 kg/ha for diquat, 1–2.4 kg/ha for gluphosinate-ammonium and 3.6 kg/ha for glyphosate.

2 

A replicated, controlled field study conducted in autumn 1995 in Portugal (Moreira et al. 1999) found that the combined application of the herbicides 2,4-D and MCPA led to a greater reduction of the cover of parrot’s feather Myriophyllum aquaticum than the application of the herbicide dichlobenil eight days after treatment but not 45 days after application. Eight days after treatment, the cover of parrot’s feather plants treated with a combination of 2,4-D and MCPA was lower than of plants treated with dichlobenil (10% vs 85%). However, after 45 days, the cover of plants treated with 2,4-D and MCPA was higher than that of plants treated with dichlobenil at a rate of 4.1 kg/ha (60% vs 20%). Each herbicide rate was sprayed onto three plots of 100 m2. Herbicide rates were 2.7 kg/ha and 4.1 kg/ha for dichlobenil and 520 g and 520 g/l for 2,4-D and MCPA respectively.

3 

A small, replicated, controlled, laboratory study conducted in 1999 in Brazil (Negrisoli et al. 2003) found that the application of the herbicide 2,4-D above a certain concentration led to a greater reduction in growth in parrot’s feather Myriophyllum aquaticum than the application of the herbicides diquat, glyphosate or imazapyr. Thirty-six days after application, control of parrot’s feather plants by 2,4-D (4–100%, visual assessment with 0% corresponding to no control and 100% to complete control) was higher than control by diquat (53–54%) in 11 out of 12 comparisons, control by glyphosate (34%), and control by imazapyr (8.5%). However, the application of 2,4-D at a concentration of 167 g/ha led only to 4% control. Fifteen parrot’s feather shoots were propagated in 120 l containers filled with water. Herbicide concentrations tested were 167, 335, 670 and 1340 g/ha for 2,4-D, 102 and 204 g/ha for diquat, 3360 g/ha for glyphosate and 250 g/ha for imazapyr. Control in the context of the visual assessments is not clearly defined.

4 

A small, replicated, randomized, controlled, laboratory study conducted in 2004 in the USA (Gray et al. 2007), found that the herbicide 2,4-D reduced growth in parrot’s feather Myriophyllum aquaticum. After three weeks, young parrot’s feather plants treated with 2,4-D had a lower dry weight (0–3.1 g/pot) than untreated plants (6.4–10 g/pot). Parrot’s feather shoots were propagated in 3.9 l plastic containers. 2,4-D application rate ranged between 100 and 1,000 μg/l and each herbicide rate was applied to three plants.

5 

A small, replicated, randomized, controlled, laboratory study conducted in 2004 in the USA (Gray et al. 2007), found that the combined application of the herbicides 2,4-D and carfentrazone-ethyl completely eliminated parrot’s feather Myriophyllum aquaticum. After three weeks, young parrot’s feather plants treated with a combination of 2,4-D and carfentrazone-ethyl were totally controlled (0 g/pot) whereas untreated plants had a biomass between 6.4 and 10 g/plot. Parrot’s feather shoots were propagated in 3.9 l plastic containers. Carfentrazone-ethyl was applied at a constant rate of 100 μg/l, whereas the rate of 2,4-D application ranged between 250 and 2,000 μg/l. Each herbicide rate was applied to three plants.

6 

A small, replicated, controlled, laboratory study conducted between 2007 and 2008 in the USA (Wersal et al. 2010), found that the application of the herbicide 2,4-D above a certain concentration reduced growth in parrot’s feather Myriophyllum aquaticum. After six weeks, the dry weight of plants treated with subsurface 2,4-D at a concentration of 5 mg/l was lower than that of untreated plants (10 vs 18 g/pot). However, the dry weight of plants treated with 2,4-D at a concentration of 2 mg/l did not differ from that of untreated plants (15 vs 18 g/pot). Dry weight of plants exposed to foliar application of 2,4-D (1 g/pot) was lower than untreated plants or those treated with 2,4-D underwater. 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.

7 

A small, replicated, controlled, laboratory study conducted in Brazil (Souza et al. 2012), found that the application of the herbicide 2,4-D reduced plant growth in parrot’s feather Myriophyllum aquaticum even when plants were exposed to simulated rainfall. Seven days after the application of 2,4-D at concentrations of 670 g/ha and 1340 g/ha, treated parrot’s feather plants were controlled by 61.5% and 81.5% respectively, when exposed to simulated rain 15 minutes after herbicide application. Exposure to simulated rain only influenced treatment if it occurred within 15 minutes of herbicide application and for a 2,4-D concentration of 670 g/ha. With or without simulated rain, the control was almost complete 21 days after the application of 2,4-D (commercial version DMA 806 BR). Parrot’s feather shoots (20 cm) were transplanted into plastic containers and each treatment had four replicates. The metric used to define control is not clearly presented.

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.