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Providing evidence to improve practice

Action: Parrot’s feather: Use of herbicides - other herbicides Control of Freshwater Invasive Species

Key messages

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Supporting evidence from individual studies

1 

A replicated, randomized, controlled, field study conducted in summer 1986 in Portugal (Moreira et al. 2010), found that the application of the herbicide glyphosate reduced the biomass of parrot’s feather Myriophyllum aquaticum. For two out of three comparisons, the fresh weight of plants treated with glyphosate was reduced relative to untreated plants (9–14 vs 22–26 kg/m2). Additionally, four and a half months after treatment, the biomass of parrot’s feather plants treated with glyphosate (13 kg/m2) was higher than plants treated with 2,4-D amine (2.2 kg/m2), but lower than plants treated with diquat (18 kg/m2). Parrot’s feather biomass was assessed in 20 x 7 m plots, with four replicates of each herbicide. Herbicide rates were 2 kg/ha for diquat, 6.5 kg/ha for 2,4-D amine, 1–2.4 kg/ha for gluphosinate-ammonium and 3.6 kg/ha for glyphosate. Herbicide was applied twice in the same area.

2 

A replicated, controlled field study conducted in autumn 1995 in Portugal (Moreira et al. 2010) found that the application of the herbicide dichlobenil led to a smaller reduction in the cover of parrot’s feather Myriophyllum aquaticum than the combined application of the herbicides 2,4-D and MCPA eight days after treatment but not 45 days after application. Eight days after treatment, the cover of parrot’s feather plants treated with dichlobenil (85% cover) was higher than of plants treated with a combination of 2,4-D and MCPA (10%). However, after 45 days, the cover of plants treated with dichlobenil at a rate of 4.1 kg/ha (20%) was lower than of plants treated with a dicholobenil at a rate of 2.7 kg/ha (60%) or with a combination of 2,4-D and MCPA (60%). Each herbicide rate was sprayed onto three plots of 100 m2. Herbicide concentration was 520 g and 520 g/l for 2,4-D + MCPA respectively.

3 

A replicated, randomized, controlled, field study conducted in summer 1986 in three drainage channels Portugal (Moreira et al. 2010) found that the application of the herbicide gluphosinate-ammonium reduced the biomass of parrot’s feather Myriophyllum aquaticum in five out of nine comparisons. For five out of nine comparisons, the fresh weight of parrot’s feather plants treated with gluphosinate-ammonium was reduced relative to untreated plants (9–22 vs 22–26 kg/m2). Additionally, four and a half months after treatment, the biomass of parrot’s feather plants treated with gluphosinate-ammonium (14–15 kg/m2) was higher than plants treated with 2,4-D amine (2.2 kg/m2) but lower than plants treated with 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 2 kg/ha for diquat, 6.5 kg/ha for 2,4-D amine, 1–2.4 kg/ha for gluphosinate-ammonium and 3.6 kg/ha for glyphosate. Herbicide was applied twice in the same area.

4 

A small, replicated, controlled, laboratory study conducted between 1999 and 2000 in New Zealand (Hofstra et al. 2006) found that the herbicide dichlobenil reduced the growth of parrot’s feather Myriophyllum aquaticum. After 17 weeks, laboratory plants treated with dichlobenil had a lower dry weight (6–21 g) than that of untreated plants (274 g). Plants were grown for approximately two months prior to herbicide application in 60 l plastic tubs. Dichlobenil was sprayed onto plants in three tubs at a concentration of 2 and 4 kg/ha and plants in four tubs were left untreated.

5 

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 treatment with the herbicide dichlobenil 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 (3–8%) than untreated plants (47%). However, after 28 weeks, vegetation cover of treated plants (70–98%) 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. Dichlobenil was applied at concentrations of 6.8 and 20.3 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.

6 

A small, replicated, randomized, controlled, laboratory study conducted in 2006 in the USA (Wersal & Madsen 2007) found that the application of the herbicide imazapyr reduced growth in parrot’s feather Myriophyllum aquaticum. After ten weeks, the biomass of parrot’s feather plants treated with imazapyr at rates of 584 and 1,123 g/ha was reduced to 0 g/pot whereas untreated plants had a biomass of 140 g/pot. The biomass of plants treated with imazapyr at a rate of 281 g/ha (160 g/pot) did not differ significantly from untreated plants (140 g/pot). Parrot’s feather shoots were propagated in 3.8 l plastic containers. Each herbicide rate (281, 584 and 1123 g/ha) was applied to three plants and three plants were left untreated.

7 

A small, replicated, controlled, laboratory study conducted in the USA (Emerine et al. 2010) found that the herbicide imazamox reduced the growth parrot’s feather Myriophyllum aquaticum. After five weeks, plants treated with imazamox had a dry weight (0.97 g) approximately 40–85% lower than that of untreated plants (3.15 g). Application of imazamox to parrot’s feather regrowth led to similar biomass reduction. Dry weight of plants treated with imazamox did not differ from the dry weight of plants treated with the herbicides glyphosate (0.49 g) or imazapyr (0.39 g). The plants were grown for approximately three weeks prior to herbicide application and each treatment had four replicates. Herbicides were sprayed on plants with no submerged growth. Concentration of imazamox ranged from 35 to 580 g/ha, glyphosate was applied at 2240 g/ha and imazapyr at 560t g/ha.

8 

A small, replicated, controlled, laboratory study conducted in the USA (Emerine et al. 2010) found that the herbicide imazapyr reduced the growth of parrot’s feather Myriophyllum aquaticum. After five weeks, plants treated with imazapyr had a lower dry weight (0.39 g) than that of untreated plants (3.15 g). Application of imazapyr to parrot’s feather regrowth led to similar biomass reduction. Dry weight of plants treated with imazapyr did not differ from the dry weight of plants treated with the herbicide imazamox (0.97 g) or glyphosate (0.49 g). The plants were grown for approximately three weeks prior to herbicide application and each treatment had four replicates. Herbicides were sprayed on plants with no submersed growth. Herbicide concentration was 560 g/ha for both imazapyr and imazamox and 2240 g/ha for glyphosate.

9 

A small, replicated, controlled, laboratory study conducted between 1999 and 2000 in New Zealand (Hofstra et al. 2006) found that the biomass of parrot’s feather Myriophyllum aquaticum treated with the herbicide fluridone did not differ significantly from that of untreated plants. After 17 weeks, the dry weight of laboratory plants treated with fluridone (176–216 g) was not significantly different from than that of untreated plants (274 g). Plants were grown for approximately two months prior to herbicide application in 60 l plastic tubs. Fluridone was sprayed onto plants in three tubs at a concentration of 0.1 and 0.5 kg/ha and plants in four tubs were left untreated.

10 

A small, replicated, controlled, laboratory study conducted between 1999 and 2000 in New Zealand (Hofstra et al. 2006) found that the biomass of parrot’s feather Myriophyllum aquaticum treated with the herbicide clopyralid did not differ significantly from that of untreated plants. After 17 weeks, the dry weight of plants treated with clopyralid (132 g) was not significantly different from than that of untreated plants (274 g). Plants were grown for approximately two months prior to herbicide application in 60 l plastic tubs. Clopyralid was sprayed onto plants in three tubs at a concentration of 1.5 kg/ha and plants in four tubes were left untreated.

11 

A small, replicated, controlled, laboratory study conducted between 2007 and 2008 in the USA (Wersal & Madsen, 2010) found that the application of the herbicide copper chelate did not affect the growth of parrot’s feather Myriophyllum aquaticum. After six weeks, the dry weight of parrot’s feather treated with copper chelate (14–16 g/pot) did not differ significantly from the biomass of untreated plants (18 g/pot). Visual assessment revealed no reduction in plant vegetation by copper chelate compared to untreated controls six weeks after herbicide application. Parrot’s feather shoots were propagated in 3.78 l pots and placed inside 246 l containers filled with water. Each herbicide rate (0.5 and 1 mg/l) was applied to four 246 l containers, each holding four plants. Number of plants used as control is not presented and control in the context of the visual assessments was not clearly defined.

12 

A small, replicated, controlled, laboratory study conducted in the USA (Richardson et al. 2008), found that the herbicide flumioxazin reduced growth in parrot’s feather Myriophyllum aquaticum. Parrot’s feather plants sprayed with flumioxazin had a lower dry weight (0.29–0.74 g) than unsprayed plants (1.43 g). Parrot’s feather shoot tips (5–10 cm) were transplanted into 9 cm2 pots. Application rate of the herbicide flumioxazin ranged between 34 and 437 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.

13 

A small, replicated, randomized, controlled laboratory study conducted in the USA (Richardson et al. 2016), found that a new herbicide tested under the code SX1552 (chemical name: 4-amino-3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)-5-fluoro-pyridine-2-benzyl ester; common name florpyrauxifen-benzyl) reduced parrot’s feather Myriophyllum aquaticum growth. Four weeks after exposure, the dry weight of parrot’s feather plants treated with SX1552 was reduced to less than 80% of the dry weight of untreated plants (data not reported). Experiments were based on laboratory stock plants grown in 15 l plastic containers. Herbicide concentration ranged between 3 and 81 µg/l. Each SX1552 concentration was tested in four plants. Plants were grown for about one week prior to treatment.

14 

A small, replicated, controlled, laboratory study conducted in the USA (Emerine et al. 2010) found that the herbicide glyphosate reduced the growth of parrot’s feather Myriophyllum aquaticum. After five weeks, plants treated with glyphosate had a lower dry weight (0.49 g) than untreated plants (3.15 g). Application of glyphosate to parrot’s feather regrowth led to a similar biomass reduction. Dry weight of plants treated with glyphosate did not differ from that of plants treated with the herbicide imazamox (0.97 g) or imazapyr (0.39 g). The plants were grown for approximately three weeks prior to herbicide application and each treatment had four replicates. Herbicides were sprayed on plants with no submerged vegetation at a concentration of 2240 g/ha for glyphosate and 560 g/ha for both imazamox and imazapyr.

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.