Water Hyacinth Control by Glyphosate Herbicide and Its Impact on Water Quality

Abstract

The aim of this study was to evaluate the herbicide glyphosate under aquatic environment conditions, in a controlled and closed experimental field, in the management of water hyacinth (Eichhornia crassipes) in reservoirs. Twenty reservoirs (polyethylene water tanks) with storage capacity of 1000 liters were used, without water flow and without evapotranspired water replacement (worst case), being 04 for each treatment. The adult plants were placed in the water tanks to provide 90% surface occupation of the reservoir. Five treatments with four repetitions were considered, being: 1) Reservoir colonized by water hyacinth without control; 2) Reservoir colonized by water hyacinth, controlled by glyphosate; 3) Reservoir colonized by water hyacinth, controlled by freezing; 4) Reservoir without water hyacinth and glyphosate application and 5) Reservoir without water hyacinth and no glyphosate application. The glyphosate herbicide was used at the highest recommended dose, 7.0 L•ha −1 or 3360 g of acid equivalent per ha, applied using carbon dioxide precision equipment (backpack sprayer), providing a flow rate of 200 L•ha −1. The water samples were collected at the time of application, 6, 12, 18 and 24 hours after application and also at 2, 4, 8, 16, 32 and 64 days after application, in the morning, always at the same time, also between 8 and 9 h. The method used for determination of residues was by high performance liquid chromatography (HPLC) and mass spectrometry with a mass selective detector. Low concentrations of glyphosate and aminomethylphosphonic acid (AMPA) were found in both reservoirs that received application of the product. The half-life of glyphosate in water to the reservoirs with water hyacinth was 11 days and in the reservoirs without water hyacinth was 21 days.

Acute toxicity of three herbicide formulations in Astyanax altiparanae (Characiformes, Characidae), an emerging Neotropical fish model species

“…In this way, other herbicides have been evaluated for this purpose, and therefore, it is necessary to assess the toxicity to aquatic communities for future use as alternative herbicides. Reglone® (Pitelli et al 2011), Arsenal® NA and Roundup® (Carvalho et al 2005), and Roundup Transorb® (Souza et al 2020) analysis must be performed in different developmental stages to identify the most sensitive to the herbicide and which herbicide is the most toxic to a specific species.…”

“…In addition to these herbicides not being allowed by Brazilian law for aquatic use, the hypothetical concentrations of these herbicides would make the active ingredients reach levels in the water higher than the allowed Brazilian MPL for glyphosate. Souza et al (2020) experimentally used Roundup Transorb® (the same formulation used in this work) to control aquatic plants, applying 7.0 L per ha or 3360 g of acid equivalent per ha in reservoirs with and without Eichhornia crassipes. It was verified that the half-life of glyphosate in water from reservoirs with the plants was 11 days and without the plants was 21 days.…”

“…However, it is inefficient for various macrophytes (Marcondes et al 2003). Other herbicides have been used experimentally to evaluate their efficacy in controlling aquatic vegetation, including Reglone® (Pitelli et al 2011), Roundup® and Arsenal® NA (Carvalho et al 2005), and Roundup Transorb® (Souza et al 2020). The use of herbicides that could be more efficient in controlling macrophytes requires knowledge of the toxicity of these herbicides on the aquatic community.…”

A Comprehensive Evaluation of the Existing Approaches for Controlling and Managing the Proliferation of Water Hyacinth (Eichhornia crassipes): Review

“…Genus: Cercospora Species: N. eichhorniae that herbicides such as 2,4-D, diquat, paraquat, and glyphosate have resulted in successful control in small, single-purpose water systems such as irrigation canals and dams of around 1 ha in size. However, Souza et al (2020) reported that the use of glyphosate herbicide at its highest recommended dose of 7.0 L ha −1 or 3,360 g of acid equivalent per ha, showed a low potential of environmental impact in the control of WH in reservoirs, but it should be used properly in specific infested sites and never in overall application to the whole infested area. In addition, an integrated approach with other control methods is recommended and seems to be unavoidable in certain circumstances.…”

Harnessing the potential of common water hyacinth as an industrial raw material for the production of quality biofuel briquettes

“…Several studies have been done on eradication, management and control of E. crassipes. The use of glyphosate herbicides, for instance, has been applied in Brazil and the USA with little success [9,10]. Nevertheless, positive results were recorded with the use of weevils for biocontrol of E. crassipes but after a long period [11].…”