Mixture toxicity assisting the design of eco-friendlier plant protection products: a case-study using a commercial herbicide combining nicosulfuron and terbuthylazine

• Published in: Scientific reports 2018-04, Vol.8 (1), p.5547-10, Article 5547
• Main Authors: Queirós, Libânia, Vidal, Tânia, Nogueira, António J. A., Gonçalves, Fernando J. M., Pereira, Joana Luísa
• Format: Article
• Language: English
• Subjects: 631/158/2455; 704/172/4081; Agricultural production; Araceae - drug effects; Araceae - growth & development; Environmental assessment; Environmental risk; Herbicides; Herbicides - toxicity; Humanities and Social Sciences; Lemna minor; multidisciplinary; Pesticides; Plant protection; Portulaca - drug effects; Portulaca - growth & development; Portulaca oleracea; Pyridines - toxicity; Research Design; Risk assessment; Science; Science (multidisciplinary); Sulfonylurea Compounds - toxicity; Toxicity; Toxicity testing; Toxicity Tests - methods; Triazines - toxicity; Weeds
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-23883-5

The development of environmentally friendly plant protection products (PPPs), including pesticides, is a challenge nowadays. A commercial herbicide combining terbuthylazine and nicosulfuron as active substances (a.s.) was selected as a model PPP. The suitability of manipulating the ratio between a.s. towards alternative formulations with reduced impacts in a non-target indicator ( Lemna minor ) was assessed. The efficacy of such eco-friendlier a.s. ratios was then assessed using a target weed, Portulaca oleracea . Single and mixture toxicity testing with L. minor revealed an antagonistic joint action of the a.s., suggesting an environmentally protective effect of the combination compared to single dosing of a.s. The efficacy testing against the target weed of single and combined treatments of the a.s. showed that (i) the a.s. behave antagonistically throughout the whole P. oleracea response surface; (ii) there were no environmentally safe a.s. combinations ensuring target-efficacy; (iii) terbuthylazine alone was effective in controlling P. oleracea with no environmental hazardous potential, dosed at concentrations 10-fold lower than those involved in commercially recommended application doses. Overall, this case-study suggests that modelling tools widely used in the field of environmental risk assessment of PPPs may also have application in PPP design stages for a more efficient meeting of efficacy and environmental friendliness requirements.