Auxinic herbicides and glyphosate inhibit horseweed seed production and germination

• Published in: Advances in Weed Science Vol. 43; p. e020250057
• Main Authors: Novello, Bruna D., Barroso, Arthur A. M., Silva, Diecson R. O. da, Bacha, Allan L., Roncatto, Eduardo, Albrecht, Alfredo J. P.
• Format: Journal Article
• Language: English
• Published: Londrina Sociedade Brasileira da Ciência das Plantas Daninhas, UFV - Depto de Fitotecnia 2025; Sociedade Brasileira da Ciência das Plantas Daninhas - SBCPD
• Subjects: 2,4-D; AGRONOMY; Biotypes; Design of experiments; Embryos; Enzymes; Germination; Glyphosate; Herbicide resistance; Herbicides; Morphology; Papillae; Plant reproduction; Seed germination; Seeds; Soybeans; Triclopyr; Brazil; United States > US; Triclopyr; Conyza bonariensis; Halauxifen-Methyl; Dicamba; Seed Viability
• ISSN: 2675-9462; 2675-9462
• DOI: 10.51694/AdvWeedSci/2025;43:00002

Background Horseweed (Conyza bonariensis) is an important weed species infesting soybean plantations. Some biotypes with multiple herbicide resistance have been recently reported. One way to avoid weed dispersion and spread to adjacent areas is by reducing and preventing seed germination.Objective We aimed to evaluate the effects of auxinic herbicides (2,4-D, dicamba, triclopyr and halauxifen-methyl), with or without mixing with glyphosate, on the production, germination and morphology of horseweed seeds.Methods With the recent release of the transgenic soybean event DAS-44406-6 in Brazil, we conducted three experiments with different horseweed biotypes (Canguiri, Palotina and Palmeira) and application stages (early and late vegetative, and early reproductive).Results Auxinic herbicides, applied alone or mixed with glyphosate, reduced the germination and production of horseweed seeds, regardless of the stage of application. The application of herbicides caused morphological changes in the seeds, such as darkening, damaged achenes and papillae, and absence of embryos.Conclusions For plants that produced seeds, there was a 100% reduction in germination, showing that the application of these herbicides can be a viable strategy in the integrated management of this species.