Herbicides reduce the severity and sporulation of Phakopsora pachyrhizi in soybean with triple herbicide resistance

• Published in: Pest management science 2023-10, Vol.79 (10), p.3749-3756
• Main Authors: Claus, Alexandre, Roncatto, Eduardo, Barroso, Arthur Arrobas Martins, May De Mio, Louise Larissa
• Format: Article
• Language: English
• Subjects: 2,4-Dichlorophenoxyacetic Acid - pharmacology; 2,4‐D; Caterpillars; chemical management; Dichlorophenoxyacetic acid; Glufosinate; Glycine max - microbiology; Glyphosate; Herbicide Resistance; Herbicides; Herbicides - pharmacology; In vivo methods and tests; Inoculation; Mixtures; Phakopsora pachyrhizi; production system; Rust fungi; Soybeans; Sporulation; Synergistic effect; transgenics
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7557

BACKGROUND Transgenic event DAS44406‐6 (E3) makes soybeans that are herbicide [glyphosate (Gly), 2,4‐dichlorophenoxyacetic acid (2,4‐D) and glufosinate] and caterpillar resistant. The E3 soybean was commercially released for the 2021/2022 harvest in Brazil. We conducted this study to test whether Gly and 2,4‐D applied alone and in a commercial mixture affect Asian soybean rust (ASR). Assays were conducted in detached leaves and in vivo, in a controlled environment using the herbicides Gly, 2,4‐D and Gly + 2,4‐D, and pathogen inoculation. Disease severity and spore production were evaluated. RESULTS Only the herbicides Gly and Gly + 2,4‐D inhibited ASR in detached leaves and in vivo. When applied preventively and curatively in vivo, these herbicides reduced the disease severity and spore production of the fungus. In vivo, inhibition of disease severity reached 87% for Gly + 2,4‐D and 42% for Gly. A synergistic effect was observed with the commercial Gly + 2,4‐D mixture. Application of 2,4‐D alone in the in vivo assays did not reduce or increase disease severity. Gly and Gly + 2,4‐D act residually in inhibiting the disease. Growing E3 soybeans may combine weed and caterpillar management benefits with ASR inhibition. CONCLUSION Application of Gly and Gly + 2,4‐D herbicides in resistant E3 soybean shows inhibitory activity for ASR. © 2023 Society of Chemical Industry. The DAS44406‐6 transgenic event (Enlist E3®) produces herbicide‐tolerant soybeans. We conducted this study to test whether the herbicides glyphosate and 2,4‐dichlorophenoxyacetic acid (2,4‐D) applied alone and in a commercial mixture affect Asian soybean rust (ASR). The application of glyphosate and glyphosate +2,4‐D herbicides affects the occurrence of ASR.