DETECTION OF GLYPHOSATE-RESISTANT PALMER AMARANTH (Amaranthus palmeri) IN AGRICULTURAL AREAS OF MATO GROSSO, BRAZIL

• Published in: Planta daninha 2015-09, Vol.33 (3), p.579-586
• Main Authors: CARVALHO, S. J. P., GONÇALVES NETTO, A., NICOLAI, M., CAVENAGHI, A. L., LÓPEZ-OVEJERO, R. F., CHRISTOFFOLETI, P. J.
• Format: Article
• Language: English
• Subjects: control; dose-response; management; pigweeds; PLANT SCIENCES; susceptibility
• ISSN: 0100-8358; 1806-9681; 0100-8358
• DOI: 10.1590/S0100-83582015000300020

ABSTRACT The recent introduction of Palmer amaranth (Amaranthus palmeri) in Brazilian agricultural areas may promote several changes on weed management, especially in no-till systems and in glyphosate-resistant crops, since glyphosate-resistant biotypes of A. palmerihave been frequently selected in other countries. Therefore, this research was developed in order to evaluate the glyphosate susceptibility of a Palmer amaranth biotype recently identified in the State of Mato Grosso, Brazil. For this purpose, glyphosate susceptibility of three Amaranthusbiotypes was compared: A.hybridus var. patulus, collected in the State of Rio Grande do Sul - Brazil; A.hybridus var. patulus, collected in the State of São Paulo - Brazil; and A.palmeri, collected in the State of Mato Grosso - Brazil. Dose-response curves were generated for all biotypes, considering eight rates of glyphosate and six replicates. All the experiments were repeated twice. Both A.hybridus biotypes were satisfactorily controlled by glyphosate, demanding rates equal to or lower than 541.15 g a.e. ha-1 for 80% control (LD80). The A.palmeri biotype was not controlled by glyphosate in any of the assessments and required rates greater than 4,500 g a.e. ha-1 to reach LD80, which are economically and environmentally unacceptable. Comparison of the Brazilian A.palmeri biotype to the A. hybridus biotypes, as well as, to the results available in scientific international literature, led to the conclusion that the Brazilian Palmer amaranth biotype is resistant to glyphosate. RESUMO A recente introdução da espécie Amaranthus palmeri em áreas agrícolas brasileiras pode promover significativas alterações no manejo de plantas daninhas, sobretudo em áreas de plantio direto e de cultivo de culturas resistentes ao glyphosate, uma vez que biótipos de A. palmeri resistentes ao glyphosate têm sido sistematicamente selecionados em outros países. Assim, este trabalho foi desenvolvido com o objetivo de avaliar a suscetibilidade ao herbicida glyphosate do biótipo de A. palmeri que foi recentemente identificado no Estado de Mato Grosso, Brasil. Para isso, procedeu-se à comparação da suscetibilidade ao glyphosate de três biótipos de caruru: A. hybridus var. patulus, coletado no Estado do Rio Grande do Sul - Brasil; A. hybridus var. patulus, coletado no Estado de São Paulo - Brasil; e A. palmeri, coletado no Estado de Mato Grosso - Brasil. Para todos os biótipos, foram desenvolvidos experimentos com curvas de doseresposta, cons