Detection of Sourgrass (Digitaria insularis) Biotypes Resistant to Glyphosate in Brazil
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Data
2011-04-01
Autores
de Carvalho, Leonardo Bianco [UNESP]
Cruz-Hipolito, Hugo
Gonzalez-Torralva, Fidel
da Costa Aguiar Alves, Pedro Luis [UNESP]
Christoffoleti, Pedro Jacob
De Prado, Rafael
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Editor
Weed Sci Soc Amer
Resumo
Sourgrass is a perennial weed infesting annual and perennial crops in Brazil. Three biotypes (R1, R2, and R3) of sourgrass suspected to be glyphosate-resistant (R) and another one (S) from a natural area without glyphosate application, in Brazil, were tested for resistance to glyphosate based on screening, dose-response, and shikimic acid assays. Both screening and dose-response assays confirmed glyphosate resistance in the three sourgrass biotypes. Dose-response assay indicated a resistance factor of 2.3 for biotype RI and 3.9 for biotypes R2 and R3. The hypothesis of a glyphosate resistance was corroborated on the basis of shikimic acid accumulation, where the S biotype accumulated 3.3, 5.0, and 5.7 times more shikimic acid than biotypes R1, R2, and R3, respectively, 168 h after treatment with 157.50 g ae ha(-1) of glyphosate. There were no differences in contact angle of spray droplets on leaves and spray retention, indicating that differential capture of herbicide by leaves was not responsible for resistance in these biotypes. The results confirmed resistance of sourgrass to glyphosate in Brazil.
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Herbicide resistance, shikimic acid, spray retention, contact angle
Como citar
Weed Science. Lawrence: Weed Sci Soc Amer, v. 59, n. 2, p. 171-176, 2011.