ABSTRACT Mapping resistant populations makes it possible to identify the evolution and dispersal of resistance cases, providing important information for control-related decision making. This study aimed to identify and map herbicide-resistant sourgrass (Digitaria insularis) populations in Brazilian regions. The results showed no glufosinate resistance, with 485 samples (96.6%) classified as putative resistant to glyphosate, while nine (1.8%) and five (1%) were considered putative resistant to haloxyfop and clethodim, respectively. Two samples were deemed putative resistant to three herbicides (glyphosate, haloxyfop, and clethodim). One of the samples characterized as a control failure for all three herbicides was used on the dose-response curve. This biotype was identified as glyphosate-resistant, with low-level resistance to clethodim and haloxyfop. Based on C50, resistance factors of 10.96, 3.26, and 3.15 were identified for glyphosate, clethodim, and haloxyfop, respectively. Mapping sourgrass resistance is vital to understand and ensure the early identification and quantification of the frequency of these plants. cases controlrelated related making herbicideresistant herbicide Digitaria insularis regions 48 96.6% 966 96 6 (96.6% glyphosate 1.8% 18 1 8 (1.8% 1% (1% respectively (glyphosate clethodim. . clethodim) doseresponse dose response curve glyphosateresistant, glyphosateresistant resistant, glyphosate-resistant lowlevel low level C50 C 1096 10 10.96 326 3 26 3.26 315 15 3.1 plants 4 96.6 9 (96.6 1.8 (1.8 (1 C5 109 10.9 32 2 3.2 31 3. 96. (96. 1. (1. ( 10. (96 (9

Abstract The objective of this work was to evaluate the effectiveness of herbicides when applied alone and in combinations at sourgrass (Digitaria insularis) post-emergence, as well as to identify a substitute to paraquat in sequential application. Field and greenhouse experiments were conducted during the 2019/2020 and 2020/2021 crop seasons. The herbicides applied alone and in combinations were: atrazine, clethodim, clodinafop, diquat, glufosinate, haloxyfop, imazapic, imazapyr, mesotrione, nicosulfuron, paraquat, glyphosate, saflufenacil, tembotrione, and tepraloxydim. In the 2019/2020 crop season, in the experiment conducted in the field, the control of sourgrass was considered low due to the dry weather condition and to the full flowering of the plants. In the greenhouse, a satisfactory control above 80% was observed at 28 days after herbicide application for most treatments. In the 2020/2021 crop season, under field conditions, the application of glyphosate combined with haloxyfop, with a sequential application of glufosinate, resulted in the highest weed control. In the greenhouse, most treatments were effective and, of these, all contained glufosinate. The sequential application of glufosinate or in combinations favors a better control of sourgrass. However, diquat and glufosinate do not differ in efficacy in sequential application and are an option for the control of the weed. Digitaria insularis postemergence, postemergence post emergence, emergence post-emergence 20192020 2019 2020 2019/202 20202021 2021 2020/202 seasons atrazine clethodim clodinafop haloxyfop imazapic imazapyr mesotrione nicosulfuron saflufenacil tembotrione tepraloxydim season plants 80 2 conditions these However 2019202 201 202 2019/20 2020202 2020/20 8 201920 20 2019/2 202020 2020/2 20192 2019/ 20202 2020/

Resumo O objetivo deste trabalho foi avaliar a eficácia de herbicidas quando aplicados isolados e em combinações na pós-emergência de capim-amargoso (Digitaria insularis), bem como identificar um substituto ao paraquat na aplicação sequencial. Experimentos em campo e em casa de vegetação foram conduzidos durante as safras de 2019/2020 e 2020/2021. Os herbicidas aplicados isolados e em combinações foram: atrazina, cletodim, clodinafope, diquate, glufosinato, haloxifope, imazapique, imazapir, mesotriona, nicossulfurom, paraquate, glifosato, saflufenacil, tembotriona e tepraloxidim. Na safra de 2019/2020, no experimento em campo, o controle de capim-amargoso foi considerado baixo devido às condições de clima seco e ao pleno florescimento das plantas. Na casa de vegetação, observou-se controle satisfatório acima de 80% aos 28 dias após a aplicação dos herbicidas para a maioria dos tratamentos. Na safra de 2020/2021, em condições de campo, a aplicação de glifosato combinado com haloxifope, com aplicação sequencial de glufosinato, resultou no maior controle da planta daninha. Na casa de vegetação, a maioria dos tratamentos foi eficaz e, destes, todos continham glufosinato. A aplicação sequencial de glufosinato ou em combinações favorece um melhor controle de capim-amargoso. No entanto, o diquate e o glufosinato não diferem em eficácia na aplicação sequencial e são opções de controle desta planta daninha. pósemergência pós emergência capimamargoso capim amargoso Digitaria insularis, insularis , insularis) 20192020 2019 2020 2019/202 20202021 2021 2020/2021 atrazina cletodim clodinafope haloxifope imazapique imazapir mesotriona nicossulfurom paraquate saflufenacil tepraloxidim plantas observouse observou se 80 2 daninha destes capimamargoso. amargoso. entanto 2019202 201 202 2019/20 2020202 2020/202 8 201920 20 2019/2 202020 2020/20 20192 2019/ 20202 2020/2 2020/

RESUMEN Juntas, Conyza bonariensis, C. canadensis y C. sumatrensis presentan 105 casos reportados de biotipos resistentes a herbicidas tales como glifosato, paraquat y los inhibidores de la acetolactato sintasa (ALS). Se cree que la aplicación de herbicidas pre-emergentes en mezclas con desecantes es efectiva para controlar Conyza spp. en el manejo pre-siembra de la soya. El objetivo de este estudio fue evaluar la eficacia de sulfentrazona/ diuron, imazetapir/flumioxazin y diclosulam, en mezcla con diquat, paraquat o glufosinato, en el control de Conyza spp. Se realizaron dos experimentos de campo en diseño de bloques al azar con cuatro repeticiones. Los tratamientos consistieron en la aplicación de herbicidas pre-emergentes en mezclas con desecantes, además del tratamiento control (sin aplicación), para un total de 10 tratamientos. El control de Conyza spp. se evaluó a los 7, 14, 21, 28 y 35 d después de la aplicación del herbicida, y se evaluaron los síntomas de daño en las plantas de soya a los 14, 21, 28 y 35 d después de la aplicación del herbicida. Los herbicidas sulfentrazona/diuron, imazetapir/flumioxazin y diclosulam en mezclas con diquat, paraquat o glufosinato, fueron efectivos para controlar Conyza spp. en la pre-siembra de la soya, destacando buenas opciones para la rotación de herbicidas antes y después de la emergencia. Las mezclas con diclosulam mostraron un mayor potencial de daño a las plantas de soya que sulfentrazona/diuron y imazetapir/flumioxazin.

ABSTRACT Together, Conyza bonariensis, C. canadensis and C. sumatrensis show 105 reported cases of biotypes resistant to herbicides like glyphosate, paraquat, and acetolactate synthase (ALS) inhibitors . The application of pre-emergent herbicides combined with burndown herbicides is believed to be effective in controlling Conyza spp. during soybean pre-sowing management. The objective of this study was to evaluate the efficacy of sulfen-trazone/diuron, imazethapyr/flumioxazin, and diclosulam in mixtures with diquat, paraquat, or glufosinate on the control of Conyza spp. Two field experiments were conducted in a randomized block design with four replicates. Treatments consisted of the application of pre-emergent plus burndown herbicides, besides the weedy control treatment (without application), for a total of 10 treatments. The control of Conyza spp. was evaluated at 7, 14, 21, 28, and 35 d after herbicide application, and symptoms of injury in soybean plants were evaluated at 14, 21, 28, and 35 d after herbicide application. The herbicides sulfentrazone/diuron, imazethapyr/flumioxazin, and diclosulam in combination with burndown herbicides diquat, paraquat, or glufosinate were effective in controlling Conyza spp. in the pre-sowing management of soybean, highlighting good options for pre- and post-emergent herbicide rotations. Mixtures with diclosulam showed a higher potential for injury to soybean plants than sulfentrazone/diuron and imazethapyr/flumioxazin.

RESUMEN Las mezclas entre herbicidas, el uso de múltiples sitios de acción y otras prácticas de manejo de malezas son necesarias para evitar otros casos de resistencia de biotipos. El objetivo de este estudio fue evaluar la eficiencia de imazapic/imazapyr y otros herbicidas en mezclas para controlar Digitaria insularis en la desecación antes de la siembra de soya. Esta investigación de campo se realizó en Umuarama, Estado de Paraná (PR), Brasil, en la cosecha de soya de 2018/19. El experimento se realizó en un diseño experimental de bloques al azar, con cuatro repeticiones y 11 tratamientos, compuestos por la aplicación de glifosato, cletodim, haloxifop, imazapic/imazapir, glufosinato, ácido 2,4-diclorofenoxiacético (2,4-D), dicamba, triclopir y saflufenacil, en mezclas. Se evaluó el control de malezas, así como el daño y el rendimiento de la soya. Se realizaron un análisis de varianza y test F, y se compararon las medias de los tratamientos con el test de Scott-Knott. Todos los tratamientos mostraron un gran control sobre la maleza y una baja tasa de daño a los cultivos mientras se mantenía el rendimiento de la soya. La aplicación de imazapic/imazapir en mezclas con otros herbicidas fue eficaz en el control de D. insularis resistente al glifosato, en desecación antes de la siembra de soya y con aplicación secuencial de haloxifop + glifosato en la etapa V3 de la soya. Este manejo químico también fue selectivo para la soya.

ABSTRACT Herbicide mixtures, use of multiple sites of action, and other weed management practices are necessary to avoid cases of biotype resistance. The aim of this study was to evaluate the efficiency of imazapic/imazapyr and other herbicides in mixtures to control Digitaria insularis at burndown before soybean sowing. This field research was conducted in Umuarama, State of Parana (PR), Brazil, in the 2018/19 soybean season. The experiment was conducted in a randomized block experimental design with four replicates and 11 treatments composed of the application of glyphosate, clethodim, haloxyfop, imazapic/ imazapyr, glufosinate, 2,4-dichlorophenoxyacetic acid (2,4-D), dicamba, triclopyr, and saflufenacil, in mixtures. Weed control was evaluated as well as soybean injury and yield. An analysis of variance and F-test were performed, and the treatment means were compared by the Scott-Knott test. All treatments showed great control over the weed and low crop injury rate while maintaining soybean yield. The application of imazapic/ imazapyr in mixtures with other herbicides was effective in controlling glyphosate-resistant D. insularis in burndown before soybean sowing and with sequential application of haloxyfop + glyphosate at V3 stage of soybean. This chemical management was also selective for soybean.

RESUMO: A planta daninha Conyza spp. está entre as principais encontradas em todo o mundo. Devido a sua agressividade, como elevada produção e dispersão de sementes e os crescentes relatos de biótipos resistentes ao glyphosate, paraquat e outros herbicidas, faz-se necessário o uso de diferentes ferramentas de manejo. Assim, o objetivo deste estudo foi avaliar a eficácia de herbicidas com aplicação sequencial de glufosinate em pré-semeadura da soja, no controle de Conyza spp. com indicativo de resistência ao paraquat. O estudo foi realizado em campo nos municípios de Assis Chateaubriand e Palotina, estado do Paraná (PR), Brasil, na safra 2018/19. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Os tratamentos foram compostos pela aplicação de glyphosate, 2,4-D, saflufenacil, glufosinate, saflufenacil/imazethapyr, diclosulam, paraquat/diuron, paraquat e imazethapyr/flumioxazin, em diferentes combinações em pré-semeadura da soja. Foram avaliados controle de Conyza spp., sintomas de injúria nas plantas de soja e variáveis relacionadas ao desempenho agronômico (altura de plantas e produtividade). Todos os tratamentos mostraram-se seletivos a soja. Visualizou-se maiores sintomas de injúria quando se tinha a presença do herbicida diclosulam, mas não resultou em danos ao desempenho agronômico da soja. De forma geral os níveis de controle foram altos para os tratamentos utilizados, em exceção para os tratamentos com paraquat na área que apresentava maior frequência de Conyza spp. com indicativo de resistência a este herbicida, e para o tratamento com imazethapyr/flumioxazin nas duas áreas. Estes resultados de controle enfatizam a importância do glufosinate neste sistema de manejo e demostram resultados promissores para saflufenacil/imazethapyr.

ABSTRACT: Conyza spp. is among the main weeds reported worldwide. Due to its aggressiveness, such as high seed production and dispersion, and the growing reports of biotypes resistant to glyphosate, paraquat, and other herbicides, different control practices are required. Thus, this study aimed to evaluate the efficacy of herbicides with sequential application of glufosinate in soybean pre-sowing for control of Conyza spp. with indicative of resistant to paraquat. The study was carried out in the field, at Assis Chateaubriand and Palotina, state of Paraná, Brazil, in the 2018/19 season. The experiments were conducted in a randomized block design with four replications. The treatments consisted in application of glyphosate, 2,4-D, saflufenacil, glufosinate, saflufenacil/imazethapyr, diclosulam, paraquat/diuron, paraquat and imazethapyr/flumioxazin, at different combinations, in soybean pre-sowing. Control of Conyza spp., crop injury to soybean plants and variables related to agronomic performance (plant height and yield) were evaluated. All treatments were selective for soybean, which showed stronger crop injury in the presence of diclosulam herbicide, but this did not compromise soybean agronomic performance. In general, control levels were high for the treatments used. Except for paraquat treatments, in the area with the highest frequency of Conyza spp. with indicative of resistant to paraquat, and imazethapyr/flumioxazin treatment in both areas. These control results emphasized the importance of glufosinate in this management system and showed promising results for saflufenacil/imazethapyr.