Abstract Background Crop tolerance to herbicides and the effectiveness of weed control are key considerations of a chemical management program. Crop tolerance levels and the mechanism involved is of great importance in ensuring the safe use of an herbicide. Objective This study aims to evaluate the effect of mefenpyr-diethyl as a safener and metabolic inhibitor (organophosphorus insecticides) on the penoxsulam tolerance of white oat cultivars. Methods We determined the relative tolerance (%) of URS Guará and URS Guria white oat cultivars to different doses of penoxsulam with and without prior application of organophosphorus metabolic inhibitors (malathion + chlorpyrifos). We then determined the relative tolerance (%) of the white oat cultivar URS Guria with and without prior application of a protective metabolization stimulator (mefenpyr-diethyl). Results Increased penoxsulam doses resulted in lower relative tolerance of both cultivars. The application of organophosphorus insecticides reduced the penoxsulam tolerance of white oat cultivars, with a 14.4 and 4.8 fold reduction of C50 in the URS Guará and URS Guria cultivars, respectively. The use of mefenpyr-diethyl increased the penoxsulam tolerance of URS Guria by a factor of 2.62. Conclusions The penoxsulam tolerance of white oat cultivars was reduced by organophosphorus insecticides and increased by mefenpyr-diethyl. Metabolization is the likely mechanism of tolerance of white oats to this herbicide.

Abstract Background The limited number of selective herbicides for white oat (Avena sativa L.) cultivation makes it managing weeds a challenge. Currently, few herbicide options are available for selective weed control in winter crops. Previous studies have indicated that ALS-inhibiting herbicides could be potential alternatives, so studies were conducted. Objective To characterize the tolerance level of white oat cultivars to ALS-inhibiting herbicides and to evaluate the level of weed control by applying penoxsulam and bispyribac-sodium. Methods Tolerance (%) was determined for white oat cultivars UFRGS 14, URS Guará, URS Guria, UFRGS 18, and URS Taura for imazethapyr, iodosulfuron, penoxsulam, and bispyribac-sodium dose-response. Also, the control efficiency of different doses of penoxsulam and bispyribac-sodium was determined on weed species of white oat, namely crabgrass (Digitaria horizontalis), siberian motherwort (Leonurus sibiricus), italian ryegrass (Lolium multiflorum), and wild radish (Raphanus raphanistrum). Results Imazethapyr and bispyribac-sodium were the least selective herbicides, whereas iodosulfuron had intermediate selectivity, and penoxsulam was the most selective for the white oat cultivars tested, with average control of 100, 72, 62.7 and 40%, respectively. Overall, bispyribac-sodium had a higher level of weed control (77.1%) than penoxsulam (62%). Label doses of penoxsulam and bispyribac-sodium resulted in low control levels of crabgrass. Conclusions All doses of bispyribac-sodium effectively control wild radish and italian ryegrass. The recommended dose of penoxsulam was selective for some cultivars of white oat and effectively controlled italian ryegrass and wild radish.

O herbicida saflufenacil é inibidor da Protox, com modo de translocação diferenciado em relação a outros herbicidas pertencentes ao mesmo mecanismo de ação. Seletividade, eficácia e segurança ao ambiente são características importantes para aplicabilidade prática de um herbicida na agricultura. O objetivo deste estudo foi determinar a tolerância de dez cultivares de feijão ao saflufenacil, aplicado em condições de pré-emergência. O experimento foi realizado em delineamento experimental de blocos ao acaso com parcelas subdivididas com dez cultivares de feijão (IAPAR 81; IPR Tiziu; IPR Corujinha; BRS Estilo; BRS Talismã; BRS Esplendor; BRS Campeiro; BRS Radiante; BRS Vereda e Jalo precoce) alocadas nas parcelas e concentrações de saflufenacil (0; 14,7 e 29,4 g ha-1) nas subparcelas. Foram realizadas avaliações de estande aos 21 e 28 dias após aplicação (DAA) e estatura de plantas aos 28 e 35 DAA. Na maturação fisiológica avaliou-se estatura da planta, altura inserção da primeira vagem, número de vagens por planta, peso de 400 grãos e rendimento de grãos de feijão. A cultivar Talismã apresentou baixa sensibilidade ao herbicida e a cultivar Jalo Precoce elevada sensibilidade ao herbicida, considerando-se todas as variáveis analisadas.

The herbicide saflufenacil is a Protox inhibitor, with differential translocation mode in comparison to other herbicides with the same mechanism of action. Selectivity, efficacy and safety to the environment are important characteristics for practical application of a herbicide in agriculture. The aim of this study was to determine the tolerance of ten dry bean cultivars to saflufenacil, applied on preemergence. The experiment was conducted in split plot randomized blocks design with ten dry bean cultivars (IAPAR 81; IPR Tiziu, IPR Corujinha; BRS Estilo; BRS Talismã; BRS Esplendor; BRS Campeiro; BRS Radiante, BRS Vereda and Jalo Precoce) allocated in plots and saflufenacil concentrations (0, 14.7 and 29.4 g ha- 1) in subplots. Evaluations were performed at 21 and 28 days after application (DAA) and plant height at 28 and 35 DAA. At physiological maturity were evaluated plant height, first pod height , number of pods per plant, 400 grains weight and dry beans grain yield. The cultivar Talismã showed low sensitivity to the herbicide and the cultivar Jalo Precoce high sensitivity to the herbicide, considering all variables analyzed.

A utilização de herbicidas com formulações com liberação controlada poderá se constituir em uma ferramenta importante para reduzir problemas de lixiviação e garantir a eficácia desses produtos. O objetivo do presente trabalho foi comparar a eficiência de controle de Urochloa plantaginea (UROPL) e o rendimento de grãos de milho entre uma formulação de atrazina comercial (WG) e uma formulação de liberação controlada (xerogel). O delineamento utilizado foi o de blocos ao acaso, em parcelas subdivididas, com quatro repetições, em um esquema (2x7)+1. Nas parcelas principais, foram locadas as formulações de atrazina (WG e xerogel) e, nas subparcelas, as concentrações dos herbicidas (0, 2400, 3200, 3600, 4200, 5400 e 8000g de atrazina ha-1). Foram determinados os níveis de controle e densidade de plantas de UROPL e o rendimento de grãos da cultura do milho. A elevação das doses de atrazina resultou em aumento dos níveis de controle de UROPL. Em avaliações realizadas aos 28 e 35 dias após a aplicação, a atrazina xerogel demonstrou eficiência agronômica superior à formulação WG. Não ocorreram diferenças de rendimento de grãos de milho em parcelas tratadas com diferentes formulações e níveis de atrazina.

The use of herbicides with controlled release formulations may constitute important tool to reduce leaching problems and increase the efficacy of atrazine in soil. The aim of this study was to compare the efficiency of control of Urochloa plantaginea (UROPL) and corn grain yield from a commercial formulation (WG) of atrazine and a controlled-release formulation (xerogel). The design was randomized blocks in split plots with four replications in a scheme (2x7)+1. Factor A consisted of the formulations of atrazine (WG and xerogel), factor B concentrations of herbicide (0, 2400, 3200, 3600, 4200, 5400 and 8000ha atrazine g-1). Variables assessed consisted of control levels, plant density of UROPL and corn grain yield. The increasing levels of atrazine resulted in increased levels of control UROPL. In assessments made at 28 and 35 days after application, atrazine xerogel showed higher agronomic efficiency than the WG formulation. There were no differences in corn grain yield from plots treated with different formulations and atrazine levels.

Genótipos de plantas de soja, cultivados em regiões de clima subtropical, podem apresentar acamamento acentuado. O acamamento de plantas é influenciado pelo tipo de solo e pela fertilidade, época de semeadura, latitude e altitude do local, população de plantas e condições gerais de desenvolvimento do cultivo. Reguladores vegetais e alguns herbicidas são capazes de evitar ou reduzir o acamamento. Este trabalho teve o objetivo de avaliar os efeitos da aplicação dos reguladores de crescimento TIBA e daminozide sobre o desenvolvimento vegetativo e o rendimento de grãos do cultivar de soja CD 214 RR. O experimento foi conduzido em campo, em delineamento de blocos ao acaso, com quatro repetições, em esquema bifatorial, sendo o fator A os reguladores TIBA e daminozide e suas concentrações e, o fator B, sete épocas de avaliação da injúria e altura de planta, ou oito épocas de avaliação do acamamento. Na faixa de doses utilizada, a aplicação de daminozide resultou em maior injúria às plantas de soja do que a aplicação de TIBA. As menores alturas de plantas foram alcançadas com a aplicação de 6 g ha-¹ de TIBA e 1200 g ha-¹ de daminozide. Os tratamentos com daminozide (100 g ha-¹) e TIBA (10 g ha-¹) destacaram-se pela redução do acamamento de plantas de soja. O peso de grãos aumentou linearmente com a elevação das doses de TIBA. Houve correlação negativa entre acamamento e rendimento de grãos de soja, e positiva, entre altura de planta e acamamento. Também foi constatada correlação negativa entre injúria à soja, causada pela aplicação dos reguladores vegetais, e peso de grão.

Soybean genotypes grown in sub-tropical climate may exhibit lodging. The plant lodging is influenced by soil type and fertility level, sowing date, latitude and altitude of the location, plant population and conditions of crop development. Plant regulators and herbicides are able to avoid or reduce plant lodging. This study aimed to verify the effects of the growth regulators TIBA and daminozide on vegetative growth and yield of soybean cultivar CD 214 RR. The experiment was carried out at a field in randomized block design with four replications in a factorial scheme. The A factor was represented by the combination of regulators TIBA and daminozide and its concentrations, and the Factor B was seven times of evaluation of injury and plant height or eight times of evaluation of lodging. In the range of doses used, the application of daminozide resulted in greater injury to soybean plants than TIBA. The smaller plant height was achieved by the application of 6 g ha-1 of TIBA and 1200 g ha-¹ of daminozide. Treatments with daminozide (100 g ha-¹) and TIBA (10 g ha-1) stood out due to the reduced lodging of soybean plants. Grain weight increased linearly when the levels of TIBA increased. There was a negative correlation between lodging and grain yield and a positive correlation between plant height and lodging. There was also a negative correlation between injury caused by the application of plant regulators and lodging.