RESUMEN El índice de selectividad es una forma de evaluar el efecto selectivo de un herbicida para un cultivo determinado mediante la observación de sus efectos sobre el cultivo y las malezas. El objetivo fue obtener el índice de selectividad del herbicida indaziflam en el cultivo de caña de azúcar IACSP95-5000 en función de cinco malezas en dos texturas de suelo diferentes. El experimento se realizó en un invernadero en Piracicaba, São Paulo, Brasil. Los tratamientos consistieron en dosis de indaziflam (0; 12,5; 25; 50; 100; 200; 400; 800 y 1,600 g ai ha-1), aplicadas en pre-emergencia de la caña de azúcar y de las malezas Urochloa decumbens, Urochloa plantaginea, Digitaria horizontalis, Panicum maximum y Rottboellia cochinchinensis. En suelo franco arenoso, 25 g de ia ha-1 proporcionaron un control del 100% para todas las malezas. En suelo arcilloso, para D. horizontalis la reducción del 90% en la masa seca total (ED90) se obtuvo a 25 g ai ha-1, para R. cochinchinensis a 193 g ai ha-1, para U. plantaginea a 152 g ai ha-1, para P. maximum a 124 g ia ha-1, y para U. decumbens a 94 g ia ha-1. Indaziflam fue selectivo para IACSP95-5000 caña de azúcar en ambos suelos, con 10% de reducción de masa seca (ED10) a 137 g ia ha-1 para suelo con textura franco arenosa y 353 g ia ha-1 para suelo arcilloso. El índice de selectividad fue superior a 1 para todas las malezas en suelo arcilloso. No fue posible obtener el índice de selectividad para suelos franco arenosos debido a la susceptibilidad de las malezas al herbicida.

ABSTRACT Selectivity index is a way of assessing the discrimination of herbicide to a given crop by observing its effects on the crop and the weeds. The aim was to obtain the selectivity index of indaziflam herbicide to sugarcane cultivar IACSP95-5000 as a function of five weed species in two soils textures. The experiment was carried out in a greenhouse at Piracicaba, São Paulo, Brazil. The treatments consisted of indaziflam doses (0; 12.5; 25; 50; 100; 200; 400; 800 and 1,600 g of the active ingredient (ai) ha-1), applied in pre-emergence of the sugarcane and of the weeds Urochloa decumbens, Urochloa plantaginea, Digitaria horizontalis, Panicum maximum and Rottboellia cochinchinensis. In sandy loam soil, a 100% control for all weeds was provided at 25 g ai ha-1. In clay soil, for D. horizontalis the 90% reduction in total dry mass (ED90) was obtained at 25 g ai ha-1, for R. cochinchinensis at 193 g ai ha-1, for U. plantaginea at 152 g ai ha-1, for P. maximum at 124 g ai ha-1, and for U. decumbens at 94 g ai ha-1. Indaziflam was selective to IACSP95-5000 in both soils, with 10% of reduction in dry mass (ED10) at 137 g ai ha-1 for soil with a sandy loam texture and 353 g ai ha-1 for clay soil. The selectivity index was higher than 1 for all weeds in clay soil. It was not possible to obtain the selectivity index for sandy loam soil due to species susceptibility to the herbicide.

RESUMO: Há poucas informações sobre a eficácia e seletividade de sulfonilureias, isoladas e associadas ao glifosato, na soja tolerante ao glifosato e às sulfonilureias. Assim, o presente estudo teve como objetivo avaliar a eficácia no controle de plantas daninhas e seletividade de sulfonilureias, isoladas e em associação com o glifosato, em pós-emergência (V4) de soja RR2/STS. Os experimentos foram conduzidos em áreas localizadas nos municípios de Piracicaba, São Paulo (SP), Brasil (experimento I) e Palotina, Paraná (PR), Brasil (experimento II). Os tratamentos foram compostos pela aplicação dos herbicidas sulfometurom, clorimurom, halossulfurom, etoxissulfurom e glifosato, isolados e em associação, no cultivar BMX Garra RR2/STS. O experimento I foi realizado com o foco principal na avaliação da eficácia no controle de plantas daninhas; ao passo que o experimento II se concentrou principalmente na avaliação da seletividade dos herbicidas. O delineamento experimental foi o de blocos casualizados, com quatro repetições. Foram avaliados sintomas de injúria, controle de plantas daninhas e variáveis relacionadas ao desempenho agronômico. Os dados foram submetidos à análise de variância, e as médias dos tratamentos foram comparadas pelo teste de Tukey. Sulfonilureias associadas ao glifosato foram eficazes no controle de plantas daninhas e seletivas para o cultivar de soja BMX Garra RR2/STS. A associação sulfometurom + clorimurom + glifosato apresentou potencial fitotóxico para o cultivar BMX Garra RR2/STS.

ABSTRACT: There is little information on the efficacy and selectivity of sulfonylureas, isolated and in association with glyphosate, in glyphosate and sulfonylurea-tolerant soybeans. Thus, the present study aims to evaluate the efficacy of weed control and selectivity of sulfonylureas, isolated and in association with glyphosate, at post-emergence (V4) of RR2/STS soybean. The experiments were conducted in the in areas located in Piracicaba City, São Paulo State (SP), Brazil (experiment I) and Palotina City, Paraná State (PR), Brazil (experiment II). Treatments were composed of application of the herbicides sulfometuron, chlorimuron, halosulfuron, ethoxysulfuron and glyphosate, isolated and in association, in the BMX Garra RR2/STS cultivar. Experiment I was conducted focusing on the evaluation of the efficacy of weed control; whereas experiment II focused mainly on the evaluation of herbicide selectivity. The experimental design was the randomized complete block, with four replications. Crop injury, weed control, and variables related to agronomic performance were evaluated. Data were submitted to analysis of variance, and the means of the treatments were compared with the Tukey test. Sulfonylureas in association with glyphosate were effective in weed control and selective for the BMX Garra RR2/STS soybean cultivar. The sulfometuron + chlorimuron + glyphosate association presented phytotoxic potential for the BMX Garra RR2/STS cultivar.

ABSTRACT The aim was to evaluate the selectivity and weed control of herbicides atrazine, nicosulfuron, mesotrione and tembotrione, applied alone and associated, in post-emergence of maize. Were carried out two experiments, one in the field in a randomized complete block design with four replications and eleven treatments, the second in greenhouse in a completely randomized design, with four replications and ten treatments. The treatments were composed of isolated and associated herbicides. Treatments were applied V4 stage of plants. For first experiment, crop injury and control evaluations were performed, as well as variables related to agronomic performance (plant height, ear insertion height, prolificacy index, yield and mass of 1,000 grains) and mass of weeds. For second experiment, evaluations of crop injury, height, diameter and dry mass of plants were performed. The lower yield for experiment one was verified in the treatment where only mesotrione was applied, which was attributed to the lower control of monocotyledons weeds. Crop injury were observed at 21 DAA in both experiments, but not exceeding 7.5%. All treatments were considered selective to maize. The herbicides atrazine, nicosulfuron, mesotrione and tembotrione, at associations, were effective in the weed control, except the association atrazine + mesotrione.

RESUMO: A “segunda geração” de soja tolerante ao glifosato (soja RR®2) foi desenvolvida por meio de uma diferente inserção do gene EPSPs insensível ao referido herbicida. Informações sobre a seletividade de glifosato, isolado ou em associação, são faltantes em soja RR2. Este estudo avaliou os efeitos do glifosato, isolado ou em associações, aplicado em pós-emergência (V4), no desempenho agronômico e na qualidade de sementes do cultivar de soja NS 6700 IPRO (RR2). Adotou-se o delineamento experimental de blocos ao acaso com quatro repetições e sete tratamentos, realizados no campo em duas safras. Os tratamentos consistiram no herbicida glifosato, isolado ou em associação com clethodim, cloransulam, chlorimuron, lactofen e fluazifop, além da testemunha sem aplicação. Foi realizada a avaliação dos sintomas de injúria e índice SPAD (Soil and Plant Analyzer Development), bem como de variáveis relacionadas ao desempenho agronômico (altura, número de vagens por planta, produtividade e massa de 1.000 sementes) e à qualidade das sementes (vigor, germinação, plântulas anormais e sementes mortas). Experimento complementar foi realizado com o mesmo cultivar e tratamentos em casa de vegetação em delineamento inteiramente casualizado com quatro repetições. Os herbicidas não afetaram o desempenho agronômico e a qualidade de sementes da soja RR2. Assim, o cultivar NS 6700 IPRO (RR2) foi tolerante ao glifosato, isolado ou em associação com outros herbicidas aplicados em pós-emergência (V4).

ABSTRACT: The “second generation” of glyphosate-tolerant soybean (RR®2 soybean) was developed through a different technique of insertion of the glyphosate-insensitive EPSPs gene. Information on the selectivity of glyphosate, alone or in combination, in RR2 soybean is lacking. This study evaluated the effects of glyphosate, isolated or in associations, applied at post-emergence (V4), at agronomic performance and seed quality of soybean cultivar NS 6700 IPRO (RR2). The experimental design was randomized block with four replications and seven treatments, conducted in the field for two growing seasons. The treatments consisted of glyphosate herbicide, alone or in combination with clethodim, cloransulam, chlorimuron, lactofen and fluazifop, besides the control without application. Analysis was performed for crop injury, Soil and Plant Analyzer Development (SPAD) index, as well as variables related to agronomic performance (height, number of pods per plant, yield and 1,000-seed weight) and seed quality (vigor, germination, abnormal seedlings and dead seeds). An additional test was conducted with the same cultivar and treatments in a greenhouse in a completely randomized design with four replications. The herbicides did not affect agronomic performance and seed quality of RR2 soybean. Thus, the soybean cultivar NS 6700 IPRO (RR2) was tolerant to glyphosate, alone or combined with other herbicides applied in post-emergence (V4).