This research studied the effectiveness of herbicide treatments in weed control and during different periods of emergence, when applied to varying amounts of straw. The experiment was conducted in a greenhouse with pre-emergent herbicides: amicarbazone, metribuzin, indaziflam, isoxaflutole, amicarbazone + indaziflam, metribuzin + indaziflam, and isoxaflutole + indaziflam, against three species (Sorghum halepense, Rottboellia exaltata, and Mucuna aterrima). The experimental design was completely randomized in a 5x4 factorial scheme, with five amounts of straw (0, 1, 2, 3, and 5 t/ha) and four periods of weed emergence (0, 30, 60, and 90 days after treatments). The residual control of indaziflam was influenced by the amount of straw. Metribuzin presented a low residual control, while isoxaflutole was not affected by the amount of straw. Amicarbazone offered residual control for Mucuna aterrima. The association between indaziflam + isoxaflutole displayed a suitable residual control against Sorghum halepense and Rottboellia exaltata. The association of indaziflam + metribuzin adequately controlled Mucuna aterrima and Sorghum halepense. herbicide physical-chemical characteristics can influence their performance, and the association of products may increase residual and weed spectrum control. Highlights This partial or total removal of remaining sugarcane straw from the soil surface alters weeds dynamics in sugarcane fields. In this situation we have monocot and dicot weeds infesting the sugarcane crops. Among these species, some plants are even more difficult to control, such as Sorghum halepense, Rottboellia exaltata, and Mucuna aterrima Indaziflam herbicide presented a better performance in controlling monocotyledonous plants than eudicot plants. The herbicides amicarbazone and metribuzin presented adequate control of Mucuna aterrima despite having lower residual control. The association of indaziflam + metribuzin, resulted in satisfactory results for Mucuna aterrima, Sorghum halepense, and Rottboellia exaltata.

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).

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O plantio de cana-de-açúcar através de minirrebolos e/ou mudas pré-brotadas, apresentam melhorias em relação a aspectos fitossanitários, em comparação com o plantio convencional,  no entanto, podem apresentar maior sensibilidade a herbicidas, quando comparados com o sistema convencional. Objetivou-se avaliar a seletividade inicial de tratamentos de herbicidas aplicados em pré-emergência em variedades de cana-de-açúcar cultivadas nos sistemas de mudas pré-brotadas (MPB) e de minirrebolos. Foram realizados dois experimentos para cada sistema de plantio, sendo que para  MPBs foram utilizadas as variedades RB966928 e IAC 5000, e para minirrebolos as variedades RB92579 e RB966928. O delineamento de cada experimento foi inteiramente casualizado, com quatro repetições e esquema fatorial 8 x 5, sendo oito tratamentos (amicarbazone (980,0 g ha-1); metribuzin (921,6 g ha-1); indaziflam (50,0 g ha-1); isoxaflutole (78,8 g ha-1); amicarbazone + indaziflam (703,5 + 37,5 g ha-1); metribuzin + indaziflam (460,8 + 37,5 g ha-1), isoxaflutole + indaziflam (56,3 + 37,5 g ha-1) e a testemunha sem utilização de herbicidas e cinco épocas de avaliação (7, 14, 21 28 e 35 dias após aplicação dos tratamentos (DAT) para as MPBs e dias após a emergência (DAE) para os minirrebolos). Em MPBs, os herbicidas amicarbazone e metribuzin, resultaram em 0,00% de fitotoxicidade para as variedades RB966928 e IAC 5000. Já nos minirrebolos, os tratamentos com isoxaflutole isolado e em associação com indaziflam resultaram em alta fitotoxicidade para as variedades RB92579 e RB966928. Conclui-se que, tanto o sistema de plantio (MPBs ou minirrebolos), quanto as variedades, podem influenciar na seletividade de herbicidas na cultura da cana-de-açúcar.