Cyhalofop-butyl stands out among the herbicides in the control of imidazolinone-resistant Echinochloa species; but, rice farmers are not always satisfied with the control achieved with this herbicide. The objectives were to evaluate in regional scale the susceptibility of Echinochloa populations to cyhalofop-butyl, and quantify the effect of the weed phenology on its efficacy of control. For this, three trials were carried out under greenhouse conditions with a fully random design, using Echinochloa populations collected in rice fields in the southern region of Brazil. In two trials, the susceptibility level of 156 (2012/13 growth season) and 103 (2013/14 growth season) populations were evaluated with the application of cyhalofop-butyl at 360g ha-1. In other trial, in which treatments were arranged in a bi-factorial design (A = 6 x B = 5), it was evaluated six cyhalofop-butyl rates and five phenological stages of E. crus-galli populations. Echinochloa populations had showed differential susceptibility to cyhalofop-butyl, especially in the 2013/14 growth season, where 20 out of the 103 populations had control lower than 90%. The efficacy of this herbicide was inversely proportional to the phenological stage, and the application timing delay contributed directly to the decrease of susceptibility to the herbicide. Cyhalofop-butyl is an effective alternative to control imidazolinone-resistant Echinochloa populations, as long as the application timing occurs in the early phenological stages (2 to 4 leaves).

<p> The present study aims to evaluate the control of C. benghalensis by herbicides applied in post-emergence and in pre-emergence sequentially in the infesting weed in the coffee crop. Two field experiments were carried out in a coffee crop, with natural infestation of C. benghalensis, the experimental design of both was completely randomized with 4 replicates. The first experiment, involving a single application of herbicides in post-emergence presented the following treatments: (1) saflufenacil (70 g i.a. ha-1); (2) glufosinate (400 g i.a. ha-1); (3) carfentrazone (20 g i.a. ha-1); (4) flumioxazin (120 g i.a. ha-1); (5) metsulfuron (6 g i.a.  ha-1), and (6) witness (without application of herbicide). In the second experiment, the treatments were: (1) saflufenacil (70 g i.a.  ha-1); (2) carfentrazone (20 g i.a. ha-1); (3) flumioxazin (120 g i.a.  ha-1); (4) metsulfuron (6 g i.a.  ha-1), all these treatments with a sequence of indaziflam (75 g i.a.  ha-1), at 21 days after the application of the treatments (DAT) of pos-emerging; (5) Witness (without application of herbicides). In the first experiment the herbicides safluenacil and flumioxazin presented the best percentages of control in post-emergence with 90 and 85.25% respectively, at 7 DAT, keeping the control superior to 80% at 21 DAT. In the second experiment, the treatments saflufenacil and flumioxazin with indaziflam sequential, presented control of 80% and 82.5% respectively at 28DAA (Days After Application). The herbicides saflufenacil and fluxioxazin represent an option for the control of C. benghalensis in post-emergence and favor the performance of the sequentially applied indaziflam herbicide. </p>

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Coffee litter and the rain that occurs after the application of pre-emergence herbicides impact on their leaching and weed control effectiveness. The objective of this study was to evaluate the leaching and control effectiveness of indaziflam, applied on coffee litter, and under simulations of different amounts of rainfall. Two experiments in greenhouse were conducted with the application of indaziflam (0.1 kg of active ingredient - a.i. - ha-1), in a completely randomized design. The first involved the leaching of the herbicide using Urochloa plantaginea as a bioindicator, in a 8 x 4 factorial arrangement, with eight depths in the PVC column (0-0.05; 0.05-0.1; 0.1-0.15; 0.15-0.2; 0.2-0.25; 0.25-0.3; 0.3-0.35; 0.35-0.4 m) and four amounts of straw (0; 1; 3 and 5 t ha-1), this factor was isolated for rainfall simulations (10, 20 and 40 mm). The second experiment tested the effectiveness in controlling U. plantaginea, in a 4 x 3 factorial arrangement, with four amounts of litter (0; 1; 3 and 5 t ha-1) and three amounts of rainfall (10, 20 and 40 mm). Both experiments had four repetitions and controls without application of the herbicide. In leaching, a greater effect of indaziflam was found at a depth of 0-0.05 m, and the higher the simulated rainfall, the greater the phytotoxicity observed in U. plantaginea, with 39.75%, 52.50% and 92.06%, for rainfall amounts of 10, 20 and 40 mm, respectively. U. plantaginea showed high susceptibility to control by the herbicide indaziflam, and the lowest control, 82%, was observed when indaziflam was applied on 5 t ha-1 with simulation of rainfall at 10 mm. The increase in the amount of litter on the soil surface, combined with lower amounts of rainfall can reduce the leaching of indaziflam and the control of U. plantaginea.