Synergism is a desired result in the interaction between herbicides because it provides many benefits, among which the reduction of doses and the increment of control efficiency, and because it positively signals for the joint application of herbicides. The objective of this study is to evaluate the effect of the association of saflufenacil with other herbicides that promote oxidative stress on the development of Euphorbia heterophylla as well as to analyze if the resulting interactions are antagonistic, additive or synergistic. The experiment was conducted in pots, in a greenhouse, using a completely randomized design with four replications. Treatments consisted of saflufenacil (0, 1,2, 2,32, 4,47, 8,63, 16,65 g ha-1) alone and associated with clomazone (288 and 504 g ha-1), metribuzin (105.6 and 206.4 g ha-1) and paraquat (20 and 40 g ha-1), as well as these herbicides applied alone at the same doses described above. Twenty-one days after the application (DAA), the shoot dry matter (SDM) of plants was evaluated in each experimental unit. The Limpel-Colby method was used to calculate the expected response of the herbicide interaction. All combinations of saflufenacil with clomazone, metribuzin and paraquat were considered synergistic. Among the treatments associated with saflufenacil, those including metribuzin at the dose of 105.6 g ha-1 were the ones that provided the most promising results, which stood out for the greater reductions of wild poinsettia shoot dry matter, compared to the application of saflufenacil alone.

The combination of herbicides and other pesticides can influence weed and crop management. This study aimed to evaluate the response of the combination of different herbicides with insecticides or fungicides of different chemical groups on the development and yield of wheat grains of the cultivar ORS Vintecinco. The experimental design was a randomized block design with three replications. The experiment consisted of 33 treatments, as follows: control without application and application of the herbicides 2,4-D (1,005 g a.e. ha-1), bentazon (756 g a.i. ha-1), metsulfuron-methyl (3 g a.i. ha-1), and pyroxsulam (16 g a.i. ha-1), isolated or combined with the insecticides chlorfluazuron (15 g a.i. ha-1), chlorpyrifos (720 g a.i. ha-1), deltamethrin (5 g a.i. ha-1), and methomyl (5 g a.i. ha-1) or with the fungicides azoxystrobin (100 g a.i. ha-1), carbendazim (250 g a.i. ha-1), and propiconazole (190 g a.i. ha-1). Relative tolerance (RT), shoot dry matter (SDM), yield components, and grain yield were evaluated. In general, pyroxsulam had the highest number of synergistic interactions with insecticides and fungicides, reducing RT and SDM, especially the combination pyroxsulam + chlorpyrifos due to a lower RT level (45%) and higher SDM reduction (52%). All combinations of herbicides with the insecticide chlorpyrifos and most of the combinations with the fungicide propiconazole led to a reduction of grain yield when compared to their isolated application or to control without application.

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Increased use of glyphosate in transgenic soybean areas has selected resistant and tolerant weed species. The aim of this study was to evaluate chemical management strategies for controlling Borreria latifolia and Richardia brasiliensis at pre-emergence (Pre), early post-emergence (Poste) and late post-emergence (Postl). Six experiments were carried out in a completely randomized design with four replicates per treatment in the Pre experiments and three in the Poste and Postl experiments, for each of the species. In the Pre experiments, tests were performed with herbicides imazethapyr, sulfentrazone, chlorimuron, diclosulam, S-metolachlor and saflufenacil. In the Poste experiments, seedlings were sprayed with herbicides bentazon, fomesafen, lactofen, flumioxazin and glyphosate. In Postl experiments, adult plants received glyphosate application associated with herbicides 2,4-D, carfentrazone, imazethapyr, flumiclorac, flumioxazin, sulfentrazone, chlorimuron, saflufenacil and glufosinate, plus three sequential applications with glyphosate only and paraquat/diuron. In the experiments, there was a control treatment without application of herbicides. In the Pre experiments, the plants established at 14 and 28 days after application (DAA) were evaluated. In the Poste and Postl experiments, shoot dry matter evaluation and visual control were performed at 14 and 28 DAA. The herbicides sulfentrazone, S-metolachlor and saflufenacil suppressed the emergence of both B. latifolia as R. brasiliensis; chlorimuron-ethyl and diclosulam were effective only on R. brasiliensis. In Poste, fomesafen, lactofen and flumioxazin reached levels of control over 90% of plants of both species. In Postl, glyphosate associated with carfentrazone, flumiclorac, flumioxazin, chlorimuron-ethyl, saflufenacil, glufosinate, and sequential applications of glyphosate/glyphosate, glyphosate/paraquat+diuron, glyphosate+2,4-D/paraquat+diuron reached levels control higher than 95%.

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Weed management with herbicides requires favorable environmental conditions, that maximize efficiency, such as soil humidity and timing of application. The aim of this study was to assess the effect of the application timing of bentazon and glyphosate herbicides on the control and activity of antioxidant enzymes in Ipomoea grandifolia, under different conditions of soil water availability. Two experiments, one for each herbicide (bentazon and glyphosate), were conducted in a factorial design with four replicates. The first factor was the two rates of each herbicide (504 and 720 g i.a. ha -1 of bentazon and 651 and 911.4 g i.a. ha -1 of glyphosate). The second factor was the six application times (1 am; 5 am; 9 am; 1 pm; 5 pm and 9 pm). The third factor, soil water content (100% and 50% of field capacity). Plus, two controls without herbicide application. At 21 days after application (DAA) of bentazon and 28 DAA of glyphosate, the fresh mass of the aboveground plants was measured. In addition, the activities of the enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) were determined. For plants under water restriction, an increase of approximately 20% in fresh mass was observed compared in plants without water restriction, indicating lower control efficiency under water stress condition. For bentazon, at 1 pm has been observed the lowest herbicide efficiency, the other times were the most efficient, and did not differ. For glyphosate, the application at 9 am was the most efficient, while at 1 am provided the worst control efficiency. Higher CAT and SOD activities after bentazon application were observed at 1 pm. Among the three enzymes evaluated, SOD presented the highest activity after glyphosate application. Generally, the times of the day with the highest peak of enzymatic activity were distinct between with and without water restriction. Highlighted Conclusions1. Water restriction reduces the efficiency of bentazon and glyphosate. 2. Better efficiency for bentazon was observed at 1 am, 5 am, 9 am, 5 pm and 9 pm. 3. Better efficiency for glyphosate was observed at 9 am.

This work was conducted with the objective to determine Euphorbia heterophylla control with fomesafen in association with surfactants applied in pre-emergence, in substrates and soils with different characteristics. Three studies were carried out in pots, conducted in greenhouse, in a completely randomized experimental design. The first two studies consisted of investigating the efficacy of pre-emergence combinations of fomesafen and surfactant in the control of E. heterophylla, applied on different substrates (Study 1) and soils (Study 2) with different textural classes. Study 3 was carried out to evaluate the effect of fomesafen, applied in pre-emergence and in combination with adjuvants with different HLB's (hydrophilic-lipophilic balances). The herbicide efficacy on E. heterophylla and plant shoot dry mass were evaluated. The association of adjuvant to fomesafen, in pre-emergence, reduced plant growth in the different substrates and soils. The fomesafen response was influenced by the addition of surfactants with different HLB's. The increase in organic matter content in substrates or soil was related to the decrease of the effect of the surfactants on the control of E. heterophylla with fomesafen, or the effect was only manifested in higher herbicide dosages. Fomesafen associated with surfactant with HLB of 8.6 provided the highest levels of weed control.