Abstract Background: Several factors may affect herbicide fate in the soil, including soil moisture which can affect herbicide availability and degradation and mixture with other degradable herbicides. Objective: The objectives of this research were to evaluate the effects of soil moisture content and association with glyphosate on S-metolachlor persistence in lowland soil. Methods: Greenhouse experiments were conducted in 2011 and repeated in 2012 using a randomized complete block design in a factorial arrangement (3×3×5) with four replications. Factor A included three soil moisture contents (air-dried, water holding capacity, and saturated), and factor B included two herbicide combinations (S-metolachlor; S-metolachlor + glyphosate) plus an untreated check. Factor C included five intervals between application and sowing of the bioindicator species (rice): 150, 120, 90, 60, and 30 days before sowing. Herbicide injury, height in rice plants, and herbicide concentration in soil was evaluated. Results: S-metolachlor concentration and injury to rice were higher under dry soil conditions regardless of application timing. In contrast, rice injury was significantly lower in the soil saturated condition. The association with glyphosate did not affect S-metolachlor persistence in lowland soil. Conclusion: These results indicate that S-metolachlor exhibits shorter persistence under saturated soil conditions; and indicated that drought periods following S-metolachlor applications may increase carryover to sensitive crops planted in rotation. Background herbicides Objective Smetolachlor S metolachlor Methods 201 3×3×5 335 3 5 (3×3×5 replications airdried, airdried air dried, dried (air-dried capacity saturated, , saturated) (S-metolachlor check (rice) 150 120 90 60 plants evaluated Results timing contrast condition Conclusion rotation 20 3×3× 33 (3×3× (rice 15 12 9 6 2 3×3 (3×3 1 3× (3× (3 (

Abstract: Background: RNA interference (RNAi) is a natural post-transcriptional gene silencing (PTGS) system of eukaryotic cells and can be used as spray-induced gene silencing (SIGS) to target genes. Due to the complexity of plant cell structure and genome, using SIGS in plants has faced many barriers. Objective: We aimed to develop a delivery strategy and appropriate siRNA design to induce PTGS by SIGS. Methods: The rice Phytoene desaturase (OsPDS) gene was used as a model to test our SIGS. Three siRNAs (siPDS1, siPDS2, and siPDS3) targeting different regions of the OsPDS transcript were applied individually or mixed siPDS2+siPDS3 in solution with SilwetTM adjuvant. Treatments were applied using a micropipette in rice seedlings (V2-stage), with the addition of proper control treatments: untreated-check and adjuvant-check. Seedlings were accessed phenotypically, physiologically, and molecularly. Results: The most prominent phenotype was observed for siPDS1 and siPDS2+siPDS3. Reduction in plant growth, chlorophyll index and shoot dry mass were reduced after siPDS2+siPDS3 application, while increasing anthocyanin content. OsPDS was downregulated after siPDS1 application with no change in the non-treated upper leaf. Conclusions: Our siRNA design and delivery strategy efficiently delivered the siRNA inside the plant and promoted target PTGS and compatible phenotype. The system used in this experiment did not show systematicity in the plant, probably due to the fast oxidative stress that hindered the systematic effect. This is an advance on the SIGS and can be a valuable tool for PTGS to find new targets for RNAi. Abstract Background RNAi (RNAi posttranscriptional post transcriptional (PTGS sprayinduced spray induced (SIGS genes genome barriers Objective Methods (OsPDS siPDS1, siPDS (siPDS1 siPDS2 siPDS3 siPDS2siPDS3 siPDSsiPDS siPDS2+siPDS adjuvant V2stage, V2stage Vstage V2 stage , V (V2-stage) treatments untreatedcheck untreated check adjuvantcheck. adjuvantcheck check. adjuvant-check phenotypically physiologically molecularly Results growth content nontreated non treated leaf Conclusions effect (siPDS siPDS2siPDS (V2-stage

Abstract: Background: Provisia rice and glyphosate-resistant soybean can control imidazolinone(IMI)-resistant weedy rice (WR-R) and reduce the soil seedbank. Objective: We evaluated different systems to reduce the WR-R soil seedbank under analysis when adopting soybean and Provisia rice (PV). Methods: From 2017 to 2022, a field experiment in randomized block design with four repetitions was performed. In 2017-2018, WR-R and Clearfield® rice (CL) were sown in the area. From 2018 to 2022, twelve systems [including CL, Provisia (PV), non-CL rice (NCL) and Soy] were used: S1) PV-PV-PV-PV, S2) CL-CL-CL-CL, S3) PV-CL-PV-CL, S4) PV-PV-Soy-CL, S5) PV-PV-CL-CL, S6) PV-Soy-PV-Soy, S7) Soy-PV-PV-Soy, S8) Soy-PV-PV-NCL, S9) PV-PV-PV-NCL, S10) Soy-PV-PV-CL, S11) Soy-Soy-PV-PV, and S12) PV-Soy-PV-CL. The WR-R management were CL – imazapyr + imazapic, PV – quizalofop-p-ethyl, NCL – no specific treatment, and Soy – glyphosate. WR-R plant density and soil seedbank were evaluated during the experiment. The systems were analyzed by year and each system over the years and the means were compared (LSD, p<0.05). Results: Over the years, no WR-R plant escapes (100% control) were observed in the systems using soybean or PV. However, even after three years of using alternative systems, the return of CL rice allowed seedbank replenishment. Thus, our results suggest that it takes more than four years to deplete the seedbank. The systems in which soybean (S6, S7, and S11) were used for two years were more efficient for soil seedbank reduction. Conclusions: Systems alternating soybean and Provisia rice for more than four years are a strategy to reduce imidazolinone-resistant weedy rice soil seedbanks. Abstract Background glyphosateresistant glyphosate resistant imidazolinoneIMIresistant imidazolinone IMI WRR WR R (WR-R Objective . (PV) Methods 201 2022 performed 20172018, 20172018 2018, 2017-2018 Clearfield (CL area including PV, , nonCL non (NCL S1 S PVPVPVPV, PVPVPVPV PV-PV-PV-PV S2 CLCLCLCL, CLCLCLCL CL-CL-CL-CL S3 PVCLPVCL, PVCLPVCL PV-CL-PV-CL S4 PVPVSoyCL, PVPVSoyCL PV-PV-Soy-CL S5 PVPVCLCL, PVPVCLCL PV-PV-CL-CL S6 PVSoyPVSoy, PVSoyPVSoy Soy, PV-Soy-PV-Soy S7 SoyPVPVSoy, SoyPVPVSoy Soy-PV-PV-Soy S8 SoyPVPVNCL, SoyPVPVNCL NCL, Soy-PV-PV-NCL S9 PVPVPVNCL, PVPVPVNCL PV-PV-PV-NCL S10 SoyPVPVCL, SoyPVPVCL Soy-PV-PV-CL S11 SoySoyPVPV, SoySoyPVPV Soy-Soy-PV-PV S12 PVSoyPVCL. PVSoyPVCL CL. PV-Soy-PV-CL imazapic quizalofoppethyl, quizalofoppethyl quizalofop p ethyl, ethyl quizalofop-p-ethyl treatment LSD, LSD (LSD p<0.05. p005 p<0.05 0 05 p<0.05) Results 100% 100 (100 However replenishment Thus S6, (S6 reduction Conclusions imidazolinoneresistant seedbanks (PV 20 202 2017201 2017-201 p00 p<0.0 10 (10 (S 2 201720 2017-20 p0 p<0. 1 (1 20172 2017-2 p<0 ( 2017- p<

Abstract Background drones for pesticide application have become more popular due to their practicality and reduction in cost. Accessing drone efficacy in herbicide application is needed. Objective This work aimed to determine the efficiency of drones in applying glyphosate and glufosinate to control ryegrass and oilseed radish compared to electrostatic and conventional ground herbicide applications. Methods The experiments were conducted in a factorial arrangement with five replications and repeated in time. Factor A consisted of spraying methods [drone, electrostatic ground spraying (electrostatic), and conventional ground spraying (conventional)], and factor B consisted of eight doses of glyphosate and glufosinate. A CO2 pressurized backpack was equipped with XR TeeJet® 11001VS spray nozzles for electrostatic and conventional applications, adjusted to a spray volume of 100 L ha-1. The drone, Pelicano® 2022 model (Skydrones), was equipped with the same spray nozzles but was regulated to a spray volume of 10 L ha-1. Results: The results demonstrated that glyphosate application via drones provided superior control of ryegrass and oilseed radish compared to terrestrial methods, whereas glufosinate’s effectiveness was comparable to that of ground-based applications. Conclusions drone application of glyphosate and glufosinate was efficient in controlling ryegrass and oilseed radish, being as good as ground spraying, even demonstrating that low spray volume does not significantly interfere with weed control in this study. cost needed applications time [drone electrostatic, , (electrostatic) conventional, (conventional)] CO TeeJet VS ha1. ha1 ha 1. 1 ha-1 Pelicano 202 Skydrones, Skydrones (Skydrones) Results glufosinates s groundbased based study (electrostatic (conventional) ha- 20 (Skydrones (conventional 2

Abstract Herbicide mineralization in the soil is affected by several factors, including the herbicide application history of the soil, soil moisture, and whether the herbicide is co-applied with another herbicide. The objective of this work was to evaluate S-metolachlor mineralization in the soil as affected by soil moisture content, history of herbicide application, and association with glyphosate. 14C-S-metolachlor mineralization increased with increasing soil moisture content. The average cumulative mineralization of S-metolachlor at 63 days of incubation was 0.03, 0.80, and 1.80% in air-dried, field capacity, and saturated soil, respectively. The mineralization rate of S-metolachlor was greater under saturated conditions and affected by the association with glyphosate. Greater mineralization of S-metolachlor occurred in cornfield soil with a history of S-metolachlor application. The average cumulative mineralization was 0.24% in cornfield and 0.89% in non-cultivated area. We can conclude that the higher the soil moisture content the higher S-metolachlor mineralization and that the mixture of this herbicide with glyphosate increased its degradation compared to the application of the herbicide alone. While there is evidence suggesting enhanced degradation of S-metolachlor in soil previously subjected to corn cultivation and S-metolachlor application, drawing a definitive conclusion is challenging due to the influence of sorption observed in our dataset. factors coapplied co applied Smetolachlor S metolachlor 14CSmetolachlor CSmetolachlor 14C C 6 003 0 03 0.03 080 80 0.80 180 1 1.80 airdried, airdried air dried, dried air-dried capacity respectively 024 24 0.24 089 89 0.89 noncultivated non cultivated area alone dataset 00 0.0 08 8 0.8 18 1.8 02 2 0.2 0. 1.

Abstract Background Eragrostis plana is the main invasive plant in the Pampa Biome of southern Brazil. This plant is highly competitive, tolerant to abiotic stresses, and very difficult to manage. Plants exposed to abiotic stresses and herbicides develop mechanisms that help alleviate or reduce damage caused by stressors and transmit this ability to the progenies. Objective The study’s objectives were to ascertain whether acclimatization to stress due to drought and sub-lethal doses of glyphosate may decrease plant sensitivity to glyphosate and investigate the possible memory mechanisms involved in this process. Methods A population of E. plana was submitted to drought, glyphosate, or a combination of drought plus glyphosate for two generations. The progenies were analyzed for sensitivity to the herbicide glyphosate and for biochemical, metabolites, and molecular responses. Results When testing sensitivity to glyphosate in the G 2 generations, the DRYxGLY (plants stressed with drought plus glyphosate) was the least sensitive (ED50 443.0 g a.e. ha-1), while CHK (without stresses) was the most sensitive (ED50 278.0 g a.e. ha-1). Evaluating the effects of glyphosate, the CHK population showed a greater accumulation of oxidative damage and shikimic acid. While DRYxGLY had greater antioxidant activity and higher expressions of the EPSPS and ABC-carrier MRP10 genes. Conclusions Recurrent selection with drought stress and sub-lethal rate of glyphosate (DRYxGLY) showed reduced sensitivity to glyphosate in the second generation ( G 2 ). The conjunction of factors, including the upregulation of EPSPS and the ABC MRP10 transporter, antioxidant enzymes seem to decrease the sensitivity of the DRYxGLY population to glyphosate.

Abstract Background: Clearfield® (CL) rice is one of the most successful tools for selective weedy rice control, using imidazolinone herbicides (IMI). However, IMI have residual soil activity and may carryover to non-tolerant crops growing in succession. It is necessary to find options to reduce IMI persistence in paddy rice fields. Objective: Evaluate the effect of water management on IMI dissipation in rice paddy and its carryover to soybean and non-CL rice. Methods: The herbicide mixture of imazapyr and imazapic totalizing 147 g a.i. ha−1 and 49 g a.i. ha−1, respectively, was applied half in preemergence (S3 stage – rice spike stage) and the other half in postemergence (V3-V4 rice stage). After herbicide application, a total of 21 samples were taken for analysis of residues. Soil samples were air dried and herbicides residues were analyzed using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Results: Calculated field dissipation half-life (DT½) of imazapyr was 182.5 and 42.0 days in continuous flooding and intermittent water management, respectively. Imazapic had a DT½ of 96.3 days on intermittent water management. No adjustment for the dissipation regression parameters was obtained for imazapic in continuous water management. No reduction in yield components was observed in soybean when grown in soil with imidazolinone residues. On the other hand, non-CL rice showed decreased shoot dry weight and stem number. Conclusion: Imidazolinone herbicides have a longer half-life under continuous rice water management than intermittent. Therefore, growers can use intermittent irrigation in ares prone to IMI carryover and can use soybean in rotation.