Glyphosate Application Research Articles

Influence of the Long-Term Application of Management Practices (Tillage, Cover Crop and Glyphosate) on Greenhouse Gas Emissions and Soil Physical Properties

Soil treatments have a significant influence on the agricultural and environmental productivity of agricultural practices. Arable lands are one of the sources of greenhouse gas emissions (GHG) that are influenced by the chemical and physical properties of the soil and are an essential contributor to climate change. We aim to evaluate the long-term management of agricultural practices, such as different tillage systems, cover crops, and glyphosate, on GHG emissions and soil physical properties. The field trial involved three tillage systems (conventional tillage (CT), reduced tillage (RT), and no-tillage (NT)), along with variations in cover cropping (with and without cover crops) and glyphosate application (with and without glyphosate). These treatments were implemented during the cultivation of oilseed rape in 2022 as part of a cropping sequence consisting of five crops: winter wheat; winter oilseed rape; spring wheat; spring barley; and field pea. Greenhouse gas emissions (carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) were directly measured using a closed static chamber system. Through the examination of these management techniques, the soil’s physical properties over the studied period were assessed for their impact on GHG fluxes. The findings of the study reveal that N2O emissions were relatively low during the first month of measurement, with significant differences (p < 0.05) observed in the interaction between cover crop and glyphosate treatments. Additionally, N2O emissions were notably elevated in the reduced (0.079 µg m−2 h−1) and conventional tillage (0.097 µg m−2 h−1) treatments at the second month of measurement. Regarding CH4, increased emissions were observed in the reduced tillage and cover crop treatments. CO2 emissions exhibited variability across all of the investigated treatments. Notably, GHG fluxes spiked at the second measurement, signifying the maximum uptake of nutrients by the main plants during the growth phase. Greenhouse gas emissions leveled off across all of the treatments following the harvest, marking the end of the cultivation period. The influence of the deployed techniques varied across the determined physical parameters of the soil. The incorporation of cover crops contributed to improved water content and, further, to electrical conductivity. Glyphosate use showed no direct impact on physical properties of the soil while the different tillage treatments had varying effects on the distribution of the physical properties of the soil with respect to the degree of disturbance or tillage-induced changes. Additionally, GHG emissions were strongly correlated with precipitation at one week and two weeks before sampling, except for CO2, which showed a weaker correlation at two weeks before GHG sampling. The findings indicate that reduced and conventional tillage methods might adversely affect greenhouse gas emissions and plant functionality, particularly concerning nutrient release and uptake, especially in temperate climate conditions.

Subtle microbial community changes despite rapid glyphosate degradation in microcosms with four German agricultural soils

Glyphosate is the world's most widely applied herbicide. Despite its extensive and heavy use in agriculture and forestry, the microbial key players involved in glyphosate breakdown and the impact of this compound on the soil microbiota including fungi is not fully understood. Here, we used microcosm experiments to determine the impact of glyphosate application on the microbial community structure and abundance of four different agricultural soils from the Ammer valley, Germany, with a history of glyphosate application. We identified putative glyphosate degraders that could be active under in-situ conditions. Glyphosate was applied to the soils in a single dose of 15 mg·kg−1, which were incubated in the dark with 60 % water-filled pore space at 20 °C for 56 days. Soil samples were taken on the day of glyphosate addition (day 0) and after 7, 28 and 56 days. Capillary electrophoresis-mass spectrometry was used to quantify glyphosate and its major transformation product aminomethylphosphonic acid. Changes in the microbial community structure and abundance were evaluated using 16S rRNA gene or internal transcribed spacer region amplicon sequencing and qPCR. Our findings demonstrate that glyphosate was rapidly degraded in the four soils, with 60–85 % of the applied glyphosate disappearing within 7 days. However, the observed impact of glyphosate application on the microbial community composition was minimal and, notably, there was no significant time-dependent glyphosate effect at 7 days across all four soils. This suggests that glyphosate degradation in soil might be a concerted effort by a wide microbial network or it might be occurring co-metabolically. In addition, the sorption/desorption dynamics of glyphosate with the soil matrix can heavily influence its bioavailability, further reasoning the subtle effects observed on the microbial community structure.

Confirmation of a four-way herbicide-resistant Palmer amaranth (Amaranthus palmeri) population in Iowa

Abstract Palmer amaranth (Amaranthus palmeri S. Watson) was first reported in Iowa in 2013 and has continued to spread across the state over the last decade. Importantly, A. palmeri is widely recognized as one of the more economically important weeds in production agriculture. The presence of A. palmeri in Iowa is concerning as the species has evolved resistance to nine herbicide sites of action, however, no formal characterization has been conducted on Iowa populations. Therefore, herbicide assays were conducted on an A. palmeri population collected in Harrison County, Iowa in 2023 (Southwest Palmer Amaranth, SWPA) and a known herbicide-susceptible population collected from Nebraska in 2001 (Palmer Amaranth Susceptible, PAS). The two populations were treated with preemergence and postemergence herbicides commonly used in Iowa. The treatments included preemergence applications of atrazine, metribuzin, and mesotrione and postemergence applications of atrazine, imazethapyr, glyphosate, lactofen, mesotrione, glufosinate, 2,4-D and dicamba at 1x and 4x the labeled rates. Survival frequency of SWPA was >90% when treated postemergence with 1x rates of imazethapyr, atrazine, glyphosate, and mesotrione compared to ≤6% for PAS. Both SWPA and PAS had 0% survival when treated with lactofen, glufosinate, 2,4-D, and dicamba at the 1x or 4x rates. Plant population density reduction for SWPA was 53% and 40% in response to 1x rates of preemergence-applied mesotrione and atrazine, respectively. Metribuzin applied preemergence reduced SWPA plant population density by >90% at both rates. Dose-response experiments revealed the 50% effective doses (ED50) of mesotrione, glyphosate, imazethapyr, and atrazine for SWPA were 9.5-,8.5-, 71- and 40-fold greater than for PAS, respectively. The results confirm that SWPA is four-way multiple herbicide-resistant. Amaranthus palmeri infestations are likely to continue to spread within Iowa, therefore diversified weed management programs that include early detection, rapid response, and effective multi-tactic management strategies will be required for control.

The effectiveness of isopropylamine glyphosate 486 g/L + metsulfuron methyl 1 g/L herbicidal combination in oil palm (Elaeis guineensis)

Lack of knowledge in weed control techniques in oil palm cultivation practices can lead to decreased productivity. One of the herbicides that can be used to control weeds in oil palm cultivation is a mixed herbicide made from isopropylamine glyphosate 486 g/L and methyl metsulfuron 1 g/L. The use of mixed herbicides with two or more active ingredients can broaden the spectrum of weed control, reduce herbicide residues, slow the emergence of herbicide-resistant weeds, and reduce production costs. Therefore, this study aims to determine the effectiveness of mixed herbicides IPA glyphosate 486 g/L and methyl metsulfuron 1 g/L in controlling weeds in oil palm plants in the producing phase. This research was conducted at Bukit Nyomot oil palm plantation Subang Regency, Jawa Barat Province from February to May 2023. The experimental design used was Randomized Complete Block Design (RCBD) with 6 treatments and each treatment was replicate 4 times. The treatments are consisted of the application of mixed herbicides IPA glyphosate 486 g/L and methyl metsulfuron 1 g/L at doses of 1 L/ha; 1.5 L/ha; 2 L/ha; 2.5 L/ha; manual weeding; and control (no treatment). The results shows that the mixed herbicide IPA glyphosate 486 g/L and methyl metsulfuron 1 g/L at a dose of 1 L/ha to 2.5 l/ha is effective in controlling weeds in oil palm, such as Paspalum conjugatum, Ottochloa nodosa, Asystasia intrusa, Ageratum conyzoides, Chromolaena odorata, other weeds, and total weeds up to 12 Weeks After Application (WAA).

Control of Urochloa decumbens Using Glyphosate Applied by Remotely Piloted Aircraft and Ground Sprayer with Different Spray Nozzles.

The use of remotely piloted aircraft (RPA) to spray pesticides currently occurs, but knowledge about this technology is lacking due to the different locations, targets, and products applied. The objective of this study was to evaluate the control of Urochloa decumbens with glyphosate applied using an RPA (10 L ha-1) equipped with different spray nozzles (XR 11001 and AirMix 11001). For the purpose of comparison, ground application was also performed (100 L ha-1). The deposition was evaluated by means of the quantification of a tracer by spectrophotometry, the droplet spectrum was evaluated with water-sensitive paper, and the control efficiency was evaluated based on visual measurements with percentage scores. Statistical process control was used to analyse the quality of the deposition in the area. The results showed that the application via RPA presented a greater amount of tracer on the leaves than the ground application, suggesting that the former is a good option for application, even providing a lower coverage and number of droplets per area. Both application methods were effective at controlling Urochloa decumbens. The nozzles showed potential for use in applications, with control efficiency higher than 84% from 21 days after application. The percentage of droplets smaller than 100 μm in the applications was less than 5%. No nonrandom behaviour was observed during deposition, indicating a high-quality process.

Control of Digitaria insularis (L.) Fedde in eucalyptus forests: shading increases sensitivity to glyphosate applied alone and in a mixture with carfentrazone-ethyl

Shading, the predominant condition in most of the eucalyptus cultivation cycle, causes changes in the morphological and physiological weed's characteristics, which can alter their responses to glyphosate and carfentrazone-ethyl, important herbicides for the crop. The objective was to evaluate the influence of light on the efficiency of glyphosate and carfentrazone-ethyl used alone and in a mixture in Digitaria insularis control, a priority pest in the crop. The experiment was carried out in a 3 × 6 factorial scheme. The first factor corresponded to 3 cultivation environments (full sunlight, 45 and 63% shading) and the second factor to doses of glyphosate and carfentrazone-ethyl applied isolated (1920 and 40 g ai ha−1) and mixed (1536 + 8; 1152 + 16; 768 + 24 and 384 + 32 g ai ha−1), respectively. Shading increased D. insularis sensitivity to glyphosate alone and in a mixture with carfentrazone-ethyl. In shading, the glyphosate application alone at a dose of 1920 g ha−1 and in a mixture with carfentrazone-ethyl at doses of 1536 + 8 and 1152 + 16 g ha−1 were efficient in D. insularis control. In the environment of 63% shading, the dose of 768 + 24 g ha−1 was also efficient in this species control. None of the doses were effective in controlling D. insularis in full sunlight. Isolated carfentrazone-ethyl was inefficient in controlling D. insularis, regardless of the growth environment. Shading increases the quantum yield of photosystem II and reduces the electron transport rate, photosynthetic rate, stomatal conductance, and transpiration rate of D. insularis. In shady environments, it is possible to control D. insularis with lower glyphosate doses, used alone and mixed with carfentrazone-ethyl.

Do sub-doses of glyphosate and 2,4-D cause hormesis in the pineapple plants? Insights into the response of the pineapple plants to this phenomenon

The slow growth of the pineapple (Ananas comosus (L.) Merr.) during the vegetative phase prolongs the crop cycle, resulting in higher production costs. When used in low doses, some herbicides can stimulate plant growth, a phenomenon known as hormesis. The aim of this study was to determine the effects of sub-doses of glyphosate and 2,4-dichlorophenoxyacetic acid (2,4-D) on growth in the Pérola cultivar of the pineapple. The treatments under study consisted of glyphosate applications of 0, 1.8, 3.6, 7.2, 18, 36, 72, 180, 360 and 720 g a.e. ha-1, and 2,4-D applications of 0, 1.68, 3.35, 6.70, 16.75, 33.5, 67, 167.5, 335 and 670 g a.e. ha-1. The experiments were completely randomised with four replications. The plants were grown in the greenhouse in pots with a capacity of 8 dm3 substrate. Growth variables were evaluated in the plants, together with the total and partitioned accumulated biomass (leaf, stem and root). The data were submitted to analysis of variance and regression. The pineapple showed greater phytotoxicity from the glyphosate herbicide at applications ranging from 18 to 720 g a.e. ha-1 and from 2,4-D in the range of 167.5 to 670 g a.e. ha-1. The hormesis effect was evidenced by the 32.25% increase in root fresh weight at the dose of 1.8 g a.e. ha-1 glyphosate. However, the slow growth of the pineapple was not overcome by the hormesis effect of the herbicides.

Evaluation of florpyrauxifen-benzyl for control of Old World climbing fern

Old World climbing fern [Lygodium microphyllum (Cav.) R. Br.; OWCF] is an invasive vine in many Florida wetlands. Management involves poodle cutting the climbing rachis at approximately 120 cm, with a subsequent foliar application of glyphosate to the remaining rooted vines. Recently, there has been increasing interest in synthetic auxin herbicides for OWCF control. Florpyrauxifen-benzyl is a new auxin mimic that was developed for weed control in aquatics and is selective at low use rates. There is limited information regarding its activity on OWCF. We conducted field studies at four wetland sites in south Florida from 2017 to 2020 to evaluate the effectiveness of florpyrauxifen-benzyl for OWCF control. In small-plot studies at two locations, florpyrauxifen-benzyl applied at 0.08 and 0.16 g L 1 reduced OWCFcover to 4%at 3 moafter treatment (MAT) and 21% at 6 MAT.However, florpyrauxifen-benzyl at these concentrations did not consistently control OWCF at 12 MAT. An additional study evaluated banded applications of florpyrauxifen-benzyl or glyphosate compared to poodle cutting for control of the climbing rachis. For both herbicides, banded applications did not control the climbing rachis, whereas poodle cutting provided complete control of all climbing rachis. Finally, an operational field study demonstrated florpyrauxifen-benzyl applied by professional applicators at 0.16 g L 1 reduced OWCF cover to 9% at 17 MAT and was not different from glyphosate applied at 14.4 g L 1. These studies indicate florpyrauxifen-benzyl is active on OWCF and future research should evaluate the effectiveness of repeat applications for longer-term control.

Characterization of a Pseudomonas sp. Isolated from Langkawi Capable of Degrading Glyphosate

Bioremediation of soil contaminants, including glyphosate, is an economically viable and environmentally friendly technique. Glyphosate, one of the most widely used herbicides for weed management, poses significant risks to wildlife and their habitats when it contaminates the environment. This study focused on the bioremediation potential of soil Pseudomonas spp. isolated from a paddy field with a long history of glyphosate application. The most promising isolate was tentatively identified as Pseudomonas sp. strain UPM-2009 through partial identification methods. This bacterium showed significant potential for glyphosate degradation under optimal conditions. Experiments demonstrated that Pseudomonas sp. degrades glyphosate most effectively at pH 7.0, a glyphosate concentration of 0.5 g/L, temperatures between 30 and 35°C, and an inoculum size of 1% (v/v). Notably, the bacterium exhibited a two-day lag period at 0.5 g/L glyphosate, achieving nearly 90% degradation after six days of incubation. Heavy metals such as Hg(II), Ag(I), and Cd(II) significantly inhibited bacterial growth, with inhibition rates of 99%, 95%, and 66%, respectively. This study underscores the potential of Pseudomonas sp. for bioremediation of glyphosate-contaminated environments. It highlights the need for further research, particularly molecular identification techniques, to fully characterize and optimize this bioremediation strategy. This approach can significantly contribute to mitigating the environmental impact of glyphosate pollution, promoting healthier ecosystems and sustainable agricultural practices.

Critical Period of Weed Control in Maize as Influenced by Soil Tillage Practices and Glyphosate Application

Increasing evidence on environmental and economic benefits has raised farmers’ interest in adopting alternative, less intensive soil management practices. To evaluate the influence of weed-competitive ability in response to a different tillage regime, a field study was conducted in maize under humid Central European climatic conditions in Slovenia. This study was established as a split-plot arrangement with three tillage practices (TPs) as the main plot: conventional (CN), conservation (CS), and no tillage (NT); this was combined with glyphosate application and the weed removal timing as the subplot. The weed removal timings were at the V3, V6, V9, V15, and R1 maize stages, with weed-free and weed season-long monitoring. The beginning and the end of the critical period of weed control (CPWC), based on a 5% maize yield loss rate, were determined by fitting the four-parameter log-logistic equations to the relative maize dry grain yield. The weed dry biomass from maize germination until the R1 growth stage in the NT TP was consistently lower than that in the CN and CS TP. Moreover, the NT TP resulted in a shorter CPWC (39 days after emergence (DAE)) compared to the CN (57 DAE) and CS (58 DAE). The results of CTWR (critical timing of weed removal) showed that less intensive tillage operations in the CS resulted in an earlier need for weed control (V2 and 23 DAE) compared to the CN (V3 and 39 DAE) and NT (V3 and 40 DAE). Our study suggests that the intensive tillage operations performed in the CN TP and the pre-sowing use of non-selective burndown herbicide in the NT delay the CTWR by more than 2 weeks, thus reducing the need for early post-emergence herbicide application in maize.

Glyphosate spraying exacerbates nitrogen and phosphorus loss in karst slope farmland.

Glyphosate herbicide is an indispensable material in agricultural production. In order to explore the potential environmental effects of glyphosate application in karst slope farmland, this paper used a variable slope steel tank to simulate the surface microtopography and underground pore structure characteristics of karst slope farmland, and combined with artificial rainfall experiments to explore the migration path of glyphosate in karst slope farmland and the impact of spraying glyphosate on soil nitrogen and phosphorus loss. The results showed that under the condition of heavy rain, glyphosate in karst slope farmland was mainly transported and diffused by surface runoff, supplemented by underground runoff; secondly, in different hydrological paths, glyphosate directly affected the content of nitrogen and phosphorus in runoff, and all showed extremely significant positive correlation (p < 0.001). In addition, rainfall conditions such as rainfall intensity, rainfall duration, and runoff affected the content of nitrogen and phosphorus in runoff to varying degrees. In conclusion, the application of glyphosate significantly increased the content of nitrogen and phosphorus in different runoff and accelerated the loss of nitrogen and phosphorus from soil, which not only led to soil degradation, but also threatened the safety of aquatic ecosystem. Therefore, in the prevention and control of agricultural non-point source pollution, the threat of glyphosate to the surrounding aquatic ecosystem cannot be ignored, especially in karst areas with frequent rainstorms and serious water erosion, long-term monitoring and risk assessment of glyphosate are needed.

Unlocking the potential of glyphosate-resistant bacterial strains in biodegradation and maize growth.

Glyphosate [N-(phosphonomethyl)-glycine] is a non-selective herbicide with a broad spectrum activity that is commonly used to control perennial vegetation in agricultural fields. The widespread utilization of glyphosate in agriculture leads to soil, water, and food crop contamination, resulting in human and environmental health consequences. Therefore, it is imperative to devise techniques for enhancing the degradation of glyphosate in soil. Rhizobacteria play a crucial role in degrading organic contaminants. Limited work has been done on exploring the capabilities of indigenously existing glyphosate-degrading rhizobacteria in Pakistani soils. This research attempts to discover whether native bacteria have the glyphosate-degrading ability for a sustainable solution to glyphosate contamination. Therefore, this study explored the potential of 11 native strains isolated from the soil with repeated glyphosate application history and showed resistance against glyphosate at higher concentrations (200 mg kg-1). Five out of eleven strains outperformed in glyphosate degradation and plant growth promotion. High-pressure liquid chromatography showed that, on average, these five strains degraded 98% glyphosate. In addition, these strains promote maize seed germination index and shoot and root fresh biomass up to 73 and 91%, respectively. Furthermore, inoculation gave an average increase of acid phosphatase (57.97%), alkaline phosphatase (1.76-fold), and dehydrogenase activity (1.75-fold) in glyphosate-contaminated soil. The findings indicated the importance of using indigenous rhizobacteria to degrade glyphosate. Therefore, by maintaining soil health, indigenous soil biodiversity can work effectively for the bioremediation of contaminated soils and sustainable crop production in a world facing food security.

Glyphosate low doses reduce waterlogging damage in lettuce plants subjected to waterlogging and contribute to hormesis

ABSTRACT Drift from herbicides in fields adjacent to non-target crops, together with waterlogging can be detrimental to lettuce (Lactuca sativa L.). The objective of the study was to determine physiological responses of lettuce plants to exposure to glyphosate and waterlogging. Lettuce plants were subjected to treatments of combinations of foliar applications of glyphosate (45 g a.e.·ha−1) and waterlogging, and a treatment with drainage condition. Herbicide in conjunction with waterlogging, and waterlogging alone, reduced accumulation of total dry matter and leaves, as was net photosynthesis related to stomatal closure, photosystem II damage, and loss of membrane stability. Application of low doses of glyphosate on waterlogged plants favored accumulation of dry mass in the root that may be related to increase in carbohydrates to produce energy under low oxygen availability, these results indicate possible hormesis in lettuce plants to glyphosate and could be useful to reduce waterlogging damage in lettuce plants.

Clopyralid applied with sponge wiper for Cirsium arvense control in hops in the western United States

Cirsium arvense L. (Canada thistle) is an important weed species commonly found in perennial crops. In hop production, the management of C. arvense is largely herbicide-based. Field studies were conducted in 2019 and 2020 in mature hopyards in Independence, OR, to compare C. arvense control in hops using a spray or targeted application of herbicides. Treatments included applying the herbicides immediately after training hops, four weeks later, or at both times. Treatments were applied as sprays directed to the base of hop plants with clopyralid or as target applications of clopyralid or glyphosate with a sponge wiper. Hop injury and weed control were evaluated 28 and 56 days after initial treatment. Herbicide residue in cones was quantified, and treatment costs were compared. Clopyralid did not injure hops, but wiper applications of glyphosate resulted in crop injury. The targeted application of clopyralid by wiper was as effective as the spray application. No differences were observed when clopyralid was applied after training or 28 days later, but two applications outperformed a single application. Clopyralid provided better control of C. arvense than glyphosate. Clopyralid hops cone levels were below the quantitation limit in both years (0.01 ppm). A partial cost analysis indicates that the targeted application of clopyralid with the wiper was 37% less costly than the spray application of clopyralid. The cost reduction was primarily driven by 84% reduced clopyralid use, and savings with the wiper application are likely to be exacerbated in a low infestation and patchy distribution of C. arvense.

Effects of Herbicide Glyphosate on Fitness Attributes of &lt;i&gt;Zygogramma bicolorata&lt;/i&gt; Pallister

In this study, the effects of glyphosate on the biology and fitness of the biocontrol agent Zygogramma bicolorata against parthenium weed. Bioassay of glyphosate was conducted using a minimum range of the field-recommended dose (0.408%). Results showed that indirect exposure to glyphosate caused significant mortality of I, II, III, and IV instar Z. bicolorata grubs. The highest mortality (23.60%) was recorded in the first instar. Furthermore, the total larval developmental period was significantly prolonged in the group exposed to glyphosate (19.50 days) compared to the unexposed group (17.73 days). The application of glyphosate also caused a variation in pupation period. In addition, the longevity of both male and female Z. bicolorata was negatively impacted by glyphosate treatment. Overall, these findings suggest that glyphosate has an ecotoxic effect on Z. bicolorata and may have significant implications for its use as a biocontrol agent for parthenium. It is important to carefully consider the potential risks associated with the use of herbicides and ensure that they are used in a safe and responsible manner to minimize any negative impacts on non-target organisms.

Self-reported and urinary biomarker-based measures of exposure to glyphosate and mancozeb and sleep problems among smallholder farmers in Uganda

ObjectiveWe aim to showcase the impact of applying eight different self-reported and urinary biomarker-based exposure measures for glyphosate and mancozeb on the association with sleep problems in a study among 253 smallholder farmers in Uganda. MethodsThe questionnaire-based exposure measures included: (1) the number of application days of any pesticide in the last 7 days (never, 1–2; >2 days) and six glyphosate and mancozeb-specific measures: (2) application status over the last 12 months (yes/no), (3) recent application status (never, last 7 days and last 12 months), (4) the number of application days last 12 months, (5) average exposure-intensity scores (EIS) and (6) EIS-weighted number of application days in last 12 months. Based on 384 repeated urinary biomarker concentrations of ethylene thiourea (ETU) and glyphosate from 84 farmers, we also estimated (7) average biomarker concentrations for all 253 farmers. Also in the 84 farmers the measured pre-work and post-work biomarker concentrations were used (8). Multivariable logistic regression models were used to assess the association between the exposure measures and selected Medical Outcomes Study Sleep Scale (MOS-SS) indices (6-item, sleep inadequacy and snoring). ResultsWe observed positive associations between (1) any pesticide application in the last 7 days with all three MOS-SS indices. Glyphosate application in the last 7 days (3) and mancozeb application in the last 12 months (3) were associated with the 6-item sleep problem index. The estimated average urinary glyphosate concentrations showed an exposure–response association with the 6-item sleep problem index and sleep inadequacy in the same direction as based on self-reported glyphosate application in the last 7 days. In the analysis with the subset of 84 farmers, both measured and modelled post-work urinary glyphosate concentration showed an association with snoring. ConclusionsSelf-reported, estimated average biomarker concentrations and measured urinary biomarker exposure measures of glyphosate and mancozeb showed similar exposure–response associations with sleep outcomes.

Negative Influence of Johnson Grass (Sorghum halepense L) on Yield of Crops Along with the Strategies to Suppress its Growth with Chemical and Other Management Approaches – A Review

Johnson grass is on the most deleterious, tenacious, threatening and pervasive weed and is found almost in complete globe except Antarctica. It is ranked in top ten worst weeds of all time. The main regions of its growth and spread are USA and Europe. The average height of Johnson grass lies between 3ft-10ft which is enough for survival and causing destruction to plants of main crop. It is narrow leafed weed belonging to family of sorghum which belong to Poaceae family. It has deep rooted system containing thick and fleshy rhizomes which are the main reason for its spread. These rhizomes have the ability to extend up to 80m. In this present review, information is gathered about the ecology and biology of Johnson grass along with its economic impact on crops and its control measures through different chemicals and management practices. The main focus of review was on growth mechanism and most importantly on its control of Johnson grass. From this whole discussion we have concluded that use of chemical herbicides is most effective in controlling its spread. Application of glyphosate and asulam as chemicals proved to be best in performance and in management practices or non-chemical methods black plastic sheet and soil solarization are well adopted conducts to suppress its growth to large extent. Along with that combination of chemicals and non-chemical practices would be recommended as they not only diminishes the growth of Johnson grass but also enhances the crop productivity.

Evaluation of chemical control and seasonal application options for smutgrass (Sporobolus indicus)

AbstractSmutgrass is a non-native perennial weed that is problematic because of its poor palatability to cattle and its difficulty to control once established. Limited literature exists to explain the effectiveness of herbicides other than hexazinone for smutgrass control and forage injury. This study aimed to evaluate seasonal applications of labeled herbicides used on forage for maximum smutgrass control. The second objective was to evaluate preemergent herbicides and hexazinone for their ability to control smutgrass germinating from seed. Hexazinone, nicosulfuron + metsulfuron-methyl, and glyphosate + imazapic were the most effective postemergence treatments, while quinclorac exhibited little activity on smutgrass. Common bermudagrass forage fully recovered from all treatments by 3 mo after treatment. Hexazinone, nicosulfuron + metsulfuron methyl, glyphosate, and imazapic were applied postemergence to smutgrass in spring, summer, and fall. Summer applications of hexazinone resulted in the greatest level of control, while spring treatments provided the least control. Applications of hexazinone or glyphosate resulted in the most effective smutgrass control. However, fall applications resulted in the least forage injury. Results of the study of preemergence herbicides indicate that treatments with indaziflam and hexazinone provide adequate control of germinating smutgrass seedlings in the greenhouse at 0.25×, 0.5×, and 0.75× of the lowest recommended labeled rate for seedling grass control. Indaziflam treatments prevented the emergence of any visible smutgrass seedling tissue, compared to hexazinone, which fully controlled the germinating seedlings by 21 d after treatment, whereas pendimethalin significantly reduced seedling numbers at the 0.5× and 0.75× rates.

Metagenomics reveals the effects of glyphosate on soil microbial communities and functional profiles of C and P cycling in the competitive vegetation control process of Chinese fir plantation

Although considerable efforts have been devoted to investigate the behavior of glyphosate on microbiome in various environment, knowledge about the soil microbial community and functional profile in weeds control process of the Chinese fir plantation are limited. In this study, shotgun metagenomic sequencing was used to determine the abundance and diversity of microbial communities and functional genes after foliar application of glyphosate for 1, 2, 3 and 4 months in a Chinese fir plantation. The results showed that glyphosate increased the copy numbers (qPCR) of 16S rRNA gene for 16.9%, improved the bacterial diversity (Shannon index) and complexity of bacterial co-occurrence network, and changed the abundances of some bacterial and fungal taxa, but had no effects on ITS gene copy numbers, fungal Shannon index, and bacterial and fungal communities (PCoA). Glyphosate application significantly decreased the amount of microbial function potentials involved in organic P mineralization for 10.7%, chitin degradation for 13.1%, and CAZy gene families with an exception of PL for 11.5% at the first month, while did not affect the profile of microbial genes response to P and C cycling in longer term. In addition, glyphosate reduced the contents of soil TOC, DOC and NH4+-H for 17.6%, 52.3% and 44.6% respectively, and decreased the starch, soluble sugar, Zn and Fe of Chinese fir leaves for 20.6%, 19.8%, 32.8% and 48.4% respectively. Mantle test, Spearman's correlation, and PLS-PM model revealed the connections among soil properties, tree nutrients, bacterial and fungal communities, and microbial function potentials were influenced by glyphosate. While our findings need to be validated in other filed and mechanistic studies, they may indicate that the foliar application of glyphosate has a potential effect on Chinese fir seedlings, and this effect may contribute to the changes of the bacterial community and soil properties including AN, DON and NH4+-H.

Effect of Demeter Adjuvant (Rizospray Extremo) in Enhancing the Effectiveness of Herbicide Mixtures for Effective Weed Control in a Matured Oil Palm Plantation in Western Ghana

An Adjuvant is an additive chemical that is known to enhance the effectiveness of pesticides like herbicides by helping to improve the absorption of the herbicides by weeds and may eventually help to reduce the dosage of the herbicides used. In the current trial, the adjuvant (Rizospray Extremo) was applied at 3 rates, i.e., 73 ml/ha, 109 ml/ha and 145 ml/ha. The herbicide mixtures used for the trial were glyphosate (glyphader) and triclopyr (garlon) mixtures at 436 ml/ha and 182 ml/ha respectively (60 mls glyphosate + garlon at 25 mls mixed in 15 litres of water). The herbicide control was glyphosate at 436 ml/ha + garlon at 182 ml/ha (with no adjuvant) whiles one plot was used as the no herbicide control. Weeds on the site include both soft weeds and woodies. Observations on weed mortality were made on weekly basis. Generally, herbicide application (with and without the adjuvant) effectively controlled the soft weeds at the site. Percentage weed growth reduction and herbicide efficacies generally increased with increasing rates of the adjuvant. Highest herbicide efficacy of 96% was obtained by the use of the adjuvant at 145 ml/ha. The treatments differed significantly mostly in their levels of control of the woody weeds at the site with adjuvant application at 145 ml/ha inducing the highest control of woody weeds (herbicide efficacy of 95.7%), whiles Adjuvant application at 73 ml/ha induced an efficacy of 88.91% on the woodies at the site. Glyphosate plus garlon application (without the use of adjuvant) induced an efficacy of 78.39%. The adjuvant was very effective in controlling weeds with waxy cuticles like the Thaumatococcus spp which were not effectively controlled without the use of theand adjuvant. The adjuvant (Rizospray Extremo) is therefore recommended for use in herbicide mixtures for spot spraying of woodies or noxious weeds at the site.