Atrazine Application Research Articles

Synergistic effect of pyridate-based herbicide mixtures for controlling multiple herbicide-resistant kochia

Abstract Multiple herbicide classes resistant (MHCR) kochia poses a serious concern for producers in the Central Great Plains, including western Kansas. Greenhouse and field experiments were conducted at Kansas State University Research and Extension Centers near Hays and Garden City, KS to evaluate pyridate-based postemergence (POST) herbicide mixtures for controlling MHCR kochia. One previously confirmed MHCR population (resistant to atrazine, glyphosate, dicamba, and fluroxypyr) and a susceptible (SUS) kochia population were tested in a greenhouse study. The kochia population at Hays field site was resistant to atrazine, dicamba, and glyphosate while kochia population at Garden City site was resistant to atrazine and glyphosate. Colby’s analysis revealed synergistic interactions when pyridate was mixed with atrazine, dicamba, dichlorprop-p, fluroxypyr, glyphosate, or halauxifen/fluroxypyr and resulted in ≥94% control and shoot dry biomass reduction of MHCR kochia in a greenhouse study. Similarly, synergistic interactions were observed for MHCR kochia control in fallow field studies at both sites when pyridate was mixed with glyphosate or atrazine. Kochia control was increased from 26% to 90% with the application of glyphosate + pyridate and from 28% to 95% with atrazine + pyridate at both sites as compared to separate applications of glyphosate or atrazine. This is the first report for such a strong synergistic effect for both glyphosate and atrazine mixtures with pyridate on a weed resistant to both. All other pyridate-based herbicide mixtures showed an additive interaction and resulted in better control of MHCR kochia (87 to 100%) as compared to their individual applications (23 to 92%) across both sites except 2,4-D. These results suggest that pyridate can play a crucial role in various POST herbicide mixtures for effective control of MHCR kochia.

Selectivity of new generation herbicide ‘Tembotrione’ under conservation agriculture-based maize (<i>Zea mays</i>) in maize-wheat-mungbean cropping system

An experiment was conducted at the ICAR-Indian Agricultural Research Institute in New Delhi during the rainy (Kharif) seasons of 2021–22 and 2022–23. The study aimed to evaluate the weed control efficiency of low dose new generation herbicide: tembotrione (34.4% SC) as a component of integrated weed management (IWM), on zero-till (ZT) and conventional till (CT) maize (Zea mays L.). The treatments were comprised of conventional tillage maize (M1: CT-M), conventional tillage maize with green manure from preceding green gram (M2: CT-M+GM), zero tillage maize with residue retention at 3 t/ha (M3: ZT-M+R), zero tillage maize with Sesbania co-culture as brown manuring (cover crop) (M4: ZT-M+BM) in the main plot and five weed control treatments, viz S1: Un- weeded check, S2: Pre +1 HW, S3: Pre + Post (tembotrione) @120g/ha, S4: Pre+ Post (Premix of Mesotrione+ Atrazine) @120 g/ha, S5: Weed free check (WFC) in the sub-plots were evaluated in split-plot design. It was ob- served that ZT-M+BM caused a considerable reduction in the population of broad-leaf weed, narrow leaf weed with sedges and total weeds (28.4% reduction at 60 days after sowing) compared to M1. The results also revealed that the sequential application of atrazine @750g/ha+pendimethalin @750g/ha(pre) followed by (fb.) tembotrione (34.4% SC) @120 g/ha (post) among the herbicide options reduced the weeds population (78.5%) and dry weight (81.3%) significantly than the un-weeded control (UWC). Maize yield attributes were higher in ZT with Sesbania co-culture (ZT-M+BM) than conventional-tilled treatments (CT-M). The application of atrazine @750g/ ha+pendimethalin @750g/ha (pre) fb. tembotrione @120 g/ha (post) combined with ZT-M+BM resulting in higher maize yield (6.88 t/ha) which was comparable with that in weed-free check (WFC). The post emergence (PoE) ap- plication of tembotrione (34.4% SC) @120 g/ha recorded highest weed control efficiency (86.2%), weed control in- dex (88.1%) and lowest value of weed index (7.04) when applied in the ZT-maize with sesbania as a cover crop. Therefore, combining zero tillage (ZT) with brown manure (Sesbania), along with atrazine and pendimethalin (@750g/ha each) as pre-emergence herbicides, and tembotrione (@120g/ha) as a post-emergence herbicide is recommended for effective weed control and high maize productivity in the North-Western Indo-Gangetic plains (IGP).

A review of the potential adverse health impacts of atrazine in humans.

Atrazine is a widely used chlorinated triazine herbicide in agricultural settings, which has raised concerns over its potential adverse effects on human health. The extensive application of atrazine has resulted in its pervasive presence in the environment, contaminating soil, groundwater, and surface water. While earlier research suggested that atrazine is unlikely to pose a health concern, recent evidence has indicated the necessity to reassess this point of view. This review aims to assess the recent evidence on atrazine's adverse effects on human health, focusing on (i) Cancer, (ii) Metabolic Diseases, (iii) Reproductive System, (iv) Neural System, and (v) Epigenetic Effects. Strategies to mitigate atrazine contamination and limitations of previous studies are also discussed. We strongly believe that further investigation is necessary to determine the potential detrimental consequences of atrazine in humans, particularly in developing countries, where herbicides are widely used without stringent safety regulations. Therefore, the current review will be beneficial for guiding future research and regulatory measures concerning the use of atrazine.

Assessing plant pigmentation impacts: A novel approach integrating UAV and multispectral data to analyze atrazine metabolite effects from soil contamination

The objective of this study was to evaluate the levels of desethylatrazine (DEA), a hydrophilic metabolite of atrazine, and its impact on plant health. This was achieved by utilizing multispectral imagery captured by Unmanned Aerial Vehicles (UAVs) in combination with ground-measured data to assess photosynthetic pigment levels in Green Cos lettuce following atrazine application in agricultural soil. Strong correlations were found between DEA levels and chlorophyll a, chlorophyll b, and anthocyanin levels in lettuce (R² > 0.70), while the correlation with carotenoid levels was weaker (R² = 0.55). This disruption to the pigments could interfere with photosynthesis, potentially hindering the plant's growth and development, and ultimately leading to a reduction in yield. The Anthocyanin Reflectance Index (ARI) demonstrated a robust positive correlation with DEA, whereas the Normalized Difference Red Edge (NDRE), Leaf Chlorophyll Index (LCI), and Normalized Difference Vegetation Index (NDVI) displayed pronounced negative correlations. Incorporating ARI, LCI, and NDRE, with or without NDVI, provided the most accurate prediction of DEA levels, with an R² exceeding 0.96. NDRE emerged as the most efficient index for forecasting chlorophyll a and chlorophyll b levels. Modified Chlorophyll Absorption in Reflectance Index (MCARI) demonstrated the best fit for carotenoids, while ARI performed exceptionally well in describing actual measurements of anthocyanins (R² = 0.90). The best-performing VI models, developed from the selection of effective single variables, exhibited the best fit to actual pigment measurements (R² > 0.83). These findings underscore the role of UAV-derived multispectral imagery in assessing DEA levels and improving environmental monitoring, aiding in better planning for agriculture and environmental remediation to enhance ecosystem health and resilience.

INFLUENCE OF SOME SELECTED ENVIRONMENTAL FACTORS ON THE NATURAL ATTENUATION OF ATRAZINE IN TROPICAL AGRICULTURAL SOILS

Understanding environmental factors that help to optimize the natural attenuation of atrazine in agricultural soils is necessary to minimize contamination risks and human health risks, as well as support a healthy soil ecosystem. This study, therefore, investigated the influence of pH, temperature, soil organic matter content, often measured as total organic carbon (TOC), and moisture content on atrazine attenuation by soil microbes. Agricultural soil with a history of atrazine application was spiked with the herbicide. The effects of pH (3, 7, 10), moisture content (10%, 15%, 25%), total organic carbon (TOC, 2%, 3%, 4%), and temperature (15°C, 25°C, 45°C) on atrazine attenuation and bacterial count were evaluated at the interval of 30 days each for 60 days of incubation in nutrient agar. The residual concentrations of atrazine attenuation were determined using GC-MS analysis at the interval of 30 days each for 60 days of incubation. The results indicate that higher bacterial counts (Arthrobacter sp.) were observed at neutral pH (7.0) and moderate moisture (10%). At a neutral pH (7), only 52.1% of the initial atrazine concentration remained after 60 days due to attenuation processes. Also, Atrazine natural attenuation increased with increasing TOC where only 25.8% attenuation residual concentration was left at 4% TOC and reached a maximum of 15% moisture content with a residual concentration of 20.13% after 60 days. Similarly, the concentration of atrazine decreased as the temperature increased, with only 29.01% of the residual concentration remaining at 45ºC treatment after 60 days. Statistical analysis revealed significant differences in natural attenuation between 30 and 60 days, but not after 30 days. These findings suggest that natural attenuation was favoured by higher organic matter content and moderate moisture levels, highlighting the importance of soil properties for atrazine fate in tropical soils and emphasizing the importance of studying natural attenuation processes as a viable strategy, particularly in tropical agricultural settings to minimize unnecessary contamination of soil to ensure a healthy and safe agricultural environment.

Investigating the Effectiveness of Various Weed Control Methods to Reduce Narrow and Broad Leaf Populations in the Oat (Avena sativa L.) Crop

Aims: It is aim to investigating the effectiveness of various weed control methods to reduce narrow and broad leaf populations in oat (Avena sativa L.) crop. Study Design: The experiment was designed using a Randomized Block design method. Place and Duration of Study: Department of agronomy, School of Agriculture, Abhilashi university, Chail Chowk, Mandi, India (H.P.) during the Rabi season of 2022. Methodology: The field trail was conducted with seven treatments and replicated thrice. The investigation included seven different weed control techniques i.e. T1 - weedy check (control), T2 - weed free, T3 - one hand weeding at 25 DAS, T4 - two hand weeding at 25 DAS and 45 DAS,T5 - pre-emergence application of Pendimethalin @ 0.75 kg a.i. ha-1 + one hand weeding at 25 DAS, T6 - post emergence application of atrazine @ 0.75 kg a.i. ha -1 at 35 DAS + one hand weeding at 25 DAS, T7 - post emergence metsulfuron methyl @ 0.004 kg a.i. ha -1 at 35 DAS + one hand weeding at 25 DAS. Results: The investigation found that the most effective ways to control weeds are by keeping the area completely weed-free or by using two-hand weeding at 25 DAS and 45 DAS. T2 (weed-free), which involved keeping the area weed-free, was found to be the most successful in terms of achieving the lowest weed density and highest weed control efficiency. Two-hand weeding at 25 DAS and 45 DAS was found to be better than using herbicides to reduce weed infestation in oat crops. Conclusion: Based on the results, it can be concluded that integrated weed management practices weed-free treatment is the most effective option for managing weeds in oats.

Growth and productivity of maize (Zea mays) as influenced by sequential and combined application of tank mix herbicides

The experiment was conducted during 2021–22 at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand to evaluate the impact of sequential and tank mix application of pre- and post-emergence herbicide on weed dynamics and maize productivity. The study was comprised of 9 treatments viz. Weedy (T1 ); Weed free (T2 ); Pre-emergence (PE) application of Atrazine -1 kg a.i./ha fb hand weeding (T3 ); PE application of Atrazine - 0.75 kg a.i./ha fb Post Emergence (Post E) application of Topramezone - 25.2 g a.i./ha (T4 ); PE application of Atrazine - 0.75 kg a.i./ha fb Post E application of Tembotrione - 120 g a.i./ha (T5 ); PE application of Atrazine - 1.0 kg a.i./ha fb Post E application of Topramezone - 25.2 g a.i./ha (T6 ); PE application of Atrazine - 1.0 kg a.i./ha fb Post E application of Tembotrione - 120 g a.i./ha (T7 ); Early Post E application of Topramezone - 25.2 g a.i./ha + Atrazine - 0.75 kg a.i./ha (T8 ) and Early Post E application of Tembotrione - 120 g a.i./ha + Atrazine - 0.75 kg a.i./ha (T9 ). Eleusine indica, Echinochloa colona, Digitaria sanguinalis and Eragrostis japonica were dominant among grassy weeds whereas broad leaf weeds included Cucumis melo, Phyllanthus niruri, Cleome viscosa and Commelina benghalensis. Cyperus rotundus was dominant among sedges. Topramezone - 25.2 g a.i./ha + Atrazine - 0.75 kg a.i./ha Early Post E resulted significantly lower total weed density and was similar to other herbicidal treatments. The highest grain yield (7.2 t/ha) was recorded in a weed-free crop that was similar to all herbicidetreated crops and significantly higher than the weedy crop. Tank mix application of atrazine - 0.75 kg a.i./ha with tembotrione 120 g a.i./ha or topramezone 25.2 g a.i./ha at 15 DAS can be suggested owing to higher grain yield and profits for farmers while lowering the dose and expenses involved in manual weeding and spraying atrazine separately.

Application of Simazine, Atrazine, and Lindane Pesticides Are Associated with Incident Parkinson’s Disease Risk in the Rocky Mountain Region (S2.002)

Application of Simazine, Atrazine, and Lindane Pesticides Are Associated with Incident Parkinson’s Disease Risk in the Rocky Mountain Region (S2.002)

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.

Prediction of atrazine degradation in soil based on XGBoost model.

We established the optimal model by using the automatic machine learning method to predict the degradation efficiency of herbicide atrazine in soil, which could be used to assess the residual risk of atrazine in soil. We collected 494 pairs of data from 49 published articles, and selected seven factors as input features, including soil pH, organic matter content, saturated hydraulic conductivity, soil moisture, initial concentration of atrazine, incubation time, and inoculation dose. Using the first-order reaction rate constant of atrazine in soil as the output feature, we established six models to predict the degradation efficiency of atrazine in soil, and conducted comprehensive analysis of model performance through linear regression and related evaluation indicators. The results showed that the XGBoost model had the best performance in predicting the first-order reaction rate constant (k). Based on the prediction model, the feature importance ranking of each factor was in an order of soil moisture > incubation time > pH > organic matter > initial concentration of atrazine > saturated hydraulic conductivity > inoculation dose. We used SHAP to explain the potential relationship between each feature and the degradation ability of atrazine in soil, as well as the relative contribution of each feature. Results of SHAP showed that time had a negative contribution and saturated hydraulic conductivity had a positive contribution. High values of soil moisture, initial concentration of atrazine, pH, inoculation dose and organic matter content were generally distributed on both sides of SHAP=0, indicating their complex contributions to the degradation of atrazine in soil. The XGBoost model method combined with the SHAP method had high accuracy in predicting the performance and interpretability of the k model. By using machine learning method to fully explore the value of historical experimental data and predict the degradation efficiency of atrazine using environmental parameters, it is of great significance to set the threshold for atrazine application, reduce the residual and diffusion risks of atrazine in soil, and ensure the safety of soil environment.

Effect of weed management practices on growth dynamics and productivity of rainfed pearl millet under conservation agriculture

An experiment was conducted on rainfed pearl millet at ICAR- IARI, New Delhi, during the kharif season of 2019, in a split-plot design with three replications. Three tillage practices, viz. Conventional tillage (CT), Zero tillage and Zero tillage + Residue@ 3t/ha (ZT+R) were evaluated in the main plot and seven weed management treatments, viz. weedy check, hand weeding (HW) at 30 and 50 days after sowing (DAS), atrazine @ 0.75 kg/ha(PE) fb 2,4-D @0.75kg/ha (PoE), atrazine @ 0.75 kg/ha PE, atrazine @ 0.75 kg/ha PE fb tembotrione @ 0.05kg/ha PoE, atrazine @ 0.75kg/ha PE fb tembotrione @ 0.075kg/ha PoE, atrazine @0.75 kg/ha PE fb tembotrione @ 0.10 kg/ha PoE. ZT+R 3t/ha resulted in enhanced growth attributes, and higher NPK uptake which led to increased grain yield. Among weed control treatments, hand weeding (HW) twice at 30 and 50 DAS along with the integration of pre-emergence application of atrazine 0.75kg/ha fb 2,4-D 0.75kg/ha PoE and tembotrione, 0.075 kg/ha or 0.1 kg/ha PoE resulted in better growth attributes which significantly resulted in higher grain yield under rainfed conditions of semi-arid tropics.

Weed Management Practices on Growth, Yield and Economics of Kharif Grain Sorghum

In the Kharif grain sorghum growing areas of Karnataka, the sorghum production suffers greatly due to weed problem, which offers limitations to crop. It was found that weed infestation become unmanageable throughout the growing period by the traditional methods of interculturing and manual weeding due to continuous and heavy rains during entire vegetative and early reproductive stages of Kharif sorghum. Hence, integration of herbicides with some cultural operations and use of pre-emergence, post-emergence herbicides in combination with mechanical methods can prove to be more successful. A field experiment entitled “Weed management in kharif grain sorghum” was conducted during Kharif 2019 at ARS, Hagari in deep black soil with neutral reaction (pH 7.50), organic carbon (5.5 g kg-1), available nitrogen (248.00 kg ha-1), available phosphorus (36.75 kg ha-1) and available potassium (312.00 kg ha-1). An experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. There were fourteen treatments comprising of weed management practices. The dominant weeds observed in the experimental fields were among grasses Brachiaria reptans, while in broad leaved weeds, Amaranthus viridis and among sedges, Cyperus rotundus. Significantly lower population of grasses, sedges, and broad leaved weeds, weed dry weight, weed index (%) and higher weed control efficiency throughout the crop growth period was noticed in sequential pre-emergence application of atrazine 50 WP @ 0.50 kg a.i. ha-1 as PE fb 2,4-D Na Salt 80 WP @ 0.75 kg a.i. ha-1 as PoE at 25 DAS except weed free treatment. Atrazine 50 WP @ 0.50 kg a.i. ha-1 as PE fb 2,4-D Na Salt 80 WP @ 0.75 kg a.i. ha-1 as PoE at 25 DAS recorded significantly higher plant height, dry matter accumulation, leaf area, test weight, grain yield, straw yield, harvest index, gross return, net return and benefit cost ratio (160.8 cm, 183.4 gplant-1, 24.1 dm2 plant-1, 30.53 g, 4195 kg ha-1, 9891 kg ha-1, 29.80 %, Rs. 1,03,675ha-1, Rs. 71,636 ha-1and 3.24, respectively) except weed free and it was on par with atrazine 50 WP @ 0.50 kg a.i. ha-1 as PE fb IC at 25 DAS and HW at 25 DAS and IC at 40 DAS.

Fate of atrazine in soybean (Glycine max L.) and corn (Zea mays L.) succession in Brazilian subtropical conditions

This work aimed to evaluate the distribution of atrazine via surface runoff, leaching, and retention in a Rhodic Ferralsol and to analyze the effect of a succession of corn and soybean crops in Brazilian subtropical edaphoclimatic conditions on the distribution of this herbicide. The mobility of atrazine was evaluated using a drainage lysimeter under conditions of intensely simulated precipitation, carried out 24 h and 48 h after a single herbicide application at 17 days after corn emergence. Surface runoff and leaching were sampled during the rainfall simulations at intervals of 5 min until completing 1 h. Corn foliar analyses were carried out to measure the residual amounts of atrazine. In addition, laboratory studies of sorption (equilibrium and thermodynamics) and dissipation were carried out to understand the dynamics of atrazine in the soil. Freundlich's non-linear isotherms presented an excellent fit in the description of atrazine sorption in a Rhodic Ferralsol. The high content of organic matter in the soil and the temperature variation directly influences the retention of atrazine in the soil. The half-life (t1/2) of atrazine in soil under controlled conditions indicates a non-persistent pesticide, with 14.44 days. However, the herbicide can persist in deep soil layers for more than 93 days after spraying. When high-intensity rainfall occurs 24 h after application, large proportions of atrazine are lost by runoff within the first 20 min of rain. At the same time, significantly inferior losses are observed when rainfall occurs 48 h after spraying. High-intensity rainfall within 24 h of atrazine application leads to substantial losses, causing an approximate 84% reduction in its concentration in corn leaves and a 94% reduction in soil. Conservationist agronomic practices that protect the soil, especially during the initial periods of corn cultivation, are essential to reduce atrazine losses by runoff or leaching. In addition, increasing the concentration of organic matter in the soil can be extremely promising in increasing the retention of this pesticide to soil colloids, preventing its loss in soils with a low content of clay minerals.

Study To Evolve Technology For Controlling Binding Weeds In Grown-Up Sugarcane Crop

Field investigations were carried out at Sugarcane Research Station, Cuddalore Tamil Nadu Agricultural University, to evolve technology for controlling binding weeds in grown-up sugarcane crops during 2015-18. The experiments were laid out in Randomized Block Design with three replications and the sugarcane variety tested wasCoC(SC)24. The treatments constituted of T1 – PE. atrazine @ 1.0 kg/ha and Po.Emetribuzin 0.75 kg/ha @ 60 DAP, T2 – PE atrazine 1.0 kg/ha and Po.E 2,4D Na salt 1.25kg/ha @ 60 DAP, T3 – P.E atrazine 1.0 kg/ha followed by weeding and earthing up on 75 DAP, T4 – Mechanical weeding by power tiller (45, 90 and 120 DAP), T5 – Intercropping of sun hemp and its incorporation as insitu on 60 DAP, T6 – Detrashing and mulching at 150th&210th DAP, and T7 – hand weeding and manual removal of weeds on 45, 90 and 120th days and T8 – Control. Based on the performance of herbicides, the Pre-emergence application of atrazine @ 1.0 kg a.i/ha followed bypost-emergence application of metribuzin @ 0.75 kg/ha on 60 days after planting was the best treatment for controlling weeds in grown-up sugarcane and also the yield attributes increased in sugarcane compared to control. The critical period of weed crop competition in sugarcane ranged between 27 and 50 days (Srivastava et al., 2003). Sugar yield as well as juice quality greatly affected by the application of weed control treatments. The presence of weeds in the sugarcane fields and no control has also led to a decrease in sugar yield (Roshan et al., 2006.; Patel et al., 2007; Kanchan, 2009) in proportion of sucrose, purity and brix ( Bahadar et al., 2004; Annual Report, 2012) . Generally, the increase in by weed growth one kilogram corresponds to a reduction in one kilogram of the crop. The reduction in cane yield due to weeds ranged from 40-60% (Kadam et al., 2011).

Increasing precipitation deteriorates the progress of pesticide reduction policy in the vulnerable watershed

Precipitation variation profoundly affects agricultural development and increases the diffuse pollution risk, which may weaken the positive effects of pesticide reduction policy. This study aimed to analyze the response of pesticide discharge loads in the large vulnerable watershed to pesticide application intensity and precipitation variance before and after implementing the pesticide reduction policy. We integrated empirical models, field observation and statistics to explore the sensitive factors of the typical pesticide atrazine before and after the pesticide reduction policy in the Yellow River Watershed. The results showed that the implementation of pesticide reduction policy effectively decreased the annual discharge load of atrazine within the watershed. In addition, the most sensitive factor of atrazine discharge loads shifted from precipitation to the atrazine application intensity after implementing the pesticide reduction policy. However, the discharge loads of atrazine significantly increased in an unusual high precipitation year in the context of increasing precipitation variability.

Efficacy of New Herbicide Formulation on the Growth and Yield of Maize (Zea mays L.)

A field experiment was carried out at a farmer’s field in the Perambalur District of Tamil Nadu, India, during the kharif season of 2021 to ascertain the effects of various weed management methods on the growth and yield of maize. The study comprised ten treatments (Pre application of Atrazine was fb post emergence application were 2,4-D, Halosulfuron methyl, Tembotrine, Tembotrine+ Atrazine, Mesotrione + Atrazine) and was set up in a Randomized Block Design. Hand weeding on 15 and 30 DAS ranked first and resulted in the lowest weed count on 45 DAS (Grasses – 2.73, Sedges – 3.12, BLW’s – 6.34), weed biomass on 30 and 45 DAS (10.89, 6.09 g), weed index (0 %) and highest weed control efficiency (93.71 %) among all the treatments examined. Among the herbicides sprayed, pre-emergence herbicide atrazine followed by post-emergence herbicide tembotrine had the lowest weed count on 45 DAS (Grasses – 2.90, Sedges – 3.44, BLW’s – 6.68), weed biomass (12.10, 12.55, 6.77 g m2), weed index (0.29%) and highest weed control efficiency (93.28%) and resulted in tallest height (204.12 cm), leaf area index (6.04), dry matter production (8.92 t ha-1), cob length (22.4 cm), grain yield (4.47 t ha-1) and stover production (5.71 t ha-1).

Productivity of Finger Millet (Eleusine coracana (L) Geartn) as Influenced by Pre-emergence Herbicides in the Northern Guinea savanna of Nigeria

Two field trials were conducted during 2011 and 2012 wet seasons at the Research Farm of the Institute for Agricultural Research, Ahmadu Bello University, Samaru Zaria (Lat. 11 o 11 1 N, Long. 07 O 38E and 686m above sea level), in the northern Guinea savannah zone of Nigeria, to evaluate the efficacy of pre-emergence herbicides on weed in finger millet. The treatments were atrazine (80WP) at the rates of (0.4, 0.8, 1.2 and 1.6 kg a.i/ha), RafT ® (500SC ) (Atrazine 250 g/l + Terbuthylazine 250 g/l ) at the rates of (0.25, 0.5, 0.75, and 1.0 kg a.i/ha) and Bullet (R) (700SC) (Atrazine 225 g/l + Terbuthylazine 225 g/l + Acetochlor 250 g/l) at the rates of (0.35, 0.75, 1.05 and 1.4 kg a.i/ha), hoe weeded control at 3 and 6 WAS and a weedy check. The treatments were laid out in a Randomized Complete Block Design (RCBD), replicated 3 times. The result shows that all the herbicide treatments significantly reduced weed dry weight than the weedy check. Application of atrazine at 0.8 kg a.i/ha or Raft at 0.5 kg a.i/ha gave lower weed dry weight and weed cover score than the hoe weeded control at 3 and 6WAS.While all the rates of Bullet, Raft at 0.75 and 0.1 kg a.i./ha and atrazine at 1.2 and 1.6 kg a.i./ha resulted in lower weed dry matter production which were comparable to hoe weeded control at 3 and 6WAS. Based on the results obtained from this study, 0.8 kg a.i./ha atrazine or 0.5 kg a.i./ha Raft gave season long weed control over hoe weeded check in finger millet with yield increase of 94.2 and 99.5%, respectively. The weedy checks reduced yield of finger millet by 66.7%.

IMPACT OF ATRAZINE AND BROMOXYNIL ON THE COLONY FORMING UNITS (CFU) OF SOIL BACTERIA

According to overwhelmingly positive effects throughout time, herbicide treatment has become a crucial component of thriving agricultural output worldwide. However, its detrimental effects on non-target soil microorganisms involved in the nitrogen cycle, nutrient degradation, and organic matter breakdown must be considered. In the current study, the consequences of the two (2) herbicides that are most often used in Pakistan, Atrazine and Bromoxynil, were evaluated on soil bacteria over the course of fifteen consecutive days (exposure period). Recommended field rate of herbicide application was followed (i.e. active ingredient of 6.17 mg for Atrazine and 2.4 mg for Bromoxynil per gm of soil). During the investigations half and double recommended doses of these herbicides were used. Time interval of 5, 10 and 15 days were used to determine the bacterial populations. Statistical analysis of the investigation revealed that the bacterial population did not exhibit any appreciable variations in relation to the exposure duration (p 0.05). The Atrazine application along with the herbicide treatments, reduced the bacterial population during all the tested interval durations with just half of the suggested field rate. The current study reflected that apart from the benefit of herbicides in controlling weeds these chemicals also effect bacterial population that is a serious issue for present and future agriculture. Further, the same study needs to be perform under field conditions to confirm the finding of laboratory results before issuing solid recommendations to the farming community.

Optimizing Establishment Methods and Weed Management Practices on Growth, Yield and Economics of Maize under Irrigated Condition

To study the performance of different crop establishment techniques and weed management practices on growth, yield attributes, yield and economics of maize hybrid, field experiment was conducted during Summer 2023 season.The treatment comprised of different sowing methods viz., pneumatic precision planter, manual rotary dibbler and manual dibbling and these treatments were compared with varied weed management practices such as pre-emergence (PE) application with atrazine 50 % WP @ 0.75 kg ha-1 at 3 DAS + power weeding at 20 and 40 DAS, pre-emergence (PE) application with atrazine 50 % WP @ 0.75 kgha-1 at 3 DAS + hand weeding at 20 and 40 DAS and pre-emergence (PE) application with atrazine 50 % WP @ 0.75 kg ha-1 at 3 DAS + early post-emergence (EPoE) application with topramezone 33.6 % SC @ 25.2 g ha-1 at 20 DAS. The results revealed that manual dibbling under conventional levelled ridges and furrows and pre-emergence application of atrazine 50 % WP @ 0.75 kg ha-1 at 3 DAS through drone followed by power weeding at 20 and 40 DAS recorded the highest vigour index, root length, volume and biomass. Early field emergence was noticed with manual dibbling under ridges and furrows which wasfollowed by pneumatic precision planter. However, higher LAI was recorded under manual rotary dibbler followed by pneumatic precision planter. Pre-emergence application of atrazine 50 % WP @ 0.75 kgha-1 at 3 DAS + hand weeding at 20 and 40 DAS had significantly less weed density and dry weight and the next best treatment was pre-emergence application with atrazine 50 % WP @ 0.75 kg ha-1 at 3 DAS + power weeding at 20 and 40 DAS. Significantly higher grain and stover yieldwas obtained under manual rotary dibbler treatment which was at par with pneumatic precision planter. Highest net returns and benefit cost ratio were observed with manual rotary dibbler followed by atrazine 50 % WP @ 0.75 kg ha-1 at 3 DAS + power weeding at 20 and 40 DAS.

Diversity and composition of weed species in a continuously grown maize field treated with selected pre-emergence herbicides

Abstract. This study analyses the floristic composition of field weeds recorded at the University of Ilorin Teaching and Research Farm (008° 27’ 23.9’N and 004° 39’ 42.9’E) in the southern Guinea savannah of Nigeria during the 2019 – 2021 growing seasons. The area is characterized by a bimodal rainfall pattern with an average annual rainfall of 1227.85 mm and sandy loam soil (plinthustaffs). The experiment was set up as a randomized complete block design and repeated three times in a field that had been continuously maize-cropped for 10 years. Treatments were pre-emergence applications of atrazine, metolachlor, and primextra at the rate of 1.5, 2.5, and 3.5 kg a.i.ha-1 and Weedy Check. Maize was sown and maintained using the recommended agronomic practices for ecology. Weed species composition was estimated using four continuous sample quadrats (0.5 m2) at 3, 6, 9, and 12 weeks after sowing. The weed flora consisted of 48% broadleaves, grasses 45%, and 7% sedges. Between 2019 and 2021 there was a gradual shift from the predominant annual broadleaves to induced annual grasses and a reduction in the floristic composition of the weed community by approximately 2 – 28%. Fifteen (15) weed species were predominant and the most stable weed species were Richardia scabra, Digitaria horizontalis and Digitaria sanguinalis. This requires finding an ideal weed control option that controls the negative impact of agricultural weeds on crop after yield while maintaining a diverse weed community.