Effective Weed Control Research Articles

Could adjuvants serve as an agroecological tool?

Adjuvants are agrochemicals or natural substances, commonly mixed with pesticides to increase their efficacy or reduce off-target movement by modifying the physical properties of the spray solution, such as surface tension, droplet size, and spreadability, which ultimately improve pesticide adhesion and coverage on target surfaces. Adjuvant use across Europe remains less widespread compared to regions like the USA, where adjuvants are often recommended or required with certain herbicide applications. This paper highlights the potential benefits of incorporating adjuvants with herbicides in weed control, particularly as a strategy to reduce overall herbicide use. Findings from dose-response research on available adjuvants suggest they may enable the application of lower herbicide rates than typically recommended, without sacrificing effectiveness, thereby contributing to the goal of reducing herbicide use by 50% by 2030 in Europe. Furthermore, literature findings indicate that adjuvants significantly improve weed control by enhancing the performance of active ingredients, with efficacy increases of up to 50% compared to using herbicides alone. The integration of adjuvants into herbicide tank mixtures offers considerable promise, especially for managing herbicide-resistant weeds and achieving effective weed control.

Efficacy of Glufosinate Ammonium Herbicide on Weed Control, Impact on Soil Chemical Properties and Heavy Metal Accumulation in Cocoa Plantations.

Prolonged use of commonly used herbicides by cocoa farmers such as paraquat and glyphosate have been observed to have residual effects on the environment. Therefore there is a need to screen herbicides such as Glufosinate ammonium-based herbicides for use by cocoa farmers. The experiment was set up at the cocoa experimental plot of the Cocoa Research Institute of Nigeria Headquarters in Ibadan. The 3 treatments which were arranged in a Randomized Complete Block Design are slashing, 100 mls and 200 mls of Glufosinate ammonium per 16L of water (100 mls/16L and 200 mls/16L). Each experimental unit was 6 m × 6 m comprising nine cocoa stands. The treatments were replicated 3 times. Data on the soil's initial physico-chemical properties and after 3 months of each treatment were recorded. Mineral and heavy metal analysis of the leaves and pods before spraying and 3 months after spraying were recorded. The % weed control of the treatments was also observed. Treatment means were separated using the Least Significant Difference (LSD) at a 0.05% probability level. Results showed that Glufosinate ammonium applied at both rates did not load the soil, cocoa leaves and cocoa beans with heavy metals. 200 mls/16L had 85.00% weed control followed by 100 mls/16L (62.70%) and slashing (51.00%) which both had the same statistical result. Glufosinate ammonium at 100 mls/16L can replace slashing to eliminate drudgery while Glufosinate ammonium at 200 mls/16L can be used for more effective weed control without negative effects on the environment and the crop.

Effect of pre- and post-emergence herbicides on weeds, productivity andprofitability of maize

A field experiment was conducted to find out the best combinations of pre- and post-emergence herbicides in maize for effective weed control and higher productivity at ICAR-Indian Institute of Maize Research, Ludhiana in 2021 and 2022. Results indicated that pre (PE)- and post-emergence (PoE) herbicide application, reduced the narrow-leaved weeds (NLW) and broad-leaved weeds (BLW) density from 62.41–91.46% and 55.53–82.11% respectively, compared to the weedy check. Among the PE, pyroxasulfone performed better than atrazine owing to selectivity towards maize with better weed control during both years. The density of Cyperus spp. was significantly reduced with halosulfuron PoE along with atrazine or pyroxasulfone PE over the years. A higher weed control efficiency (WCE) was found with pyroxasulfone followed by (fb) topramezone (90.4), while pyroxasulfone fb tembotrione (84.1) and atrazine fb topramezone (84.8) had similar WCE. Pyroxasulfone fb topramezone gave a 46.97% increase in grain yield over a weedy check. Pyroxasulfone fb topramezone and pyroxasulfone fb tembotrione resulted in higher net returns and B:C. Therefore, the application of pyroxasulfone as PE fb tembotrione as PoE or pyroxasulfone as PE fb topramezone as PoE may be recommended for better weed control and higher maize grain yield in NWPZ of India.

Effect of pre- and post-emergence herbicides on weeds, productivity andprofitability of maize

A field experiment was conducted to find out the best combinations of pre- and post-emergence herbicides in maize for effective weed control and higher productivity at ICAR-Indian Institute of Maize Research, Ludhiana in 2021 and 2022. Results indicated that pre (PE)- and post-emergence (PoE) herbicide application, reduced the narrow-leaved weeds (NLW) and broad-leaved weeds (BLW) density from 62.41–91.46% and 55.53–82.11% respectively, compared to the weedy check. Among the PE, pyroxasulfone performed better than atrazine owing to selectivity towards maize with better weed control during both years. The density of Cyperus spp. was significantly reduced with halosulfuron PoE along with atrazine or pyroxasulfone PE over the years. A higher weed control efficiency (WCE) was found with pyroxasulfone followed by (fb) topramezone (90.4), while pyroxasulfone fb tembotrione (84.1) and atrazine fb topramezone (84.8) had similar WCE. Pyroxasulfone fb topramezone gave a 46.97% increase in grain yield over a weedy check. Pyroxasulfone fb topramezone and pyroxasulfone fb tembotrione resulted in higher net returns and B:C. Therefore, the application of pyroxasulfone as PE fb tembotrione as PoE or pyroxasulfone as PE fb topramezone as PoE may be recommended for better weed control and higher maize grain yield in NWPZ of India.

Comparative analysis of weed management techniques in taro (Colocasia esculenta (L.) Schott)

Weed management poses a significant challenge in taro cultivation since it’s a long-duration crop grown during the monsoon season. The warm, humid conditions of its extended growing period promote rapid weed germination and growth, complicating weed management efforts. To address this issue, a study was conducted at the Bangladesh Agricultural Research Institute, Jashore, in 2021 and 2022 to evaluate sustainable weed management strategies for taro. The experiment, designed as a randomized complete block (RCB) with three replications, tested seven weed control methods: T1= straw mulching (SM), T2= pre-emergence herbicide+SM, T3= poly mulching (PM), T4= pre-emergence herbicide+PM, T5= intercropping+two hand-weeding, T6= pre-emergence herbicide, and T7= four hand-weeding, alongside T8= weed-free and T9= weedy control treatments. Results indicated that all mulching treatments achieved 70% to 80% weed control efficiency, significantly reducing weed growth up to 120 days after emergence (DAE). The intercropping+hand-weeding treatment provided 75% to 80% weed control up to 90 DAE. Among the mulches, straw mulching resulted in the tallest and widest plant base girths, leading to the highest yield and benefit-cost ratio, followed by other mulch and intercropping+hand-weeding treatments. Pre-emergence herbicide treatments were ineffective due to their short duration of action. Additionally, combining mulching (SM & PM) with pre-emergence herbicide offered no advantage over mulching alone. These findings highlight straw mulch as the most effective weed management strategy for taro, eliminating the need for herbicides. Where mulch is unavailable, intercropping combined with hand weeding can be a viable alternative for effective weed control.

Steaming soil is effective in eliminating invasive alien plants (IAPs) - part I: effect of exposure method.

As regulations on pesticides become more stringent, it is likely that there will be interest in steam as an alternative approach for soil disinfestation. This study investigates the feasibility of utilizing a soil steaming device for thermal control of invasive plants. Seeds of Echinochloa crus-galli, Impatiens glandulifera, Solidago canadensis, and rhizome fragments of Reynoutria × bohemica were examined for thermal sensitivity through two exposure methods: (1) steam treatment of propagative material in soil; (2) exposure of propagative material to warm soil just after heated by steam. Soil temperatures in the range of 60-99 °C and dwelling period of 3 min were tested. Increased soil temperature decreased seed germination/rhizome sprouting. The exposure method had a significant effect where higher temperatures were needed to reduce the seed germination/rhizome sprouting in method 2 explained by the effect of extra heat given in method 1. Using method 1, for E. crus-galli and S. canadensis, the maximum mean temperature of approximately 80 °C was enough to achieve the effective weed control level (90%). This was lower for I. glandulifera and higher for R. × bohemica. Using method 2, 90% control was achieved at 95 °C for S. canadensis; more than 115 °C for I. glandulifera; and more than 130 °C for E. crus-galli and R. × bohemica. Our findings showed a promising mortality rate for weeds propagative materials through soil steaming. However, the species showed varying responses to heat and therefore steam regulation should be based on the differences in weeds' susceptibility to heat. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimizing cotton production through efficient weed management using herbicides: A promising solution for labour-scarce farming

Cotton, often referred to as ‘White gold’ and the ‘King of fibre crops’ holds a significant position as a cash and fibre crop in India. Weeds contribute to approximately 45 % yield reduction in cotton cultivation at the national lev?el, making weed management a critical factor in determining cotton productivity, particularly in high-density planting systems (HDPS). Effective weed control optimizes resource allocation, leading to improved growth parameters and higher yields. This study investigates the efficacy of various weed management practices, including pre-emergence and post-emergent herbicide applications, in enhancing cotton yield under HDPS. The results clearly demonstrate that a combination of PE Pendimethalin (1.0 kg a.i./ha), Metolachlor (1.0 kg a.i./ha), POE Pyrithiobac sodium (0.075 kg a.i./ha), and Quizalofop ethyl (0.075 kg a.i./ha) led to significantly greater plant height (113.4 cm) and dry matter production (7609 kg ha-1 ) . This treatment also resulted insignificantly improved yield parameters, with a higher seed cotton yield of 2098 kg ha-1 , and yielded higher net returns of Rs.141961 ha-1 and a Benefit Cost Ratio (BCR) of 3.09. In the face of increasing labour scarcity, these herbicide-based weed management practices offer a viable solution for maximizing cotton productivity under HDPS. This approach supports the rapid expansion of cotton acreage in the current era of farm mechanization.

Weed management in direct wet-seeded rice - A comprehensive review to higher productivity

This review examines various weed control strategies for Direct Seeded Rice systems. The diverse weed flora in DSR includes grasses (Echinochloa colona), sedges (Cyperus iria) and broadleaf weeds (Ludwigia parviflora) being prevalent. Integrated weed management combining cultural, mechanical, biological and chemical methods is recommended for sustainable control. Cultural practices such as stale seedbed techniques, crop rotations and flooding help suppress the growth of weeds. Mechanical methods, including hand weeding and the use of weeders, are effective but labour-intensive. Chemical control via pre-emergence (pretilachlor) and post-emergence (bispyribac-sodium) herbicides has shown promising results optimally. This review highlights that an integrated approach utilizing multiple complementary weed management tactics is essential for effective and sustainable weed control in direct-seeded rice. The proper timing of interventions, combinations of methods, and consideration of local conditions are essential factors. Although chemical herbicides are still valuable tools, there is a growing emphasis on reducing their use by integrating alternative methods. Overall, continued review of innovative biological and ecological approaches can further enhance the existing options for weed management in DSR systems.

Weed Management Effects on Weed Dynamics, Yield and Economics of Spring Maize at Dang, Nepal

Weeds pose a significant challenge in maize fields in the Dang district, leading to a substantial 52% reduction in yield. Hence, this study was conducted in Satbariya village of Dang, Nepal, in 2023 to evaluate the impact of various weed management practices on weed dynamics, growth, and yield of spring maize. The experiment included seven treatments: a weedy check, weed-free plot, pre-emergence application of atrazine at 1.25 a.i. kg/ha (AtPrE), post-emergence application of atrazine at 1.25 a.i. kg/ha (AtPoE), manual weeding at 30 DAS, mini-tiller at 30 DAS, and LaPoE (tembotrione 42% SC + atrazine 50% WP) applied as post-emergence. The Subarna variety of maize was chosen for the study. Fifteen weed species from seven different families were identified in the experimental area. Specific morphological and phenological parameters, such as plant height and days to tasseling and silking, were not significantly influenced by the weed control methods. However, significantly lower weed density and biomass were observed in the weed-free plot and LaPoE. Similarly, weed-free plots and LaPoE exhibited significantly higher weed control efficiency (WCE) and weed control index at both 45 and 60 DAS, leading to a lower weed index (0.00–16.71%) and more effective weed control. Concerning the yield parameters, cob length, number of kernels per row, and 1000-grain weight were significantly higher in weed-free plots, followed by LaPOE, and the highest grain and biological yield were observed in weed-free plot (6.14–15.18 tons/ha) and LaPoE (5.12–13.32 tons/ha). Moreover, the benefit-cost ratio and net return were observed to be highest with LaPoE. This study suggests that LaPoE can be an effective and economical weed management strategy for increasing maize yield and profitability. Further research could explore the long-term effects of using LaPoE on weed control and crop productivity.

Effect of Chemical Weed Control on Growth, Herb Yield and Oil Content of Mentha (Mentha arvensis L.) Across Northern Eastern and Central Highlands of India

A field experiment was carried out during the summer season of 2015 at Crop Research Farm of Sam Higginbottom Institute of Agriculture, Technology & Sciences, Allahabad to study the effect of various weed management options on weed dynamics and production of mentha. In the experiment six treatments namely, propaquizafop 10% EC @ 50 ml/ha, propaquizafop 10% EC @ 62.5 ml/ha, propaquizafop 10% EC @ 75 ml/ha, fenoxaprop-p-ethyl 9.3% EC @ 100 ml/ha, hand weeding and un-weeded control were laid out in Randomized Complete Block Design (RCBD) with four replications. The results revealed that a significantly lower weed density and weed dry matter weight, weed index and higher weed control efficiency were recorded under hand weeding which was found at par to fenoxaprop-p-ethyl 9.3% EC @ 100 ml/ha and propaquizafop 10% EC @ 75 ml/ha. The higher plant height, herbage yield (21.8 t/ha) and dry matter yield (6.00 t/ha) and oil yield (136.9 l/ha) of mentha were also obtained with hand weeding which was found at par to fenoxaprop-p-ethyl 9.3% EC @ 100 ml/ha and propaquizafop 10% EC @ 75 ml/ha. fenoxaprop-p-ethyl 9.3% EC @ 100 ml/ha also resulted in the most effective herbicide against grassy weed and generated maximum net return (Rs. 92303/ha) and benefit: cost ratio (2.30) followed by propaquizafop 10% EC @ 75 ml/ha.

Integrated Weed Management in Cucurbit Production Using Spring-seeded Grass Cover Crops

Achieving commercially acceptable weed control in plasticulture vegetable production systems can be challenging because many herbicides do no provide season-long control. Additionally, several weed species have recently evolved resistance to labeled herbicides. Consequently, multiple cultivations or frequent hand-weeding are needed to control emerged weeds. Cover crops have recently gained attention as a tool for helping to manage weeds. Field studies were conducted in Maryland and New Jersey to assess the efficacy of combining spring-seeded grass cover crops and herbicide treatments for weed control in cucumber and watermelon production. Three spring cover crop treatments consisting of cereal rye, spring oats, or cereal rye and spring oats were hand-broadcasted after laying plastic in Apr 2021 and 2022. Postplant treatments were applied to cover crops and emerged weeds 78 days later, ∼3 weeks after planting each crop. Postplant treatments included shielded herbicide applications (paraquat or clethodim) or crimping without an herbicide. Residual herbicide (fomesafen + S-metolachlor) was included or not with each postplant treatment. Cover crops decreased broadleaf weed density before and 2 weeks after postplant treatment (WAT) by 73% and 68%, respectively, and weed biomass 6 WAT by 84% compared with no cover. Terminating an oat cover crop with paraquat totally suppressed smooth pigweed 2 WAT compared with clethodim or crimping treatments. Overall, cover crop treatments showed 50% greater weed control compared with no cover. Weed control in the interrow area ranged from 90% to 95% when paraquat was applied to a cover crop compared with less than 75% following crimping a cover crop. Cucumber and watermelon commercial yield decreased 63% and 52%, respectively, when cover crops were not used. These results show that spring-seeded cereal cover crops can be successfully integrated with an herbicide strategy to provide effective weed control in cucurbit production.

Automatic Lettuce Weed Detection and Classification Based on Optimized Convolutional Neural Networks for Robotic Weed Control

Weed management plays a crucial role in the growth and yield of lettuce, with timely and effective weed control significantly enhancing production. However, the increasing labor costs and the detrimental environmental impact of chemical herbicides have posed serious challenges to the development of lettuce farming. Mechanical weeding has emerged as an effective solution to address these issues. In precision agriculture, the prerequisite for autonomous weeding is the accurate identification, classification, and localization of lettuce and weeds. This study used an intelligent mechanical intra-row lettuce-weeding system based on a vision system, integrating the newly proposed LettWd-YOLOv8l model for lettuce–weed recognition and lettuce localization. The proposed LettWd-YOLOv8l model was compared with other YOLOv8 series and YOLOv10 series models in terms of performance, and the experimental results demonstrated its superior performance in precision, recall, F1-score, mAP50, and mAP95, achieving 99.732%, 99.907%, 99.500%, 99.500%, and 98.995%, respectively. Additionally, the mechanical component of the autonomous intra-row lettuce-weeding system, consisting of an oscillating pneumatic mechanism, effectively performs intra-row weeding. The system successfully completed lettuce localization tasks with an accuracy of 89.273% at a speed of 3.28 km/h and achieved a weeding rate of 83.729% for intra-row weed removal. This integration of LettWd-YOLOv8l and a robust mechanical system ensures efficient and precise weed control in lettuce cultivation.

Improving Cole Crops Safety and Weed Control Response with Chloroacetamide and Oxyfluorfen Herbicides Combinations

Abstract In 2022, trials were carried out in New Jersey and New York to assess the efficacy of weed management and the response of two cole crops to various herbicide combinations and rates. The experiments involved the application of S-metolachlor and micro-encapsulated (ME) acetochlor either alone or combined with oxyfluorfen. Different application timings of oxyfluorfen were tested in greenhouse and field studies. Results from the greenhouse trials showed that substituting S–metolachlor with ME acetochlor in over-the-top applied mixes with oxyfluorfen caused 15% to 22% less crop injury and increased seedling biomass by 33%. In field studies, nontreated plots exhibited significant weed growth, reaching up to 71% coverage 28 days after transplanting (DAT), whereas herbicide-treated plots exhibited weed cover at or below 10% by 28 DAT. Mixtures or sequential applications of oxyfluorfen and chloroacetamides achieved excellent control (≥99%) of the weed species complex compared to single applications of oxyfluorfen or chloroacetamides. However, applying both oxyfluorfen and a chloroacetamides post-transplanting, either as tank mixture or in sequence resulted in ≥19% injury. Despite the effective weed control achieved with herbicide treatments, mixing herbicides post-transplanting reduced relative commercial yield by 46% to 94% compared to oxyfluorfen applied alone or followed by chloroacetamides. The findings from these experiments will inform regional crop safety guidelines and support potential modifications to oxyfluorfen labels regarding sequential applications with chloroacetamides.

Italian Ryegrass Control Using a Capsule Suspension Formulation of S-metolachlor in Fenclorim-treated Wheat

Abstract Italian ryegrass control is one of the most significant limitations in wheat production in the U.S. today. Resistance to Herbicide Resistance Action Committee (HRAC)/Weed Science Society of America (WSSA) Groups 1, 2, and 9 in Arkansas have further complicated postemergence control, while residual herbicides still show effective weed control. One problem is the potential of HRAC/WSSA Group 15 herbicides to injure wheat when applied preemergence, indicating the need for a herbicide safener. A series of experiments were conducted in Fayetteville, AR, to evaluate crop tolerance and Italian ryegrass control using a capsule suspension formulation of S-metolachlor in conjunction with fenclorim-treated wheat. Experiments were conducted as a two-factor factorial with S-metolachlor applied at three rates (0.37, 0.74, and 1.12 kg ai ha-1) and a microencapsulated formulation of acetochlor at 1.05 kg ai ha-1, and three rates of a fenclorim seed treatment at 0, 0.5, and 2.0 g ai kg-1 of seed. Separate experiments utilized either a preemergence (PRE) or a delayed-preemergence (DPRE) application timing. In both experiments, S-metolachlor at 0.74 and 1.12 kg ai ha-1 provided 77 to 96% control of Italian ryegrass by preharvest, whereas acetochlor only provided 49 to 72% control. Visible wheat injury from PRE applications ranged from 7 to 49% for all treatments 21 d after treatment (DAT), with a reduction in injury when fenclorim-treated wheat was used for both the 0.74 and 1.12 kg ai ha-1 rate of S-metolachlor. In the DPRE experiments, wheat injury ranged from 5 to 16% 21 DAT with no noticeable safening from the presence of fenclorim at any herbicide rate. The results of these experiments indicate that a DPRE application using a CS formulation of S-metolachlor would be more favorable for producers to mitigate the potential for injury to wheat while providing Italian ryegrass control. Additionally, at the DPRE application timing, fenclorim is unnecessary for S-metolachlor to be safely applied at the rates evaluated.

Effective weed control through post-emergence herbicides to enhance blackgram (Vigna mungo L.) productivity in South India

Pulses are essential components of vegetarian diet and play a pivotal role in addressing malnutrition by providing a vital source of dietary protein. However, weed competition remains as a significant obstacle to blackgram (Vigna mungo L) production, resulting in 25 to 35% yield losses. A field experiment was carried out at the National Pulses Research Centre, Tamil Nadu Agricultural University, Vamban, Pudukkottai, India during Kharif seasons of 2020 and 2021, to assess the suitable post-emergence herbicides for appropriate weed control in blackgram grown under irrigated conditions. The experimental field was observed to contain notable grass weed flora, specifically Dactyloctenium aegyptium and Chloris barbata, as well as broadleaved weeds, such as Flaveria australica, Cleome gynandra, Eclipta alba, Convolvulus arvensis, Digera arvensis, Vicia spp., and Celosia argentea. The results demonstrated that among the chemical weed management methods, spraying of Fomesafen @ 220 g + Fluzifop p-butyl @ 220 g ha−1 at 20 days after sowing (DAS) as a post-emergence herbicide treatment exhibited superior weed control efficiency, recording 66.80% and 68.53% at 30 and 45 DAS, respectively and recorded higher seed yield of 1088 kg ha−1. Additionally, this method generated 8.1% higher net income and 12.5% more benefit–cost ratio than hand weeding, making it an economically profitable strategy for maximizing blackgram yield and effective labour management.

A comparative study of drone and manual herbicide application for weed management in wet direct-seeded rice (Oryza sativa L.)

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, during the Navarai season (January-April) of 2024 to assess the efficiency of drone-based herbicide application in terms of weed control, energy use, and cost effectiveness in wet direct-seeded rice (Oryza sativa L.). The study compared the effectiveness of weed control using herbicide combinations applied as pre-emergence followed by early post-emergence, with both drone and knapsack sprayer. The treatments included the application of pretilachlor followed by early post-emergence bispyribac sodium, and pyrazosulfuron followed by penoxsulam + cyhalofop butyl, using both drone and knapsack sprayer. Additionally, weed-free and unweeded control plots were included. Results indicated that the application of pretilachlor followed by bispyribac sodium using a drone sprayer significantly reduced weed density and weed dry weight compared to the unweeded plot. This treatment also resulted in a higher grain yield (5286 kg ha-1). Moreover, drone application of pretilachlor followed by bispyribac sodium provided a higher net return (? 51631/ha), benefit-cost ratio (2.17), energy-use efficiency (9.53), and energy productivity (0.30 kg/MJ). The experiment concluded that drone-based spraying of pretilachlor followed by bispyribac sodium is an effective weed management strategy for wet direct-seeded rice, offering superior yield attributes, energy use efficiency, and profitability.

Selectivity of pre-emergent herbicides in cassava (Manihot esculenta Crantz) and its relationship with the stem cutting planting system

Cassava (Manihot esculenta Crantz, Euphorbiaceae), an important source of food for millions of people in the world, is distributed mainly in Asia, Africa, Latin America, and the Caribbean. Weeds are important biotic constraints on cassava production, and herbicide application can provide effective weed control in this crop. However, the different possibilities of herbicide selectivity (factors associated and not associated with the plants) must be studied before implementation. The aim of this study was to evaluate the effects of the combination of different pre-emergence herbicides and two stem cutting planting systems (vertical and horizontal) on phytotoxicity and several agronomic traits of the cassava crop. The experiment was conducted through a factorial arrangement in a completely random design in Corrientes, Argentina. The factors studied were planting systems (horizontal and vertical position), weed control methods (hoeing or application of diuron, S-metolachlor, pendimethalin or clomazone, 625; 1920; 900 and 1000 g a.i. ha−1, respectively), and cropping seasons (2018–2019 and 2019–2020). The following variables were measured: phytotoxicity, plant height, relative plant stand, total weight of tuberous roots per plant, starch concentration of tuberous roots, and starch production per ha. The highest precipitations occurred in the 2018–2019 cropping season. The vertical planting system in combination with herbicides showed lower phytotoxicity values and higher values of plant height, starch concentration, and starch production per ha than the horizontal planting system. The highest phytotoxicity values were recorded with the application of diuron combined with the horizontal planting system and in the 2018–2019 season, with a 33.33% decrease in relative plant stand compared to the use of hoeing. Starch concentration remained unchanged with the use of clomazone and pendimethalin, whereas the effect of these herbicides on starch production varied with the cropping season, decreasing only in 2019–2020. Starch production was significantly lower with the use of S-metolachlor (up to 55.29% in 2018–2019) and of diuron (up to 60.57% in 2019–2020) than with the use of hoeing. In conclusion, phytotoxicity values were higher for the horizontal planting system than for the vertical system. The herbicide with the highest phytotoxic effect on the cassava crop was diuron; the effect increased when combined with the horizontal planting system in the cropping season with higher rainfall. This work provides the basis for integrated weed management concerning the use of herbicides and their selectivity according to planting systems for cassava crops.

The Impact of Polydimethylsiloxane as a Herbicide Adjuvant for Weed Control in the Lime Citrus × aurantifolia (Christm.) Swingle Plot

The objective of this research was to evaluate the effect of polydimethylsiloxane (PDMS) CH3[Si(CH3)2O]nSi(CH3)3 as an adjuvant in bioherbicides and synthetic herbicides (chemicals) for weed (Johnson grass S. halepense and star grass Cynodon sp.) management in the lime plot. A total of 20 treatments were conducted, which included bioherbicides and synthetic herbicides, each with three replications, the dose was 50% more polydimethylsiloxane and 100% according to the product label. The experimental design was a randomized block design, with a factorial arrangement with three factors: A (products) with 10 levels, B (adjuvants) with 2 levels and C (evaluation dates) with 5 levels, each block consisted of an area of 5 m by 4 m. The assessment was carried out periodically, every week (5 evaluations), the scale proposed by EWRS was used. The results were in percentages and a 3-factor factor analysis was performed, where A (products) = 10 levels, B (adjuvants) = 2 levels and C (evaluation dates) = 5 levels, and the mean comparison test with Tukey (α ≤ 0.05), using SAS software. According to the results obtained, a significant difference is only presented between factors A (products) and B (adjuvants) (P < .0001). In factor A, the highest levels in weed control were glyphosate, diuron + carfentrazone and ammonium glufosinate with an average of 80.8, 74.0 and 70.8%, respectively. Regarding the interaction between the factors, only the A*B factors were present (P < .0001), only in the glyphosate, BH2 and diuron were the treatments with the highest interaction when using the 50% dose + polydimethylsiloxane as an adjuvant at a dose of 2 ml per 1 L of water with 76.2, 72.93 and 71.33%, respectively. The date when the treatments had the highest weed control effect was at the second and third week. These results underline the effect of polydimethylsiloxane to optimize the use of herbicides, not only in combination with chemical herbicides, but also with bioherbicides, offering an efficient and economic alternative for weed management (Johnson grass S. halepense and star grass Cynodon sp.).

Raw feedstock vs. biochar from olive stone: Impact on the sorption–desorption of diclosulam and tropical soil improvement

The addition of carbon-rich materials, such as raw feedstocks (RAW) and biochars, to agricultural soils is on the rise. This activity has many advantages, such as improving fertility, increasing water retention, and sequestering carbon. However, they can also increase the sorption of residual herbicides in the soil, reducing the effectiveness of weed control. Thus, the objective of this study was to evaluate soil improvement and the sorption–desorption process of diclosulam in soil unamended and amended with RAW from olive stone and their biochars produced in two pyrolysis temperatures (300 and 500 °C). Oxisol was used in this study, unamended and amended with RAW and biochars (BC300 and BC500) in a rate of 10% (w w−1). The sorption–desorption process was assessed by batch-equilibrium experiments and the analysis was performed using high-performance liquid chromatography (HPLC). The addition of the three materials to the soil increased the contents of pH, organic carbon, P, K, Ca, Mg, Zn, Fe, Mn, Cu, B, cation exchange capacity, base saturation and decreased H + Al. The unamended soil had Kf (Freundlich sorption coefficient) values of diclosulam sorption and desorption of 1.56 and 12.93 mg(1 − 1/n) L1/n Kg−1, respectively. Unamended soil sorbed 30.60% and desorbed 13.40% of herbicide. Soil amended with RAW, BC300, and BC500 sorbed 31.92, 49.88, and 30.93% of diclosulam and desorbed 13.33, 11.67, and 11.16%, respectively. The addition of RAW and biochars from olive stone has the potential to change the soil fertility, but does not interfere with the bioavailability of diclosulam in weed control under field conditions, since the materials slightly influenced or did not alter the sorption–desorption of diclosulam.

Bio-efficacy of herbicides on weeds in direct-seeded rice in Konkan region of India

Rice cultivation by direct seeding is viewed as both cost and labor-saving practice and becoming popular alter- native to transplanting. Weeds are a more serious problem in DSR than in transplanted rice. The field experimen- tal is conducted to evaluate the bio -efficacy of pre and post – emergence herbicides, hand-weeding on weed con- trol, yield components, yield and their economic feasibility for cost effective weed control in direct seeded rice. The experiment was laid out in randomized block design with three replications and seven treatments, viz. Pre-emer- gence oxadiargyl 80% WP @ 100 g/ha, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb HW at 30 DAS, oxadiargyl 80% WP (PE) @ 100 g/ha fb Post-emergence bispyribac- Na @ 25 g/ha at 25 DAS, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb Post-emergence metasulfuron- methyl + chlorimuron – ethyl @ 4 g/ha at 25 DAS, Pre-emergence oxadiargyl 80% WP @ 100 g/ha fb Post-emergence carfentrazone ethyl 40% @ 25 g/ha at 25 DAS. Weed density under weedy check (WC) situation showed that monocot weeds (grasses and sedges) were more pre-dominant wherein grasses and sedges constituted 74.80% and 11.48%, respectively, BLWs 14.20% of total weed density at 60 DAS of crop. Amongst the herbicide treatments, application of Oxadiargyl (PE) @ 100 g/ha fb HW at 30 DAS recorded significantly lowest number of weeds/m2, dry weight/m2. The highest grain yield (4.02 t/ha) and benefit cost (1.48) were recorded with the pre-emergence application of Oxadiargyl (PE) @ 100 g/ha fb HW at 30 DAS.