Postemergence Treatments Research Articles

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.

РОСТСТИМУЛИРУЮЩАЯ АКТИВНОСТЬ БАКТЕРИЙ ENTEROBACTER LUDWIGII BLK ПРИ ОПТИМИЗАЦИИ СРЕДЫ КУЛЬТИВИРОВАНИЯ

A method for optimizing the cultivation of Enterobacter ludwigii BLK and the treatment of wheat plants using a preparation based on this bacterium is proposed. By reducing the concentration of peptone and partially replacing it with an alternative nitrogen source – yeast extract – in the culture medium, the cost of producing the drug was reduced without reducing its effectiveness. It was found that the preparation, produced in a modified environment, activated root growth and promoted the accumulation of chlorophyll in bread wheat leaves. The stimulating effect was more pronounced with a combination of pre-sowing and post-emergence treatment.

Cultivo de soja em área de arroz irrigado para reduzir a infestação de plantas daninhas

ABSTRACT Lowland rice in Santa Catarina (SC), Brazil, is grown as a sole crop, which has aggravated problems with weeds. In this context, the objective of this study was to evaluate the efficacy of weed management systems in soybean crops to decrease weed infestation in lowland rice production areas, using pre- and post-emergence herbicides. The experiment was conducted in Turvo, SC, from August 2021 to April 2022. A randomized block design with four replications was used, in a 6 × 5 factorial arrangement. The factors consisted of six pre-emergence herbicides treatments (S-metolachlor, diclosulam, sulfentrazone, sulfentrazone + diuron, pyroxasulfone + flumioxazin, and a control without herbicide), and five post-emergence herbicide treatments: control without herbicide, glyphosate at two rates (930 and 1,550 g a.e. ha-1), applied alone or in combination with clethodim. The herbicide sulfentrazone caused persistent phytotoxicity and resulted in the lowest soybean grain yield. The herbicide S-metolachlor was ineffective in controlling weed species, except barnyard grass, even when combined with post-emergence application. The poor control of these weed species does not result in significant interference, causing no significant decreases in grain yield of soybean crops grown in floodplain soils. The use of S-metolachlor, diclosulam, and pyroxasulfone + flumioxazin, combined with post-emergence application of glyphosate (930 g a.e. ha-1), resulted in highly effective control of barnyard grass, inhibiting weed seed production. Only the combination of glyphosate (1,550 g a.e. ha-1) with clethodim can suppress barnyard grass seed production without using pre-emergence herbicides.

Optimizing herbicide types and concentrations: Crucial elements for achieving intensive cultivation of common buckwheat

An appropriate herbicide type and concentration is essential for effective weed management and enhancing crop yield. However, the optimal herbicide type and corresponding application concentration for controlling weeds in common buckwheat on the Loess Plateau region of Northwestern China remain unclear. To address this gap, experiments were conducted to investigate the effects of various herbicides on weed control, dry matter accumulation, and grain yield in common buckwheat, and to analyze the variances in weed control efficacy and grain yields of the optimal herbicides at different concentrations. The results showed that both metolachlor and quizalofop-P-ethyl demonstrated effective weed control with lower phytotoxicity. Dry matter accumulation was lower under metolachlor, with no significant differences observed among the post-emergence herbicide treatments. Importantly, metolachlor and quizalofop-P-ethyl promoted the allocation of dry matter to grains. Remarkably, metolachlor and quizalofop-P-ethyl increased the grain yield by 15.59% and 26.97%, respectively, compared to spraying an equivalent amount of water. Additionally, the m2.25, q0.9, and q1.2 treatments exhibited excellent weed control effectiveness. And the higher grainnumber per plant observed under m2.25, q0.9, and q1.2 contributed to the increase in grain yield. Consequently, m2.25, q0.9 and q1.2 increased the grain yield by 34.42%, 38.86% and 33.16%, respectively. These findings demonstrate that applying metolachlor and quizalofop-P-ethyl at 2.25 L ha−1 and 0.9 or 1.2 L ha−1 respectively, is beneficial for efficient weed management and yield enhancement in common buckwheat cultivation on the Loess Plateau region of Northwestern China. These studies provide important guidance for promoting common buckwheat cultivation in this region.

Multiple herbicide-resistant kochia (Bassia scoparia) control in glufosinate-resistant canola

Multiple herbicide-resistant kochia ( Bassia scoparia (L.) A.J. Scott) has grown in prevalence in the canola ( Brassica napus L.) production region of North America. Glufosinate-resistant canola facilitates kochia management since glufosinate-resistant kochia is not known to occur. Field experiments were conducted from 2013 to 2015 in five environments near Lethbridge and Coalhurst, Alberta, to identify herbicide strategies targeting acetolactate synthase inhibitor-resistant kochia with and without glyphosate resistance in glufosinate-resistant canola. Sequential glufosinate treatments (500 g ai ha−1) postemergence (POST) caused excellent (≥90%) kochia control and biomass reduction across environments. Preplant (PP) carfentrazone + sulfentrazone (9 + 105 g ai ha−1) alone or followed by (fb) POST glufosinate (9 + 27 fb 500 or 9 + 105 fb 500 g ai ha−1) resulted in excellent kochia control in all environments tested. PP carfentrazone + sulfentrazone (9 + 53 g ai ha−1) alone, and a single POST treatment with glufosinate (500 or 590 g ai ha−1) alone or preceded by fall-applied ethalfluralin (1100 fb 500 g ai ha−1) with or without PP carfentrazone (1100 fb 9 fb 500 g ai ha−1) caused ≥80% kochia control and biomass reduction in all environments tested. However, treatments containing PP carfentrazone + sulfentrazone caused unacceptable canola injury or yield loss in at least one environment. In conclusion, single or sequential treatments of glufosinate POST managed multiple herbicide-resistant kochia effectively in canola. Layering fall-applied/PP ethalfluralin and/or PP carfentrazone with glufosinate POST may help alleviate resistance selection pressure placed on glufosinate in canola.

Hygienic assessment of occupational risk for workers during pre- and post-emergence herbicide treatments of sunflower crops

Modern agriculture extensively uses pesticide formulations at various stages of crop growth. Sunflower cultivation accounts for 31% of the global production. Assessing the occupational risk associated with pesticide application in sunflower farming is of paramount importance. Improper handling and application of pesticide formulations can have immediate adverse effects on workers, leading to acute poisoning, long-term health consequences, and the potential for chronic illnesses, including neurotoxic effects. The aim of this study was to conduct a hygienic assessment of the professional risk faced by workers during pre- and post-emergence herbicide applications in sunflower cultivation. This assessment was carried out to establish the regulations for their safe usage. Research samples after the application of the herbicides AGAT, GARPUN, KORVUS, and PARUS (patches from overalls, gloves, skin swabs from exposed areas (face-neck, hands), air samples (atmospheric air, working zone and drift zone). The assessment of professional risk was conducted in accordance with the methodological recommendations provided by experts from the L.I. Medved's Research Center of Preventive Toxicology, Food and Chemical Safety, Ministry of Health, Ukraine (State Enterprise). Statistical analysis of the results was carried out using the licensed statistical software packages MedStat v.5.2 (Copyright© 2003-2019) and Microsoft® Excel® for Microsoft 365 MSO (Version 2305, Build 16.0.16501.20074). It has been determined that under real conditions, during pre- and post-emergence herbicide applications in sunflower cultivation using AGAT, GARPUN, KORVUS, PARUS preparations, while adhering to recommended agrotechnical and hygiene safety regulations, the inhalation, dermal, complex, and combined (AGAT and PARUS) risks for applicators are 0.0409±0.0179, 0.0429±0.0193, 0.0838±0.0224, and 0.1557±0.1322 a.u., respectively, and for tractor operators – 0.0818±0.0358, 0.0425±0.0192, 0.1243±0.0356, and 0.2347±0.1567 a.u., respectively. There is no observed increase in hygiene standards in the workplace atmosphere and in the air of the potential drift zone. It has been proven that the professional risk of their use does not exceed permissible limits (<1). It has been determined that during the performance of techno­logical operations, the mentioned risks in applicators and tractor operators did not differ significantly (p>0.05). However, a significant difference was found in the proportion of percutaneous risk (42.7±17.4% in applicators compared to 34.8±17.0% in tractor operators; p=0.034). The regulations for the safe use of the investigated pesticide formulations have been substantiated. Statistical analysis of the obtained results revealed that the values of inhalation, dermal, and combined risks during the application of these pesticides did not significantly differ during the various technological operations (applicators and tractor operators) (p>0.05). The values of the combined comprehensive risk associated with the use of the studied preparations also did not show significant differences (p>0.05). The proportion of dermal risk was significantly higher in applicators compared to this parameter determined in tractor operators (p=0.034).

Integrating cover crops and herbicides for weed control in soybean

Abstract In mid-southern, southeastern, and northeastern U.S. soybean production regions, the evolution of herbicide-resistant weeds has become a significant management challenge for growers. The rising herbicide costs for managing herbicide-resistant weeds are also a growing concern, leading to the utilization of cover crops as an integrated weed management strategy for addressing these challenges. Field experiments were conducted at two locations in Alabama in 2022 to evaluate winter cereal cover crops, including a mixture and herbicide system integration in soybean. Treatments included five cover crops: oats, cereal rye, crimson clover, radish, and a cover crop mixture. Cover crops were evaluated for their weed-suppressive characteristics compared to a winter fallow treatment. Additionally, four herbicide treatments were applied: a preemergence (PRE) herbicide, a postemergence (POST) herbicide, PRE plus POST herbicides, and a nontreated (NT) check. The PRE herbicide was S-metolachlor; the POST treatment contained a mixture of dicamba and glyphosate. The PRE plus POST system contained the PRE application followed by POST application. Results show that cereal rye and the cover crop mixture provided weed biomass reduction compared to all cover crop treatments across both locations. Furthermore, we observed greater soybean yield following the cereal rye cover crop than following the winter fallow treatment at one location. POST and PRE plus POST herbicide treatment resulted in greater weed biomass reduction and improved soybean yield than the PRE herbicide treatment alone and the NT check at both locations.

Plant growth regulators differentially suppress goosegrass and smooth crabgrass in creeping bentgrass turf

Abstract Goosegrass and smooth crabgrass in creeping bentgrass turf are difficult to control due to a lack of selective herbicides. Based on preliminary field observations, we hypothesized that paclobutrazol and flurprimidol would reduce the overall competitiveness of goosegrass and smooth crabgrass in creeping bentgrass. Greenhouse and field studies were designed to evaluate the effect of several plant growth regulators (PGRs) on goosegrass and smooth crabgrass competitive indices. In greenhouse studies, flurprimidol, paclobutrazol, trinexapac-ethyl, and prohexadione-calcium were applied either preemergence only or preemergence plus two biweekly postemergence applications to goosegrass and smooth crabgrass plants to simulate the first 1.5 mo of typical PGR programs used on golf courses. Two weeks after the final postemergence treatment, aboveground biomass and root biomass were recorded. Programmatic flurprimidol and paclobutrazol applications reduced smooth crabgrass aboveground biomass by 67% and 69%, respectively, and more than trinexapac ethyl or prohexadione-calcium. When averaged across application programs, flurprimidol and paclobutrazol reduced smooth crabgrass root biomass by 74% and goosegrass biomass by 73% to 80%. Field studies were established to further evaluate the influence of PGRs on smooth crabgrass coverage in creeping bentgrass turf. Treatments consisting of flurprimidol, trinexapac-ethyl, flurprimidol plus trinexapac-ethyl, paclobutrazol, and fenoxaprop-p were applied every 3 wk from April to August. Weed coverage data were collected throughout the growing season, and final smooth crabgrass control data were collected at the end of the season. In general, flurprimidol-containing treatments more effectively reduced smooth crabgrass coverage throughout the growing season than trinexapac ethyl. After the studies, regimens that contained flurprimidol controlled smooth crabgrass by 68% to 73%, greater than any other PGR program evaluated. Results from these studies indicate that flurprimidol may be used to effectively control smooth crabgrass or goosegrass in creeping bentgrass turf. These are the first reported data regarding the use of flurprimidol for smooth crabgrass or goosegrass control in turf.

Integrated weed management in rabi sorghum (Sorghum bicolor L.) under rainfed conditions

A field experiment was conducted to assess the impact of weed management on growth and yield of grain sorghum at the Regional Agricultural Research Station, Vijayapura during rabi 2022-23. The experiment was laid out in a Randomized Complete Block Design with three replications and comprised eleven treatments. These treatments included five preemergence herbicide treatments (Atrazine @1000 g a.i. ha-1, Metribuzin @ 350 and 700 g a.i. ha-1, Metolachlor @ 750 and 1500 g a.i. ha-1) followed by two intercultivation at 30 & 60 DAS, as well as four post-emergent herbicide treatments (Metribuzin @ 350 and 700 g a.i. ha-1, Mesotrione + Atrazine (RM) @ 550 and 825 g a.i. ha-1) followed by one intercultivation at 60 DAS. These nine herbicide treatments were compared to a weedy check and a weed free check. The experimental results showed that weed free condition recorded minimal weed infestation, better crop growth, higher yield and economical returns. Among the herbicidal treatments, application of Metolachlor 50EC @ 1500 g a.i. ha-1as pre-emergence followed by two intercultivations at 30 and 60 DAS recorded significantly lower weed count (1.67 m-2), weed biomass (4.67 g m-2) and higher weed control efficiency (92%) for total weeds at 60 DAS, with a reduced weed index of 7.21%. Additionally, this treatment led to significantly higher grain yield (1389 kg ha-1), stover yield (3031 kg ha-1), gross returns (`73,759 ha-1), net returns (`40,968 ha-1) and benefit cost ratio (2.25). In contrast, the weedy check treatment resulted in lower grain yield, net returns, and benefit cost ratio.

EFFICACY AND SELECTIVITY OF HERBICIDES TO CONTROL WEEDS IN CHICKPEA CROP AT MOARA DOMNEASCĂ, ROMANIA

This paper presents the data regarding the control of weeds in chickpea crop. The observations and determinations aimed the selectivity and efficacy of some simple, complex or associated herbicides, applied pre- and post-emergent, in order to determine their influence on the production yield. The chickpea crop was strongly infested with mono and dicotyledonous species, including perennial species that are difficult to control (Cirsium, Convolvulus, Sonchus). The best results were obtained in the experimental variants in which the pre-emergent treatments were followed by post-emergent treatments. Perennial species were not sufficiently controlled. The herbicide Pulsar 40 (imazamox, 40 g/l) showed phytotoxicity, the harvest being delayed and the production lower.

Efficiency of Gibberellic Acid and some Modern Insecticides in Control Earias Insulana (Bosid)

A field experiment was conducted in the Al-Mashroo area / Al-Hamzawi, affiliated to Al-Musayyib district, located 35 km north of Babylon, in order to know the effect of bio-fertilizer and pesticide spraying on potato yield and its quality traits under the influence of different irrigation periods. The experiment was conducted according to a split-split plot design within the (Randomized Complete Block Design) RCBD with three replicates. The experiment included three factors, the first factor is the irrigation periods (5, 7, and 9) days, which represent the main plots. The second factor is biofertilizer with three levels (control treatment without adding CO, inoculation treatment with rhizobia R, inoculation treatment with mycorrhizal M) and the sub-plots are represented. The third factor is metribuzin with four levels (no addition of CO, pre-emergence, post-emergence, late post-emergence) and the sub-sub plots are represented. The results of the statistical analysis showed that the pre-emergence and post-emergence treatments were significantly superior in the number of stems, chlorophyll content in leaves and leaf area, and the fertilizer treatment (Myco) and chlorophyll content in leaves were excelled, and the number of leaves reached (23.06 and 24.66 SPAD, 28.10 and 29.15 (leaf.plant-1) The irrigation treatment every 7 days was significantly excelled in the number of leaves and leaf area (30.25 and 31.35 leaf.plant-1, 193.5 and 195.5 cm2). (28.3 and 3.53 stem.plant-1 and 3.58 and 3.88 stem.plant-1, 36.77 and 35.97 leaf.plant-1 and 37.77 and 37.68 leaf.plant-1, 219.2.224.4 cm2 and 215.5 and 227.1 cm2) and the bi-interaction between Irrigation periods and biofertilizer had a significant effect and the 7-day Myco × interaction was superior in the number of stems, number of leaves and leaf area (3.34 and 3.76 stems. plant-1, 32.40 and 33.65 leaves. plant-1, 216.3 and 219.0 cm2) and the two-way interaction between the two pesticides was The biofertilizer had a significant effect, and the interaction of post × Myco was excelled in the number of stems (3.24 and 3.78 stems. plant-1). -1, 268.6 and 271.8 cm2).

Effect of Biofertilizer and Metribuzin on the Yield Traits of Potato under the Influence of Water Stress

A field experiment was conducted in Al-Mashroo area / Al-Hamzawi, affiliated to Al-Musayyib district, 35 km north of Babylon, to determine how bio-fertilizer and herbicide spraying affected potato yield and quality under different irrigation periods. The RCBD (Randomized Complete Block Design) split-split plot design was used to conduct the experiment with three replications. The experiment had three factors: irrigation periods (5, 7, and 9) days for the main plots. The second element, biofertilizer, has three levels (control treatment without CO, rhizobia R, mycorrhizal M) and sub-plots. The third component, metribuzin, has four stages (no CO, preemergence, postemergence, late postemergence) and sub-sub plots. The statistical investigation indicated that it excelled the following traits: number of marketable tubers plant-1, weight of marketable tubers (g), total yield of one plant (g. plant-1), marketing yield (ton.ha-1). The number of tubers, marketing yield, and plant yield substantially impacted pre-emergence and post-emergence treatments. The (Myco) fertilizer treatment performed better in tuber quantity, weight, and marketing yield (3.26 and 3.77 tuber plant-1, 106.5 and 107.67 g, 23.17 and 24.78 tons ha-1) for both seasons. Irrigation every 7 days increased tuber quantity, weight, yield per plant, and marketing yield (3.37 and 3.89 tubers). 384.3 and 462.3 gm, Plant-1, 112.2 and 115.53 g Plant-1 (20.85 and 22.08 tons ha-1) both seasons. The bilateral interaction between irrigation periods and herbicide was significant in tuber number and marketing yield (3.66 and 3.94 tubers.plant-1, 4.28 and 4.52 tubers.plant-1, 25.57 and 22.83 tons ha-1 and 27.11 and 24.34 tons ha-1) for both seasons. The interaction between irrigation times and biofertilizer was more significant than the 7-day interaction. For both seasons, Mycox produced 4.01 and 4.64 tubers plant-1, 113.6 and 119.70 gram, 25.52 and 27.18 tons ha-1, and marketing yield. The herbicide-bio-fertilizer interaction significantly impacted tuber production, with post-Myco interaction leading to 3.89 and 4.41 tubers per plant-1 in both seasons. The triple interaction was substantial, with 7 days post-Myco resulting in a higher number of tubers (5.32 tubers plant-1) in both seasons.

Integrative Weed Management Tactics for Rice (Oryza sativa L.) under Direct-Seeding in Kymore Plateau and Satpura Hills

Aims: Weed infestation is the major problem in wide adoption of direct-seeding technology by rice farmers. Integration of herbicides with different manual and mechanical methods only can be a permanent solution of weed problem in direct-seeded rice.
 Study Design: Randomized block design was taken with three replications for this field experiment.
 Place and Duration of Study: The experiment was carried out during kharif, 2019 at the Experimental Farm of Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh.
 Methodology: The treatments were comprised of eight post-emergence weed management treatments including hand weeding twice at 20 days after sowing (DAS) and 40 DAS, respectively and weedy check treatment. All the treatments were allocated randomly in each replication.
 Results: Spraying of bispyribac sodium 10% SC at 25 g a.i. ha-1 at 20 DAS + conoweeder at 40 DAS was best in decreasing the infestation of grassy weeds such as Eleusine indica and Echinochloa colona and a sedge weed, Cyperus rotundus during the crop growing period except hand weeding. But broadleaved weeds such as Alternanthera sessilis and Ludwigia parviflora were controlled more effectively with metsulfuron methyl 10% WP + chlorimuron ethyl 10% WP at 4 g a.i. ha-1 at 20 DAS + conoweeder at 40 DAS than the earlier treatment. Highest grain yield (3155.67 kg ha-1), gross monetary return (Rs 57736 ha-1), net monetary return (Rs 1140 ha-1) and benefit-cost ratio (1.91) were registered under the spraying of bispyribac sodium 10% SC at 25 g a.i. ha-1 at 20 DAS + use of conoweeder at 40 DAS among the chemical and integrative weed control options.
 Conclusion: The spraying of bispyribac sodium 10% SC at 25 g a.i. ha-1 at 20 DAS followed by use of conoweeder at 40 DAS could be the best sustainable option to control the weed infestation in direct-seeded rice.

Rationalizing Herbicide Use in Maize within the Framework of Climatic Change and Extreme Hydrometeorological Phenomena

The aim of this study was to investigate specific management methods for controlling weeds under different climate conditions by reducing the risk of herbicide resistance in maize. Herbicide trials were placed at two locations during 2017 and 2018 and organized in a randomized block design with four replicates of all herbicide combinations (terbuthylazine—pre-emergence and mesotrione post-emergence treatment, terbuthylazine + mesotrione in post-emergence treatment, and terbuthylazine—pre-emergence and dicamba in post-emergence treatment). In the trials, 13 specific weeds were observed. High effectiveness was achieved when using commercial preparations with two active ingredients (terbuthylazine and mesotrione) in both years of research. As the year 2018 featured a higher amount of precipitation, uneven weed sprouting occurred, which resulted in a large number of Setaria glauca (18.50 No m−2), Solanum nigrum (16.50 No m−2), Datura stramonium (13.75 No m−2), and Chenopodium hybridum (10.50 No m−2) plants. Herbicide phytotoxicity was not expressed in maize. Ambrosia artemisiifolia, Solanum nigrum, and Datura stramonium had the highest competitive index (CI 10). The highest maize yield was observed under the application of terbuthylazine + mesotrione in post-emergence (14.223 t/ha). This combination led to the highest weed control costs (35.60 EUR/ha) in 2018, while in 2017, the yield was 12.829 t/ha, with a control cost of 33.99 EUR/ha.

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.

Herbicide and additive impacts on Bradyrhizobium japonicum growth in solution

AbstractPlant biostimulants include beneficial fungi and bacteria, and are often applied to foliage to improve crop growth, yield, and/or crop quality. Crop improvements due to biostimulant addition may be modest; therefore, solo applications may not be economical or climate smart. However, biostimulants combined with other postemergence treatments, such as herbicides, may provide an alternative application method, if mixtures do not harm the living organism(s). The growth of Bradyrhizobium japonicum, as a biostimulant surrogate, was assessed in solutions of glyphosate [N‐(phosphonomethyl)glycine] and dicamba (3,6‐dichloro‐2‐methoxybenzoic acid), with and without common spray additives (ammonium sulfate [AMS] and nonionic surfactant) in laboratory studies over 72 h. Solution turbidity, using optical density as a surrogate of bacterial growth, was measured at 600 nm at 24, 48, and 72 h after inoculation, and colony forming units (CFUs) per milliliter were estimated. Growth was not detected in either the glyphosate or AMS solutions, most likely due to the low pH and high electrical conductivity of the solutions, respectively. When herbicides were mixed with a nonionic surfactant, CFUs per milliliter were about 25% greater than the positive control. These data suggest that mixing bacteria with postemergence herbicide + surfactants/additives combinations can hinder or maintain growth when preparing for agrochemical applications. Biostimulant type and the agrichemical combination(s) should be evaluated prior to tank mixing to determine if detrimental interactions occur. After application, an evaluation of the effectiveness of the biostimulant to the crop and efficacy of the agrichemical to the target organism should be conducted.

Characterization of imazamox-resistant shattercane (Sorghum bicolor L.) populations from Kansas

AbstractShattercane is a problematic summer annual grass weed species in regions that produce grain sorghum. Three shattercane populations (DC8, GH4, and PL8) collected from sorghum fields from northwestern Kansas survived the field-use rate (52 g ha−1) of postemergence-applied imazamox. The main objectives of this research were to 1) confirm and characterize the level of resistance to imazamox in putative imazamox-resistant (IMI-R) shattercane populations, 2) investigate the underlying mechanism of resistance, and 3) determine the effectiveness of postemergence herbicides for controlling IMI-R populations. A previously known imazamox susceptible (SUS) shattercane population from Rooks County, KS, was used. All three putative populations exhibited a 4.1-fold to 6.0-fold resistance to imazamox compared with the SUS population. The ALS gene sequences from all IMI-R populations did not reveal any known target-site resistance mutations. A pretreatment with malathion, which inhibits cytochrome P450, followed by imazamox at various doses, reversed the resistance phenotype of the PL8 population. In a separate greenhouse study, postemergence treatments with nicosulfuron, quizalofop, clethodim, and glyphosate resulted in ≥96% injury to all IMI-R populations. The lack of known ALS target-site mutations and the reversal of resistance phenotype by malathion suggest the possibility of metabolism-based resistance to imazamox in PL8 shattercane population.

Estratégias de manejo para Anredera cordifolia na cultura do café

ABSTRACT Coffee plantations installed at high altitudes and near forested areas have been highly infested with Anredera cordifolia. The objective of this work was to evaluate the effectiveness of different pre- and post-emergence herbicide treatments on A. cordifolia after mechanical mowing. A field experiment was carried out in a coffee plantation with natural infestation of A. cordifolia in a completely randomized design with a split-plot scheme and four replicates, in which the main plot an herbicides application and the subplot was the days after the initial application (DAI). The treatments were as follows: saflufenacil + glyphosate (70 + 960 g a.i. ha-1); chlorimuron + glyphosate (80 + 960 g a.i. ha-1); metsulfuron + glyphosate (6 + 960 g a.i. ha-1); flumioxazin + glyphosate (25 + 960 g a.i. ha-1), and glyphosate (960 g a.i. ha-1); with sequential application of glyphosate (960 g a.i. ha-1); glyphosate + indaziflam (960 + 75 g a.i. ha-1); indaziflam (75 g a.i. ha-1); and a control without herbicide application. Mechanical control, followed by the application of the treatments flumioxazin + glyphosate and metsulfuron + glyphosate in the first application and sequential application of indaziflam, proved to be effective. Control of this weed should be based on the removal of its plant residues from the field to reduce the regrowth and germination of aerial tubers.

Standardization of Management Strategy for Chickpea (Cicer arietinum L.) under Different Levels of Crop Residue Retention in Conservation Agriculture

A field experiment was conducted at ICAR- Indian Institute of Soil Science (IISS), Bhopal (Madhya Pradesh) to evaluate the impact of different levels of crop residue retention and herbicidal weed control measures on weed dynamics, crop growth and yield characteristics of chickpea crop under conservation agriculture. Data were recorded on weed study, crop growth and yield characters of chickpea. Results indicate that pre-emergence herbicide application treatments (H1 and H2) were found to be effective in reducing weed density at 30 DAS (63.56%) as compared to post emergence treatments which were applied after recording observations on weed density at 30 DAS. It has been observed that post emergence application of imazethapyr @ 25 g a.i. ha-1 was found to restrict crop growth for a period of 10-15 days as compared to pre-emergence treatments. The results on crop growth and yield parameters revealed that higher residue retention level treatment (90% crop residue retention) recorded significantly higher plant height (54.81cm), dry matter plant-1 (18.39 g plant-1), number of pods plant-1 (36.46), seeds plant-1 (47.11), seed yield (1202 kg ha-1) and straw yield (2916 kg ha-1) as compared to no crop residue retention.

Yield and Economics of Onion as Influenced by Pre and Post Emergence Herbicdes

Onion (Allium cepa L.) weed interference lowers bulb yield and financial return for onion growers who pay for labour. During the Rabi seasons of 2011–12 and 2012–13, a field experiment was worked out at the Horticultural College and Research Institute, Dr.Y.S.R Horticultural University, Venkataramanagudem, Tadepalligudem, West Godavari District, A.P to examine the effects of pre and post emergence herbicides on the economics of onion cv.N–53. Ten pre- and post-emergence herbicide treatments (Pendimethalin, Oxyflourfen, Imazethapyr, and Quizalofopethyle) and their combinations, reproduced in a random block design, made up the experiment. Significantly, T9 (weed free-hand weeding at 30, 60, and 90 DAT) outperformed the other treatments in terms of gross and net returns, which was followed by T8 (Oxyfluorfen 0.125 kg a.i as PE + Quizalofopethyl @ 75g a.i per hectareas POE) and T6 (Pendimethalin 0.75 kg a.i as PE + Quizalofop ethyl @ 75 a.iper hectare). When compared to T6 (Pendimethalin @ 0.75 kg a.iper hectare as PE + Quizalofop ethyl @ 75 g a.iper hectare as POE), T8 (Oxyfluorfen @ 0.125 kg a.iper hectareas PE + Quizalofop ethyl @ 75 g a.iper hectare as POE) had a considerably greater B:C ratio. Hand weeding made farming more expensive. This suggested that chemical weed treatment was used to obtain the most profit per acre.