Application Of Metribuzin Research Articles

The impact of leftover herbicide residue applied to okra on weeds and crops of subsequent blackgram

In the present study, the impact of residual herbicide was studied from previous applications on okra plants, explicitly concerning the growth of weeds and subsequent black gram crops. The relative density of different weed species was determined, revealing that Echinochloa colonum had the highest density at 16.56% and 12.88%, followed by Leptochloa chinensis at 13.01% and Acrachne racemosa at 10.82%. However, within the group of sedges, Cyperus rotundus and Cyperus haspan had a greater relative density of 13.01% and 9.79%, respectively. The weed-free control treatment achieved the highest seed output of black gram, followed by two manual weeding on the 20th and 40th DAS. The herbicide residue resulted from application of metribuzin 500 g ha-1 on 3rd DAS, followed by post-emergence (POE) application of quizalofopethyl 50g ha-1 on 20 DAS recorded higher plant height 5.7%, dry matter production 32.7%, clusters plants-1 33.3%, pods plant-1 79.6%, grain yield 41.0%, halum yield 44.7%, nitrogen uptake 54.3%, phosphorus uptake 117.5%, and potash uptake 81.8% as compared to the weedy check.

Effects of Metribuzin on Soil Microbiome and Weed Management Under Varying Planting Practices and Potato Seed Dormancy

AbstractWeed infestation in potato field has become a major concern to smallholder farmers and environment, requiring sustainable intervention. This study aimed to determine (i) whether metribuzin application rate (0, 0.5, 1 (standard), 1.5, and 2 kg ai ha−1) has effects on soil microbes and soil nutrients in the short term using potted soil and (ii) the influence of potato seed dormancy (short; Shangi variety and long; Unica variety) and planting technique (surface, ridge, or furrow planting) on the efficacy of weed management practice (metribuzin (480 g L−1) herbicide and hoeing) in the field. Bacterial colony counts were recorded upon isolation from the potted soil. Soil nutrients were also analysed before and after metribuzin treatment. Data on crop growth (height and stem count), weed abundance, yield, costs, and revenues were recorded from a field experiment. Morphologically distinct bacterial strains were tested for Gram reaction and response to carbon utilization using analytical profile index kits (API 50 CH and 20 NE). In total, nine distinct bacterial strains were isolated and all were Gram positive, with variation in response to carbon substrates. Concentration of 2.0 kg a.i ha−1 significantly (p ≤ 0.05) reduced bacterial count in the first day, followed by an increase in the subsequent incubation days, while 1.0 and 1.5 kg a.i ha−1 concentrations had the highest colony development index and species richness. Significant effects of metribuzin on soil pH, total N, and total organic C in the short term were revealed. Notably, weedy plots had the highest Shannon weed index. Weeds reduced stem count and height growth by 57% and 62% respectively. Plots with Shangi had 9.8% lower weed count than those with Unica and hence higher yield was recorded from the former. While surface planting had the lowest weed control efficacy, crop growth attributes, and yield, furrow and ridge planting were not significantly different. Weed abundance and crop growth attributes in metribuzin and hand-hoed plots did not differ significantly, yet hoeing resulted in 5.30 t ha−1 above that obtained from plots managed using metribuzin. Higher dry matter and tuber yield were observed from hoed plots with Shangi planted in furrow or ridge. Use of metribuzin resulted in higher net benefit ratio and marginal rate of return than hand hoeing. The results reveal that use of metribuzin early and later in the potato growing phase can minimize weed infestation, but the efficacy depends on planting method and seed dormancy.

Pyroxasulfone based tank-mix herbicide combinations for diverse weed flora control in wheat

Field studies were conducted to assess the efficacy of pyroxasulfone alone and its combinations with other herbicides at different time of application against a diverse weed flora in wheat (Triticum aestivum L). Applications of pyroxasulfone at 125 g/ha as pre-emergence (PE) or early post-emergence (EPO) at 20 days after sowing effectively controlled the grass weeds (Phalaris minor Retz. and Avena ludoviciana Durieu). However, pyroxasulfone alone exhibited poor control of broad-leaved weeds, such as Medicago denticulata Willd and Rumex dentatus L. To address the limitations in controlling broad-leaved weeds, tank mix combinations of pyroxasulfone at 125 g/ha with either pendimethalin at 1000 g/ha or metsulfuron at 4 g/ha or metribuzin at 300 g/ha proved highly effective. Pre-emergence pyroxasulfone application in combination with either metsulfuron (125 + 4 g/ha) or with metribuzin (125 + 300 g/ha) in wheat gave effective control of diverse weed flora and improved wheat productivity by 52.1% and 51.2%, respectively, over untreated control. Ready mix combination of clodinafop + metribuzin 60 + 210 g/ha applied as post emergence (32 DAS) provided >99% control of P. minor, A. ludoviciana, M. denticulata and R. dentatus L., however the phytotoxicity with this treatment produced 6.7% lower yield as compared to season long weed free conditions. Among the herbicidal treatments, pre-emergence application of pyroxasulfone + metsulfuron at 125 + 4 g/ha had the highest net returns followed by alone application of pre-emergence metribuzin at 300 g/ha.

Application and Effects of Different Herbicides against Weed Flora in Wheat Crop for Sustainable Agriculture

Weed management is a sustainable approach which promotes the majority of crop production. To control weeds in various cropping systems, farmers employ a variety of techniques, although nowadays, the most popular method is the application of herbicides, which can be attributed to labour shortage. Application and effects of different herbicides against weed flora in wheat crop for sustainable agriculture," was conducted in 2020 and 2021. The experiment's goal was to assess how many herbicides performed against complex weed flora in wheat crop. The experiment was planned and laid out with nine treatments which are pre-emergance application of pendinethalin 1.0 kg a.i. ha-1 at (3 DAS) (T2) and post emergence application of metribuzin 0.3 kg a.i. ha-1 (T1), sulfosulfuron 0.03 kg a.i. ha-1 (T3), metsulfuron-methyl 0.005 kg a.i. ha-1 (T4), clodinafop-propargyl 0.04 kg a.i. ha-1 kg (T5), 2,4-D 0.6 kg a.i. ha-1 (T6), carfentrazone-ethyl 0.025 kg a.i. ha-1 (T7), weed free (T8) and weedy check (T9) and four replications under randomized block design. The major weeds infesting the wheat crop field were Anagallis arvensis, Chenopodium album, Phalaris minor, Parthenium hysterophorus and Cyperus rotundus. The post-emergence application of carfentrazone-ethyl 0.025 kg a i/ha at 33 days after sowing was most efficient in controlling the weeds (both grassy and non-grassy) among the various applied herbicides. Weed growth suppression effect of carfentrazone-ethyl 0.025 resulted significant increase the growth parameters, yield attributes and higher economic yield of wheat over check control in order to promote the sustainability.

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.

Control of giant ragweed (Ambrosia trifida) in mesotrione-resistant soybean

Abstract Preemergence applications of mesotrione, an herbicide that inhibits 4-hydroxyphenolpyruvate dioxygenase (HPPD), have recently gained regulatory approval in soybean varieties with appropriate traits. Giant ragweed is an extremely competitive broadleaf weed, and biotypes resistant to acetolactate synthase inhibitors (ALS-R) can be particularly difficult to manage with soil-residual herbicides in soybean production. This study investigated control of giant ragweed from preemergence applications of cloransulam (32 g ai ha–1), metribuzin (315 g ai ha–1), and S-metolachlor (1,600 g ai ha–1) in a factorial design with and without mesotrione (177 g ai ha–1) at two different sites over 2 yr. Treatments with mesotrione were also compared with two commercial premix products: sulfentrazone (283 g ai ha–1) and cloransulam (37 g ai ha–1), and chlorimuron (19 g ai ha–1), flumioxazin (69 g ai ha–1), and pyroxasulfone (87 g ai ha–1). At 42 d after planting, control and biomass reduction of giant ragweed were greater in treatments with mesotrione than any treatment without mesotrione. Giant ragweed biomass was reduced by 84% in treatments with mesotrione, whereas treatments without mesotrione did not reduce biomass relative to the nontreated. Following these preemergence applications, sequential herbicide treatments utilizing postemergence applications of glufosinate (655 g ai ha–1) plus fomesafen (266 g ai ha–1) and S-metolachlor (1,217 g ai ha–1) resulted in at least 97% control of giant ragweed at 42 d after planting, which was greater than sequential applications of glufosinate alone in 3 of 4 site-years. Preemergence applications of mesotrione can be an impactful addition to soybean herbicide programs designed to manage giant ragweed, with the potential to improve weed control and delay the onset of herbicide resistance by providing an additional effective herbicide site of action.

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).

Effect of Weed Management Practices on Growth, Yield of Vegetable Cowpea (Vigna unguiculata (L.) Walp.) cv. Kashi Kanchan

The present investigation contains seven different treatments viz., weedy check (control), weed free check (3 hand weeding) (first hand weeding at 25 DAS), pre-emergence application of Pendimethalin @ 6ml/L, pre-emergence application of Pendimethalin @ 6ml/L + one hand weeding, pre- emergence application of Pendimethalin @ 6ml/L + post emergence @ 40-50 g/ha at 25 DAS, post-emergence application of Metribuzin @ 525g/ha at 25DAS and post-emergence spray of Imazethapyr @ 100 g ai/ha at 25 DAS replicated thrice. The cowpea variety ‘Kashi Kanchan’ was used in experiment. Results of the experiment revealed that though, the weed free check (T2) recorded zero weed population and slightly higher values of growth and yield parameters but among tested treatments, pre-emergence application of Pendimethalin @ 6ml/L + one hand weeding (T4) and pre-emergence application of Pendimethalin @ 6ml/L + Quizalofop ethyl @ 40-50 g/ha at 25 DAS(T5) significantly reduced weed number (48.12 and 52.18/m2) and produced significantly highest plant height (47.30 and 45.98 cm), pod length (21.64 and 20.86 cm), number of pods/plant (35.94 and 34.18), average pod weight(11.18 and 11.06 g), green pod weight/plant (367.84 and 348.63g), green pod weight/plot (11.24 and 10.54 kg) and green pod yield per hectare(118.96 and 111.55q). However, these three treatments (T2, T4 and T5) were statistically at par with each other in terms of growth and yield parameters.Hence, these two weed management practices (T4 and T5) may serve as alternative of manual weeding and may be recommended for farmers of the central plain zone of Uttar Pradesh for higher returns from vegetable cowpea crop.

Effect of Conventional and Conservation Agriculture Practices on Dissipation of Metribuzin and Clodinafop-Propargyl, Soil Enzymatic and Microbial Activities in Wheat in a Rice-Wheat System

ABSTRACT Soil enzymes and microbial activity are an indicator of soil quality for assessing the sustainability of agricultural ecosystems. The present study determined the persistence of metribuzin and clodinafop-propargyl and response of soil quality indicators to (1) conservation agriculture (continuous zero tillage and surface residue retention) and conventional agriculture (continuous tillage and removal/incorporation of residues) practices and (2) weed management practices in a wheat field under rice-wheat system. The shift from conventional to conservation agriculture practices increased the dissipation of metribuzin and clodinafop propargyl and significantly enhanced soil dehydrogenase (DHA) and urease activity. The residues of metribuzin and clodinafop in grain and straw samples from all treatment were below maximum residue limits (<0.01 µg g−1). Post-emergence application of clodinafop-propargyl plus metribuzin caused significant inhibition in DHA and urease activity at 7 days after treatment (DAT) compared to unsprayed control. However, from 31 DAT till crop harvest (115 DAT), herbicide treated plots had higher enzymatic activity than unsprayed plots. Intervention of one hoeing following herbicide application had greater stimulation in enzyme activity than sole herbicide. Conservation agriculture practices had higher colony development (CD) and ecophysiological (EP) indices than conventional agriculture practices for heterotrophic bacteria, fungi and actinomycetes. All tillage, residue and weed management practices had non-significant effect on alkaline phosphatase activity and phosphate solubilizers, in soil. Adoption of conservation agriculture practices along with integrated weed management seems to be the best way of sustaining the soil biological parameters and cycling of various important soil nutrients which may potentially alter vital soil processes resulting in increased agricultural sustainability.

Weed Control, Growth, and Yield of Tomato After Application of Metribuzin and Different Pendimethalin Products in Upper Egypt

Weeds are very problematic for tomato production worldwide. Differences in formulations of the same herbicide have different effects on weeds and crops. There are no published studies on the effect of the capsule suspension of pendimethalin (Pend) products on tomato in Egypt. The present study aims at evaluating three pre-plant Pend products compared with a post-plant metribuzin (Met) and hand hoeing on their efficiency on weed control and on the growth, yield, yield attributes, stand loss rate of tomato plants, and their economic benefit implications in tomato production. During the fall-winter seasons of 2019/2020 and 2020/2021, six weed control treatments were studied including three pre-plant Pend products, a post-plant Met, hand hoeing, and un-weeded control in tomato field experiments. Weed density, fresh weight [FW], and FW reduction% were measured. Tomato measurements included stand loss rate, vegetative growth parameters, leaf chlorophyll concentration, fruit diameter and length, marketable and total yields, fruit total soluble solids, and pH. All herbicides and hand hoeing treatments significantly reduced weeds FW. Stand loss rates of tomato were 0% in hand hoeing followed by Sencor (~ 9.3–11.1%). Vegetative growth and leaf chlorophyll concentration were improved in all treated plots as compared to the control. The highest significant increases in tomato branch number, plant height, stem diameter, and shoot FW were observed in Sencor and Mostmicro treatments. The highest marketable and total fruit yields were observed with Sencor. Met had the highest benefit–cost ratio in the study. All herbicides were effective against various noxious weeds, but tomato “hybrid 65,010” was more tolerant to Met which resulted in better yields than those obtained with Pend products. The most cost-effective method of weed control was Met.

Yield enhancement in sesame (Sesamum indicum L.) var. TMV 7 through weed management practices

A field experiment was conducted during summer season of 2021 with a view to find out a suitable weed management practice for sesamum by excluding commonly used herbicides and including botanical herbicides along with hand weeding. The experiment was conducted in randomized block design with 10 treatments and was replicated thrice. The treatments included one pre-emergence herbicide metribuzin at two levels, one early post- emergence herbicide imazethapyr and one post-emergence herbicide quizalofop ethyl and were applied individually and in sequence along with HW. Two plant products Ageratum conizoides and Ocimum sanctum were tried each at two levels along with HW. These treatments were compared with twice HW and unweeded control. Among the treatments, the least weed density (9.92, 9.88), weed DMP (4.96, 13.54 g/m2), highest grain yield (684 kg/ha) and stalk yield (2069 kg/ha) were recorded in pre-emergence application of metribuzin @ 100 g a.i./ha on 3 DAS+Early post-emergence application of imazethapyr @ 30 g a.i./ha on 10 DAS+HW on 20 DAS. Further, this treatment gave the highest BCR of 2.46. Treatments involving herbicides fb HW were better than plant products fb HW treatments in terms of weed density and yield.

Effects of Metribuzin Herbicide on Some Morpho-Physiological Characteristics of Two Echinacea Species

Echinacea is a perennial plant that is used for its phytotherapeutic potential. Echinacea crops are often affected by invasive weeds. One of the most effective strategies in weed control is the use of chemicals such as herbicides. However, herbicides also affect the physiological and morphological processes of Echinacea. For this reason, the aim of this study was to determine the effects of different dosages (0, 250, 500, 750, 1000, and 1250 g ha−1) of the postemergent herbicide metribuzin on some morphological and physiological characteristics of Echinacea purpurea and Echinacea angustifolia collected from different locations in Iran (E. purpurea from the Shiraz and Isfahan regions and E. angustifolia from the Ardestan and Kazerun regions). Application of metribuzin decreased leaf dry weight for both Echinacea species at high doses (750 and 1250 g ha−1). At high metribuzin dose (1250 g ha−1), E. purpurea Shiraz leaves showed an increase in MDA (malondialdehyde) up to 9.14, while in other species the MDA content was lower. Minimum and maximum fluorescence increased at both the registered dosage (500 g ha−1) and at high doses (750–1250 g ha−1) of metribuzin treatments in both species. The Fv/Fm (maximum quantum yield) value was reduced in herbicide treated species, compared to the control, starting at the 250 g ha−1 dose, and was lowest at 750 g ha−1 dose. The results of this study indicate that metribuzin has adverse effects on the physiology and morphology of Echinacea species at dosages above 500 g ha−1.

Persistence of metribuzin in aridisols as affected by various abiotic factors and its effect on soil enzymes

ABSTRACT Herbicide degradation is one of the key processes determining whether the use of herbicide will have any impact on environmental quality, and it is dependent on various biotic and abiotic factors. The present study evaluates the impact of various abiotic factors such as soil type, application rate, incubation temperature, soil pH, soil microorganisms and sunlight on persistence of metribuzin and its effect on soil enzymes. Half-lives (DT50) varied significantly with application rate of metribuzin and physicochemical properties of soil and ranged from 15.17 to 46.59 days. Metribuzin degraded 2.2 to 6.5 times slower in sterilised soil (DT50 = 35.21 to 115.60 days) as compared to unsterilised soil, indicating microbial degradation is one the most predominant contributors towards degradation of metribuzin in soil. Increase in degradation rate on exposure to sunlight indicated photodegradation also contributes significantly to the degradation of metribuzin. Deaminometribuzin, diketometribuzin and deaminodiketometribuzin metabolites of metribuzin were detected in all treatments. Dehydrogenase and alkaline phosphatase activities were significantly affected by application of metribuzin while urease activity remained unaffected. The physicochemical properties viz. pH, organic matter content and temperature should be considered along with application rate of metribuzin in order to achieve satisfactory weed control and reduce environmental risk associated with the use of metribuzin in different crops.

Synergistic integration of crop residue mulch and cultural practices with herbicides for managing weed complex in turmeric in North-Western India

Turmeric being a wide spaced and long duration crop, weeds pose a serious problem due to its delayed emergence and slow initial growth which provide ideal environment for weeds to grow. This warrants for synergistic integration of residue mulch, cultural practices, and herbicides for effective weed management. Two field experiments were conducted during 2012-13 - 2013-14 and 2014-15 - 2015-16 at CCS Haryana Agricultural University, Regional Research Station, Karnal to evaluate different approaches involving integration of crop residue mulch and cultural practices with herbicides for effective and economical weed management in turmeric. The uncontrolled weeds caused 42-66% turmeric yield loss. Based on four years studies, it may be concluded that pre-emergence (PE) application of metribuzin 700 g/ha or pendimethalin 1000 g/ha or atrazine 750 g/ha integrated with rice straw mulching (10 t/ha) after herbicide application at 3 days after sowing (DAS) and hand weeding at 50 or 75 DAS provided effective control (86-100%) of complex weed flora in turmeric with improved rhizome yield (14.29 to18.60 t/ha), which was comparable to weed free, better economic returns without phyto-toxicity on the crop and detectable herbicidal residues in the turmeric rhizomes and soil at harvest. Integration of 2-hoeing with metribuzin 700 g/ha PE or pendimethalin 1000 g/ha PE were the two other viable options of integrated weed management (IWM) strategy. Among post-emergence (PoE) herbicides, fenoxaprop 67 g/ha 45 DAS, was safe to turmeric while metsulfuron 4 g/ha PoE was toxic. Glyphosate 0.3% PoE at 25 DAS could also be integrated with hoeing twice at 45 and 75 DAS for effective weed management in turmeric. Use of rice straw in IWM strategies in turmeric will also help in reducing herbicide dose, crop residue management without burning, conservation of soil moisture and other natural resources which will helps in long term sustainable and economical production system.

Effect of integrated weed management on turmeric under mid hill conditions of Himachal Pradesh

A field experiment was carried out on silty clay loam soil, acidic in reaction, high in available phosphorus, medium in available potassium and low in available N during kharif 2017 at the Research Farm of Department of Agronomy, CSKHPKV, Palampur to study effective weed control strategy for this important crop. The results revealed that Alternanthera philoxeroides was the major weed constituting 16% of the total weed flora. This was followed by Cynodon dactylon and Echinochloa colona with 14 and 12% of total weed population, respectively. The count of Echinochloa colona, Alternanthera philoxeroides, Commelina benghalensis, Digitaria sanguinalis and Ageratum conyzoides was maximum at 120 DAP and there after it gradually decreased. All herbicide treatments brought significant reduction in the count on Echinochloa, Alternanthera and Ageratum over weedy check. The lowest count of these weeds was recorded in metribuzin fb straw mulch fb hand weeding and the maximum count was in case of weedy check. All the weed control treatments significantly reduced the total weed count and dry weight of weeds as compared to the weedy check. Amongst different herbicide treatments application of metribuzin @ 0.70 kg/ha fb straw mulch fb hand weeding resulted in significantly lowest weed count at all stages of observation as well as at harvest though this treatment was at par with metribuzin @ 0.70 kg/ha fb two hand weedings and treatments in which atrazine 0.75 kg/ha and hand weedings were applied with or without the use of straw mulch resulted in significantly lower dry matter accumulation by weeds as compared to other herbicide treatments. Weed index calculated at 120 DAP was highest with use of metribuzin @ 0.70 kg/ha and atrazine @ 0.75 kg/ha used along with straw mulch and one or two hand weedings proving effective as compared to other herbicides tested. From the present study it seems that mulching must be included in any effective weed management strategy for turmeric. Also among different herbicides metribuzin and atrazine are effective and their integration with mulching and/or hand weeding gave good control of weeds in turmeric.

Tomato tolerance to preemergence herbicides in plasticulture using narrow bands and precision technology

Preemergence (PRE) herbicides are broadcast-applied over the entire top of raised beds prior to plastic mulch installation. Following mulch installation, broadleaves and grasses only emerge from the planting holes. For this reason, the majority of PRE herbicides that are broadcast-applied underneath the plastic mulch are unnecessary for weed control. To reduce off-target herbicide application, we evaluated (1) tomato tolerance to herbicides applied in narrow bands over the planting holes at 2 weeks after transplant (WATP), and (2) tomato tolerance to herbicides that were precisely applied to individual planting holes immediately prior to transplant using a precision herbicide applicator that was previously developed at the University of Florida. Halosulfuron, metribuzin, pendimethalin, and S-metolachlor applied in narrow bands over the planting holes at 2 WATP did not significantly injure tomato, stunt growth, nor reduce yield. However, significant tomato injury (7%) was observed when fomesafen was applied in narrow bands over the planting holes where tomato plants have been transplanted for 2 weeks. Precision application of fomesafen, metribuzin, oxyfluorfen, and S-metolachlor in a carrier volume of 187, 374, or 561 L ha−1 using the precision hole-punch sprayer to the individual planting holes prior to transplant caused minimal early-season tomato injury (≤4%) and did not significantly stunt tomato plant growth or reduce yield. Overall, results demonstrated a safe and effective way to reduce off-target herbicide application in plastic-mulched tomato by applying herbicides in bands over the planting holes after transplant or precisely applying herbicides to individual planting holes prior to transplant using a precision hole-punch applicator.

Weed Control Using Paddy Straw Mulch in Integration with Herbicides in Autumn Potato in North-West India

Weeds are a major problem in potato production. Two years of trials were conducted to study the efficacy of herbicides and integrated use of mulch with herbicides in controlling weeds and for improving the growth and yield of autumn potato crop at Ludhiana, north-west India, during autumn 2016 and 2017. Each trial had a randomized complete block design with three replicates. There were 11 treatments including weed-free and weedy controls. Uncontrolled weeds caused a yield reduction of 49.7%. Metribuzin at 350 g/ha pre-emergence resulted in 82.4% weed control efficiency at 30 days after planting but this control was reduced to 23.9% at harvest. In contrast, metribuzin at 350 g/ha applied post-emergence controlled broadleaf weeds and grasses very effectively. Clodinafop at 60 g/ha post-emergence resulted in control of grasses only. The post-emergence application of pre-mix clodinafop plus metribuzin at 260 g/ha provided effective weed control and resulted in more tuber yield and economic returns and was significantly better than an application solely of metribuzin or clodinafop. The integrated weed control treatment of paddy straw mulch (PSM) at 6 t/ha with clodinafop plus metribuzin at 195 g/ha post-emergence resulted in the highest tuber yield with weed control efficiency of 95.3% at harvest. The next best one was an integrated treatment of PSM at 6 t/ha with metribuzin at 275 g/ha pre-emergence.

Herbicide Tolerance of Sugarcane Genotypes to Post-emergence Application of Halosulfuron Methyl and Metribuzin: An Inadvertent Preliminary Assessment

Thirty-one sugarcane genotypes were planted in the experiment and post-emergence application of Halosulfuron Methyl 75% WG and Metribuzin 70% WP was carried out at the rate of 67.5 g and 1000 g a.i. per hectare on 42 days after planting (DAP). Lower leaves of some of the genotypes were found to show injuries on 5 days after spraying (DAS). Phytotoxicity was recorded in visual scoring scale of 0 to 10 at 7, 15, 21 and 30 DAS. Phytotoxicity rating of the 31 genotypes studied ranged between 0 and 4. Nine genotypes showed no visual injury and found tolerant, while eight genotypes showed moderate toxic effect (rating 4). All the genotypes (14 nos.) that showed phytotoxicity rating of 1 to 3 recovered visually (leaf injuries) except Co 06027 at 30 DAS, while all the genotypes that showed moderate phytotoxicity did not recover completely except Co 94008. The genotypes with Co 7201 and Co 775 as one of the parents showed phytotoxicity rating ranging from 1 to 4. The genotypes, Co 06030, Co 86032, Co 11015, Co 92005 and Co 09004 did not exhibit phytotoxicity symptoms, while their parent, CoC 671 exhibited phytotoxicity. Seven parental genotypes showed 100% probability of no herbicidal injury in their progenies and exhibited herbicidal tolerance from initial stage. Cane yield reduction (> 5%) was observed only in Co 8021, Co 94008 and Co 99006 with herbicide treatment over no herbicide application. The present study provides a preliminary information on the genetic variation among sugarcane genotypes for herbicide tolerance and their parental relationship, which could be utilized for the development of herbicide tolerant varieties for effective weed management in sugarcane agriculture.

Impact of PRE- and POST herbicide on purple nut sedge (Cyperus rotundus L.) control and plasticulture tomato yields

Purple nut sedge (Cyperus rotundus L.) is a problematic weed in plasticulture tomato (Solanum lycopersicum L.) production in Iran as it is difficult to control due to its ability to penetrate plastic mulch. Field trials were carried out at the experimental area of the state farm Safadasht, Shahriar region, Iran, over the fall of 2015 and spring of 2016 to investigate PRE- and POST herbicide programs (PRE transplanting, POST transplanting, and combination of PRE- and POST transplanting) to control purple nut sedge in plasticulture tomato production. PRE herbicide treatment metribuzin and (S)-metolachlor were not effective when applied alone, and did not reduce purple nut sedge plants compared to the weedy control. POST transplanting application of halosulfuron did not significantly affect purple nut sedge plants at 12 wk after application (WAA) in the fall 2015, but treatment favorably reduced density of purple nut sedge at 16 WAA in both seasons. PRE transplanting application of metribuzin or (S)-metolachlor plus POST halosulfuron exerted the greatest control, and purple nut sedge numbers were eventually diminished in both seasons. Experimental treatments did not negatively affect tomato height and yields. Based on our findings, multiple PRE and POST herbicide programs were effective in greater purple nut sedge suppression compared to the lone application of PRE and POST herbicides. The herbicides were selected due to routine use by tomato producers in the area. Using active ingredients from the various herbicide families with different modes of action could facilitate effective management of herbicide-resistant purple nut sedge in tomato fields.

Russian thistle (Salsola tragus L.) control with soil-active herbicides in no-till fallow

AbstractThe benefits of no-till fallow, which include reduced soil erosion, improved soil health, and increased stored soil water, are in jeopardy because of the widespread development of glyphosate resistance in Russian thistle. The objective of this research was to evaluate the efficacy of soil-active, residual herbicides for Russian thistle control in no-till fallow. The combinations of sulfentrazone + carfentrazone and flumioxazin + pyroxasulfone, and metribuzin alone were each applied in late fall, late winter, and split-applied in late fall and late winter at three sites: Adams, OR, in 2017–2018; Lind, WA, in 2018–2019; and Ralston, WA, in 2019–2020. All treatments provided good to excellent control of the initial flush of Russian thistle when assessed in mid-May, except the late-fall application of metribuzin at all three sites, and the late-fall application of sulfentrazone + carfentrazone at Adams. Cumulative Russian thistle densities, evaluated monthly throughout the fallow season, were lowest for the sulfentrazone + carfentrazone treatments, except for the late-fall application at Adams. However, flumioxazin + pyroxasulfone and metribuzin provided greater control of tumble mustard and prickly lettuce than did sulfentrazone + carfentazone. Sulfentrazone + carfentrazone, flumioxazin + pyroxasulfone, and metribuzin can all be used for Russian thistle control in fallow. To reduce the risk for crop injury to subsequently planted winter wheat, a late-fall application of sulfentrazone + carfentrazone may be the preferred treatment in low-rainfall regions where winter wheat–fallow is commonly practiced. A late-winter application may be preferred in higher rainfall regions where a 3-year rotation (e.g., winter wheat–spring wheat–fallow) is common. Flumioxazin + pyroxasulfone should be considered if other broadleaf weeds, such as tumble mustard or prickly lettuce, are of concern. The use of these soil-applied herbicides will reduce the need for the frequent application of glyphosate for Russian thistle control in no-till fallow.