Preemergence Herbicides Research Articles

Weed control of oil flax in the area of unstable moistening in the south of Russia

The work aimed at determining the optimal methods of using herbicides that ensures the control of gramineous and dicotyledonous weeds when growing oil flax in the conditions of unstable moistening of the south of Russia. A single treatment with a pre-emergence herbicide Dual Gold after sowing a crop against monocotyledonous gramineous or with a foliar Tifi at the stage of true leaves development of flax against dicotyledonous weeds contributed to the of 0.07-0.09 t/ha higher yield than in the control with manual weeding. However, the sequential introduction of these preparations led to a decrease in crop yield by 0.14 t/ha on one plot. We noted a slight increase in yield (+0.04 t/ha) under the separate application of Miura graminicide and anti-dicotyledonous herbicide Sekator Turbo, and a decrease in yield (-0.16 t/ha) and seed oil content (-0.8 %) under application of their tank mixture. The separate foliar herbicide treatments should be a priority in weed control of oil flax.

Quality of soybean seeds under application of herbicides or growth regulators

Seeds may undergo interference from chemical products that are applied to the mother-plant, either impairing or improving their features, and to determine if there was interference in the seeds, germination and vigor tests are carried out. This study aimed to assess the quality of soybean seeds subjected to pre- and post-emergence herbicides and post-emergence growth regulators. At experiment 1, pre-emergence soybean herbicides were applied, and seeds were sown at the same day of application, at experiment 2, herbicides and growth regulators were applied at post-emergence soybean (V4). Seeds were harvested and subjected to the necessary tests, namely 1,000-seed weight, moisture content, germination, seedling length, tetrazolium and electrical conductivity. In general, herbicides and growth regulators did not cause an adverse impact on soybean seeds quality. Application of flumioxazin or mepiquat chloride caused minimal effects on the soybean seeds quality, with minor reductions in vigor, and no effect on germination.

Future efficacy of pre-emergence herbicides in corn (Zea mays) is threatened by more variable weather.

BACKGROUNDBy 2050, weather is expected to become more variable with a shift towards higher temperatures and more erratic rainfall throughout the U.S. Corn Belt. The effects of this predicted weather change on pre‐emergence (PRE) herbicide efficacy have been inadequately explored. Using an extensive database, spanning 252 unique weather environments, the efficacy of atrazine, acetochlor, S‐metolachlor, and mesotrione, applied PRE alone and in combinations, was modeled on common weed species in corn (Zea mays L.).RESULTSAdequate rainfall to dissolve the herbicide into soil water solution so that it could be absorbed by developing weed seedlings within the first 15 days after PRE application was essential for effective weed control. Across three annual weed species, the probability of effective control increased as rainfall increased and was maximized when rainfall was 10 cm or more. When rainfall was less than 10 cm, increasing soil temperatures had either a positive or negative effect on the probability of effective control, depending on the herbicide(s) and weed species. Herbicide combinations required less rainfall to maximize the probability of effective control and had higher odds of successfully controlling weeds compared with the herbicides applied individually.CONCLUSIONSResults of this study highlight the importance of rainfall following PRE herbicide application. As rainfall becomes more variable in future, the efficacy of common PRE herbicides will likely decline. However, utilizing combinations of PRE herbicides along with additional cultural, mechanical, biological, and chemical weed control methods will create a more sustainable integrated weed management system and help U.S. corn production adapt to more extreme weather.© 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Seed traits correlate with herbicide resistance in Italian ryegrass (Lolium perenne ssp. multiflorum).

Italian ryegrass (Lolium perenne ssp. multiflorum) is one of the major winter annual weeds worldwide. In this research, diversity for seed morpho-physiological traits such as seed weight, seed size, awnedness, dormancy, speed of germination, and seed vigor among Italian ryegrass populations collected from the Texas Blacklands region were assessed, and potential association with herbicide resistance was investigated. A high degree of diversity was observed among the populations for 100-seed weight (125-256 mg), seed length (4.8-6.6 mm), awn length (0-6 mm), and total seedling length (9-14 cm at 21 days after seed germination). Inter-population range for seed dormancy was higher in the freshly harvested seed (31-85%), which reduced to 18 to 62% at 9months after harvest. Populations with high initial seed dormancy (> 70% dormancy) released dormancy at a faster rate than the low dormancy group (< 40%). Percent survival status to multiple postemergence herbicides was positively correlated with 100-seed weight and fresh or initial seed dormancy. Early emerging cohorts are easily controlled by pre-plant tillage and preemergence herbicides, whereas late emerging cohorts (facilitated by seed dormancy) are exposed to postemergence herbicides wherein greater opportunities exist for resistance evolution, likely explaining the occurrence of high seed dormancy in Italian ryegrass populations resistant to postemergence herbicides. High seed weights can further allow seedling emergence from greater burial depth, thereby exposing more seedlings to postemergence herbicides and increasing the likelihood of resistance evolution. Results provide unique insights into the association between seed traits and herbicide resistance in this species. © 2021 Society of Chemical Industry.

Resource conservation technology for sustainable productivity of intensive rice-based cropping pattern in Bangladesh

Exhaustive conventional tillage and removing residues of previous crops in the rice-based cropping system are labor intensive, costly, soil destructive and non-ecofriendly. In recent years, increased concerns for healthier food production and environmental quality, and increased emphasis on sustaining the productive capacity of soils, have raised concern in the maintenance and improvement of soil organic matter through appropriate land use and management practices. Strip tillage with the application of herbicides and crop residue mulching are being developed to overcome this challenge. A two-year experiment of the summer rice-mustard-winter rice (R-M-R) system was conducted at the farmers’ field in the northern Bangladesh during 2014-2016. Summer rice (BRRI hybrid dhan6), mustard (BARI Mustard 14) and winter rice (BRRI dhan28) were grown under, T1: Conventional tillage (CT) + three hand weeding (Control) and T2: Pre-plant herbicide (PRE) + strip tillage (ST) + pre-emergence herbicide (PE) + post-emergence herbicide (PO) with two levels of crop residue mulching, M0: no-mulch and M50: 50% standing mulch. The CT consisted of two primary tillage operations by a two-wheel tractor, and ST had done by a Versatile Multi-crop Planter in a single-pass process. The PRE (glyphosate) and PE (pendimethalin) in all crops and the PO (ethoxysulfuron-ethyl in rice and isoproturon in mustard) were applied at recommended dose and time. The combination of applied PRE, ST, followed by PE and PO herbicide and the retention of 50% mulch fetched the highest yield and economic returns of individual crop and the productivity of the summer rice-mustard-winter rice system.

Influence of PRE-emergence herbicides on soybean development, root nodulation and symbiotic nitrogen fixation

Widespread occurrence of herbicide-resistant weeds has further limited effective POST-emergence herbicide options in soybean (Glycine max (L.) Merr.) leading to an increased adoption of PRE-emergence herbicides. The objective of this study was to investigate the influence of 11 commonly used PRE herbicides on soybean development, root nodulation, and symbiotic N fixation. Soybean plants were grown under greenhouse conditions in pots (10 L; 4 plants per pot) filled with silt loam soil and treated one day after planting with a labeled field rate of imazethapyr, chlorimuron-ethyl, cloransulam-methyl, metribuzin, sulfentrazone, flumioxazin, saflufenacil, acetochlor, S-metolachlor, dimethenamid-P, pyroxasulfone and no herbicide (nontreated control). Sulfentrazone reduced soybean canopy at the VC growth stage but no canopy reduction was observed at the V2 growth stage from any of the herbicide treatments. At the R2 growth stage, herbicides had no effect on soybean development (root and shoot biomass), root nodulation (# nodule per plant, nodule diameter, and nodule biomass) and symbiotic N fixation (acetylene reduction assay and 15N natural abundance). According to our findings, although PRE herbicides may slightly affect early-season soybean development, the impacts on plant growth, root nodulation, and symbiotic N fixation were negligible. Thus, when sprayed according to the label, the benefits of PRE herbicides for weed control likely outweigh any potential concern regarding soybean development, root nodulation, and N fixation.

Target-Site and Non-target-Site Resistance Mechanisms Confer Multiple and Cross- Resistance to ALS and ACCase Inhibiting Herbicides in Lolium rigidum From Spain.

Lolium rigidum is one the worst herbicide resistant (HR) weeds worldwide due to its proneness to evolve multiple and cross resistance to several sites of action (SoA). In winter cereals crops in Spain, resistance to acetolactate synthase (ALS)- and acetyl-CoA carboxylase (ACCase)-inhibiting herbicides has become widespread, with farmers having to rely on pre-emergence herbicides over the last two decades to maintain weed control. Recently, lack of control with very long-chain fatty acid synthesis (VLCFAS)-inhibiting herbicides has been reported in HR populations that are difficult to manage by chemical means. In this study, three Spanish populations of L. rigidum from winter cereals were confirmed as being resistant to ALS- and ACCase-inhibiting herbicides, with broad-ranging resistance toward the different chemistries tested. In addition, reduced sensitivity to photosystem II-, VLCFAS-, and phytoene desaturase-inhibiting herbicides were confirmed across the three populations. Resistance to ACCase-inhibiting herbicides was associated with point mutations in positions Trp-2027 and Asp-2078 of the enzyme conferring target site resistance (TSR), while none were detected in the ALS enzyme. Additionally, HR populations contained enhanced amounts of an ortholog of the glutathione transferase phi (F) class 1 (GSTF1) protein, a functional biomarker of non-target-site resistance (NTSR), as confirmed by enzyme-linked immunosorbent assays. Further evidence of NTSR was obtained in dose-response experiments with prosulfocarb applied post-emergence, following pre-treatment with the cytochrome P450 monooxygenase inhibitor malathion, which partially reversed resistance. This study confirms the evolution of multiple and cross resistance to ALS- and ACCase inhibiting herbicides in L. rigidum from Spain by mechanisms consistent with the presence of both TSR and NTSR. Moreover, the results suggest that NTSR, probably by means of enhanced metabolism involving more than one detoxifying enzyme family, confers cross resistance to other SoA. The study further demonstrates the urgent need to monitor and prevent the further evolution of herbicide resistance in L. rigidum in Mediterranean areas.

Effect Spraying Volume of Cosmos sulphureus Cav. Flower Extract on Weed Dominance and Soybean Yield

Allelochemical based herbicides are environmentally friendly management alternatives. Thus, cosmos (Cosmos sulphureus Cav.) flower extract as a bioherbicide was investigated in soybean productions. This study aimed to determine effective spraying volume of C. sulphureus flower extract to manage weeds based on weed dominances and soybean yield. This research was conducted at Banguntapan Village, Bantul District, Special Region of Yogyakarta Province, Indonesia on August to November 2018. This study was set as a single factor Randomized Complete Block Design (RCBD) with three replications set as blocks. Three spraying volumes; 1000, 2000, 3000 L.ha−1 and two weed management practices were used as control. Continued weed free and weeded treatments were used to determine soybean yield lost. Data were analyzed using Analysis of Variance (ANOVA), continued with Least Significant Differences (LSD) at the 0.05 probability level. Results showed weed species in soybean fields was dominated by purple nutsedge (Cyperus rotundus L.). The 400 g.L−1 extract concentration applied at 3000 L.ha-1 resulted in similar weed control and soybean yield compared to pre-emergence herbicide application and manual weeding at 1 and 3 weeks after planting (WAP). These findings showed that extract of cosmos flowers possess bioherbicidal activity against weed without having detrimental effects on the soybean plants.

The influence of maize – winter wheat rotation and pre-emergence herbicides on weeds and maize productivity

Crop rotation is a simple and effective part of an Integrated Weed Management (IWM) system. This approach makes it possible to rotate herbicides with different modes of action (MOA), avoiding or postponing herbicide resistance. Besides all the known advantages and benefits, it is still not widely used in maize (Zea mays L.) production. In Serbia, about 20% of total maize production is a continuous cropping. The aim of this research was to test the benefits of growing maize in crop rotation with winter wheat (Triticum vulgare L.) compared with a continuous cropping, combined with pre-emergence herbicide application. Field trials started in 2009, and five maize-winter wheat rotations have been completed. Weeds were controlled with a herbicide mixture of isoxaflutole and S-metolachlor, applied at either the full label rate or half rate, while one plot was kept weed free (manually), and one was a control. Integrating crop rotation and PRE herbicides decreased the biomass of weeds and their density by 98% and 99%, respectively. In continuous maize, perennial weeds became dominant after the first rotation. Crop rotation significantly influenced maize productive parameters, decreasing the variation in leaf area index and grain yield, increasing values with the number of cycles. The biggest differences in the analyzed parameters were observed in 2015, 2017 and 2019, indicating many positive long-term benefits of crop rotation on maize leaf area index and grain yield.

Effect of hollow‐tine cultivation on crabgrass infestation in cool‐season turf

AbstractHollow‐tine cultivation is a common management practice in cool‐season turfgrass lawns. Research examining the effect of hollow‐tine cultivation on annual crabgrass (Digitaria spp.) infestations in the absence of preemergence herbicides is limited. Multi‐year experiments were conducted on Kentucky bluegrass (Poa pratensis L.) and tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] monostands at the Rutgers University Horticulture Research Farm No. 2 in North Brunswick, NJ to evaluate the effect of hollow‐tine cultivation in early spring, late spring, and autumn on crabgrass infestations. Herbicides to control crabgrass were not applied at any time during the experiments. These monostands were maintained as simulated lawns; mowing, irrigation, fertilizer, fungicide, and insecticide inputs were provided to maintain high turfgrass density. Crabgrass cover was evaluated in late summer each year. In the tall fescue experiment, hollow‐tine cultivation treatments did not affect crabgrass cover. However, in the third year of the tall fescue experiment, a non‐significant trend (P = .08) emerged in which early and late spring cultivation treatments resulted in more crabgrass cover (30 and 35%, respectively) than autumn (24%) and no cultivation (26%). A similar non‐significant trend (P = .056) was observed only during the first year the Kentucky bluegrass experiment as both spring cultivation treatments increased crabgrass cover. This research indicates hollow‐tine cultivation in the springtime does not appreciably increase crabgrass infestations in Kentucky bluegrass or tall fescue in the absence of preemergence herbicides.

Field evaluation of fluorochloridone for broad-spectrum weed control in carrot (Daucus carota L.) in north-west India

Weed management has been one of the major components of carrot production where the critical period of weed competition is longer as the development of a carrot canopy is very slow. Thus, hand weedings must be applied to control weeds. In this context, use of residual herbicides assumes greater significance in this important root vegetable. The field efficacy of fluorochloridone, a residual pre-emergence herbicide, was evaluated in carrot over two years at Ludhiana, India. Fluorochloridone at 625 and 750 g ha−1 provided >90% control of annual grasses [Digitaria sanguinalis (L.) Scop, Echinochloa colona (L.) Link, and Eleusine indica (L.) Gaertn.], and broad leaf weeds [Digera arvensis Forssk., Chenopodium album (L.), and Amaranthus viridis (L.)] until 60 days after application. Fluorochloridone at 625 and 750 g ha−1 gave the highest carrot root yield (28.4–31.7 t ha−1) which was similar to the hand weeded check (29.5–32.6 t ha−1) and 25.4–26.3% higher than the weedy check (23.1–25.1 t ha−1) in both years. Findings imply that application of fluorochloridone at 625 g ha−1 could be a suitable option for pre-emergence residual control of annual grass and broadleaved weeds in carrot.

Assessment of Energy Budgeting and Its Indicator for Sustainable Nutrient and Weed Management in a Rice-Maize-Green Gram Cropping System

Sustainability and climate change are the two major challenges to the agricultural production system. The trade-off between them is essential for higher profitability. The energy assessment is essential for judging the sustainability and vulnerability of a production system. Besides, nutrient management and weed management are equally imperative to sustainability. Thus, the present study was executed to assess the energy balance, key energy indicators and profitability of rice–maize–green gram system under different nutrient and weed management practices. Application of Brassicaceous seed meal (BSM) along with mineral fertilizer attributed the highest rice (5.62 t ha−1) and maize (6.48 t ha−1) yield which was 11.6%, 8.3% and 3.7% in maize and 10.0%, 6.2% and 8.7% in rice for the conjoint application with vermicompost, farmyard manure (FYM) and neem cake, respectively. Moreover, BSM recorded the highest net energy gain, energy use efficiency and energy efficiency ratio and the lowest specific energy in all the crops. Application of pre-emergence herbicides followed by hoeing was found to be best in all respects including yield, profitability, energy use efficiency, energy effectiveness, etc. The appropriate combination of integrated nutrient management with BSM and pre-emergence herbicide application followed by hoeing provided an additional advantage not only in terms of yield but also an efficient use of energy, profitability and environmental safety. BSM and neem cake could be the alternative organic manure in the integrated nutrient-cum-weed management module and they could be able to compensate the paucity of FYM and vermicompost in the country.

Effect of cinmethylin against Alopecurus myosuroides Huds. in winter cereals

Cinmethylin is a potential new pre-emergence herbicide in Europe inhibiting the fatty acid thioesterases in the plastid against Alopecurus myosuroides and other grass-weeds in winter cereals and oil-seed rape. Five field experiments were conducted in Southwestern Germany from 2018 until 2020 to assess the control efficacy of cinmethylin and other common pre-emergence herbicides alone and combined with post-emergence herbicides against A. myosuroides and yield response of winter wheat and winter triticale. In four experiments, the effect of early and late sowing of winter cereals was included as the second factor in the experiment to investigate if late sowing can reduce A. myosuroides density weed control efficacy. All fields were heavily infested with A. myosuroides with average&lt;br /&gt; densities of 110–730 plants/m&lt;sup&gt;2&lt;/sup&gt;. Late sowing reduced densities in three out of four experiments. Herbicides controlled 42–100% of the A. myosuroides plants. However, none of the treatments was consistently better than the other treatments over all experiments. In three out of 5 experiments, grain yields were significantly increased by the herbicide treatments. The results demonstrate that cinmethylin increases the options for controlling A. myosuroides in winter cereals. However, it needs to be combined with other control tactics.

Optimizing the Application Time of Pre-emergence Herbicide Pendimethalin and Oxyfluorfen Application for Effective Weed Management in Irrigated Blackgram (Vigna mungo L.) and Its Residue Persistence

Background: Time of pre-emergence herbicide application is an important factor that decides the efficiency of herbicide. If the pre-emergence herbicide is not applied at appropriate time, it may cause ineffective weed control or toxicity to crops. With this background, a field experiment was conducted at TNAU, Madurai to optimize the time of pre-emergence herbicides namely pendimethalin and oxyfluorfen application for effective weed management in irrigated blackgram. Methods: The experiment was laid out in randomized block design with three replication. Treatments were application of pendimethalin at 0.75 kg ha-1 and oxyfluorfen at 0.2 kg ha-1 on 1, 2, 3, 4 days after sowing, weed free check and unweeded check. Result: Results of the study revealed that oxyfluorfen gave maximum weed control efficiency as compared to pendimethalin, but toxicity to the crop was observed when oxyfluorfen was sprayed after 2 days of sowing. Yield and economics were achieved higher with application of 0.75 kg ha-1 of pendimethalin at 2 DAS, which was on par with application of 0.2 kg ha-1 of oxyfluorfen at 1 DAS due to lesser toxicity. Application of 0.75 kg ha-1 of pendimethalin and 0.2 kg ha-1 of oxyfluorfen didn’t leave any herbicide residue after harvest. Hence, application of 0.75 kg ha-1 of pendimethalin at 2 DAS and 0.2 kg ha-1 of oxyfluorfen at 1 DAS can be recommended for effective weed management in irrigated balckgram.

Photosynthetic and physiological responses to acetochlor in paired near-isogenic lines of waxy maize (Zea mays L.).

Acetochlor is always used in maize (Zea mays L.) fields as a common pre-emergence herbicide. In this field study, we investigated the effects of acetochlor on the photosynthetic characteristics, chlorophyll fluorescence parameters, and antioxidant enzyme activities in acetochlor-resistant (BWC95) and acetochlor-sensitive (BWC12) near-isogenic lines. We sprayed acetochlor after sowing, using water treatment as the control. After spraying acetochlor, the net photosynthetic rate, stomatal conductance, transpiration rate, and the function of chloroplasts were significantly lower in BWC12 than BWC95, whereas the intercellular CO2 concentrations and stomatal limitation values were higher. In addition to nonphotochemical quenching, chlorophyll fluorescence measurements obtained using leaves showed that the maximum photochemical efficiency of photosystem II (PSII), actual photochemical efficiency of PSII, photochemical quenching of chlorophyll fluorescence, and electron transport rate were higher in BWC95 than BWC12 after acetochlor treatment. H2O2 and O2˙- levels were higher in BWC12 than BWC95, which resulted in severe membrane lipid peroxidation due to sustained oxidative stress. Thus, the malondialdehyde content increased significantly with the exposure time in BWC12, and the antioxidant enzyme activities were lower in BWC12 than BWC95. The results show that acetochlor resistance is directly related to a high photosynthetic rate and a protective antioxidant enzyme system.

Pre-sowing application of combinations of burndown and pre-emergent herbicides for Conyza spp. control in soybean

Together, Conyza bonariensis, C. canadensis and C. sumatrensis show 105 reported cases of biotypes resistant to herbicides like glyphosate, paraquat, and acetolactate synthase (ALS) inhibitors. The application of pre-emergent herbicides combined with burndown herbicides is believed to be effective in controlling Conyza spp. during soybean pre-sowing management. The objective of this study was to evaluate the efficacy of sulfentrazone/diuron, imazethapyr/flumioxazin, and diclosulam in mixtures with diquat, paraquat, or glufosinate on the control of Conyza spp. Two field experiments were conducted in a randomized block design with four replicates. Treatments consisted of the application of pre-emergent plus burndown herbicides, besides the weedy control treatment (without application), for a total of 10 treatments. The control of Conyza spp. was evaluated at 7, 14, 21, 28, and 35 d after herbicide application, and symptoms of injury in soybean plants were evaluated at 14, 21, 28, and 35 d after herbicide application. The herbicides sulfentrazone/diuron, imazethapyr/flumioxazin, and diclosulam in combination with burndown herbicides diquat, paraquat, or glufosinate were effective in controlling Conyza spp. in the pre-sowing management of soybean, highlighting good options for pre- and post-emergent herbicide rotations. Mixtures with diclosulam showed a higher potential for injury to soybean plants than sulfentrazone/diuron and imazethapyr/flumioxazin.

Pre‐emergence herbicides, not carrier volume, impacted weed management in conventional tillage systems

AbstractThe use of pre‐emergence (PRE) herbicides is resurging as a standard practice for weed management in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] in the U.S. north‐central region. The increased use of PRE herbicides warrants investigation on the impact of spray carrier volume on weed control. Field experiments were established at Arlington, WI, in 2018 and 2019 and Janesville, WI, in 2018 to evaluate the influence of carrier volume on weed control of PRE herbicides in conventional tilled corn and soybean. Each experiment included three PRE herbicide premixes applied at crop planting at five carrier volumes (2.5, 5, 10, 15, and 17.5 gal acre−1). A nontreated control was also included in the experiment. Carrier volume did not influence weed control but PRE herbicide selection did. In corn, acetochlor + clopyralid + mesotrione and bicyclopyrone + mesotrione + S‐metolachlor provided 10–13% better annual grass, common ragweed (Ambrosia artemisiifolia L.), and giant ragweed (A. trifida L.) control than fluthiacet‐methyl + pyroxasulfone. In soybean, dimethenamid‐P + saflufenacil resulted in similar common ragweed control as the flumioxazin + pyroxasulfone treatment (79–85%), and 6 and 14% higher annual grass control and biomass reduction, respectively, compared to metribuzin + chlorimuron‐ethyl at Arlington. At Janesville, due to the high giant ragweed density in soybean, all herbicide treatments provided low levels of giant ragweed control (48–56%). Results from these field experiments suggest that lower carrier volumes could be used for PRE herbicide applications without compromising weed control in conventional tillage systems.

Efficacy of weed control treatments on weeds and productivity of chickpea under Jatropha based agroforestry

A field experiment was conducted at Research Farm, Department of Forestry, JNKVV, Jabalpur during Rabi season 2019-20 to find out the effect of weed management on weeds and productivity of Chickpea under Jatropha based Agroforestry. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications and 12 herbicidal treatments consisted of Pendimethalin (1000 g ha-1), Imazathaper (900 g ha-1), Atrazine (1000 g ha-1), Metribuzin (300 g ha-1), Oxyflorfen (100 g ha-1), Pendimethalin (500 g ha-1) fb Imazathaper (450 g ha-1), Pendimethalin (500 g ha-1) fb Oxyflorfen (50 g ha-1), Metribuzin (150 g ha-1) fb Oxyflorfen (50 g ha-1), Atrazine (500 g ha-1) fb Metribuzin (150 g ha-1), Imazathaper (450 g ha-1) fb Atrazine (500 g ha-1), hand weeding (30 DAS) and Weedy check (control). The field was infested with 4 major weed species Medicago denticulata Willd., Vicia sativa L., Cynodon dactylon L., and Cyperus rotundus L. Minimum weed density per m2 (7.53) and weed dry weight (5.42 q ha-1), was found under hand weeding 30DAS over weedy check. Minimum dry weight of weeds was found under hand weeding (30 DAS) 5.42q ha-1 as compare to weedy check (control) 16.84q ha-1). The highest weed control efficiency was found in hand weeding (30DAS) 89.75%, Pendimethalin (1000 g ha-1) 78.50 %, Atrazine (1000 g ha-1) 67.67 %, Oxyflorfen (100 g ha-1) 66.83 %, and Metribuzin (150 g ha-1) fb Oxyflorfen (50 g ha-1) 65.41%. The loss of grain yield was significantly reduced where weeds were control by Pendimethalin (1000 g ha-1) 11.16 %, and Metribuzin (150 g ha-1) fb Oxyflorfen (50 g ha-1) 11.19 %. Amongst the different herbicidal treatments higher seed yield was found under Pendimethalin (1000 g ha-1) 12.54 q ha-1, higher stover yield was found under Pendimethalin (1000 g ha-1) 37.46 q ha-1, higher crop biomass was found under Pendimethalin (1000 g ha-1) 50.00 q ha-1 and higher harvest index was found under Pendimethalin (1000 g ha-1) 24.99 % as compared to other treatments. The perusal data showed that higher harvest index was found under hand weeding (30DAS) 25.06 % which was significantly superior over weedy check (control) 18.74 % and rest of the weed control treatments. Pre emergence herbicides and hand weeding can further enhance the weed suppressive effect of the crop under Jatropha based Agroforestry.

Effect of weed management practices on moong crop yield

The prevailing experiment entitled “effect of Weed management Practices on Moong Crop Yield” become conducted in the course of the kharif season of 2019-20 underneath, SAGE university, Rau, Indore (M.P.) to find out the impact of different plant spacing along side weed manipulate strategies on the increase and yield of mungbean. The objectives of the investigation had been First is to examine the impact of various stages of plant spacing at the boom, yield attributes, Second is yields of mungbean to discover an appropriate method of weeding for max yield of mungbean and Third is to examine the mixed impact of plant spacing and weeding technique on the increase and yield of mungbean. The experiment was laid out in a break up plot design with 3 replications. The test comprised with elements viz., (i) Row spacing and (ii) Weed control. Three plant spacings (A1= 20x10 cm2, A2= 30x10 cm2, A3= 40x10 cm2) and 5 weeding treatments no weeding (B1), one hand weeding at 20 DAS (B2), hand weedings at 20 DAS and forty DAS (B3), Pendimethalin @ 1.25 kg/ha (B4) and Imazethapyr @ a hundred g/ha (B5)., Pendimethalin @ 1.25 kg/ha a pre-emergence herbicide become implemented after final land practise. Imazethapyr @ 100 g/ha, a publish-emergence herbicide turned into implemented at 25 DAS whilst weeds were 2-three leaf degree had been used. There have been 15 treatment combos. Plant spacing turned into placed along the primary plot and weeding methods had been placed along the sub plot. Statistics on specific increase, yield contributing characters and yield were recorded from the experimental discipline and analyzed statistically.

Germination ecology and management of Portulaca oleracea L. - a weed of summer vegetable crops in Punjab

Portulaca oleracea L. is a major weed infesting many summer vegetable crops in Punjab. The present study was conducted to evaluate the effect of different environmental factors viz., temperature, light, salinity, pH, moisture stress and seed burial depth on germination and early seedling growth of this weed. The effect of different pre-emergence herbicides on emergence of P. oleracea was also studied. Untreated control seeds of this weed were dormant and exhibited 27% germination. Soaking of seeds in 1000 ppm GA for 24 hrs was most effective in overcoming seed dormancy. Optimum temperature required for germination of P. oleracea was 30°C. Germination of this weed was found to be independent of light, thus it can emerge under tree and crop canopies in both non-cropped and cropped areas. Germination decreased with increase in NaCl concentration from 0 to 250 mM and was inhibited by 50% at 163.56 mM NaCl. Germination also decreased with decrease in osmotic potential from 0 to -0.8 MPa and 50% inhibition of germination was recorded at -0.51 MPa. P. oleracea was able to germinate over a pH range of 6.5 to 8.5. Seedling emergence decreased with increase in seed burial depth and no emergence was observed when seeds were buried at soil depth greater than 2 cm. Emergence of P. oleracea seeds was found to be inhibited by all the tested herbicides viz., oxyfluorfen, pendimethalin, sulfentrazone, oxadiargyl and clomazone.