Weed Density Research Articles

Effect of 2, 4-D sodium salt on weeds, growth and yields in rabi maize (Zea mays L.)

A field investigation was conducted during winter (rabi) season of 2021 at Agricultural Research Farm of Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, to study the efficacy of doses of 2, 4-D sodium salt 80% WP on weeds, productivity and economics of rabi maize (Zea mays L.). Application of 2, 4- D sodium salt 80% WP @ 1,250 g/ha at 25 days after sowing (DAS) resulted in to lesser weed density and weed dry weight of Physalis minima Roem. & Schult, Chenopodium album (L.), Melilotus indicus (L.) and Cichorium intybus (L.) as compared to 2, 4-D sodium salt 80% WP @ 1,000 g/ha and 2, 4-D sodium salt 80% WP @ 750 g/ha at 60 DAS, with higher weed control efficiency (77.3 %) and lesser weed index (34.9 %). At 60 DAS, 2, 4-D sodium salt 80% WP (applied @1250 g/ha at 25 DAS) produced higher plant height, number of leaves, chlorophyll content, leaf area index and plant dry-matter over other treatments except weed free and two hand weeding at 20 and 40 DAS. Application of 2, 4-D sodium salt 80% WP @ 1,250 g/ha at 25 DAS recorded higher number of cobs, number of kernels, number of kernels/row and seed index as compared to 2, 4-D sodium salt 80% WP @ 1,000 g/ha, and 2, 4-D sodium salt 80% WP @ 750 g/ha. Higher kernel (3.7 t/ha) and stover yield (4.7 t/ha) of maize was recorded due to application of 2, 4-D sodium salt 80% WP @ 1,250 g/ha at 25 DAS with higher harvest index (44.5%) and monetary returns (62.5 × 103 `/ha) as compared to 2, 4-D sodium salt 80% WP @ 1,000 g/ha, and 2, 4-D sodium salt 80% WP @ 750 g/ha.

Effect of <i>Dactyladenia barteri</i> mulch and NPK fertilizer on weed density, ginger production and soil recapitalization in Umudike, Southeast Nigeria

A field study conducted on a Gleyic Luvisol in Umudike, southeastern Nigeria, in 2017 and 2018 evaluated the effect of Dactyladenia barteri mulch and NPK fertilizer 15:15:15 on weed density, ginger production and soil health. Treatment consisted of three levels of mulch (0, 2 and 4 t ha–1) and two levels of NPK fertilizer (0.00 and 400 kg ha−1) laid in a randomized complete block design with 3 replicates on 2 x 2 m plots, using 0.20 x 0.20 m spacing. Planting was done in May each year and harvested eight months after planting. Results showed that control plot had 187.80 higher significant weed density than 2 and 4 t ha–1 mulch (88.20 and 81.80), respectively. Fertilizer had no significant effect on weed density. Ginger survival at 2.00 and 4.00 t ha–1 mulch (94.40 and 96%) differed significantly from the control plot (42.20%). Number of tillers in mulched plots (t ha–1) followed the order: 4 > 2 > 0 in both years. Fertilizer rate at 400 kg ha–1 gave higher significant rhizome yield more than 0 kg ha–1 in both years. Mulch at 4 t ha–1 increased soil pH by 12% relative to 7.94% increase by NPK fertilizer. Total N, available P and exchangeable K were increased by 12.30, 64.30 and 14.30% respectively, by mulch at 4 t ha–1, while NPK fertilizer increased total N, available P and exchangeable K by 5.60, 31.40 and 9.38%, respectively. It was concluded that application of Dactyladenia barteri mulch and NPK fertilizer reduced weed density, improved ginger production and recapitalized soil in Umudike, southeastern, Nigeria.

Results of Weed Density, Yield Attributes, and Yield on Wheat Crop were Influenced by Varying Broad-spectrum Herbicide Treatments in Eastern U.P., India

In the year 2015-16, a field experimental trial was conducted during the rabi season to assess the impact of various broad spectrum herbicide treatments on weed density and yield in wheat crops. The experiment followed a randomized block design with four replications, and a total of eight treatments were tested. The wheat cultivar DBW-17 was used as the test crop. Results showed that weed density and dry matter accumulation of weeds increased up to 90 days of crop growth, but decreased at 120 days in the weedy check treatment. In contrast, no weeds were recorded in the weed-free plot throughout the crop period. In terms of the wheat crop, the weed-free plot had the highest total dry matter accumulation at all stages (30 DAS-32.62, 60 DAS-278.26, 90 DAS-934.49 and 120 DAS-1276.28 g/m2), number of spikes (303.00/m2), number of grains/spike (51.00), test weight (40.40 g), length of spike (11.12 cm) and grain yield (5.422 t/ha). On the other hand, the weedy check treatment had the lowest total dry matter accumulation at all stages (30 DAS-28.78, 60 DAS-207.24, 90 DAS-679.82 and 120 DAS-932.76 g/m2), number of spikes (208.00/m2), number of grains/spike (42.00), test weight (36.41 g), length of spike (10.31 cm) and grain yield (2.641 t/ha).

Effect of Integrated Weed Management Practices on Weed Dynamics, Growth Performance and Yield of Direct Sown Finger Millet (Eleusine coracana L.)

Background: Finger millet is an important dryland crops since they can tolerate unfavorable weather and are frequently planted in soils with low nutrient and poor water holding capacity in soils. The main cause for yield loss is weed infestation which occurs in finger millet. Several integrated weed management techniques were carried out to control them particularly and to increase yield which benefits farmers. Methods: In this context a field experiment was conducted in Karunya Institute of Technology and Sciences, Coimbatore, during Rabi season of 2022-23 in direct sown finger millet under irrigated condition. The experiment was laid out in RCBD with ten treatments and three replications viz., PE pendimethalin @ 0.75 kg ha-1 8 DAS + Hand weeding @ 35 DAS, PoE 2,4-D @ 2 kg ha-1 40 DAS + Hand weeding @ 35 DAS, PE pretilachlor @ 0.75 kg ha-1 8 DAS + Hand weeding @ 35 DAS, PoE 2,4-D @ 2 kg ha-1 40 DAS + Twin wheel hoe @ 30 DAS, PE pendimethalin @ 0.75 kg ha-1 8 DAS + Twin wheel hoe @ 30 DAS, PE pretilachlor @ 0.75 kg ha-1 8 DAS + Twin wheel hoe @ 30 DAS, Hand weeding @ 25 and 40 DAS, Twin wheel hoe @ 25 and 40 DAS, Hand weeding @ 25 DAS + Twin wheel hoe @ 40 DAS and Unweeded control. The CO 14 finger millet was used a test variety with 110 days medium duration. Result: The result showed that pre-emergence pretilachlor @ 0.75 kg ha-1 8 DAS + Twin wheel hoe weeding @ 30 DAS significantly decreased weed density, importance value index and summed dominance ratio of weeds with higher weed control. The same treatment combination recorded higher plant height (115.8 cm) and grain yield (2368 kg ha-1) at harvest.

Weed density evaluation using KCCA-CFBLS based on fusion of visual and tactile features in special paddy field environment

Accurately evaluating weed density in paddy fields is crucial for achieving high-quality control of rice weeds, as it enables precise application of herbicides or matching of mechanical weeding intensity. However, visual methods alone may not provide ideal classification of weed density in specialized paddy field environments due to complex backgrounds, environmental interference, and visual occlusion. In this study, we propose an innovative method that combines vision and tactile features to achieve accurate weed density evaluation. We first obtained tactile data containing weed density information using a self-made tactile sensor, while simultaneously capturing corresponding visual images. We then utilized the kernel canonical correlation analysis (KCCA) algorithm to maximize the correlation of discriminating features extracted from the tactile data and visual images, and obtained fusion eigenvectors that characterize the weed density. These eigenvectors were used as input for a broad learning system (BLS), in which the random feature mapping was replaced by a cascade feature node to construct a KCCA-based cascade feature broad learning system (KCCA-CFBLS). Our method achieved accurate evaluation of weed density in low, medium, and high weed conditions using a novel weed dataset from a specialized paddy field environment. We analyzed the accuracy and running time, and found that KCCA-CFBLS outperformed methods based on SVM and YOLOv5-Lite, achieving 11.56% and 7.56% higher accuracy, respectively, with less time consumption. Experimental results demonstrated significant advantages of our method in terms of accuracy and real-time performance compared to visual methods, providing a decision-making basis for the implementation of intelligent chemical and mechanical weeding in specialized paddy field environments.

Mechanical Weed Control: Sensor-Based Inter-Row Hoeing in Sugar Beet (Beta vulgaris L.) in the Transylvanian Depression

Precision agriculture is about applying solutions that serve to obtain a high yield from the optimization of resources and the development of technologies based on the collection and use of precise data. Precision agriculture, including camera-guided row detection and hydraulic steering, is often used as an alternative because crop damage can be decreased and driving speed can be increased, comparable to herbicide applications. The effects of different approaches, such as uncontrolled (UC), mechanical weed control (MWC), herbicide weed control (HWC), and mechanical + herbicide control (MWC + HWC), on weed density and yield of sugar beet were tested and evaluated in two trials (2021 and 2022) in South Transylvania Depression at the tested intervals BBCH 19 and 31. Weed control efficacy (WCE) depends on the emergence of the weeds and a good timing of weed controls in all the trials and methods, though the highest yield of sugar beet roots was recorded in the treatment MWC + HWC, with an increase up to 12–15% (56.48 t ha−1) yield from HWC (50.22 t ha−1) and a yield increase of more than 35–40% than MWC (42.34 t ha−1). Our trials show that it is possible to increase yield and have fewer chemical applications with the introduction of new precision technologies in agriculture, including sensor-guided mechanical controls.

Chemical Control Against Aggressive Broad Leaves Weed Ipomea sp. in Drill Seeded-rice (Oryza sativa L.)

Two field experiments were carried out at the Experimental Farm of Rice Department, Sakha Agricultural Research Station, Kafrelsheikh, Egypt throughout 2020 and 2021 summer seasons to identify an efficient chemical control program against Ipomea sp. as perennial Convolvulaceae weed in drill seeded-rice. The experimental design was split-plot with three replications. Three times of herbicidal application at 20, 30 and 40 days after sowing (DAS) were allocated randomly in main plots, while in sub-plots, six weed control treatments were randomly distributed included three single herbicides application (bentazone at rate of 1.714 kg ai ha-1, fluroxypyr at rate of 0.0952 kg ai ha-1 and bensulfuron-methyl at rate of 0.0714 kg ai ha-1) in addition to two herbicide mixtures were bentazone + fluroxypyr (1.344 kg ai ha-1 + 0.0952 kg ai ha-1) and bensulfuron + fluroxypyr (0.0714 kg ai ha-1 + 0.0952 kg ai ha-1) as compared to un-treated (weedy check) plots. Chemical control at early stage (20 DAS) achieved the best Ipomea control and recorded the lowest values of tillers number m-2, fresh and dry weights during 2020 and 2021, consequently recorded the highest rice dry matter, panicles number m-2, panicle weight and grain yield during both seasons. The results also showed that herbicide mixtures exceeded single application of herbicide in controlling Ipomea as broad leaf weed, bentazon + fluroxypyr ranked first in weed control efficiency percentage and recorded the lowest weed density m-2, fresh and dry weights of Ipomea during the two seasons of study as well as achieved the best values in rice dry matter, panicles per square meter, panicle weight and grain yield during 2020 and 2021 seasons, while the mixture of bensulfuron + fluroxypyr ranked second in this respect. The combination of bentazone + fluroxypyr sprayed at 20 DAS recorded the best Ipomea chemical control efficiency (95.4 %) and recorded the best rice grain yield (9.322 t ha-1) as an average for Giza 178 cv under drill seeded-rice conditions.

Exploring the Feasibility of Integrating Weed and Nitrogen Management with Seed Meals in Organic Vegetables

Corn gluten meal (CGM) and soybean meal (SBM) have demonstrated value as bioherbicides and organic fertilizers, but suggested application rates usually target either weed suppression or crop nutrition, not both. The objective of this study was to explore the feasibility of integrating weed and nitrogen management by evaluating effects of increasing seed meal rates within planting holes of plastic mulch film on weed density, soil nitrogen availability, and crop yield in tomato (Solanum lycopersicum) and broccoli (Brassica oleracea). CGM (10% N) or SBM (7% N) were applied at rates of 0.5, 1, 2, 3.5, or 5 g planting hole−1 N (depending on crop and year) after crops were transplanted, and 40 weed seeds per planting hole were seeded. Weed density decreased with increasing seed meal rate, regardless of type, and velvetleaf (Abutilon theophrasti) was more susceptible than the grass weeds tested. Velvetleaf suppression at the 5 g planting hole−1 N rate ranged from 66% to 97%, relative to the weedy control. Soil nitrogen availability increased with the application rate, but ammonium mineralized from seed meals applied at the highest rates were likely phytotoxic to weeds and crops. Seed meals never increased the crop yield and reduced the tomato yield in 2018 by 39% to 64%, relative to the weed-free control. The results suggest that integrating the management of weeds and nitrogen with seed meals in plastic mulch planting holes is not feasible because application rates required for consistent weed suppression are also toxic to crops.

Weed communities after decades of mineral fertilization and tillage treatments in a corn–soybean rotation

Abstract Soil fertility and disturbance can potentially modify weed dynamics in a corn–soybean rotation. Knowing how added mineral fertilizers and tillage influence weed populations in the long term can provide insight into weed community shifts, which may affect future weed management requirements. The first objective of this study was to evaluate the effect of 24 to 25 years of nitrogen and phosphorus fertilization treatments and tillage (moldboard vs. no-till) on weeds (density, biomass, and composition) before and after herbicide applications in 2016/corn and 2017/soybean. The second objective was to evaluate the effect of the same treatments 6 yr after no postemergence weed management in 2022/corn. Since the last evaluation performed in 2004, weed density, richness, and diversity increased, and more annual grasses were observed under both tillage regimes. No fertilization effect was observed on any weed variables, including composition, except for increased biomass when left to grow all season after crop planting. In managed plots, the density and biomass of annuals and perennials were generally higher in no-till, and discrepancies were highest for annual grass densities before herbicide application. Weed species richness and diversity based on counts were equivalent between tillage regimes, but total biomass was distributed between more species in no-till. Higher weed densities and concurrent weed biomass, observed in no-till, reduced crop yields in 2016/soybean only. The combination of low crop diversity and low use of residual herbicides during the trial potentially led to the observed species shifts and increased weed density.

Effect of Row Spacing and Weed Management Practices on Growth and Yield Components of Tomato (Solanum Lycopersicum L.) in Yola, North-Eastern Nigeria

Field trial was conducted during 2020 and 2021 dry seasons at experimental farm site of the Department of Crop Production and Horticulture, Modibbo Adama University, Yola to study the Effect of row spacing and some weed management practices on growth and yield components of Tomato (Solanum lycopersicum L) in Yola north-eastern Nigeria. The experiment was layout in a split plot arrangement of a Randomize Complete Block Design (RCBD) with (5) treatments Zero weeding (Control), Weedy check (Weeding at 2 and 4 Weeks After Transplanting), Maize straw at 1.0 kg m-1, S-metolachlor at 1.5 kg ha-1 and Pendimethalin at 1.44 kg ha-1) replicated three (3) times. Row spacing of 40x40cm, 60x60cm and 80x80cm was assigned to main plot while the different weed management treatments were assigned to sub-plot. The parameters measured on the crop include tomato plant height, number of branches per tomato plant, number of tomato fruits per plant. And weed parameters measured were number of broadleaf weeds/m2, grasses/m2, sedges/m2, total weed density/m2, weeds dry weight/m2, weed control efficiency (%) and weed index at harvest. The data collected were analyzed statistically using analysis of variance (ANOVA) and Duncan’s Multiple Range Test to separate the means at 5% level of probability. The results shows significant differences on plant height of tomato. Weedy check and 40cm row spacing recorded the tallest tomato plant heights of (18.54) at 2 WAT in 2020 while the tallest plant, was recorded at the interaction between weedy check and 60 cm row spacing of (22.58 cm) in 2021. The highest number of branches for the two experimental years of 2020 and 2021, were recorded at the interaction between 40 cm row spacing and weedy check treatment of (7.17) and (11.50), compared with Pendimethalin that recorded the lowest tomato plant heights, number of branches of (1.00) and (2.00) at 4 & 5 WAT. Similarly, the result for weed parameters also indicated that weedy check and 40cm row spacing has the lowest weed density m-2 of (1.84) at 30 days after application in 2020 and (1.77) in 2021 compared to Zero weeding plot and 80cm row spacing that recorded with the highest weed density of (7.04) & (7.16) for both 2020 and 2021 experimental years, also the percentage of weed dry matter. Weedy check also recorded highest weed control efficiency and weed index compared with remaining treatments. Therefore, the finding of this work said “weedy check treatment and 40 cm x 40cm row spacing were the best among weed management practice and row spacing” and are recommended for use as an alternative to the use of herbicide and 60 cm x 60 cm row spacing for effective weed control and maximum yield output of the tomato production in Yola, Nigerian.

Dynamic changes in weed abundance and biodiversity following different green manure establishment

Weeds have a negative impact on agricultural production by competing with cultivated crops for resources and fostering conditions conducive to disease and insect pest dissemination. Hence, optimal weed management is of paramount importance for sustainable agricultural. In this study, the ability of four distinct green manure species to suppress weeds was determined in a field experiment conducted in Chongqing, Southwest China. After cultivating the green manure species, the weed density and diversity were monitored over the following year. The findings highlight a notable trend in the suppressive ability of green manures, with increased suppression observed from November to March, an optimal level observed from March to May, and a gradual decline observed thereafter. Poaceae (Lolium perenne L.) demonstrated the highest efficacy in suppressing weeds. The meta-analysis underscore the exceptional suppressive effects of poaceous green manures on weed as well and prove sustained planting for three or more consecutive years yielded superior weed suppression outcomes. Green manure had the most prominent inhibitory effect on poaceae weeds, followed by Polygonaceae and Caryophyllaceae. The field experiment also investigated the effect of green manures on weed community composition, they increased in the proportion of perennial weeds within these communities. This study offers valuable insights that can guide policymakers, agricultural experts, and farmers in devising effective weed management strategies. By highlighting the potential benefits of green manures and unraveling their nuanced impact, this study contributes to the arsenal of sustainable agricultural practices.

An intelligent spraying system for weeds in wheat fields based on a dynamic model of droplets impacting wheat leaves.

Targeted herbicide application refers to precise application of herbicides in weed-infested areas according to the location and density of farmland weeds. At present, targeted herbicide application in wheat fields generally faces problems including the low herbicide adhesion rate, leading to omission and excessive loss of herbicides. To solve these problems, changes in the impact force of herbicide and the weed leaves in the operation process of a spraying system were studied from the interaction between weeds and herbicides applied. A dynamic model of weed leaves was established. On this basis, the research indicated that the herbicide adhesion rate is highest under spraying pressure of 0.4 MPa and flow rate of 0.011 kg/s when the spray height is 300 mm. To study the dynamic deformation of weed leaves and the distribution of liquid herbicides in the external flow field under weed-herbicide interaction, a dynamic simulation model of herbicide application was built using the finite element method. The results show that when the spray height is 300 mm, the maximum weed leaf deformation index (LDI) is 0.43 and the velocity in the external flow field is 0 m/s under spraying pressure of 0.4 MPa and flow rate of 0.011 kg/s. This finding indicates that the herbicide is not splashed elsewhere and the turbulence intensity in the weed area is 2%, implying steady flow of the herbicide, most of which can be retained on weed leaves. Field test results of application quality of the herbicide show that the maximum LDI is 0.41 and the coverage of the herbicide in the sheltered area below the leaves is 19.02% when the spraying pressure is 0.4 MPa, flow rate is 0.011 kg/s, and spray height is 300 mm. This solves the problem of a low rate of utilization of herbicides because the herbicide passes through weed plants, and achieves the precision herbicide application in wheat fields.

Influence of Weed Management Practices and Biochar on Weed Dynamics of Fenugreek (Trigonella foenumgraecum L.)

A field experiment was conducted at Instructional farm, Rajasthan College of Agriculture, MPUAT, Udaipur (Rajasthan) during rabi season 2021-22 and 2022-23 to study the influence of weed management practices and biochar on weed dynamics of fenugreek. The experiment consists of eight weed management treatments and three biochar levels thereby involving 24 treatment combinations replicated thrice in factorial randomized block design. The pooled results revealed that pre-emergence application of oxyfluorfen 120 g ha-1 recorded significantly lowest density and dry matter of narrow-leaved, broad-leaved and total weeds and highest weed control efficiency (78.28%).

Survey of Portulacaceae family flora in Taif, Saudi Arabia.

The presence of weeds in areas of agricultural activities is a hinderance to the development of these activities. It is important to take advantage of the vast open spaces suitable for agriculture and provide food security for humans, and also it is an important indicator for determining the feasibility of growing crops, benefiting from yield and determining the percentage of loss, clearing fields through agricultural practices, that protect crops from weed attack and agricultural practice method must be followed that will reduce weed presence. This study was conducted during the years 2018 to 2020 to evaluate Portulacaceae of Flora in the Taif area in the Kingdom of Saudi Arabia at different altitudes (Area 1 =1700 m, Area 2 =1500 m, Area 3 =1500 m, Area 4 =500 m ِ Area 5 = 2200 m, and Area 6 = 2200 m). The results show that there were 2,816 individuals of Portulaca oleracea weed, with the highest density found in A 1, followed by A 2, while in A 5 and A 6, no weeds were recorded. The highest density of weeds were in the Pomegranate fields, followed by Grape fields. The lowest density was found in A man field. The results of this study will help to take the necessary measures to combat weeds and its management in areas of agricultural activity, while more studies are needed to survey the ecology of weeds of Taif in The Kingdom of Saudi Arabia.

Effect of herbicide programs on control and seed production of multiple herbicide–resistant Palmer amaranth (Amaranthus palmeri) in corn resistant to 2,4-D/glufosinate/glyphosate

Abstract Multiple herbicide–resistant (MHR) Palmer amaranth is among the most problematic summer annual broadleaf weeds in Nebraska and several other states. A new MHR corn cultivar (resistant to 2,4-D/glufosinate/glyphosate, also known as Enlist corn) has been commercially available in the United States since 2018. Growers are searching for herbicide programs for control and reduce seed production of MHR Palmer amaranth among Enlist corn crops. The objectives of this study were to evaluate herbicides applied preemergence, early postemergence, or preemergence followed by (fb) late postemergence for the management of MHR Palmer amaranth in Enlist corn fields and to assess their effect on Palmer amaranth biomass, density, seed production, and corn yield. Field experiments were conducted near Carleton, NE, in 2020 and 2021, in a grower’s field of Enlist corn infested with acetolactate synthase–inhibitor/atrazine/glyphosate–resistant Palmer amaranth. Herbicides applied preemergence, such as flufenacet/isoxaflutole/thiencarbazone-methyl, acetochlor/clopyralid/flumetsulam, or acetochlor/clopyralid/mesotrione, provided 75% to 99% control of Palmer amaranth 30 d after preemergence. Preemergence fb late postemergence herbicides resulted in 94% Palmer amaranth control 90 d after late postemergence, reduced weed density to 0 to 8 plants m−2 30 d after late postemergence, and reduced biomass to 2 to 14 g m−2 15 d after late postemergence compared to preemergence-only (59% control, 0 to 15 plants m−2, and 4 to 123 g m−2) and early postemergence–only herbicides (78% control, 6 to 30 plants m−2, and 8 to 25 g m−2). Based on contrast analysis, Palmer amaranth seed production was reduced to 14,050 seeds m–2 in preemergence fb late postemergence herbicide programs compared with 325,490 seed m–2 in preemergence-only and 376,750 seed m–2 in early postemergence–only programs. Based on orthogonal contrast, higher corn yield of 12,340 and 11,730 kg ha−1 was obtained with preemergence fb late postemergence herbicide programs compared with preemergence-only (10,840 and 11,510 kg ha−1) and early postemergence–only programs (10,850 and 10,030 kg ha−1) in 2020 and 2021, respectively.

Effect of in-row spacing on weed suppression and yield of ‘Covington’ and ‘Monaco’ sweetpotato

Abstract Organic sweetpotato growers have limited effective weed management options, and most rely on in-season between-row cultivation and hand weeding, which are time consuming, are costly, and deteriorate soil quality. Studies were conducted at the Samuel G. Meigs Horticulture Research Farm, Lafayette, IN, and at the Southwest Purdue Agricultural Center, Vincennes, IN, in 2022 and 2023 to determine the effects of in-row plant spacing and cultivar selection on weed suppression and organic sweetpotato yield. The experiment was a split-split plot design, with in-row spacings of 20, 30, and 40 cm as the main plot factor, weeding frequency (critical weed-free period and weed-free) as the subplot factor, and sweetpotato cultivar (‘Covington’ and ‘Monaco’) as the sub-subplot factor. However, in 2022, we evaluated only in-row spacing and weeding frequency because of the poor establishment of ‘Monaco’. In 2023, sweetpotato canopy at 5 wk after transplanting (WAP) decreased as in-row spacing increased from 20 to 40 cm, and sweetpotato canopy cover of ‘Monaco’ (62%) was greater than that of ‘Covington’ (44%). In-row spacing did not affect weed density at 4, 5, and 6 WAP. As in-row spacing increased from 20 to 40 cm, total sweetpotato yield pooled across both locations in 2023 decreased from 30,223 to 21,209 kg ha−1 for ‘Covington’ and from 24,370 to 20,848 kg ha−1 for ‘Monaco’; however, jumbo yield increased for both cultivars. Findings from this study suggest that an in-row spacing of 20 cm may provide greater yield than the standard spacing of 30 cm for both ‘Monaco’ and ‘Covington’.

Efficacy of dicamba and dicamba/tembotrione with and without ammonium sulfate for broadleaf weed control

Abstract Mixing ammonium sulfate (AMS) can increase dicamba volatility. Therefore, AMS cannot be used with dicamba products in dicamba-resistant soybean. However, most dicamba products applied in corn are labeled to mix with AMS. The objectives of this study were to evaluate broadleaf weed control with dicamba (DiFlexx®) and dicamba/tembotrione (DiFlexx® DUO) applied alone or with AMS or AMS substitute and their effect on broadleaf weed density and biomass. Field experiments were conducted in Illinois, Missouri, and Nebraska in 2018 and 2019. In Illinois and Nebraska, mixing AMS + crop oil concentrate (COC) with dicamba applied at 1,120 g ae ha−1 increased the control of Palmer amaranth and waterhemp (Amaranthus species) from 78% to 92% and velvetleaf from 73% to 96% compared with dicamba applied alone 14 d after application (DAA); however, Missouri data showed no difference. Mixing AMS + COC with dicamba/tembotrione at 597 and 746 g ai ha−1 did not improve broadleaf weed control 14 DAA at any site compared with dicamba/tembotrione applied alone. Control of Amaranthus species was increased from 82% with dicamba applied at 840 g ae ha−1 to 96% when mixed with AMS + COC 28 DAA in Illinois; however, control was similar to dicamba applied at 1,120 g ae ha−1. Broadleaf weed control did not differ among dicamba or dicamba/tembotrione 28 and 56 DAA in Missouri and Nebraska. Broadleaf weed density decreased from 64 plants m−2 to 24 plants m−2 with dicamba at 1,120 g ae ha−1 with AMS + COC 14 DAA in Nebraska; however, no differences were observed in broadleaf weed density or biomass 56 DAA in any state. The results suggest that dicamba or dicamba/tembotrione can be applied without AMS or AMS substitute, especially at higher rates, without losing broadleaf weed control efficacy.

The Manual, Chemical, Cultural, and Integrated Weed Management in Soybean Production

A field experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka, from December 2021 to April 2022 to study the effect of weed management practices in soybean (Glycine max L.). The experiment was laid out in a Randomized three-Complete Block Design (RCBD) with twelve weed management treatments- no weeding (Control), two hand weeding (at 15 and 30 DAS), pre-emergence herbicide (Herbilin 33% EC @ 400 ml ha-1), post-emergence herbicide Irish EC @ 1200 ml ha-1, pre + post-emergence herbicide, pre-emergence + 1 hand weeding {40 days after sowing (DAS)}, post-emergence herbicide + 1 hand weeding (40 DAS), pre + post-emergence herbicide + 1 hand weeding(40 DAS), straw mulching, intercrop with Amaranthus dubius, and Zea mays, and weed-free. The experimental result showed among seven different weed species found, Cyperus rotundus was the most prevalent weed, with the highest weed density (123 and 128.67 m-2) and relative weed emergence (43.16 and 38.79 %) in the control plot at 30 and 60 DAS. The treatment pre + post-emergence herbicide + 1 hand weeding (40 DAS) showed the longest pod length (4.16 cm) and number of seeds pod-1 (3.89). The weed-free treatment resulted in the highest 1000-seed weight (111.00 g), seed yield (1.86 t ha-1), stover yield (2.16 t ha-1), biological yield (4.03t ha-1), and harvest index (46.35 %). However, the highest benefit-cost ratio (2.85) was obtained under post-emergence herbicide (Irish EC) treatment. Therefore, applying Irish EC was the best broad-spectrum effective herbicide to manage the various weed floras in soybeans for profit. SAARC J. Agric., 21(2): 195-206 (2023)

Evaluation of weed management approaches on weed dynamics, yield and economics of puddled rice under different plant techniques

A field experiment was conducted in January to May, 2022 (Navarai) to find out the effective weed management practices in puddled rice. The experiment was carried out in a split-plot design, which included two planting techniques viz., drum seeded rice and system of rice intensification (SRI) in main plot, as well as eight weed management practices viz., hand weeding, cono weeding, pretilachlor, bispyribac sodium and fenoxaprop - p - ethyl as pre and post emergence application in sub plot. The results of the experiment demonstrated that among the planting techniques and weed management practices tested, the system of rice intensification and sequential application of pretilachlor @ 0.5 kg a.i ha-1 fb bispyribac sodium @ 20 g a.i ha-1 has revealed lowest weed density (39.67, 71.25 and 17.02, 33.97 no m-2) and highest weed control efficiency (55.89, 65.78 and 84.99, 82.33 %) grain yield (4.55 and 5.47 t ha-1), gross and net income (Rs. 12116 and Rs. 64336 ha-1). However, drum seeded rice resulted higher return-1 rupee invested due to lower cost of cultivation. Hence, the SRI planting method with sequential application of pretilachlor @ 0.5 kg a.i ha-1 followed by bispyribac sodium @ 20 g a.i ha-1 has proven to be effective in controlling weeds and achieving higher grain yield and net income.

Integrated weed management in soybean [Glycine max (L.) Merrill

A field experiment was conducted to study the effect of integrated weed management on growth and yield of soybean at Agricultural Research Station, Hukkeri, Belagavi, during kharif, 2022. The experiment was laid out in RCBD with three replications. The experiment consisted of 10 treatments comprising of 8 pre-emergence herbicides (Sulfentrazone + Clomazone, Sulfentrazone + Metolachlor, Metolachlor, Metribuzin, Pendimethalin + Imazethapyr, Flumioxazin, Pendimethalin, Diclosulam) and they were tested along with one intercultivation operation. Among the herbicidal treatments, application of Sulfentrazone 28% + Clomazone 30% WP (350 + 375 g a.i ha-1) RM @ 1250 g ha-1 as PE followed by one inter cultivation at 35 DAS recorded significantly lower weed density (2.27 m-2), dry weight of weeds (2.42 g m- 2) and higher weed control efficiency (88%) for total weeds at 15 days after herbicide application (DAHA) with lower weed index (5.30%). It also recorded higher plant height (53.89 cm), number of branches (7.75 plant-1), total dry matter production (16.80 g plant-1), seed yield (2413 kg ha-1), gross returns (`115824 ha-1), net returns (`70887 ha-1) and benefit cost ratio (2.58). The lower seed yield, net returns and benefit cost ratio was recorded with Metribuzin 70% WP (0.35 kg a.i. ha-1) @ 500 g ha-1 as PE followed by one inter cultivation at 35 DAS due to phytotoxicity of Metribuzin on soybean. Seed quality was not influenced by herbicidal treatments.