Johnsongrass Research Articles

Survey of Weeds in Sesame in the Major Growing Area of Ethiopia

The survey of weeds was conducted in high sesame growing areas of Ethiopia namely, Metekel, Gonder, and Humera Zones during 2018/19 cropping season to assess the abundance and distribution. It was done at the crop seedling stage using a systematic sampling technique and in quadrant counts (0.5 m²). Weed species composition and their quantitative measures were calculated using descriptive formulas. The result showed 23 weed families that comprised 135 weed species. The most dominant families were Commelinaceae (5.92%), Asteraceae (11%), Cyperaceae (7.40%), Fabaceae (12.59%), and Poaceae (18.51%) respectively. Most of the species (70%) were erect annual herbs and grasses, the rest were perennials that had vegetative propagating structures, annual prostrate herbs, annual, perennial climbers, or perennial shrubs. In the morphological classification, 88 species of broadleaf weeds (65.18%) were found, followed by 33 grasses (24.44%) and 14 (10.37%) types of sedge weeds. Dicotyledonous species were found to be more dominant than monocotyledonous ones in the survey area. The highest weed densities were recorded near the crop harvest stage. Weed species composition varied between crop stages within the same location and across locations at both crop stages. Also, weed composition varied in both crop stages at different locations, indicating a devising different weed management options, which would be considered for different locations in weed flora composition. From this investigation, it can be deduced that Sorghum halepense, Convolvulus arvensis, Amaranthus spp, and Cyperus rotundus turned into a drawback in the sesame production areas.

Rate of crop-weed hybridization in Sorghum bicolor × Sorghum halepense is influenced by genetic background, pollen load, and the environment.

The potential for gene flow between cultivated species and their weedy relatives poses agronomic and environmental concerns, particularly when there are opportunities for the transfer of adaptive or agronomic traits such as herbicide resistance into the weedy forms. Grain sorghum (Sorghum bicolor) is an important crop capable of interspecific hybridization with its weedy relative johnsongrass (Sorghum halepense). Previous findings have shown that triploid progenies resulting from S.bicolor×S.halepense crosses typically collapse with only a few developing into mature seeds, whereas tetraploids often fully develop. The objective of this experiment was to determine the impact of S.bicolor genotype and pollen competition on the frequency of hybridization between S.bicolor and S.halepense. A total of 12 different cytoplasmic male sterile S.bicolor genotypes were compared with their respective male fertile lines across 2 years, to assess the frequency of hybridization and seed set when S.halepense served as the pollinator parent. Results indicate significant differences in the frequency of interspecific hybridization among the S.bicolor genotypes, and pollen fertility in S.bicolor reduced the rate of this interspecific hybridization by up to two orders of magnitude. Further, hybridization rates greatly varied across the two study environments. Results are helpful for developing appropriate gene flow mitigation strategies and indicate that gene flow could be reduced by the selection of appropriate seed parents for sorghum hybrids.

Plastic/fiber composite using recycled polypropylene and fibers from Sorghum halepense L.

Leaf and stem fibers of Sorghum halepense L. (SH) were investigated as fillers for recycled polypropylene (RPP) at 10, 20, and 30 wt%. The effects of SH in RPP on the thermal and mechanical properties of composites were investigated by tensile and bending tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). It was found that mechanical properties of the RPP composites decreased but their elasticity modulus increased. The addition of SH fibers to the polymer matrix changed the thermal properties of RPP. A slight decrease in DSC crystallinity was observed with the addition of 10% SH leaf and stem fiber to the polymer matrix and then the percentages of crystallinity increased with the addition of 20% and 30% SH leaf and stem fiber. The SEM images showed that the SH fibers mixed well with the polymer matrix without agglomeration, and the fracture sections of the composites were less rough than that of the RPP by itself.

(.Effect of Quizalofop-p-Tefuryl herbicide in combination with Johnson grass extract on weed control in flax crop (Linum usitatissimum L

A field experiment was carried out to determine the best effect of Johnson grass extract, alone or in combination with Quizalofop-p-Tefuryl herbicide, to achieve the benefit of their integration into weed control programs to reduce reliance on herbicides in controlling weeds, increasing yield and reducing environmental pollution by these herbicides. The randomized complete block design (RCBD) with the split plot arrangement by three replicates was applied, the distance between the rows (20, 25 and 30 cm) represents the main plots. The control treatments : weed-free (T1), application Quizalofop-p-Tefuryl at rate 2 ml/l (T2), Johnson grass extract at rate 18 l/ha (T3), half herbicide amount + half extract amount (T4) and weedy treatment (T5) , represent the sub-plots . The results showed that of distance 20 cm achieved lowest density of companion weeds (52.20 weeds/m2) and highest percentage of weed control (50.42) after 60 days of application, and highest seed yield, oil yield reached 1.781 and 0.675 t/ha, respectively. The distance 30 cm achieved highest number of capsules (14.790 capsules/plant) seeds (8.337 seeds/capsule) and highest weight of 1000 seeds reaching 7.379 g. Application of Quizalofop-p-Tefuryl (T2) achieved lowest weed density (54.78 weeds/m2), highest weed control percentage (52.22) after 60 days of application. Besides, highest number of capsules (14.956 capsules/plant), seeds were (8.580 seeds/capsule), highest weight of 1000 seeds was 7.611 g, and highest seed yield , oil yield reached 1.779 and 0.7113 t/ha, respectively. Distance 20 cm with treatment (T2) achieved lowest number of weeds reaching (44.67 weeds/m2), highest percentage of weed control (57.59) after 60 days of application, highest seed yield, oil yield reached 2.067 and 0.7267 t/ha, respectively. Distance 30 cm and treatment (T2) achieved highest number of capsules (16.05 capsules/plant), seeds (8.580 seeds/capsule) and highest weight of 1000 seeds reaching 7.873 g.

Evaluation of Herbicides for the Control of Yellow Nutsedge (Cyperus esculentus L.) and Johnsongrass (Sorghum halepense L.) Under Non-Crop Conditions

Yellow nutsedge (Cyperus esculentus L.) and Johnsongrass (Sorghum halepense (L.) Pers.) are two of the most difficult weeds to control mostly due to their asexual reproduction. Yellow nutsedge reproduces through underground tubers and Johnsongrass through rhizomes. In addition, Johnsongrass is a problematic weed because of its competitive nature due to its C4 carbon fixation pathway metabolism. It typically grows to 1.8 to 2.5 m tall and can severely reduce yields in corn, cotton, soybeans, and other crops. Two separate field studies were conducted in 2020 at the Delta Research and Extension Center in Stoneville, Mississippi to evaluate the effectiveness of various herbicides on yellow nutsedge and Johnsongrass control in a non-crop scenario. The experiments were conducted as randomized complete block designs with 7 and 11 herbicide treatments for yellow nutsedge and Johnsongrass, respectively. All treatments were replicated three times. Research plots were 4-m wide and 6-m long with 3-m alleys between replications. The 7 yellow nutsedge herbicide treatments consisted of trifloxysulfuron, bentazon, halosulfuron, halosulfuron + thifensulfuron, glyphosate, glufosinate, and paraquat. The 11 Johnsongrass herbicide treatments included clethodim, quizalofop, fluazifop, cyhalofop, fenoxaprop, pinoxaden, glufosinate, glyphosate, clethodim + glyphosate, glufosinate + clethodim, and glufosinate + clethodim + glyphosate. Glyphosate and halosulfuron + thifensulfuron provided only 77 and 72% control of yellow nutsedge by five-weeks after application (WAA). On the other hand, glyphosate, clethodim + glyphosate, glufosinate + clethodim, and glufosinate + clethodim + glyphosate provided 99 to 100% Johnsongrass control 4 WAA. Johnsongrass regrowth evaluation was assessed 3-weeks after the experimental area was mowed. Johnsongrass regrew in every herbicide treatment except for glyphosate which was the only treatment that provided 100% Johnsongrass control with no-regrowth.

Effect of glyphosate in Johnsongrass submitted to different soil water potentials

This work aimed to study the efficiency of herbicide glyphosate to control Johnsongrass plants (Sorghum halepense) in different phenological stages of development and when submitted to different types of soil water potentials. The study was conducted in a completely randomized design, with four repetitions. The treatments were arranged in a triple factor scheme 3 × 3 × 2, being: three soil water conditions [no water deficit (−0.03 MPa), intermediate water deficit (−0.07 MPa), and high water deficit (−1.5 MPa)], associated with three doses of glyphosate (0.0, 270.0, and 540.0 g a.e. ha−1) applied in two phenological stages (4–6 leaves and 1–3 tillers). Visual control evaluations were conducted at 7, 14, 21, and 35 days after the herbicide application. Biometric and morphophysiological parameters were also analyzed. With the increase of water restriction, there was a decrease in Johnsongrass morphophysiological components, such as specific leaf area, stomatal conductance, and the difference between environment and leaf temperature, as well as the accumulation of aerial part and roots dry matter, independently of the phenological stage evaluated. The development stage of Johnsongrass influenced the control provided by glyphosate, independently of the dose used. The different water deficits studied reduced the control of glyphosate in the two Johnsongrass development stages evaluated. Severe water deficits reduced the control of glyphosate in Johnsongrass using the recommended dose. In conditions of moderate water deficit, the control was not affected. Thus, the control with lower doses can be the most affected by water deficit.

DATA ON THE PRESENCE OF INVASIVE AND POTENTIALLY INVASIVE ALOGEN PLANTS IN OLT COUNTY (ROMANIA)

The research carried out in Olt County regarding invasive and potentially invasive alogen plant species is a necessary step in order to complete the information on their distribution at the national level. The data obtained will be able to be used for a careful monitoring of these plants and the adoption of the necessary management measures regarding the eradication or prevention of their introduction and spread.
 In this sense, an inventory of invasive and potentially invasive plant species identified on the territory of Olt county is presented, with information on the geographical origin, life form, biological form, an assessment of the degree of invasiveness, chorological data, habitat, as well as aspects related to the impact they exert on native vegetation, human health or the economy.
 The preliminary analysis of the list of invasive and potentially invasive alogen plants identified in Olt County highlights, in particular, the presence of some species of concern for the European Union (such as Ailanthus altissima, Asclepias syriaca and Elodea nuttallii). Besides these, the most widespread invasive species found in Olt county are Ambrosia artemisiifolia, Robinia pseudoacacia, Morus alba, Amorpha fruticosa, Acer negundo, Amaranthus retroflexus, Erigeron annuus, E. canadensis, Lycium barbarum, Sorghum halepense, Xanthium orientale subsp.italicum. It is well known that the impact of invasive species on the environment, the economy and in some situations even on human health is major and that is why these organisms must be subject to an extensive and continuous monitoring process. Also, in order to control the introduction and spread of invasive and potentially invasive species, a series of appropriate management measures are required.

Effects of some control methods on Johnson grass and yield components in tomato fields

Johnson grass is one of the most dangerous and difficult to control weeds. The aim of this study was to determine the effect of different control methods on Johnson grass in tomato fields and to investigate the effect of these methods on the phenological stages and yield indicators of tomatoes. The study was carried out during the 2019 and 2020 seasons. The experiment treatments were as follows: hand hoe, mulch, preemergence herbicide pendimethalin (5 L/ha), postemergence herbicide fluazifop-P-butyl (1 L/ha), and control parcels. The number of flowers, the number of branches, and the length of the plant were determined in tomato. The yield and characteristics of the fruit were calculated and the fruits were analyzed. For Johnson grass, the time for germination, flowering, and seed maturity were determined. Plant height, fresh and dry biomass weight of weed, and rhizomes were also calculated. The results of this experiment showed that the best yield was 64.943 kg/ha in the hand hoe and the fluazifop-P-butyl treatment. The lowest density and fresh biomass of Johnson grass were detected in the fluazifop-P-butyl (217.3 stem/mm$^{2}$, 1009.4 g/m$^{2}$) and the mulch (251.7 stem/mm$^{2}$, 1355.2 g/m$^{2}$) treatments, respectively. The highest density and fresh biomass were detected in control parcels (448.8 stem/m$^{2}$, 3239.2 g/ m2), and in the pendimethalin treatment (334.2 stem/m$^{2}$, 1956.4 g/m$^{2}$), respectively. The percentage of lost yield in the control parcels was 90.1%. Hand hoe was found to be the most effective control method against Johnson grass followed by fluazifop-P-butyl, mulch, and pendimethalin.

Evaluation of the allelopathic effect of some cruciferous plants on germination and growth of Johnsongrass

Johnsongrass [Sorghum halepense (L.) Pers.] is a dangerous weed causes great losses in agricultural crops. It is difficult to control due to its reproduction by rhizomes, and its resistance to herbicides. This study aims to evaluate the allelopathic performance of five species of cruciferous plants on germination and some growth indicators of Johnsongrass seeds and rhizomes. Cruciferous species are white cabbage, red cabbage, broccoli, turnip, and garden rocket. The aqueous extracts of all these plants were prepared in 2%, 5%, 10%, and 20% concentrations. Germination inhibition rate, shoot, and radicle length of the seedlings of Johnsongrass were calculated over control environment. The powders of whole cruciferous plants were also analyzed using GC-MS. The results showed that garden rocket had the highest effect on the germination inhibition of both seeds and rhizomes. Garden rocket extracts at 10% and 20% concentrations reduced seeds germination by 100%. On the other hand, rhizomes germination inhibition for 10% and 20% concentrations were found 85.3% and 92.7% respectively. The effects of aqueous extracts of cruciferous plants on shoots and radicals were similar to their effects on the germination of Johnsongrass. The allelopathic effect also increased with increasing concentration of the aqueous extract. The most effective cruciferous plant on the biomarkers of Johnsongrass was garden rocket, while red cabbage was the least. The cruciferous plants, especially garden rocket, have a strong allelopathic effect that can be used as an alternative to herbicides in the control of Johnsongrass.

Efikasnost herbicida u suzbijanju korova u lucerki

Alfalfa is one of the most important perennial fodder crops, and it is also the most economical. Alfalfa provides first class fodder that is suitable for feeding all livestock, especially ruminants. Grass and broadleaf weeds are a serious threat to the quality and viability of alfalfa stands. Weeds can reduce the nutritional value of the crop and cause significant reductions in yield, as they compete aggressively for water, nutrients, sunlight, and space. In this study, herbicides (Butoxone DB, Agil, Basagran, Corum, Fusilade forte, Pulsar and Focus ultra) were used for controlling weeds in alfalfa. The presence of annual and perennial weeds, typical of alfalfa plantations: Capsella bursa-pastoris, Stellaria media, Lamium amplexicaule, Viola arvensis, Amaranthus retroflexus, Setaria spp., Sorghum halepense, Cirsium arvense, Plantago lanceolate, Rumex crispus and others, was observed on the tested surfaces. Our research has shown that the most effective herbicides are Basagran, Butoxone DB and Corum, which are intended to suppress broadleaf weeds. Meanwhile, herbicides Fusilade forte and Pulsar proved to be very effective in controlling grass weeds. A very good reaction was also observed with the combinations of herbicides Pulsar + Fusilade forte and Pulsar + Basagran, as these combinations expand the spectrum of activity to the grass and broadleaf weeds. The aim of this paper was to determine which herbicide is most effective in controlling weeds in alfalfa.

Participatory evaluation of ethno-veterinary livestock health practices byfarmers from surrounding villages in Ranthambore Tiger Reserve, India

The present study was conducted to document the ethno-veterinary practices, 360 livestock farmers from the 30villages surrounding the tiger reserve were interviewed using anopen-ended interview schedule to enlist all the practices against the ailments of livestock from the purposefully chosen zone namely Critical Tiger Habitat and buffer zone of the tiger reserve. For participatory assessment of the identified ethno-veterinary practices, Quantification of Indigenous Knowledge and to identify the best practices among overall practices one way variance followed by DMRT method was applied.Use of Drimiaindica (Roxb.) Jessop was found most effective practice against mastitis and use of seeds of Sorghum halepense L. against thediarrhoea, stem bark of Salodora persica L. for fever, and fruits of Areca catechu for treatment of prolapse in the livestock were found most effective practices. The pharmacodynamics of the see thno-veterinary techniques could therefore be studied before further replication and implementation.

Sorghum halepense (Zacate Johnson) as a potential natural corrosion inhibitor

Corrosion inhibitors can trigger health and/or environmental problems due to their toxicity. For this reason, it has been suggested to use plant extracts as natural corrosion inhibitors, because they represent a rich source of chemical compounds, they are non-toxic, biodegradable and abundant in nature. Sorghum halepense is a herbaceous weed, commonly known as johnson grass, belongs to the family gramíneae or poaceae, the choice of this plant is due to its zero cost and easy availability. In this systematic review, were used keywords such as Sorghum halepense johnson grass, phytochemistry, phytotherapy, phytoremediation, antidiabetic, antioxidant, cytotoxicity, antifungal, antimicrobial, anticancer, biological activity, medical activity, allelochemicals, among others. To do this, were used databases such as Scielo, Dialnet, Redalyc, Google Scholar, DOAJ, Wiley online library, BioOne, EBSCOHost, Knovel, ScienceDirect, SpringerLink y VirtualPro. Previous studies on this weed have reported its therapeutic potential against cancer, diabetes, prostatitis, hepatoprotective activity, antioxidant, antimicrobial, antifungal, as well as abortifacient and placental delivery in veterinary medicine. In view of the numerous organic molecules present in this plant, this study proposes Sorghum halepense as a potential natural corrosion inhibitor.

STUDY CONCERNING ALIEN FLORA FROM DÂMBOVIȚA COUNTY (ROMANIA)

A comprehensive analysis of alien flora from Dâmbovița county (Romania) was performed both on data from literature and personal observations in the field. The assessment of alien flora was focused on taxonomy, species origin, way of introduction, invasiveness status, introduction period, lifespan, bioforms, characteristic habitats and population size. There were identified 187 alien species of which 70 taxa are invasive and potentially invasive. A number of 138 species have been introduced intentionally in the area of Dâmbovița county, most of them being neophytes. There were identified some hotspots where 11 alien taxa have a high density, as follows: Ambrosia artemisiifolia, Sorghum halepense, Amaranthus retroflexus, Erigeron canadensis, Xanthium orientale subsp. italicum, Reynoutria x bohemica, Solidago canadensis, Reynoutria japonica, Erigeron annuus subsp. annuus, Robinia pseudoacacia, Eriochloa villosa. The largest populations of alien species were recorded in natural and anthropogenic habitats such as: railway embankments, roadsides, vacant lands, abandoned arable lands, wastelands, croplands, riparian habitats and degraded grasslands. The information regarding the habitats, size of populations and spreading of alien species are useful in order to take specific measures for their control.

Comments on the article “Set of additions and changes to Check-list of the flora for the Republic of Buryatia between 2001 to 2020” about the flora of the Baikalsky Reserve

This article analyzes the materials of the “Set of additions and changes to the check-list of the flora of the Republic of Buryatia from 2001 to 2020”. Corrections and comments are given on 50 species of higher vascular plants, both erroneously cited as novelties, and, on the contrary, absent from the original publication, regarding the territory of the Baikalsky State Nature Reserve and its buffer zone. Two taxa amongst omitted in the source material are included in the Red Data Book of the Russian Federation (Aconitum paskoi subsp. arcto-alpinum and Asplenium sajanense), and 10 species are alien for the flora of Buryatia (Achillea ptarmica, Alchemilla baltica, Atriplex sagittata, Carthamus tinctorius, Centaurea phrygia, Convolvulus inflata, Epilobium tetragonum, Persicaria maculosa, Setaria pumila, Sorghum halepense). Several plant species actually were firstly recorded for Buryatia earlier than the period from 2001 to 2020 or have been already known for this territory much earlier; Rhynchospora alba is one of such species, and it is included in the all the editions of the Red Data Books of the Republic of Buryatia. In some cases of references to early indications and herbarium collections, modern ideas about the taxonomy of groups and ranges of species are considered for clarification.

Aphelinus nigritus Howard (Hymenoptera: Aphelinidae) Preference for Sorghum Aphid, Melanaphis sorghi (Theobald, 1904) (Hemiptera: Aphididae), Honeydew Is Stronger in Johnson Grass, Sorghum halepense, Than in Grain Sorghum, Sorghum bicolor.

How aphid parasitoids of recent invasive species interact with their hosts can affect the feasibility of biological control. In this study, we focus on a recent invasive pest of US grain sorghum, Sorghum bicolor, the sorghum aphid (SA), Melanaphis sorghi. Understanding this pest's ecology in the grain sorghum agroecosystem is critical to develop effective control strategies. As parasitoids often use aphid honeydew as a sugar resource, and honeydew is known to mediate parasitoid-aphid interactions, we investigated the ability of SA honeydew to retain the parasitoid Aphelinus nigritus. Since SAs in the US have multiple plant hosts, and host-plant diet can modulate parasitoid retention (a major component in host foraging), we measured SA honeydew sugar, organic acid, and amino acid profiles, then assessed via retention time A. nigritus preference for honeydew produced on grain sorghum or Johnson grass, Sorghum halepense. Compared to a water control, A. nigritus spent more time on SA honeydew produced on either host plant. Despite similar honeydew profiles from both plant species, A. nigritus preferred honeydew produced on Johnson grass. Our results suggest the potential for SA honeydew to facilitate augmentation strategies aimed at maintaining A. nigritus on Johnson grass to suppress SAs before grain sorghum is planted.

Insect Feeding on Sorghum bicolor Pollen and Hymenoptera Attraction to Aphid-Produced Honeydew.

Pollinators are declining globally, potentially reducing both human food supply and plant diversity. To support pollinator populations, planting of nectar-rich plants with different flowering seasons is encouraged while promoting wind-pollinated plants, including grasses, is rarely recommended. However, many bees and other pollinators collect pollen from grasses which is used as a protein source. In addition to pollen, Hymenoptera may also collect honeydew from plants infested with aphids. In this study, insects consuming or collecting pollen from sweet sorghum, Sorghum bicolor, were recorded while pan traps and yellow sticky card surveys were placed in grain sorghum fields and in areas with Johnsongrass, Sorghum halepense to assess the Hymenoptera response to honeydew excreted by the sorghum aphid (SA), Melanaphis sorghi. Five genera of insects, including bees, hoverflies, and earwigs, were observed feeding on pollen in sweet sorghum, with differences observed by date, but not plant height or panicle length. Nearly 2000 Hymenoptera belonging to 29 families were collected from grain sorghum with 84% associated with aphid infestations. About 4 times as many Hymenoptera were collected in SA infested sorghum with significantly more ants, halictid bees, scelionid, sphecid, encyrtid, mymarid, diapriid and braconid wasps were found in infested sorghum plots. In Johnsongrass plots, 20 times more Hymenoptera were collected from infested plots. Together, the data suggest that sorghum is serving as a pollen food source for hoverflies, earwigs, and bees and sorghum susceptible to SA could provide energy from honeydew. Future research should examine whether planting strips of susceptible sorghum at crop field edges would benefit Hymenoptera and pollinators.

Quantifying the impacts of symbiotic interactions between two invasive species: the tawny crazy ant (Nylanderia fulva) tending the sorghum aphid (Melanaphis sorghi).

The establishment of new symbiotic interactions between introduced species may facilitate invasion success. For instance, tawny crazy ant (Nylanderia fulva Mayr) is known to be an opportunistic tender of honeydew producing insects and this ants' symbiotic interactions have exacerbated agricultural damage in some invaded regions of the world. The invasive sorghum aphid (Melanaphis sorghi Theobald) was first reported as a pest in the continental United States-in Texas and Louisiana-as recent as 2013, and tawny crazy ant (TCA) was reported in Texas in the early 2000s. Although these introductions are relatively recent, TCA workers tend sorghum aphids in field and greenhouse settings. This study quantified the tending duration of TCA workers to sorghum aphids and the impact of TCA tending on aphid biomass. For this study aphids were collected from three different host plant species (i.e., sugarcane, Johnson grass, and sorghum) and clone colonies were established. Sorghum is the main economic crop in which these aphids occur, hence we focused our study on the potential impacts of interactions on sorghum. Quantification of invasive ant-aphid interactions, on either stems or leaves of sorghum plants, were conducted in greenhouse conditions. Our results show that although these two invasive insect species do not have a long coevolutionary history, TCA developed a tending interaction with sorghum aphid, and aphids were observed excreting honeydew after being antennated by TCA workers. Interestingly, this relatively recent symbiotic interaction significantly increased overall aphid biomass for aphids that were positioned on stems and collected from Johnson grass. It is recommended to continue monitoring the interaction between TCA and sorghum aphid in field conditions due to its potential to increase aphid populations and sorghum plant damage.

Allelopathic effect of five invasive plants on seed germination and growth of wild mustard

Presently, chemical control is the most used method for plant protection. However, it is not an approach that is environmentally sustainable. Alternative IPM methods include biological control such as Allelopathy can be a good alternative in plant protection.Allelopathy is defined as a direct or indirect interaction, whereby allelochemicals released by one organism influence the physiological processes of other neighboring organisms.Laboratory experiments were conducted to investigate the allelopathic effect of five weeds, Eriochloa villosa (ERIVI), Panicum miliaceum (PANMI), Cannabis sativa (CANSA), Sorghum halepense (SORHA), Asclepias syriaca (ASCSY) on germination and growth of wild mustard (Sinapis arvensis L.). These weeds are dangerous during field cultivation and their weed control is difficult.The extracts from the leaves and stem were used to examine the potential of inhibition of germination, root length, shoot length and full plant growth.The phenomenon of allelopathy was detected in the examined plants. In the case of plants, the allelopathic effect also increased with increasing concentration. The results show that extracts of Johnson grass had the most significant inhibition effect of growth and seed germination.

Weed Community in Soybean Responses to Agricultural Management Systems

Weed infestation is a major cause of the poor yield of soybeans (Glycine max (L.) Merr.); therefore, proper weed management represents one of the most important and expensive steps in soybean production. Field experiments were established in northeastern parts of Croatia, in the Vukovar-Syrmia county from 2014 to 2016, arranged in a split-plot design with four replications. Two different studies were conducted: the first study was to determine the weed interference, weed biomass accumulation, yield, and yield components of soybeans growing in three different rows spacing (25, 50, and 70 cm), and the second study aimed to simulate a risk analysis by building models of probabilities for generating profit as a result of weed control. The weed community in soybean during the study period comprised 34 dicot and grass species of a varied perennation. Compositional differences in the weed community tended to be affected most by the year (humid–arid environment), followed by row spacing. There were no differences in the weed biomass accumulation with a reduction in row spacing from 70 to 50 and 25 cm. The dominant weed species Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album, Datura stramonium, Setaria viridis, and Sorghum halepense formed the main biomass and were spread over all row spacings. There was a significant influence of row spacing, the duration of weed interference, and year on soybean yield and yield components. Weed infestation until the second trifoliate (V2) stage had no detrimental effect on soybean yield, regardless of the row spacing. The number of pods per plant significantly decreased at the same V2 stage in 25 and 50-cm rows, but in 70-cm soybean rows, this process started later, at four unfolded trifoliate leaves (V4 stage). A 1000 kernel weight was less sensitive to weed infestation and was significantly decreased at full flowering (R2 stage) in 25 and 70 cm rows, while it already decreased at the V4 stage in 50 cm rows. The probability distribution of achieving a profit showed the best results for soybeans growing in 70 cm rows, with preemergence herbicide application and two inter-row cultivation.

Identification of an acetyl‐CoA carboxylase‐resistant johnsongrass (Sorghum halepense L.) population from a cotton field in northern Greece

AbstractA putative resistant johnsongrass (Sorghum halepense L.) population from a cotton field in northern Greece was studied to determine the levels of resistance to acetyl‐CoA carboxylase (ACCase)‐inhibiting herbicides and elucidate related mechanisms of resistance. The johnsongrass population showed cross‐resistance to the ACCase‐inhibiting herbicides fluazifop‐p‐butyl, quizalofop‐p‐ethyl, and propaquizafop, with poor levels of control even with four times of the recommended rates of these herbicides. However, the johnsongrass population was highly sensitive (100% control) to the ACCase inhibitors cycloxydim and clethodim and to the acetolactate synthase inhibitor nicosulfuron. Amplification and sequencing of the ACCase gene fragment from johnsongrass plants revealed an Ile to Asn substitution at codon 2041 of the ACCase enzyme. This is the first record of a molecularly confirmed ACCase‐resistant johnsongrass population from cotton fields in Europe. These findings highlight a threat against the sustainable use of ACCase‐inhibiting herbicides in controlling johnsongrass and other grasses in cotton fields.