Echinochloa Crus-galli Research Articles

Synthesis, Herbicidal Activity, and Molecular Mode of Action Evaluation of Novel Aryloxyphenoxypropionate/Amide Derivatives Containing a Quinazolinone Moiety.

To develop aryloxyphenoxypropionate herbicides with a novel structure and improved activity, a total of 39 aryloxyphenoxypropionate/amide derivatives containing quinazolinone moiety were synthesized and further bioevaluated. The bioassay results in the greenhouse showed that most of the target compounds had good herbicidal activity under postemergence conditions, of which, QPP-I-6 displayed excellent herbicidal activity against Echinochloa crusgalli, Digitaria sanguinalis, Spartina alterniflora, Eleusine indica, and Pennisetum alopecuroides with inhibition rates >90% at a dosage of 187.5 g ha-1. More importantly, QPP-I-6 displayed higher crop safety to Gossypium hirsutum, Glycine max, and Arachis hypogaea than the commercial herbicide quizalofop-p-ethyl. Studying the molecular mode of action by phenotypic observation, membrane permeability evaluation, transcriptomic analysis, and in vivo ACCase activity evaluation reveals that QPP-I-6 is a novel ACCase inhibitor. The present work demonstrates that QPP-I-6 can serve as a lead compound for further developing novel ACCase-inhibiting herbicides.

The Evaluation of Sweetcorn (Zea mays saccharata Sturt.) Infestation of Barnyardgrass (Echinochloa crus-galli) Depending on Weather Conditions and Crop Rotation

This paper focuses on the weed species Echinochloa crus-galli, commonly known as barnyardgrass, which is a persistent threat to crop yield and quality, especially in maize (Zea mays) cultivation. It is one of the most problematic weeds in agricultural fields due to its aggressive growth, adaptability to different environmental conditions and prolific seed production. The incidence of Echinochloa crus-galli in maize fields has increased in recent years. This study aims to provide a comprehensive understanding of the characteristics and behavior of Echinochloa crus-galli, and to suggest effective measures to control it. This research on sweetcorn was conducted from 1992 to 2019 at the Research and Education Center Gorzyń, Złotniki branch, which belongs to the Poznań University of Life Sciences. The evaluation of weed infestation was carried out in experiments focusing on chemical weed control in maize. The experiments were designed as a one-factor randomised block design with four field replications. The condition and the degree of weed infestation (number of weeds and fresh weight of weeds) in the control plots was assessed on an annual basis at the end of June and in July. The aim of the study was to evaluate the dynamic changes in the status and extent of barnyardgrass (Echinochloa crus-galli) infestation in maize grown after various other crops in the Wielkopolska region, with a focus on the weather conditions. The study found that barnyardgrass was most likely to occur when maize was sown after winter wheat in a dry and warm year, and least likely when maize was grown in rotation after winter wheat in a cold year with average rainfall. The proportion of barnyardgrass weed mass in the total weed mass was significantly lower after winter rye than after winter wheat, winter oilseed rape and winter triticale. Further research into the biology and ecology of barnyardgrass is key to effectively controlling this weed and safeguarding sweetcorn yields.

Weediness of spring cereal ear crops depends on the forecrop, tillage, fertilizers and herbicides

Goal. To analyze the species composition of weeds, their dominant role and to determine the type and level of weediness of spring cereal ear crops depending on different forecrops, methods of basic tillage, fertilization systems and herbicides in the conditions of the Eastern Forest-Steppe of Ukraine.
 Methods. The investigations were conducted in field experiments of spring cereal crops (barley, wheat, triticale) in a stationary field, fixed nine-course-fallow-grain-row crop rotation by means of route surveys.
 results. According to the data of 2016—2018, during the cultivation of spring cereal ear crops in crop rotation after soybeans, corn for grain and sugar beets as forecrops, 38, 34 and 45 species of weeds were identified, respectively. In total, 52 species of weed plants were found in the crops, of which 27 species occurred after all forecrops. The largest number of weeds in agrocenoses was represented by early and late spring species (48.9—58.8%), and the second and third places were respectively occupied by wintering, winter and biennial (26.5—31.1%), and perennial (14.7—20.0%). The main species of weeds in cereal crops were: after soybean forecrop, Setaria glauсa, Echinochloa crus-galli, Chenopodium album, Ambrosia artemisiifolia, Cirsium arvense, Convolvulus arvensis; after corn for grain forecrop, S. glauсa, E. crus-galli, C. album, Amaranthus retroflexus, Solanum nigrum, A. artemisiifolia, Polygonum lapathifolium, C. arvense, C. arvensis; after sugar beets forecrop, S. glauсa, E. crus-galli, C. album, A. retroflexus, S. nigrum, A. artemisiifolia, P. lapathifolium, C. arvense, Sonchus arvensis, C. arvensis. The largest number of weeds (33 species each) was found after sugar beets forecrop in the control (plowing, without fertilizers) and after chisel tillage (manure, after effect 30 t/ha + N30P30K30). Herbicides and forecrops significantly influenced the dominant and subdominant positions of certain weed species. In the crops, the cereal annual-bicotyledonous-root-sprouting type of weediness predominated (44.2%). The type of weediness of the crops depended on the use of agricultural practices in the years of research.
 Conclusions. In the conditions of the Eastern Forest-Steppe of Ukraine, weediness of spring cereal ear crops depended significantly on the forecrop, the method of basic tillage, the fertilization system, and the use of herbicides.

Ecological methods of weed control in paulownia (Paulownia tomentosa) plantations

Goal. To study the dynamics of weed infestation in young paulownia (Paulownia tomentosa) plantations and develop a weed control system that ensures the successful growth and development of paulownia plantations. To investigate the possibility of using environmentally friendly methods of weed control in the paulownia plantations in the Forest Steppe zone of Ukraine.
 Methods. Field methods were used in the experiment. The statistical processing of the experimental data was performed using Microsoft Office Excel.
 Results. The experiment was carried out to study weed control methods and ensure efficient use of soil water. The soil in the plant zone was mulched with straw (10 cm layer), covered with black polyethylene (25 mkm) film or spanbond (100 g/ m2). In the young paulownia plantations of the 10th year of cultivation, where no weed control measures were applied, the active growth of weeds was observed. The highest number of weeds was represented by Setaria glauca L. (17.5 plants/ m2), Echinochloa crus-galli (25.2 plants/ m2), Chenopodium album (15.1 plants/ m2), Elymus repens (21.2 plants/ m2), Sinapis arvensis (7.0 plants/ m2), Convolvulus arvensis (6.7 plants/ m2), and others.
 Conclusions. It was found that the mulching of young paulownia plantations with straw (10 cm layer) is an effective practice that ensures a high productivity of paulownia, with a plant height of 166 cm. The most effective method was covering the soil with black polyethylene film, with a plant height of 173 cm.

Effect of Black Soldier Fly Larvae and Food Substrates on Weed Seed Emergence

Black soldier fly larvae (Hermetia illucens; BSFL) composting is biotechnology used for organic waste management and an alternative to traditional composting. We designed a two-phase experiment to evaluate the effect of BSFL composting on the emergence of the following six weed species: barnyardgrass (Echinochloa crus-galli), common ragweed (Ambrosia artemisiifolia), giant foxtail (Setaria faberi), ivyleaf morningglory (Ipomoea hederacea), redroot pigweed (Amaranthus retroflexus), and velvetleaf (Abutilon theophrasti). The first experiment phase was in the laboratory (laboratory composting phase), which consisted of 100 seeds of each weed species subjected to five composting treatments [two controls (nontreated and standard Gainesville diet alone) and three types of substrates (standard Gainesville diet, vegetable waste, food waste) + BSFL]. Live pupa weighed 179 mg with the standard Gainesville diet + BSFL and 205 mg with the food waste diet + BSFL. Dry pupa weighed 68 mg and 70 mg, respectively. The BSFL in the vegetable waste + BSFL treatment did not pupate. During the second experiment phase, the composting treatments were placed in a greenhouse to evaluate weed emergence. Emergence in the nontreated control was 62% for barnyardgrass, 38% for common ragweed, 26% for giant foxtail, 66% for ivyleaf morningglory, 3% for redroot pigweed, and 69% for velvetleaf. Compared with the nontreated control, all treatments with BSFL reduced the emergence of each weed species to ≤1%, except for velvetleaf. This study suggests that BSFL composting may effectively reduce weed seed emergence of many weed species and could be a safe alternative to conventional composting processes to minimize weed pressure in compost. However, efficacy may vary by weed species and may be dependent on seed characteristics, such as an impermeable seedcoat.

Effects of Bipolaris yamadae strain HXDC-1-2 as a bioherbicide against Echinochloa crus-galli in rice and dry fields.

Barnyardgrass (Weed Science Society of America recommended) or Barnyard grass (Britannica recommended) (Echinochloa crus-galli (L.) P. Beauv.) is one of the most problematic and dominant weeds in world agricultural systems, especially in paddy fields, where tillering and grain yield can be reduced by 50-70% because of its competitive pressure. The frequent use of chemical herbicides to control E. crus-galli has led to the evolution of herbicide resistance. Developing bioherbicides using pathogenic fungi to control E. crus-galli could be an alternative option. In a previous study we showed that a strain of Bipolaris yamadae (HXDC-1-2) was promising in controlling gramineous weeds. Here we present a study that evaluated this fungus as a mycoherbicide against E. crus-galli in greenhouse and paddy fields, characterized mycelium growth and conidial production, and examined the infection development. The median effective dose (ED50) and 90% effective dose (ED90) values of microcapsulated B. yamadae strain HXDC-1-2 on E. crus-galli in the greenhouse were 7.17 × 102 and 9.35 × 103 conidia mL-1, respectively. Conidial germination, mycelial growth, and attachment formation occurred on E. crus-galli leaves within 1 to 6 h. The hyphae directly invaded cells and stomata, primarily from the appressorium on the epidermis, and necrotic lesions were observed on the leaf surface within 20 to 24 h. Applied to E. crus-galli plants at 1 × 105 conidia mL-1, the fungus reduced the weed's fresh weight of 75%. B. yamadae strain HXDC-1-2 has the potential to be developed as a bioherbicide against E. crus-galli plants, especially in rice fields. © 2024 Society of Chemical Industry.

Effects of Penoxsulam on Photosynthetic Characteristics and Safety Evaluation of Foxtail Millet

Foxtail millet planting has a long history and profound role in agricultural civilization. However, weeds have become one of the obstacles restricting the development of the foxtail millet industry. Penoxsulam, as an early post-emergence herbicide for controlling gramineous weeds in paddy fields, is effective for some broadleaf weeds. In this study, six different doses (CK, 0.5X, 1X, 2X, 3X, 4X) of penoxsulam were sprayed at the 3–5 leaf stage of the conventional variety Jingu 21 to study its effect on the growth and development of foxtail millet, in order to screen out the appropriate spraying concentration. The main results are as follows: Within 15 days after spraying penoxsulam, the plant height and leaf area of foxtail millet decreased with the increase in spraying dose, and gradually recovered 15–25 days after spraying, but there were still significant differences compared with CK. The photosynthetic pigment content, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), the maximum photochemical efficiency (Fv/Fm), photosynthetic system II actual photochemical efficiency (Y(II)), and photochemical quenching coefficient (qP) of foxtail millet decreased with an increase in the penoxsulam spraying dose, while the intercellular CO2 concentration (Ci) and non-photochemical quenching coefficient (NPQ) showed an upward trend. There was almost no significant difference in each index between the spraying dose of 0.5X and 1X and CK, but the photosynthesis of foxtail millet leaves was still significantly inhibited under a spraying dose of 3X and 4X. Penoxsulam had certain growth-inhibiting effects on Echinochloa crus-galli (L.) Beauv. (E. crus-galli), Digitaria sanguinalis (L.) Scop. (D. sanguinalis), Chenopodium album L. (C. album), and Amaranthus retroflexus L. (A. retroflexus) which increased as the spraying dosage increased. Our study found that spraying dose groups of 0.5X and 1X penoxsulam were safe for foxtail millet growth and could be used to control gramineous weeds in fields. Other spraying doses are not recommended in the field due to their serious phytotoxicity to foxtail millet, which provides a new measure for weed control in foxtail millet fields.

A first survey for herbicide resistant weeds across major maize growing areas in the North Island of New Zealand.

Weeds are increasingly documented with evolved resistance to herbicides globally. Three species have been reported as resistant in maize crops in New Zealand: Chenopodium album to atrazine and dicamba, Persicaria maculosa to atrazine and Digitaria sanguinalis to nicosulfuron. Despite knowledge of these cases, the distribution of these resistant biotypes is unknown. This study aimed to determine the prevalence of known resistant weeds in major maize growing areas in New Zealand, and to pro-actively screen other species for resistance. Weed seeds of broadleaf and grass species were collected from 70 randomly selected maize growing farms in the North Island in 2021-2022. Seeds were grown and treated with herbicides at recommended field rates. Atrazine-resistant C. album were recorded in a third of surveyed farms and nicosulfuron-resistant D. sanguinalis in a sixth. Half of Waikato farms and a quarter of Bay of Plenty farms (no Hawkes Bay or Wellington farms) had atrazine-resistant C. album. Dicamba-resistant C. album were not detected, nor were atrazine-resistant P. maculosa. Nicosulfuron resistant D. sanguinalis was recorded in 19% of Waikato farms, 6% of Bay of Plenty farms and 9% of Hawkes Bay farms (no Wellington farms). Amaranthus spp., Fallopia convolvulus, Persicaria spp., Solanum spp., Echinochloa crus-galli, Panicum spp. and Setaria spp. were not resistant to any of the herbicides tested. Twenty-nine to 52% of maize farms in the North Island are estimated to have herbicide resistant weeds. Resistance is common in maize farms in Waikato and western Bay of Plenty. Resistance is rare in southern regions, with only one instance of nicosulfuron-resistant D. sanguinalis and no resistant C. album. Most annual weeds in maize are not resistant to herbicides; although atrazine resistant C. album is widespread, it is currently controlled with alternative herbicides. Resistant D. sanguinalis appears to be an emerging problem.

Identification of Phytochemicals in Cleome rutidosperma DC. Methanol Extract and Evaluate its Efficacy on Some Common Rice Field Weeds

Screening different plant species for herbicidal activity and identifying new allelochemicals with novel structures and phytochemical activity could be promising candidates for reducing the negative consequences of chemical herbicides. Our study aims to investigate the allelopathic substance(s) and herbicidal efficacy of Cleome rutidosperma DC. on rice filed weeds in the lab and glasshouse. The phytochemical constituents of the methanol extract of Cleome rutidosperma were analyzed by high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). The allelopathic effect of C. rutidosperma has been further studied on the germination and early development of five common rice field weeds: Echinochloa crus-galli (L.) P. Beauv., Fimbristylis miliacea (L.) Vahl, Oryza sativa f. spontanea Roshev., Leptochloa chinensis (L.) Nees, and Cyperus iria L. The seed germination and growth of tested weeds under lab and glasshouse conditions were compared to three concentrations of C. rutidosperma methanol extract at 2.5, 5, and 10% with the control (only distilled water). The results indicated the presence of 64 and 10 known chemicals using positive and negative ionization techniques, the majority of which were toxic. The inhibitory effect of C. rutidosperma was stronger in the lab than in the glasshouse. No seed germination of the tested species was observed when 10% C. rutidosperma extract was applied. The photosynthesis rate of C. iria exhibited a higher reduction (70.56%) compared to other species at higher doses (10%) of C. rutidosperma. These findings demonstrated that C. rutidosperma is a significant source of phytotoxic components and can be used to develop future bio-herbicides. The outcome of this study can be employed in the organic management of weeds and reduce our heavy reliance on synthetic herbicides.

The effect of caraway oil-loaded bio-nanoemulsions on the growth and performance of barnyard grass and maize

A proper formulation is crucial to improve the herbicidal effects of essential oils and their selectivity. In this study, we investigated the physicochemical properties of bio-based nanoemulsions (CNs) containing several concentrations of caraway (Carum carvi) essential oil stabilized with Eco Tween 80, as a surfactant, maintaining 1:1 proportions. Detailed physicochemical characteristics of the CNs revealed that their properties were most desired at 2% of the oil and surfactant, i.e., the smallest droplet size, polydispersity index, and viscosity. The CNs caused biochemical changes in maize and barnyard grass (Echinochloa crus-galli) seedlings, however, to a different extent. Barnyard grass has overall metabolism (measured as a thermal power) decreased by 39–82% when exposed to the CNs. The CNs triggered changes in the content and composition of carbohydrates in the endosperm of both species' seedlings in a dose–response manner. The foliar application of CNs caused significant damage to tissues of young maize and barnyard grass plants. The effective dose of the CN (ED50, causing a 50% damage) was 5% and 17.5% oil in CN for barnyard grass and maize tissues, respectively. Spraying CNs also decreased relative water content in leaves and affected the efficiency of photosynthesis by disturbing the electron transport chain. We found that barnyard grass was significantly more susceptible to the foliar application of CNs than maize, which could be used to selectively control this species in maize crops. However, further studies are needed to verify this hypothesis under field conditions.

Isolation and Identification of Allelopathic Substances from Forsythia suspensa Leaves, and Their Metabolism and Activity.

The fruit of Forsythia suspensa (Thunb.) Vahl has been used in traditional Chinese medicine as "Forsythiae fructus". The species is also grown in parks and gardens, and on streets and building lots, as an ornamental plant, but it requires pruning. In this study, the allelopathic activity and allelopathic substances in the leaves of pruned branches of F. suspensa were investigated to determine any potential application. The leaf extracts of F. suspensa showed growth inhibitory activity against three weed species; Echinochloa crus-galli, Lolium multiflorum, and Vulpia myuros. Two allelopathic substances in the extracts were isolated through the bioassay-guided purification process, and identified as (-)-matairesinol and (-)-arctigenin. (-)-Matairesinol and (-)-arctigenin, which showed significant growth inhibitory activity at concentrations greater than 0.3 mM in vitro. The inhibitory activity of (-)-arctigenin was greater than that of (-)-matairesinol. However, both compounds were more active than (+)-pinolesinol which is their precursor in the biosynthetic pathway. The investigation suggests that F. suspensa leaves are allelopathic, and (-)-matairesinol and (-)-arctigenin may contribute to the growth inhibitory activities. Therefore, the leaves of the pruned branches can be applied as a weed management strategy in some agricultural practices such as using the leaf extracts in a foliar spray and the leaves in a soil mixture, thereby reducing the dependency on synthetic herbicides in the crop cultivation and contributing to developing eco-friendly agriculture.

Allelopathy and Identification of Five Allelochemicals in the Leaves of the Aromatic Medicinal Tree Aegle marmelos (L.) Correa.

Aegle marmelos (L.) Correa is an economically and therapeutically valuable tree. It is cultivated as a fruit plant in southeast Asian countries. In this research, we investigated the allelopathy and possible allelochemicals in the leaves of A. marmelos. Aqueous methanol extracts of A. marmelos exhibited significant inhibitory effects against the growth of Lepidium sativum, Lactuca sativa, Medicago sativa, Echinochloa crusgalli, Lolium multiflorum, and Phleum pratense. Bioassay-directed chromatographic purification of the A. marmelos extracts resulted in identifying five active compounds: umbelliferone (1), trans-ferulic acid (2), (E)-4-hydroxycinnamic acid methyl ester (3), trans-cinnamic acid (4), and methyl (E)-3'-hydroxyl-4'-methoxycinnamate (5). The hypocotyl and root growth of L. sativum were considerably suppressed by these compounds. Methyl (E)-3'-hydroxyl-4'-methoxycinnamate also suppressed the coleoptile and root growth of E. crusgalli. The concentrations of these compounds, causing 50% growth reduction (I50) of L. sativum, were in the range of 74.19-785.4 μM. The findings suggest that these isolated compounds might function in the allelopathy of A. marmelos.

Genome sequences of Colletotrichum eleusines and C. echinochloae: two pathogens from Poaceae weeds.

We present two whole-genome sequences of Colletotrichum strains which were isolated from Eleusine indica and Echinochloa crus-galli using Nanopore and Illumina technologies, as part of screening for potential mycoherbicide. The genome sequences will provide important genetic information and will be useful for further research into secondary metabolites of Colletotrichum.

Echinochloa spp response to preemergence and postemergence herbicides in California rice (Oryza sativa L.)

Historically, herbicides were used for Echinochloa spp control in California rice production which led to the selection of herbicide-resistant biotypes. Field surveys were conducted across the seven major rice-growing counties in 2020 and Echinochloa spp samples including barnyardgrass (Echinochloa crus-galli (L.) P.Beauv.), junglerice (Echinochloa colona (L.) Link), late watergrass (Echinochloa oryzicola (Vasinger) Vasinger) and coast cockspur (Echinochloa walteri (Pursh) Heller) were collected. Greenhouse experiments were carried out to determine their suspected resistance to common preemergence and postemergence rice herbicides used in California in Fall and Winter of 2021. A total of 62 and 63 samples were characterized for suspected resistance to four preemergence granular and three postemergence foliar-applied herbicides, respectively. When granular herbicides were evaluated, samples suspected of resistance in Winter were a subset of samples that were suspected of resistance in Fall. Results indicate >90% of Echinochloa spp samples were resistant to thiobencarb, benzobicyclon + halosulfuron and penoxsulam when combined across species and counties. Cross-resistance between benzobicyclon + halosulfuron and penoxsulam was observed in >90% of the samples when combined across species and counties. Suspected clomazone resistance was observed in <75% of the samples when combined across species and counties. Suspected resistance to cyhalofop and propanil was observed in <50% of the samples when averaged across both runs. Multiple-resistance to foliar herbicides ranged from 48-60% of the samples across species and experimental runs. These results indicate the necessity for rotating herbicides during alternate cropping seasons and emphasizing integrating non-chemical strategies for Echinochloa spp control in California rice production.

A synopsis of the segetal flora of the Saratov Province

The publication presents a synopsis of the segetal flora of the Saratov Province. The list is based on the results of our own research over the years using the Herbarium of cultivated plants of the world, their wild relatives and weeds (WIR). For each species, the agrobiological group (according to the classification of weeds), the life form according to Christen Raunkiær, the ecological group in relation to moisture, as well as the occurrence in crops and floristic areas of the Province are indicated. To indicate the geographical distribution, we used the floristic zonation of the Saratov Province by Yuriy Bulany (2011). Saratov Province is situated in the southeast of European Russia, it spreads for 101240 km2 and is divided by the Volga river in almost equal parts, i.e. droughty Zavolzhye (Transvolga region) and Pravoberezhye (the Right Bank region) where the climate is more mild. The segetal flora includes 206 species of vascular plants belonging to 141 genera of 32 families. The families that lead in terms of the number of species are Asteraceae, Brassicaceae, Poaceae, Fabaceae and Chenopodiaceae, while such genera are Artemisia, Chenopodium, and Amaranthus. The highest occurrence and abundance are characteristic of Amaranthus retroflexus L., A blitoides S. Wats., Chenopodium album L., Cirsium arvense (L.) Scop., Convolvulus arvensis L., Descurainia sophia (L.) Webb. ex Prantl, Echinochloa crus-galli (L.) P. Beauv., Euphorbia virgata Waldst. & Kit., Fallopia convolvulus (L.) Á. Löve, Lactuca tatarica (L.) C.A. Mey., L. serriola L., Lamium amplexicaule L., Lappula patula (Lehm.) Menycharth., Setaria viridis (L.) P. Beauv., S. pumila (Poir.) Roem. & Schult., Sonchus arvensis L. The list for the Volga Left Bank Region is supplemented by Avena fatua L. and Fumaria vaillantii Loesel., while that for the Right Bank Region ‒ by Camelina microcarpa Andrz., Galeopsis ladanum L. and Persicaria lapathifolia (L.) Delarbre

Towards a true conservation zero tillage system: “A proposed solution based on computer vision to herbicide resistance.”

The Zero Tillage (ZT) or Non-Tillage system constitutes an agricultural production approach designed for improved soil conservation, reduced fossil fuel usage, mitigation of waterway pollution, water and wind erosion, and addressing soil compaction, among other objectives. In this way, ZT promises more sustainable agriculture. However, current ZT production systems depend on herbicide applications for weed control. The use of herbicides with the same modes of action over many years has led to numerous resistant weed species, which end up threatening the success of the herbicide weed control and, consequently, the overall success of the ZT system. Being able to automatically detect and classify weed species directly under the sprayer during the chemical application is an alternative to control populations of weeds since it would allow selecting the herbicide and dose for those particular species. This study, conducted over 15 years in commercial fields utilizing Zero Tillage (ZT) management, examined various ground covers intrinsic to the ZT system originating from previous crops or residues post-harvest. ZT features a broad spectrum of contexts due to the complexity of different ground cover types, which challenge computer vision techniques. The assessment focused on the automatic detection and classification of among the most problematic monocotyledonous and dicotyledonous weed species in the province of Cordoba in Argentina, with the objective of enabling a more targeted and selective approach to their control. These are Amaranthus palmeri, Echinochloa crus-galli, Eleusine indica, Parietaria debilis and Conyza sumatrensis. Additionally, some species belong to the same botanical families with several morphological resemblances that defy vision algorithms. This work proceeded through a machine learning approach applied to computer vision features such as SIFT (scale-invariant feature transform), K-means (clustering), and Bag of Features over the Support Vector Machine for classification. The results showed an accuracy between 89 % and 98 % over the species, allowing a significant reduction of herbicide while applying the adequate active ingredient. Moreover, virtual binary maps from weed patches are devised to be implemented through ISOBUS protocol. Thus the current research contributes significantly to the issue of controlling populations of weeds in the ZT agriculture system.

Bioprospection of Phytotoxic Plant-Derived Eudesmanolides and Guaianolides for the Control of Amaranthus viridis, Echinochloa crus-galli, and Lolium perenne Weeds.

The phytotoxicities of a selection of eudesmanolides and guaianolides, including natural products and new derivatives obtained by semisynthesis from plant-isolated sesquiterpene lactones, were evaluated in bioassays against three weeds of concern in agriculture (Amaranthus viridis L., Echinochloa crus-galli L., and Lolium perenne L.). Both eudesmanolides and guaianolides were active against the root and shoot growth of all the species, with the eudesmanolides generally showing improved activities. The IC50 values obtained for the herbicide employed as positive control (on root and shoot growth, respectively, A. viridis: 27.8 and 85.7 μM; E. crus-galli: 167.5 and 288.2 μM; L. perenne: 99.1 and 571.4 μM) were improved in most of the cases. Structure-activity relationships were discussed, finding that hydroxylation of the A-ring and C-13 as well as the position, number, and orientation of the hydroxyl groups and the presence of an unsaturated carbonyl group can significantly influence the level of phytotoxicity. γ-Cyclocostunolide was the most active compound in the series, followed by others such as dehydrozaluzanin C and α-cyclocostunolide (outstanding their IC50 values on A. viridis)─natural products that can therefore be suggested as models for herbicide development if further research indicates effectiveness on a larger scale and environmental safety in ecotoxicological assessments.

Field assessment of Echinochloa crusgalli (L.) residues for allelopathic effects on both crops and weeds

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during the period from August 2020-June, 2021 to assess the allelopathic effects of the Echinochloa crusgalli residues on both rice yields and weeds therein. The experiment consisted five treatments of doses of residues of E. crusgalli viz. i) no residues (control), ii) E. crusgalli residues @ 0.7 t ha-1, iii) E. crusgalli residues @ 1.4 t ha-1, iv) E. crusgalli residues @ 2.1 t ha-1, v) farmers practice (two hand weeding @ 15 and 30 days after transplanting); and three treatments of the time of the application of the residues of E. crusgalli viz. i) one week before transplanting, ii) at the time of transplanting, iii) one week after transplanting. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Five weeds belonging to the five families were identified in the field such as Echinochloa crusgalli, Marsilea quadriflia, Monochori vaginalis, Paspalum scrobiculatum and Fimbristylis miliacea. The doses of residues of E. crusgalli had significant effect on yield and yield contributing characters of rice except number of non-effective tillers hill-1 and grains panicle-1. The highest grain yield (5.13 t ha-1), straw yield (6.19 t ha-1) biological yield (11.32 t ha-1) and harvest index (45.18%) were recorded when residues applied @ 2.1 t ha-1. In case of time of application of the residues, the highest grain yield (3.84 t ha-1) and straw yield (5.21 t ha-1) were found when the residues applied one week before transplanting. In case interaction between doses and time of application of the residues of E. crusgalli the highest the grain yield (5.98 tha-1), straw yield (6.67 t ha-1) and biological yield (11.32 t ha-1) were found when residues applied @ 2.1 tha-1 at one week before transplanting. Results of the study shows that the residues of Echinochloa crusgalli possess weed suppressing ability. Therefore, Echinochloa crusgalli residues could be applied to the rice field before one week of transplanting of seedlings to control weed growth and to get higher rice production.

New library of pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives: Synthesis, herbicidal activity, and molecular docking study

The development of nitrogen-containing heterocyclic compounds with novel structure and remarkable biological activity is always in demand. Herein, new library of pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives (1–98) was designed, synthesized, and characterized by Fourier Transform Infrared Spectoscopy (FT-IR), nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), high-resolution mass spectroscopy (HRMS), and X-ray single-crystal diffraction. Their herbicidal activities were screened for the first time by Petri dish assay and pot experiment in a glasshouse. The results indicated that some of title compounds (e.g.,1, 4, 5, and 7–11) exhibited 100 % inhibition rate against the roots and stalks of Cucumis sativus, Raphanus sativus, Sorghum bicolor and Echinochloa crusgalli at a dosage of 100 mg/L, higher than the positive control Flumetsulam, a well-known commercial acetolactate synthase (ALS) inhibiting herbicide. 2-((2,4-Dichlorophenoxy)methyl)-10-(methylthio)-8-(pentylthio)-5-propyl-5,6-dihydropyri- mido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine 7 showed notable postemergence herbicidal activity against Abutilon theophrasti, Amaranthus spinosus, Chenopodium album, Digitaria sanguinalis, Echinochloa crusgalli, and Setaria viridis at a rate of 375 g/ha, and its activities were similar to the positive control Flumetsulam. Enzymatic bioassays revealed that 7, 8, and 40 displayed good inhibitory potency against ALS with 39.6 %, 39.1 %, and 40.9 % inhibition rate, respectively, comparable to that of Flumetsulam (43.5 % inhibition rate). Moreover, molecular docking analysis was conducted by using ALS protein and target ligand molecule 7. The results of molecular docking were consistent with the bioassay experiments, showing compound 7 with a new structure and excellent herbicidal potency was potent inhibitors of ALS.

Synthesis and Biological Activity Evaluation of Novel Chalcone Analogues Containing a Methylxanthine Moiety and Their N-Acyl Pyrazoline Derivatives.

On the basis of the structures of natural methylxanthines and chalcone, a series of novel chalcone analogues containing a methylxanthine moiety, Ia-Ig, and their N-acyl pyrazoline derivatives IIa-IIz and IIaa-IIaf were synthesized and identified through melting points, 1H NMR, 13C NMR, and HRMS. The single crystal of compound IId was obtained, which further illustrated the structural characteristics of the methylxanthine-acylpyrazoline compounds. The biological tests showed that some of them displayed favorable insecticidal activities toward Plutella xylostella L. and were superior to the natural methylxanthine compound caffeine while being comparable with the insecticide triflumuron (e.g., compound Ic: LC50 = 16.8508 mg/L, IIf: LC50 = 1.5721 mg/L, against P. xylostella). Of these compounds, Ic, IIf, and IIu could serve as novel insecticidal leading structures for further study. Some of the compounds showed good fungicidal activities (e.g., compound Ig: EC50 = 14.74 μg/mL, against Rhizoctonia cerealis; IIf: EC50 = 7.06 μg/mL, against Physalospora piricola; IIac: EC50 = 5.37 and 8.19 μg/mL, against Phytophthora capsici and Sclerotinia sclerotiorum, respectively); Ic, Ig, IIa, IIf, IIr, IIs, IIv, IIac, and IIaf could be novel fungicidal leading compounds for further exploration. Furthermore, most of the tested compounds exhibited apparent herbicidal activities against Brassica campestris at a concentration of 100 μg/mL; among others, compound IIa was the best one both toward Brassica campestris and Echinochloa crusgalli and deserves further investigation. The structure-activity relationships of these compounds were also summarized and discussed in detail. The contrast experiment results of compounds C-1 and C-2 showed a positive effect on the biological activity enhancement from the combination of the methylxanthine moiety with the N-dichloroacetyl phenylpyrazoline skeleton. In addition, two 3D-QSAR models with predictive capability were constructed based on the insecticidal and fungicidal activities to afford deep insight into the bioactivity profiles of these compounds. This research provides useful guidance and reference for the discovery and development of novel xanthine natural product-based pesticides.