Weed Species Research Articles

Detection of Sedge Weeds Infestation in Wetland Rice Cultivation Using Hyperspectral Images and Artificial Intelligence: A Review

Sedge is one type of weed that can infest the rice field, as well as broadleaf and grasses. If sedges are not appropriately controlled, severe yield loss will occur due to increased competition with cultivated rice for light, space, nutrients, and water. Both sedges and grasses are monocots and have similar narrowed leaf characteristics, but most sedge stems have triangular prismatic shapes in cross sections, which differ them from grasses. Event sedges and grasses differ in morphology, but differentiating them in rice fields is challenging due to the large rice field area and high green color similarity. In addition, climate change makes it more challenging as the distribution of sedge weed infestation is influenced by surrounding abiotic factors, which lead to changes in weed control management. With advanced drone technology, agriculture officers or scientists can save time and labor in distributing weed surveys in rice fields. Using hyperspectral sensors on drones can increase classification accuracy and differentiation between weed species. The spectral signature of sedge weed species captured by the hyperspectral drone can generate weed maps in rice fields to give the sedge percentage distribution and location of sedge patch growth. Researchers can propose proper countermeasures to control the sedge weed problem with this information. This review summarizes the advances in our understanding of the hyperspectral reflectance of weedy sedges in rice fields. It also discusses how they interact with climate change and phenological stages to predict sedge invasions.

Weed Management Using UAV and Remote Sensing in Malaysia Paddy Field: A Review

Controlling weed infestation is pivotal to achieving the maximum yield in paddy fields. At a time of exponential human population growth and depleting arable land mass, finding the solution to this problem is crucial. For a long time, herbicides have been the most favoured approach for weed control due to their efficacy and ease of application. However, adverse effects on the environment due to the excessive use of herbicides have prompted more cautious and effective herbicide usage. Many weed species tend to dominate the field, and the weed thrived in patches, rendering conventional broad herbicide spraying futile. Site-specific weed management (SSWM) consists of two strategies: weed mapping and selective herbicide application. Since its introduction into the agriculture sector, unmanned aerial vehicles (UAV) have become the platform of choice for carrying both the remote sensing system for weed mapping and the selective application of herbicide. Red-Green-Blue (RGB), multispectral and hyperspectral sensors on UAVs enable highly accurate weed mapping. In Malaysia, adopting this technology is highly possible, given the nature of government-administrated rice cultivation. This review provides insight into the weed management practice using remote sensing techniques on UAV platforms with potential applications in Malaysia's paddy field. It also discusses the recent works on weed mapping with imaging remote sensing on a UAV platform.

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.

Facilitating early boreal forest succession on waste rock using Ramial Chipped Wood mulch: A five-year study

After a mine is closed, waste rock storage areas must be revegetated to facilitate the return of ecosystem services and meet legal and social expectations. The restoration of forest ecosystems on waste rock through spontaneous colonization associated with primary succession can take decades and is still poorly studied. Adding a mulch of ramial chipped wood (RCW) could improve the physicochemical properties and microclimate conditions of waste rock, thus facilitating substrate colonization by plants. In 2016, a fully randomized block design was installed on waste rock from a closed gold mine located in the boreal forest in Abitibi-Témiscamingue, Quebec, Canada. The design included four treatments: scarified waste rock as the control (WR), 2 cm of RCW mulch on top of scarified waste rock (RCW/WR), and 10 cm layer of sand on top of scarified waste rock with or without 2 cm of RCW mulch (RCW/S and S, respectively). Over a period of five years, we followed the natural colonization of forest species as well as abiotic (substrate microclimate conditions and physicochemistry) and biotic (herbaceous plant colonization) factors influencing woody plant colonization success. Six boreal woody species spontaneously colonized the area (five individuals per m2, on average, all species combined). Salix sp. and Picea glauca seedlings were more abundant on substrates with RCW mulch (especially sand) than those without mulch, and P. glauca had greater aerial biomasses with RCW mulch. Substrate water content during the growing season and the presence of the weed species Tussilago farfara were determining environmental factors in substrate colonization by Abies balsamea. In the absence of Tussilago farfara, RCW mulch increased A. balsamea colonization. RCW mulch increased the total cover of colonizing herbaceous plants (23.3–58.2%) as compared to mineral substrates alone (4.78–52.3%), which negatively affected the number of A. balsamea individuals. The colonizing herbaceous species were mostly primary succession species, Pilosella caespitosa, Anaphalis margaritacea, and Tussilago farfara being dominant; no exotic species were observed. The results highlight the potential of RCW mulch in promoting forest recolonization on waste rock, including mid-successional species like Picea sp., which could be useful for facilitating ecosystem succession in post-mining landscapes.

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.

Is There a Place for New Herbicides Targeting Photosynthetic Electron Transport?

Abstract Due to increased food demand, the need for use of herbicides is both necessary and on the rise. Several herbicide classes target photosynthetic electron transport: HRAC Groups 5, 6 and 22. These herbicides are used in large amounts in many different cropping systems to control several species of broadleaf and grass weeds. This article provides a comprehensive review of what these photosynthesis inhibitors are, how they are used and their mode of action. Presently, commercial herbicides only inhibit electron flow at two different sites photosystem II (PSII) and photosystem I (PSI). Those which inhibit electron flow at PSII block the movement of electrons down the electron transport chain, while those which inhibit at PSI accept electrons. Necrosis developing on the leaves of plants treated with PSII and PSI inhibitors is due to the accumulation of reactive oxygen species. Evolution of resistance, toxicity concerns, and other limitations of these herbicides call for the exploration of new chemistries which can be used to target this pathway.

Genetic diversity of Sinapis arvensis L. (wild mustard) in Türkiye determined by microsatellite markers

Wild mustard (Sinapis arvensis L.) is a self-fertilizing weed species that exerts negative impacts on wheat production and herbicides are intensively used to manage it. Cross-fertilization may lead to genetic differentiation in this species. Therefore, this study investigated genetic diversity among wild mustard populations collected from wheat fields across various regions in Türkiye. Genetic variation was evaluated using 5 simple sequence repeat (SSR) markers in populations collected from 30 different locations. Populations were analyzed using UPGMA (unweighted pair group method with arithmetic mean) and principal component analysis (PCA). The mean genetic diversity (GD) and polymorphism information content (PIC) values were 0.752 and 0.844, respectively. High genetic variability was recorded among populations within geographic locations. The populations were categorized into two major groups by UPGMA. There was no apparent geographic isolation among tested populations, which displayed a high degree of variability. The primary source of this variability is thought to be the adaptability of wild mustard seeds dispersed through various methods across diverse locations. Despite being a predominantly self-pollinating species, wild mustard may also employ some cross-pollination mechanisms. In conclusion, SSR markers proved useful in determining genetic diversity in outcrossing species, especially where no prior genotypic information is available. The study suggests that genetic diversity is maintained in wild mustard populations even with rotational farming practices and intensive use of herbicides.

Prediksi Kehilangan Hasil Jagung (Zea mays L.) Akibat Kompetisi Gulma Poaceae di Lahan Kering

This research aims to determine the Poaceae weed species that have a significant effect on corn yield loss in dry land. The research method was descriptive and data collection using survey techniques in 10 sample plots measuring 1 m2 which were placed using random sampling. Observation parameters include the number of species and populations of weeds, the population of corn plants in plot-1 and the dry biomass weight of weeds and corn in plot-1. Quantitative data analysis by calculating relative density, relative frequency and relative dominance values ​​to calculate the importance value index and Summe Diminance Ratio (SDR). The results showed that the diversity, evenness, dominance and abundance of Poaceae weeds in corn plants in dry land was high. So it was found that seven species of weeds were dominant and continued to exist while the corn was growing, namely Paspalum vasginatum Sw., Leersia hexandra Sw., Digitaria longiflora (Retz.) Koel., Digitaria ciliaris (Retz.) Koel., Cynodon dactylon L., Eleusine indica Gaertn., and Panicum repens L. The competitiveness and ability to reduce corn yields of the weeds Paspalum vasginatum, Leersia hexandra and Digitaria longiflora are higher than other weeds, so that corn yield losses due to competition reach 16.45%, 7.48% and 4.40%. The weeds Brachiaria reptans, Axonopus compressus and Echinochloa colonum do not need to be controlled in corn after the plants are 45 DAT, because their competitiveness and ability to eliminate crop yields is very low.

Spectral mixture analysis for weed traits identification under varying resolutions and growth stages

Spectral and spatial resolutions are critical factors in Site-Specific Weed Management (SSWM) applications, which aim to adjust and apply herbicides according to the weed composition and coverage during early growth. Thus, a reliable SSWM requires high spectral and spatial resolution data to create informative maps indicating and spatially localizing the weed species. Besides, upscaling and improving the mapping process are essential to motivate farmers to adopt SSWM practices. However, high-resolution data in spectral and spatial domains is not always available, and mixed pixels are highly probable. Therefore, evaluating approaches that deal with such pixels that pose a significant problem for weed classification tasks is vital. In this regard, Spectral Mixture Analysis (SMA) can exploit subpixel information from coarse-resolution data. However, despite its potential, SMA has not been examined for subpixel weed mapping. In this work, we aim to evaluate the potential advantages of SMA for coverage estimation of different weed traits (weed botanical group, photosynthetic pathway, and species). For this purpose, we first created a dataset containing weed species characterized by different botanical groups and photosynthetic pathways. Then, we evaluated the performance of SMA in estimating the weed’s coverage at varying growth stages and spectral and spatial resolutions. The experimental results revealed that using botanical weed groups as Endmembers (EM) is advantageous over other traits. A quantitative evaluation revealed strong correlation values between the actual and predicted weed coverage and a Mean Absolute Error (MAE) lower than 10 % for the different EM at all resolutions and growth stages. Besides, SMA outperformed the traditional classification-based approach in estimating weed coverage with up to ∼ 30 % lower Mean Absolute Error. Finally, our study establishes a basis for incorporating SMA in various SSWM practices.

Causal agent for disease symptoms on passionflower in Adim, Cross River State, Nigeria

The stinking passionflower (Passiflora foetida L.) is generally regarded as a weed, although its tender fruits are consumed by a few; while the plant is mostly regarded for its medicinal properties. Cucumber mosaic virus is known not just to cause significant losses among crops, but also present in many weeds species. The objective of this study was to identify the causal agent of the disease symptoms observed from P. foetida in Adim, Cross River State, Nigeria. Leaves of P. foetida with virus symptoms were collected from various locations in Adim. Antigen-coated plate enzyme-linked immunosorbent assay (ACP-ELISA) and reverse transcription polymerase chain reactions (RT-PCR) were used for virus detection and characterisation. The symptomatic leaves reacted positively with the CMV antisera in ACP-ELISA and sequences from RT-PCR products showed the highest identity (98.5%) with a CMV isolate from Xanthosoma sp. (MG021460) in Uganda. Phylogenetic reconstruction aggregated the isolates with other Nigerian CMV sequences in a separate uncharacterised subgroup, closest to MH798809 (Nigeria), MW655577 (Nigeria) and HQ874434 (Austria). The tree also revealed the isolates as members of subgroup IB. This study provides the first molecular evidence of CMV infection on P. foetida in Nigeria and adds to the list of possible natural host for the virus in the country.

CottonWeeds: Empowering precision weed management through deep learning and comprehensive dataset

In sustainable crop production, effective weed management is crucial for agricultural productivity. Although deep learning techniques for weed detection have gained attention, their adoption is hindered by the lack of comprehensive datasets. Addressing this gap, we present ‘CottonWeeds,’ a meticulously curated database with 7578 images of horse purslane (Trianthema portulacastrum L.) and purple nutsedge (Cyperus rotundus L.), two common weed species in cotton (Gossypium hirsutum L.) fields. Captured under diverse conditions in the Indian subcontinent during the 2021 growth season, these labeled images constitute a valuable resource. We rigorously evaluated 11 state-of-the-art image classification models using deep transfer learning (DTL), achieving exceptional accuracy exceeding 93% within a 3-h training period. MobileNet emerged as the top performer, reaching 95.43% accuracy. Challenges arose with limited purple nutsedge training samples, impacting conventional models. To address this, we introduced a weighted cross-entropy loss function, significantly enhancing purple nutsedge classification. For instance, VGG16's purple nutsedge accuracy improved from 92.00% to 96.57%. Additionally, we assessed the dataset's utility for object detection, employing pre-trained YOLOv5 models. YOLOv5x exhibited exceptional performance, with a mAP_0.5:0.95 score of 72.5% and a mAP_0.5 score of 87.4%, proving invaluable for weed identification in cotton fields. Our study underscores CottonWeeds' potential as a foundational training platform for real-time, in-field weed recognition models.

Composition of the weed flora in sugar beet cultivation in Germany – nationwide trials 1995–2022

Long-term data from 449 herbicide trials across Germany from 1995–2022 were used to characterise the weed composition in sugar beet cultivation. The assessments of 1782 untreated control plots showed local weed species composition and weed pressure. The most common weeds were Chenopodium album (82.3% of all plots), Polygonum convolvulus (52.2%) and Galium aparine (25%). The average number of weed species in the field trials decreased from 4.9 in 1995 to 2.6 in 2022, significantly influenced by trial location and year. The occurrence of the most frequent weeds has also changed. C. album and P. convolvulus increased while G. aparine and Matricaria chamomilla decreased. Possible reasons for these changes are different tillage systems and intensities as well as changes in crop rotation with decreased crop diversity. Herbicide treatments and different active ingredients also affect the occurrence and proportion of weeds. The trial sites were assigned to clusters accounting for climate attributes and soil properties to identify regional differences in weed infestation. Regions with low soil quality, high temperatures and low precipitation had higher weed diversity, presumably due to low crop cover and, thus, lower weed suppression. The proportion of C. album was very high in all regions because it can grow under a wide range of environmental conditions. For P. convolvulus, significant regional differences existed in its proportion of total weed infestation. Its importance was lower in regions with poorer soils.

Synthesis and Herbicidal Activity of 2-(2-Oxo-3-pyridyl-benzothiazol-6-yloxy)hexanoic Acids.

The discovery of a lead compound is fundamental to herbicide innovation, but the limited availability of valuable lead compounds has hindered their development in recent years. By utilizing the structural diversity-oriented inactive group strategy, 3-(2-pyridyl)-benzothiazol-2-one was identified as a promising lead scaffold for herbicides, starting from benzothiazole which is an inactive moiety commonly found in herbicides such as mefenacet, benazolin, benzthiazuron, and fenthiaprop-ethyl. To investigate the structure-activity relationship (SAR) of these chemicals, a series of 2-(2-oxo-3-pyridyl-benzothiazol-6-yloxy)hexanoic acid derivatives (VI01 ∼ VI28) were synthesized through classical nucleophilic SNAr reaction using halogenated pyridines and 6-methoxybenzothiazole-2-one. The chemical structures of all the title compounds were confirmed by NMR and MS analysis. Petri dish assays indicated that many compounds exhibited potent herbicidal activity against both broad-leaf weeds and grass weeds at 1.0 mg/L. The SAR analysis revealed that the presence of a trifluoromethyl group at the 5-position of pyridine is essential for herbicidal activity. Furthermore, carboxylic esters exhibit higher herbicidal activity compared to carboxylic amides and free acids, and the activity decreased with the extension of the carbon chain. The postemergence herbicidal activity of VI03 against 16 species of weeds was tested by pot experiments in a greenhouse. VI03 demonstrated comparable efficacy in controlling broadleaf weeds and superior efficacy in controlling grass weeds compared to carfentrazone ethyl. The present study has unveiled a novel molecular scaffold exhibiting remarkably potent herbicidal activity. These findings are anticipated to provide valuable insights for the advancement of new herbicides and offer an alternative approach for managing resistant weeds.

Survival and alterations in reproductive organs of the cotton boll weevil, Anthonomus grandis grandis, fed alternative food

AbstractThe cotton boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is one of the most important insect pests of cotton, causing significant yield losses. This insect completes its life cycle only on the flower structures of some Malvaceae species, with cotton being its preferred host. However, during the cotton off‐season, the boll weevil enters a reproductive dormancy state, in tropical regions, with important alterations in their reproduction organs. During this period, a remaining insect population survives feeding on a variety of other food sources, but the insects do not reproduce. We hypothesized that these alterations in the insect's reproductive organs are associated with the nutritional levels provided by alternative food sources during the cotton off‐season. To test our hypothesis, we first investigated food sources that sustain insect survival for long periods, such as weed species and fruits of cultivated crops. Then, we evaluated how various food sources affect the reproductive organs and reproductive capacity of the boll weevil. Among the alternative food sources tested, insect longevity was highest on banana (Musa paradisiaca L.), mango (Mangifera indica L.), papaya (Carica papaya L.), milkweed (Euphorbia heterophylla L.), and lilac tasselflower (Emilia sonchifolia L.). However, only banana and mango resulted in greater longevity than cotton squares. Banana was the preferred food and resulted in the highest levels of nutrients in the insects. Additionally, insects previously fed on banana made more oviposition punctures on cotton squares than those fed only on cotton squares, which resulted in a significantly higher number of emerged adults. Histological analysis of the insects' reproductive organs showed that feeding on papaya resulted in morphological changes and testicle degradation. In conclusion, we present evidence that boll weevils fed on alternative food sources (other than cotton squares or similar‐quality food) display a nutritional imbalance, associated with substantial alterations in the reproductive tissues of this insect, which may trigger the reproductive dormancy state.

Effects of cultural practices on weed community and seedbank dynamics in a potato rotation

ContextStagnant yields and declining soil health are common characteristics of high-intensity, low-residue cropping systems, such as potato, particularly in northeastern North America. Incorporating cultural practices including cover cropping and manure application is a way to combat declines in agroecosystem health and potato productivity. However, manure application and the use of cover crops may exacerbate weed issues through seedbank additions. ObjectiveThis study was aimed at investigating how the cultural practices of cover cropping and manure application and their associated management activities can alter weed community dynamics and weed seedbank composition in a northeastern North American potato rotation. MethodsThe study evaluated the use of eight cover crop mixtures—annual and perennial grasses and legumes—grown over two years with/without manure added in year one of the rotation. It also examined the effects of the cover crop mixtures and the presence/absence of manure on the weed community and on seedbank dynamics within a three-year potato rotation between 2019 and 2021. ResultsIn year one of the study and directly after application, manure plots had greater weed seedbank density and species richness; however, this did not result in greater in-season weed biomass. Manure application resulted in a gradual decline in weed seedbank density over time regardless of cover crop treatment. Further, manure application increased the in-season competitive ability of cover crops, resulting in greater weed suppression per unit of cover crop biomass. In contrast, in the absence of manure, weed seedbank density remained largely unchanged through time regardless of cover crop treatment. We found that management practices associated with annual and perennial cover crops had distinct ecological filtering effects throughout the rotation on the weed community and prevented the dominance of any particular species. ConclusionTogether, our results demonstrate that combining the cultural practices of annual or perennial cover cropping and manure application contributes to weed suppression and should be considered an important component of sustainable potato production.

Revisiting a pollen-transmitted ilarvirus previously associated with angular mosaic of grapevine

We report the characterization of a novel tri-segmented RNA virus infecting Mercurialis annua, a common crop weed and model species in plant science. The virus, named "Mercurialis latent virus" (MeLaV) was first identified in a mixed infection with the recently described Mercurialis orthotospovirus 1 (MerV1) on symptomatic plants grown in glasshouses in Lausanne (Switzerland). Both viruses were found to be transmitted by Thrips tabaci, which presumably help the inoculation of infected pollen in the case of MeLaV. Complete genome sequencing of the latter revealed a typical ilarviral architecture and close phylogenetic relationship with members of the Ilarvirus subgroup 1. Surprisingly, a short portion of MeLaV replicase was found to be identical to the partial sequence of grapevine angular mosaic virus (GAMV) reported in Greece in the early 1990s. However, we have compiled data that challenge the involvement of GAMV in angular mosaic of grapevine, and we propose alternative causal agents for this disorder. In parallel, three highly-conserved MeLaV isolates were identified in symptomatic leaf samples in The Netherlands, including a herbarium sample collected in 1991. The virus was also traced in diverse RNA sequencing datasets from 2013 to 2020, corresponding to transcriptomic analyses of M. annua and other plant species from five European countries, as well as metaviromics analyses of bees in Belgium. Additional hosts are thus expected for MeLaV, yet we argue that infected pollen grains have likely contaminated several sequencing datasets and may have caused the initial characterization of MeLaV as GAMV.

Weed Species’ Diversity and Composition as Shaped by the Interaction of Management, Site, and Soil Variables in Olive Groves of Southern Greece

Gaining a comprehensive understanding of how weed communities respond to both environmental and human-induced factors is of paramount importance in developing effective and ecologically sound weed control strategies. The objectives of the current research were to (1) assess the effect of the main weed management practices used in Greek olive groves on weed species’ diversity; (2) explore the filtering effect of management, site, and soil variables in determining weed species’ composition; and (3) shed light on the association between weed species’ composition and the diversity of the understory vegetation of olive groves. To accomplish these objectives, winter weed species’ coverage was assessed in 116 olive groves, both conventional and organic, distributed across three provinces in southern Greece. The investigation encompassed 29 explanatory variables, categorized into three groups: soil (22), management practices (6), and site conditions (1). It was confirmed that glyphosate use may lower biodiversity and species richness; however, this trend was not universal. In fact, the negative influence of the presence of Oxalis pes-caprae L. on species richness and diversity far outweighed the effect of spraying glyphosate. Redundancy analysis (RDA) revealed that among the 29 variables used to describe the ecological niche, eight (i.e., Mn, Mg, chemical spraying, mowing, rotary tiller, grazing, irrigation, and elevation) were significant and explained 21.5% of the total variation in weed species’ data. Interestingly, the soil Mn concentration was identified as the most influential one, highlighting the importance of soil micronutrients in determining weed species’ composition. The variation partitioning procedure demonstrated that the effect of the management variables on weed species’ composition accounted for 2.2 times the variance of soil variables and 4.5 times the variance of elevation. The present findings might help to enhance optimal management in olive groves that can sustain the biodiversity of flora and, in turn, provide various ecosystem services to agro-ecosystems.

The first record of milk thistle (Silybum marianum, Asteraceae) as an alien invasive weed species in Addis Ababa City, Ethiopia.

Abstract Since 2020, milk thistle Silybum marianum, an invasive weed species, has been widely observed in urban green spaces and roadsides in Addis Ababa city, Ethiopia. To plan future management activities, this study aimed to determine the current distribution status of the weed in urban green areas of Addis Ababa city. Weed surveys were conducted across 42 urban green sites located in Yeka, Lemi Kura, Bole, Nifas Silk-Lafto, Kolfie Keraniyo, Akaky Kality, and Gullele sub-cities during the main rainy season from June to September 2023. Urban green areas were selected using purposive sampling techniques. Field observations confirmed that Silybum marianum can invade and colonize a wide range of habitats and is highly competitive, posing a threat to important native plant species. High weed density rates and dense stands of weeds were recorded in the 34 urban green areas surveyed. The survey results strongly suggest implementing fast integrated weed management options such as mowing/tilling, weeding before the plant goes to seed, cutting (stems and/or seed heads), and burning (collected plant parts and/or seed heads) into a prepared burrow to minimize the spread of the weed and its ecological impacts. The purpose of this survey study is to provide information about Silybum marianum to minimize or avoid its distribution and associated impacts by following sustainable invasive weed management programs in the city before spreading to other cities in the country.

Control of multiple herbicide-resistant waterhemp (Amaranthus tuberculatus) with acetochlor-based herbicide mixtures in corn

Abstract Waterhemp is a summer annual, broadleaf weed with high fecundity, short seed longevity in the soil, and wide genetic diversity. Populations have evolved resistance to five herbicide modes of action (Groups 2, 5, 9, 14, and 27), which are present across southern Ontario; this has increased the challenge of controlling this competitive weed species in corn, the most important grain crop produced worldwide, and the highest value agronomic crop in Ontario. Acetochlor is a Group 15 soil-applied residual herbicide that has activity on many grass and broadleaf weeds but has yet to be registered in Canada. The objective of this study was to ascertain whether mixtures of acetochlor with flumetsulam, dicamba, atrazine, isoxaflutole/diflufenican, or mesotrione + atrazine applied preemergence would increase the control of multiple herbicide-resistant (MHR) waterhemp in corn. Five field trials were conducted between 2022 and 2023. No corn injury was observed. Acetochlor applied alone controlled MHR waterhemp 97% 12 weeks after application (WAA). All herbicide mixtures controlled MHR waterhemp similarly at ≥98% 12 WAA; there were no differences among herbicide mixtures. Flumetsulam, dicamba, and atrazine provided lower MHR waterhemp control than all other herbicide treatments and did not reduce density or biomass. Acetochlor reduced waterhemp density 98%, while the acetochlor mixtures reduced density similarly at 99 to 100%. This study concludes that the acetochlor mixtures evaluated provide excellent waterhemp control; however, control was not greater than acetochlor alone. Herbicides herbicide mixtures should be used as a best management practice to mitigate the evolution of herbicide resistance.

Emerging Perspectives on Non-Chemical Weed Management Tactics in Container Ornamental Production in the United States

Weeds are undesirable plants that can interfere with human activities and can hamper crop production and practices. The competition among ornamentals and weeds for space, nutrition, light, and moisture within a restricted area, such as in container production, can be intense and destructive. In response to increasing concerns regarding herbicide injuries and the effects of pesticide use on the environment, many growers are extremely interested in non-chemical pest-management approaches. There are various non-chemical strategies to control weeds in containers, which include scouting, sanitation practices, hand weeding, mulching, irrigation management, substrate stratification, mulch discs or geo discs, lid bags, and fertilizer placement. In a restricted growth environment, weeds have been shown to reduce crop growth significantly. Limited information is available on the effects of weed densities and container sizes on ornament–weed competition within containerized production and how the concepts of fertilizer placement can be used efficiently to control weeds in containers without using any herbicides on the ornamentals. There is an immediate need to evaluate the interference and competitive effects of pernicious weed species in container-grown ornamentals in the North Central United States and to develop effective non-chemical weed control strategies by altering fertilizer placement in container production.