Cyst nematodes of the genus Heterodera comprise 87 nominal species of economically important plant parasites, with the Avenae-group one of the largest, consisting of 12 species. Samplings for cyst nematode studies were carried out from multiple locations in Greece from 2013 to 2021. Cysts of the genus Heterodera were recovered from potato fields, athletic stadium turfgrass and a garlic field. The recovered populations were identified using sequences of 28S, ITS1 and ITS2 rRNA, mitochondrial COI, and nuclear Hsp90. Using integrative taxonomic approaches, the recovered isolates were identified as H. filipjevi (from potato fields and turfgrass), H. hordecalis (from potato fields) and H. mani (from a garlic field), representing new records for Greece. Population diversity within each species was investigated using statistical parsimony of ITS rRNA and mtCOI, revealing haplotypes of the Greek populations and their relationships to others found in the Mediterranean basin and worldwide.

Zinc oxide nanoparticles (ZnO NPs) exhibit diverse applications, including antimicrobial, UV-blocking, and catalytic properties, due to their unique structure and properties. This study focused on the characterization of zinc oxide nanoparticles (ZnO NPs) synthesized from Juglans regia leaves and their application in mitigating the impact of simultaneous infection by Meloidogyne arenaria (root-knot nematode) and Macrophomina phaseolina (root-rot fungus) in cowpea plants. The characterization of ZnO NPs was carried out through various analytical techniques, including UV–visible spectrophotometry, Powder-XRD analysis, FT-IR spectroscopy, and SEM-EDX analysis. The study confirmed the successful synthesis of ZnO NPs with a hexagonal wurtzite structure and exceptional purity. Under in vitro conditions, ZnO NPs exhibited significant nematicidal and antifungal activities. The mortality of M. arenaria juveniles increased with rising ZnO NP concentrations, and a similar trend was observed in the inhibition of M. phaseolina mycelial growth. SEM studies revealed physical damage to nematodes and structural distortions in fungal hyphae due to ZnO NP treatment. In infected cowpea plants, ZnO NPs significantly improved plant growth parameters, including plant length, fresh mass, and dry mass, especially at higher concentrations. Leghemoglobin content and the number of root nodules also increased after ZnO NP treatment. Additionally, ZnO NPs reduced gall formation and egg mass production by M. arenaria nematodes and effectively inhibited the growth of M. phaseolina in the roots. Furthermore, histochemical analyses demonstrated a reduction in oxidative stress, as indicated by decreased levels of reactive oxygen species (ROS) and lipid peroxidation in ZnO NP-treated plants. These findings highlight the potential of green-synthesized ZnO NPs as an eco-friendly and effective solution to manage disease complex in cowpea caused by simultaneous nematode and fungal infections.

During a survey of plant-parasitic nematodes in South Africa's Limpopo Province, two species of Helicotylenchus were identified, namely H. dihystera and H. pseudorobustus. The morphological and molecular characteristics of these species were found to be consistent with those of the known species. A phylogenetic analysis of Helicotylenchus populations based on 28S rDNA was conducted, and it was found that the H. dihystera identified in this study belonged to the same group as other H. dihystera specimens with a 1.00 posterior probability support. Moreover, phylogenetic analysis of H. pseudorobustus based on 18S rDNA placed the test population close to other H. pseudorobustus specimens with 0.97 posterior probability. Scanning electron microscopy (SEM) for Helicotylenchus species also revealed noticeable dissimilarities in the labial disc and lateral field of the tail region between the two species from the present study, including H. pseudorobustus, and H. dihystera. The redundancy analysis (RDA) showed that H. pseudorobustus had a correlation with pH and clay of the soil. In conclusion, despite the challenges associated with identifying Helicotylenchus species, SEM and rDNA markers can be considered as highly effective tools to distinguish the species correctly and accurately.

Turfgrass is a crop used extensively in athletic fields and golf courses in Maryland. A soil sample collected in July 2023 from an athletic field in Baltimore County, Maryland, part of a turfgrass nematode survey, contained Belonolaimus longicaudatus. In the southeastern United States, B. longicaudatus is an economically important pathogen of warm season turfgrass. The density was four individuals/100 cm3 of soil, and no visual symptoms were observed in the bermudagrass field. Morphological features and morphometrics of males and females were consistent with B. longicaudatus and placed the Maryland population in a subclade that was geographically represented by populations from north and west Florida, Texas, and South Carolina. Sequencing of the internal transcribed spacer region ITS1 and ITS2 and 28S large ribosomal subunit D2-23 expansion region confirmed the species' identity. Phylogenetic trees and parsimony network analysis placed the Maryland isolate in a large grouping of B. longicaudatus populations including those from Alabama, Delaware, Florida, Indiana, Mississippi, South Carolina, and Texas. To our knowledge, this is the first report of B. longicaudatus in Maryland.

Meloidogyne naasi Franklin, 1965, the barley root-knot nematode, was originally found in field crops such as cereals, grasses, and sugar beet (Beta vulgaris L.) in England and Wales, (Franklin,1965). This nematode is one of the most significant root-knot nematodes impacting grains in European countries (Santos et al. 2020). Among root-knot nematode species, M. naasi, exhibits a distinct preference for grasses, with documented impacts on turfgrasses leading to reduced growth and vigor (Skantar et al., 2023; Cook and Yeates, 1993). In September 2022, root-knot nematode females and second-stage juveniles (J2) were recovered from roots of fowl manna grass, Glyceria striata (Lam.) Hitchc., during a nematode survey on natural vegetation at the Allegheny National Forest (41°30'13.8"N 79°09'46.2"W). Second-stage juvenile specimens were recovered from soil using sugar centrifugal flotation (Jenkins, 1964). Small galls with egg masses were dissected from fowl manna grass roots originally collected from the surveyed areas. In parallel, five plants of non-infected fowl manna grass were placed in a pot in the greenhouse using naturally nematode-infested soil collected from the same forested area. Small galls and female specimens recovered from these plants were dissected and processed for further analyses. Female and J2 were fixed in 3% formaldehyde solution and processed to glycerin (Golden, 1990; Hooper, 1970). The specimens were examined by light microscopy, morphometric measurements, and molecular markers, which included the D2-D3 region of the large ribosomal subunit 28S, and the rDNA internal transcribed spacer region (ITS). The perennial pattern of five females analyzed morphologically were consistent to the patterns observed for M. naasi. The perennial patterns had coarse ridges on the cuticle in dorsal region forming broken irregular lines around anal and phasmid area. We also noted a prominent fold that covered some of the anus and showed a curved line between vulval slit and phasmids, typical of M. naasi. The area around the vulval area had a few or no striae except for a few lines radiating from the vulval slit as in the original description. Measurements of ten J2 had a body length ranged between 380 and 410 µm, stylet 11-13 µm, tail 50-70 µm long with a hyaline tail terminus between 12-22 µm in length, 4 lines in the lateral field, a and c ratio between 29.23-35.91 and 5.79-7.9 fitting the original description by Franklin, 1965 and others populations found in the USA (Skantar et al., 2023). The matrix codes for the female specimes are A32, B324, C3, D3 and for J2's A2, B21, C123, D1, E3, F12 (Subbotin et al., 2021). The amplified DNA fragments were sequenced, resulting in an 726 bp fragment flanked by the D2-D3 primers (PP097762), while for the ITS primers an 634 bp fragment was obtained (PP092043). Both generated sequences for the specimens collected in Pennsylvania revealed >99% similarity to M. naasi sequences deposited at GenBank, and therefore, validating the morphological analyses. Based on both morphological and molecular analyses the specimens collected in the state of Pennsylvania were identified as M.naasi. To our knowledge, this is the first report of this species from this state and being associated with naturally infected fowl manna grass.

Root-knot nematodes (Meloidogyne spp., RKN) are among the most destructive endoparasitic nematodes worldwide, often leading to a reduction of crop growth and yield. Insights into the dynamics of host-RKN interactions, especially in varied biotic and abiotic environments, could be pivotal in devising novel RKN mitigation measures. Plant growth-promoting bacteria (PGPB) involves different plant growth-enhancing activities such as biofertilization, pathogen suppression, and induction of systemic resistance. We summarized the up-to-date knowledge on the role of PGPB and abiotic factors such as soil pH, texture, structure, moisture, etc. in modulating RKN-host interactions. RKN are directly or indirectly affected by different PGPB, abiotic factors interplay in the interactions, and host responses to RKN infection. We highlighted the tripartite (host-RKN-PGPB) phenomenon with respect to (i) PGPB direct and indirect effect on RKN-host interactions; (ii) host influence in the selection and enrichment of PGPB in the rhizosphere; (iii) how soil microbes enhance RKN parasitism; (iv) influence of host in RKN-PGPB interactions, and (v) the role of abiotic factors in modulating the tripartite interactions. Furthermore, we discussed how different agricultural practices alter the interactions. Finally, we emphasized the importance of incorporating the knowledge of tripartite interactions in the integrated RKN management strategies.

Summary A new needle nematode species, Longidorus patuxentensis n. sp., was collected along the banks of the Western Branch Patuxent River from Upper Marlboro, MD, USA, and described herein. Female body length of the new species ranges from 3.8 to 5.2 mm, with a set off lip region by depression, 77-92 μ m long odontostyle, 40-53 μ m long odontophore, vulva located at 46.3-50.1% and tail conoid with bluntly rounded tip. The new species has four juvenile developmental stages and no males. It looks morphologically similar to L. breviannulatus , L. elongatus , L. martini , L. americanus , L. grandis , L. sabalanicus and L. sturhani by having a ventrally curved to spiral body, generally similar lip region and conoid tail with a rounded terminus, but differs from these species by the odontostyle, odontophore, total stylet length and a few other characters. Phylogenetic analysis of the D2-D3 expansion segments of 28S rRNA gene sequences placed L. patuxentensis n. sp. in a clade with L. litchi , L. fangi , L. jonesi , L. diadecturus and Longidorus sp. The D2-D3 sequence of L. patuxentensis n. sp. was identical to that of Longidorus sp.5 collected from Juglans sp. growing in Butte County, California, USA. The D2-D3 of 28S and ITS1 rRNA and COI gene sequences indicated that the Maryland and California populations belong to the same species, described herein as L. patuxentensis n. sp.

Plant-parasitic nematodes are microscopic worms that cause an estimated $10 billion of crop losses each year in the United States and over $100 billion globally. The current study offers both morphological and molecular insights into a Boleodorus volutus population recovered from the rhizosphere soil of medicinal hemp cultivated in a field located in Baltimore County, MD in 2019. Nematodes were extracted from 100 cm3 3 soil through sieving and decanting followed by sucrose centrifugal flotation. Boleodorus volutus was identified by anatomical features and measurements of females and males. Molecular sequencing and phylogenetic analysis of 18S and 28S rDNA markers were used to characterize B. volutus, , which represents a new record of this species from the United States.

In the present era of climatic shift, due to many natural and anthropogenic activities, it is imperative to use eco-friendly products to improve the soil quality and production of food crops, including okra (Abelmoschus esculentus L. Moench). As chemical nematicides are damaging to the environment, there is a need for developing alternate eco-friendly measures for the management of root-knot nematodes (Meloidogyne spp.) which cause major losses to vegetable crops globally. In this regard, a pot experiment was performed under optimal environmental con-ditions to study the nematicidal properties of fly ash (FA) on okra. Various grades of fly ash were applied in pots containing autoclaved soil before seed sowing. Results indicated that the application of 20% FA level (80:20 w/w field soil: fly ash) was found most beneficial for soil health, improving growth and yield traits, physio-biochemical attributes, and antioxidant properties of okra by alleviating the harmful effects of root-knot nem-atode (Meloidogyne incognita Kofoid and White, 1919; Chitwood, 1949) compared to other treatments. Stomatal attributes of okra also improved at 20% FA level, as demonstrated by scanning electron microscopy. Galls, egg mass formation and reproduction factor of M. incognita was significantly reduced at 20% FA level. Moreover, laser confocal microscopy combined with scanning electron microscopy revealed that 20% FA application enhanced root cell viability and detoxifies the accumulation of reactive oxygen species.

Summary Plant-parasitic nematodes limit potato production by feeding on roots, reducing tuber yield and quality, and resulting in poor growth. Dagger nematodes ( Xiphinema spp.) can pose a significant threat to crop production even in low numbers. Dagger nematodes have been reported in North Dakota, USA, potato fields. In this study, a dagger nematode species was identified and its reproduction potential in 21 potato cultivars was evaluated. The dagger nematode was identified as X. americanum via morphometric measurements and DNA sequence analysis. At the molecular level, D2-D3 of 28S ribosomal RNA (rRNA) and internal transcribed spacer (ITS)-regions of rDNA were targeted. Sequencing data of D2-D3 (749 bp) showed 98.18% similarity with three isolates of X. americanum . ITS sequence (860 bp) analysis showed 97.68% similarity with an isolate of X. americanum but lower similarity with other species of Xiphinema . The phylogenetic analysis of ITS region further confirmed the species of dagger nematode as X. americanum . Using naturally infested soil, two glasshouse experiments were conducted to assess the reproduction rate of X. americanum on 21 potato cultivars belonging to four distinct market potato classes (yellow, red, white and russet). The reproduction rates were found to vary among the potato classes and cultivars. Numerically, X. americanum population density was higher in ‘Soraya’, whereas ‘Ranger Russet’, ‘Manistee’, ‘Kennebec’, ‘Russet Norkotah 278’, ‘Modoc’, ‘Pomerelle Russet’ and ‘Dakota Rose’ reduced nematode reproduction in both trials. This is the first study demonstrating the reproduction of X. americanum in potato cultivars and could be helpful to manage dagger nematodes.

Specimens of a tylenchid nematode were recovered in 2019 from soil samples collected from a corn field, located in Pickens County, South Carolina, USA. A moderate number of Tylenchus sp. adults (females and males) were recovered. Extracted nematodes were examined morphologically and molecularly for species identification, which indicated that the specimens of the tylenchid adults were a new species, described herein as Tylenchus zeae n. sp. Morphological examination and the morphometric details of the specimens were very close to the original descriptions of Tylenchus sherianus and T. rex . However, females of the new species can be differentiated from these species by body shape and length, shape of excretory duct, distance between anterior end and esophageal intestinal valve, and a few other characteristics given in the diagnosis. Males of the new species can be differentiated from the two closely related species by tail, spicules, and gubernaculum length. Cryo-scanning electron microscopy confirmed head bearing five or six annules; four to six cephalic sensilla represented by small pits at the rounded corners of the labial plate; a small, round oral plate; and a large, pit-like amphidial opening confined to the labial plate and extending three to four annules beyond it. Phylogenetic analysis of 18S rRNA gene sequences placed Tylenchus zeae n. sp. in a clade with Tylenchus arcuatus and several Filenchus spp., and the mitochondrial cytochrome oxidase c subunit 1 ( COI ) gene region separated the new species from T. arcuatus and other tylenchid species. In the 28S tree, T. zeae n. sp. showed a high level of sequence divergence and was positioned outside of the main Tylenchus-Filenchus clade.

Root-knot nematodes (Meloidogyne spp.) are sedentary endoparasites that cause severe economic losses to agricultural crops globally. Due to the regulations of the European Union on the application of nematicides, it is crucial now to discover eco-friendly control strategies for nematode management. Biocontrol is one such safe and reliable method for managing these polyphagous nematodes. Biocontrol agents not only control these parasitic nematodes but also improve plant growth and induce systemic resistance in plants against a variety of biotic stresses. A wide range of organisms such as bacteria, fungi, viruses, and protozoans live in their natural mode as nematode antagonists. Various review articles have discussed the role of biocontrol in nematode management in general, but a specific review on biocontrol of root-knot nematodes is not available in detail. This review, therefore, focuses on the biocontrol of root-knot nematodes by discussing their important known antagonists, modes of action, and interactions.

The North American beech leaf disease (BLD) nematode, Litylenchus crenatae mccannii Handoo, Li, Kantor, Bauchan, McCann, Gabriel, Yu, Reed, Koch, Martin and Burke, 2020, is recognized as a newly emergent nematode species that causes BLD in beech trees (Fagus spp.) in North America (Carta et al. 2020; Kantor et al. 2022a). Since the first report of BLD on American beech (Fagus grandifolia Ehrh) within the Lake County, located at the north-eastern corner of the state of Ohio in 2012 (Carta et al. 2020), the disease has rapidly spread to other US states and a province in Canada (Erwing et al. 2018; Carta et al 2020; Marra and LaMondia 2020; Reed et al 2020; Kantor et al. 2022b). Currently, besides Ohio, this nematode has been reported in Pennsylvania, New York, Connecticut, Massachusetts, Maine, Rhode Island, New Jersey, West Virginia, and Virginia, as well as Ontario, Canada. Different life stages of L. crenatae mccannii were isolated from symptomatic American beech leaves from an isolated natural maple-beech stand in rural Saint Clair Cty., Michigan, US; presenting typical symptoms of beech leaf disease, i.e., swelling and darkening of interveinal leaf tissues. Samples were taken to the Forest Pathology Laboratory at Michigan State University where L. crenatae mccannii presence was confirmed in the leaves after which samples were sent to the Mycology and Nematology Genetic Diversity and Biology Laboratory (USDA-ARS) in Beltsville, Maryland for official confirmation. Nematodes were identified based on morphology and sequence analysis of the internal transcribed spacer (ITS), and the D2D3 region of the 28S large subunit ribosomal DNA. To validate the morphological identification two different ribosomal DNA loci were amplified, sequenced and the phylogenetic relationships were generated. The amplification yielded fragments of 784 and 741 bp flanked by the ITS (GenBank accession no. OP689654) and D2D3 (GenBank accession no. OP689710) primers, respectively. The sequences obtained for the specimens collected in Michigan revealed 100% similarity to L. crenatae mccannii sequences obtained from specimens collected from other geographical areas in the US, and therefore validating the morphological analyses as well. The ITS sequence shared a 99.75% similarity with the subspecies L. crenatae (GenBank accession no. LC383724.1), and 90.53% similarity to L. coprosma Zhao, Davies, Alexander and Riley, 2011 (GU727548.1). While the D2D3 sequences of both L. crenatae subspecies revealed a 100% similarity (versus LC383725.1), they revealed 95.35% similarity to L. coprosma (KY679564.1). Since the first confirmed detection of BLD in June 2022 in St. Clair Cty, BLD has been reported in Oakland and Wayne Ctys (7 reports total across the three counties), suggesting BLD spread in the SE of Michigan. BLD confirmation was based on either physical symptoms (leaf banding), and/or the presence of the beech leaf nematode by morphological or molecular confirmation. The presence of the beech leaf nematode in symptomatic leaves follow the results obtained by Carta et al. (2020) after inoculation of beech seedlings with L. crenatae mccannii. Based on both morphological and molecular analyses the specimens collected in the state of Michigan were identified as L. crenatae mccannii. To our knowledge, this is the first report of this species in conjunction with symptomatic F. grandifolia leaves in this state.

In Egypt, phytoparasitic nematodes have been recognized as important plant pests and major constraints to agricultural production especially in sandy and coarse soils. A review of the historical nematode records indicate the occurrence of about 60 genera and 170 species of phytoparasitic nematodes found on crop plants, grasses, and weeds. Some of these nematode species such as Heterodera goldeni were described from Egypt, while others such as H. rosii, Globodera rostochiensis, and Xiphinema rivesi were recorded for the first time in Egypt and other African countries. Important phytoparasitic nematodes found in Egypt include species of Tylenchulus, Globodera, Heterodera, Xiphinema, Hoplolaimus, Criconemella, Mesocriconema, Pratylenchus, Meloidogyne, Helicotylenchus, and Tylenchorhynchus. Among these, Tylenchulus, Heteroderidae, Pratylenchus, Meloidogyne, and Helicotylenchus were the most frequently encountered nematode genera in Egypt.

Barley root-knot nematode, Meloidogyne naasi Franklin, 1965, is one of the most important pest nematodes infecting monocots (Franklin, 1965). Two-inch core soil samples collected from a golf course in Ada County, Idaho were submitted for identification in November of 2019. A high number of Meloidogyne sp. juveniles were recovered from both soil samples using sieving and decantation followed by the sugar centrifugal flotation method. They were examined by light microscopy, morphometric measurements, and multiple molecular markers, including the ribosomal 28S D2-D3 and intergenic spacer 2 (IGS-2) regions, mitochondrial markers cytochrome oxidase I (COI) and the interval from COII to 16S, and the protein-coding gene Hsp90. Morphometrics as well as BlastN comparisons with other root-knot nematode sequences from GenBank were consistent with identification as M. naasi. Phylogenetic trees inferred from 28S, IGS-2, COI, or Hsp90 alignments each separated the Idaho population into a strongly supported clade with other populations of M. naasi, while the COII-16S interval could not resolve M. naasi from M. minor. This report represents the first morphological and molecular characterization of Meloidogyne naasi from turfgrass in Idaho.