Rotylenchulus Reniformis Research Articles

Comprehensive overview of host plant resistance and its progress in wilt resistance in castor bean (Ricinus communis L.)

Castor bean, a non-edible monotypic species known for its unique hydroxy fatty acid, is susceptible to a range of pathogens. Wilt caused by Fusarium oxysporum f. sp. ricini is the most complex and destructive disease. Chemical control of wilt has proven ineffective due to the systemic nature of the disease and the seed and soil borne nature of the pathogen. Physical, chemical, biological, and integrated management methods have shown only limited success in controlling wilt. Host plant resistance, however, stands out as the most promising strategy, offering a viable pathway for the genetic improvement of castor beans for wilt resistance. Screening techniques are well established, and several resistant donors have already been identified. While significant progress has been made in understanding the inheritance of wilt resistance, a complete understanding of its genetic mechanisms still requires further research. Single Nucleotide Polymorphism (SNP) markers and genomic regions linked to wilt resistance have been successfully identified. Reniform nematode (Rotylenchulus reniformis) has been identified as a predisposing factor for wilt, and genomic regions linked to nematode resistance have also been identified. However, Marker-assisted selection has not yet been utilized to develop wilt-resistant castor varieties. Further research is required to explore the pathogen diversity, host-pathogen interactions, and mechanisms underlying wilt resistance including the metabolites responsible for preventing the emergence of new pathogenic races and ensuring long-term protection against wilt.

The Distribution of Reniform Nematode (Rotylenchulus reniformis) in Cotton Fields in Central Queensland and Population Dynamics in Response to Cropping Regime.

Reniform nematode (Rotylenchulus reniformis) causes significant yield loss in cotton worldwide. In 2012, its detection in the Dawson-Callide region of Central Queensland prompted extensive surveys of cotton fields. The nematode was confirmed in 68% of sampled fields, with populations ranging from 2 to 3870 R. reniformis/200 mL of soil. Soil monitoring revealed increasing populations associated with consecutive cotton crops. However, when corn or sorghum replaced cotton, soil nematode populations significantly decreased. A two-year replicated field trial demonstrated that growing a non-host crop (such as biofumigant sorghum 'Fumig8tor', grain sorghum, or corn) significantly reduced nematode populations in the top 15 cm of soil compared to cotton. Unfortunately, when cotton was replanted the following season, nematode populations rebounded regardless of the previous crop. Only the 'Fumig8tor'-cotton rotation resulted in significantly lower nematode populations than continuous cotton. Vertical soil sampling showed that rotating with a non-host crop significantly reduced nematode densities to a depth of 100 cm compared to cotton. However, when the field was replanted with cotton, nematode populations recovered, unaffected by cropping or soil depth. This study emphasises the importance of monitoring reniform nematodes in cotton soils for early detection and defining distribution patterns within a field, which may improve the effectiveness of management practices. These results suggest that one rotation out of cotton is not sufficient, as populations return to high levels when cotton is grown again. Therefore, two or more rotations out of cotton should be considered to manage this nematode.

Summarized Distribution of the Reniform Nematode, Rotylenchulus reniformis, in Field Crops in the United States

The reniform nematode, Rotylenchulus reniformis Linford & Oliveira, 1940 is one of the most important yield-limiting pathogens of agronomic and vegetable crops across tropical and subtropical climates worldwide. Monitoring the distribution of nematode species across the United States can be helpful to identify areas where scouting and management are needed. Given that R. reniformis has been detected in new states and new counties on field crops since the last report nearly 35 years ago, an updated map is needed. The map created herein is an updated resource summarizing the distribution of R. reniformis on field crops (e.g., agronomic and vegetable crops) at the county level across the contiguous United States.

Management of Rotylenchulus reniformis in soybean using genetic and biological approaches

Management of Rotylenchulus reniformis in soybean using genetic and biological approaches

Sensitivity of Meloidogyne incognita and Rotylenchulus reniformis to Cyclobutrifluram.

Cyclobutrifluram, a succinate dehydrogenase inhibitor fungicide, is being evaluated as a seed-applied nematicide in cotton and soybean to manage plant-parasitic nematodes. Currently, there is no information on the toxicity, ovicidal activity, nematode recovery, or effects on nematode infection for Meloidogyne incognita or Rotylenchulus reniformis after exposure to low concentrations of cyclobutrifluram. Nematode toxicity assays were performed in aqueous solutions of cyclobutrifluram, and root infection assays were conducted on tomato. Nematode paralysis was observed after 2 h of exposure to 0.5 μg/ml cyclobutrifluram for both nematode species. Based on an assay of nematode motility, the 2-h effective concentration of fungicide required for 50% growth inhibition (EC50) value for M. incognita and R. reniformis was 0.48 and 1.07 μg/ml, respectively. In a comparable assay with a similar nematicide, continuous exposure to 0.5 μg/ml cyclobutrifluram for 24 h resulted in at least 45% more immotile nematodes for both species compared with those treated with 0.5 μg/ml fluopyram. Continuous exposure to concentrations greater than 1.0 μg/ml suppressed hatching for both species compared with the water control. Nematode recovery from paralysis was greater than 80% for M. incognita and R. reniformis 24 h after nematodes were rinsed and removed from a 1-h treatment to their respective 2-h EC50 concentrations. Nematode infection of tomato roots was reduced following a 1-h treatment with aqueous solutions of cyclobutrifluram, ranging from 0.12 to 0.48 μg/ml for M. incognita and 0.27 to 1.07 μg/ml for R. reniformis. Overall, the toxicity of cyclobutrifluram to these nematode species was greater than that of fluopyram, and although the effects of cyclobutrifluram were reversible, low concentrations were effective at reducing the ability of both nematodes to infect tomato roots.

Molecular Characterization of Sweet Potato Plant Parasitic Nematodes in Different Agroecological Zones of Kirinyaga County, Kenya

Plant parasitic nematodes (PPNs) are widely distributed in all agroecological zones (AEZs) within Kenya. Plant parasitic nematodes are important pests of many cultivated crops and they exert a detrimental influence on a wide range of vascular plants, leading to significant crop losses by reducing both quantity and quality of the yield. However, due to inadequate taxonomic descriptions and a low number of diagnostic features, the morphological diagnosis of many species remains a challenge. The objective of this study was to characterize PPNs associated with sweet potatoes in different agroecological zones of Kirinyaga County, Kenya, using 18S rRNA gene sequencing. Seventy-seven soil samples from sweet potato tubers rhizosphere were collected from different agroecological zones and nematodes were extracted using Baermann’s technique. Thirteen nematode isolates were obtained and only seven could be identified morphologically to their genus level based on their distinct phenotypes. Seven isolates that could not be identified through the microscope were advanced to molecular sequencing. The nematode DNA were extracted and the PCR amplification and sequencing of 18S rRNA gene carried out. The study identified six PPN species, including Mylonchulus hawaiiensis, Aporcelaimellus nigeriensis, Rotylenchulus reniformis, Rotylenchulus borealis, Aporcella femina, Heterodera dunensis, and a predatory nematode (Dorylaimus aff. stagnalis) as part of the soil biota. This study showed significant distribution of plant parasitic nematodes across the agroecological zones. Thus, the occurrence of a nematode species complex in sweet potato farms requires the development of specific and appropriate sustainable control strategies.

Enhancing Reniform Nematode Management in Sweetpotato by Complementing Host-Plant Resistance with Nonfumigant Nematicides.

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) adversely impacts the quality and quantity of sweetpotato storage roots. Management of R. reniformis in sweetpotato remains a challenge because host plant resistance is not available, fumigants are detrimental to the environment and health, and crop rotation is not effective. We screened a core set of 24 sweetpotato plant introductions (PIs) against R. reniformis. Four PIs were resistant, and 10 were moderately resistant to R. reniformis, suggesting these PIs can serve as sources of resistance for sweetpotato resistance breeding programs. PI 595869, PI 153907, and PI 599386 suppressed 83 to 89% egg production relative to the susceptible control 'Beauregard', and these PIs were employed in subsequent experiments to determine if their efficacy against R. reniformis can be further increased by applying nonfumigant nematicides oxamyl, fluopyram, and fluensulfone. A 34 to 93% suppression of nematode reproduction was achieved by the application of nonfumigant nematicides, with oxamyl providing the best suppression followed by fluopyram and fluensulfone. Although sweetpotato cultivars resistant to R. reniformis are currently not available and there is a need for the development of safer yet highly effective nonfumigant nematicides, results from the current study suggest that complementing host plant resistance with nonfumigant nematicides can serve as an important tool for effective and sustainable nematode management.

Registration of upland cotton recombinant inbred lines MS‐4857 and MS‐4878 with resistance to root‐knot nematode and reniform nematode

AbstractThe root‐knot nematode (RKN; Meloidogyne incognita Kofoid & White) and reniform nematode (RN; Rotylenchulus reniformis Linford & Oliveira) are serious pathogens of upland cotton (Gossypium hirsutum L.) that significantly affect yield and fiber quality annually. Here, we describe two upland cotton germplasm lines that have combined resistance to RKN and RN while maintaining good yield and fiber quality traits. Upland germplasm lines MS‐4857 (Reg. no. GP‐1147, PI 704481) and MS‐4878 (Reg. no. GP‐1148, PI 704482) are F6 recombinant inbred lines from a cross between M240 RNR (RKN resistant) and MT2468 Ren1 (moderately RN resistant). These lines are highly resistant to RKN and show ∼30% fewer RN eggs g−1 root than the MT2468 Ren1 parent due to significantly improved root system development compared with MT2468 Ren1. Yield and fiber quality traits are equivalent or superior to the parental lines. The upland‐derived RN resistance in these lines provides a valuable alternative source of resistance to cotton breeding programs, especially in combination with high‐level RKN resistance.

Prevalence of Plant-Parasitic Nematodes in Horticultural Fields of Assam Agricultural University: Jorhat Campus, India

A random survey of the horticultural crops was conducted to assess the nematode community structure in the Experimental field of Department of Horticulture, AAU, Jorhat during Rabi and Kharif season, 2022-2023. Soil and root samples, representing 200 locations were examined. Analysis of 200 soil and root samples collected from the root rhizosphere of different vegetable, fruit and ornamental crops showed the presence of root-knot nematode(Meloidogyne incognita), reniform nematode (Rotylenchulus reniformis), root-lesion nematode (Pratylenchus spp.), lance nematode (Hoplolaimus spp.), spiral nematode (Helicotylenchus spp.), stunt nematode (Tylenchorhynchus spp.) along with Criconema spp., Xiphinema spp, Longidorus spp., free-living nematodes, mycophagous nematodes and predatory nematodes. Among all the isolated plant-parasitic nematodes, root-knot nematode (Meloidogyne incognita) was found to be more abundant with prominence value of 136.7, 81.3 and 76.3 in vegetable crops, fruit crops and ornamental crops, followed by Helicotylenchus spp. and Rotylenchulus reniformis. The prominence value of reniform nematode (Rotylenchulus reniformis) was found to be 90.5, 54.1 and 54.1 in vegetable crops, fruit crops and ornamental plants respectively.

In vitro Evaluation of Rhizobacteria Isolated from Different Oilseed Growing Areas against Fusarium oxysporum f.sp. ricini and Rotylenchulus reniformis Infesting Castor

A study was conducted to evaluate the efficacy of 108 rhizobacterial isolates collected from different Oilseed rhizospheres against the wilt pathogen, Fusarium oxysporum f.sp. ricini and reniform nematode, Rotylenchulus reniformis under in vitro conditions. Among the 108 isolates tested, four isolates were reported to inhibit the radial growth of Fusarium oxysporum f.sp. ricini by more than 50% and caused more than 80% of juvenile (J4) mortality of reniform nematode. The effective rhizobacterial isolates were subjected to morphological and biochemical characterization for the assessment of plant growth promoting traits and bio-control properties.

Study on the Population and Composition of Parasitic Nematodes related to Da Xanh Pomelo (Citrus maxima) in Tien Giang Province, Vietnam

Da Xanh grapefruit is a fruit tree with many nutrients and high economic value. However, nematode attack is one of the factors that limit productivity. Based on the approach of surveying gardens with symptoms of yellow leaves and root rot, collect and analyze samples. Results of surveying the composition of plant parasitic nematodes in Tien Giang province discovered 11 genera belonging to 8 families of plant parasitic nematodes present in the soil and root zone of Da Xanh grapefruit trees. Thus, 12 nematode species have been identified including: Aphelenchus avenae, C. onoensis, Helicotylenchus crenacauda, H. digonicus, P. coffeae, Rotylenchulus reniformis, Rotylenchus dalhousiensis, Tylenchorhynchus leviterminalis, Tylenchulus semipenetrans, Xiphinema insigne, X. longicaudatum. The species T. semipenetrans appeared at 80% and 76.67% in soil and root samples, which is an important species that needs to be controlled; P. coffeae and R. reniformis are dominant in roots and should be of concern as populations increase. Besides, it also shows that in garden samples with yellow leaf and root rot symptoms, the population of T. semipenetrans nematodes is very high compared to previous studies.

A 2‐year, multi‐county survey of plant‐parasitic nematodes in North Carolina flue‐cured tobacco

AbstractNorth Carolina is the leading producer of flue‐cured tobacco (Nicotiana tabacum L.) in the United States. Production in the state is threatened by numerous plant‐parasitic nematodes, including Meloidogyne spp. (root‐knot), Globodera tabacum (tobacco cyst), Pratylenchus spp. (lesion), Rotylenchulus reniformis (reniform), and Tylenchorhynchus spp. (stunt) nematodes. The invasive Meloidogyne enterolobii is also a major threat as it can infect tobacco varieties carrying the Rk gene, which conditions resistance to other Meloidogyne species. To gain an updated understanding of which nematode taxa are present in tobacco production and investigate distribution of M. enterolobii in North Carolina, a 2‐year survey was conducted. From 2021 to 2022, 188 fields were sampled across 24 tobacco‐growing counties. Samples were assayed for identification and quantification of nematodes at the genus level; where Meloidogyne spp. was identified, molecular testing was used to determine the species. Data were also collected on the previous crop and tobacco variety grown. In both years, lesion, root‐knot, dagger, and stunt nematodes were found in the highest incidence among samples. In 2022, M. enterolobii was identified in a single sample each from Granville and Pitt counties; this is the first report of M. enterolobii from Granville County. Tobacco variety NC 196 and soybean were the most common variety and previous crop grown, respectively, in both years of the survey. Tobacco variety did not have an effect on nematode population density. The previous crop had a significant effect on root‐knot and spiral nematodes in 2021, and lesion and stubby root nematodes in 2022.

Transcriptome Analysis of Resistant Cotton Germplasm Responding to Reniform Nematodes.

Reniform nematode (Rotylenchulus reniformis) is an important microparasite for Upland cotton (Gossypium hirsutum L.) production. Growing resistant cultivars is the most economical management method, but only a few G. barbadense genotypes and some diploid Gossypium species confer high levels of resistance. This study conducted a transcriptome analysis of resistant genotypes to identify genes involved in host plant defense. Seedlings of G. arboreum accessions PI 529728 (A2-100) and PI 615699 (A2-190), and G. barbadense genotypes PI 608139 (GB 713) and PI 163608 (TX 110), were inoculated with the reniform nematode population MSRR04 and root samples were collected on the fifth (D5) and ninth (D9) day after inoculation. Differentially expressed genes (DEGs) were identified by comparing root transcriptomes from inoculated plants with those from non-inoculated plants. Accessions A2-100 and A2-190 showed 52 and 29 DEGs on D5, respectively, with 14 DEGs in common, and 18 DEGs for A2-100 and 11 DEGs for A2-190 on chromosome 5. On D9, four DEGs were found in A2-100 and two DEGs in A2-190. For GB 713, 52 and 43 DEGs were found, and for TX 110, 29 and 117 DEGs were observed on D5 and D9, respectively. Six DEGs were common at the two sampling times for these genotypes. Some DEGs were identified as Meloidogyne-induced cotton (MIC) 3 and 4, resistance gene analogs, or receptor-like proteins. Other DEGs have potential roles in plant defense, such as peroxidases, programmed cell death, pathogenesis related proteins, and systemic acquired resistance. Further research on these DEGs will aid in understanding the mechanisms of resistance to explore new applications for the development of resistant cultivars.

Cotton host resistance as a tool for managing Rotylenchulus reniformis in Louisiana.

The reniform nematode, Rotylenchulus reniformis, is a major yield-limiting pest of upland cotton (Gossypium hirsutum) in the United States that has been steadily increasing in incidence in many states. Reniform nematode-resistant cotton cultivars have recently become commercially available for cotton producers; however, few field trials have evaluated their efficacy as a nematode management tool. The aim of this study was to evaluate reniform nematode population development, plant growth, and seed cotton yield of reniform nematode-resistant cotton cultivars in two nematode-infested fields in Louisiana. Replicated small-plot field trials were conducted in St. Joseph, LA (NERS field) and Winnsboro, LA (MRRS field) during the 2022 and 2023 growing seasons. In 2022, cultivars evaluated included: (1) DP 1646 B2XF (susceptible/tolerant), (2) DP 2141NR B3XF (resistant), (3) PHY 332 W3FE (resistant), (4) PHY 411 W3FE (resistant), and (5) PHY 443 W3FE (resistant). In 2023, an additional susceptible cotton cultivar, PHY 340 W3FE, was also included. All nematode-resistant cotton cultivars evaluated provided suppression of reniform nematode population development relative to that of the susceptible cotton cultivars, with suppression of nematode soil population densities at harvest ranging from 49 - 81% relative to DP 1646 B2XF. The resistant cultivar PHY 411 W3FE provided the most consistent suppression of reniform nematode population development, reducing reniform nematode soil population densities at harvest in both field locations and both trial years. In contrast, DP 2141NR B3XF only reduced soil population densities at harvest in the NERS field in 2023. Despite relatively consistent nematode suppression and improvements in plant vigor ratings and canopy coverage associated with the resistant cotton cultivars, a yield increase was only observed with PHY 332 W3FE and PHY 411 W3FE planted at the NERS field in 2023. Despite strong resistance to reniform nematode in the evaluated cotton cultivars, nematode soil population densities still increased during the growing season in plots planted with resistant cotton cultivars, emphasizing the need for additional management tactics to use alongside host resistance. This study indicates that new reniform nematode-resistant cotton cultivars show promising potential to reduce nematode population development during the growing season in Louisiana.

Occurrence of the Reniform Nematode Rotylenchulus reniformis Parasitizing Cucumber and Eggplant in Mexico

Cucumber and eggplant exhibiting symptoms of root necrosis and yellowing foliage were observed in two shade houses in Culiacán, Sinaloa, Mexico. Through morphological characterization and molecular analysis of the coxI sequences, Rotylenchulus reniformis was identified as the causal agent. This identification was further confirmed by the infection and reisolation of the nematodes. This is the first report of R. reniformis causing diseases in cucumber and eggplant in Mexico.

Detection of Resistance, Susceptibility, Tolerance, and Virulence in Plant-Nematode Interactions: Part II: Migratory and Semi-endoparasitic Nematodes.

This chapter is a continuation of Chap. 3 . Initially, protocols for the screening of several host plants to their major migratory and semi-endoparasitic nematodes are presented. Then the problems related to assessment of tolerance to these nematodes are described, followed by the determination of nematode races. The main plant-nematode interactions considered are annuals and perennials to Pratylenchus spp.; banana to Radopholus similis; potato to Nacobbus aberrans; several crop plants, including onion, alfalfa, clovers, and potato, to Ditylenchus dipsaci; broad bean to D. giga; potato and sweet potato to D. destructor; peanut to D. africanus; rice to D. angustus and Aphelenchoides besseyi; wheat to Anguina tritici; different plants to Rotylenchulus reniformis; and citrus to Tylenchulus semipenetrans. Schemes to identify races or biotypes are only presented for D. dipsaci and T. semipenetrans. The occurrence of pathotypes in other nematode species is also discussed. Finally, comments are made on ectoparasitic nematodes.

The identification, characterization, and management of Rotylenchulus reniformis on Cucumis melo in China

The reniform nematode, Rotylenchulus reniformis, is a sedentary root parasite that poses a significant threat to agricultural production in tropical and subtropical regions worldwide. In 2021–2022, a population of R. reniformis was identified in a melon greenhouse in Jimo District, Qingdao, China. To characterize this population, we employed morphological, morphometric, and molecular methods, which confirmed the identity of the nematodes as R. reniformis. Our investigation revealed that R. reniformis successfully infected the roots of melon plants and laid eggs, which could have led to significant crop damage. This report represents the first documented example of R. reniformis infecting melon plants in China. We evaluated several control strategies to combat this nematode, and our results indicated that soil solarization and the use of fosthiazate or chitooligosaccharide copper in combination with soil solarization were effective measures for managing R. reniformis in a greenhouse setting. In addition, combining soil solarization with chitooligosaccharide copper promoted melon plant growth and increased the relative abundance of microorganisms with biocontrol potential.

Two Intra-Individual ITS1 rDNA Sequence Variants Identified in the Female and Male Rotylenchulus reniformis Populations of Alabama.

Around 300 different plant species are infected by the plant-parasitic reniform nematode (Rotylenchulus reniformis), including cotton. This is a devasting nematode with a preference for cotton; it is commonly found in Alabama farms and causes severe reduction in yields. Its first internal transcribed spacer (ITS1) region can be sequenced, and potential mutations can be found in order to study the population dynamics of the reniform nematode. The goal of our study was to sequence the ITS1 rDNA region in male and female RNs that were collected from BelleMina, Hamilton, and Lamons locations in Alabama. After separating the single male and female RNs from the samples collected from the three selected listed sites above, the ITS1 region was amplified selectively using specific primers, and the resulting products were cloned and sequenced. Two distinct bands were observed after DNA amplification of male and female nematodes at 550 bp and 730 bp, respectively. The analysis of sequenced fragments among the three populations showed variation in average nucleotide frequencies of female and male RNs. Singletons within the female and male Hamilton populations ranged from 7.8% to 10%, and the variable sites ranged from 13.4% to 26%. However, female and male BelleMina populations had singletons ranging from 7.1% to 19.7% and variable regions in the range of 13.9% to 49.3%. The female and male Lamons populations had singletons ranging from 2.5% to 8.7% and variable regions in the range of 2.9% to 14.2%. Phylogenetic (neighbor-joining) analysis for the two ITS1 fragments (ITS-550 and ITS-730) showed relatively high intra-nematode variability. Different clone sequences from an individual nematode often had greater similarity with other nematodes than with their own sequences. RNA fold analysis of the ITS1 sequences revealed varied stem and loop structures, suggesting both conserved and variable regions in the variants identified from female and male RNs, thus underscoring the presence of significant intra- and inter-nematodal variation among RN populations in Alabama.

Phytochemical profiling and nematicidal activity of leaf extracts of Tinosporacordifolia against reniform nematode (Rotylenchulus reniformis)

Reniform nematode, Rotylenchulus reniformis is an important nematode associated with castor influencing the productivity of the crop. Efficacy of the leaf extract of Tinospora cordifolia at different concentrations viz., 0.1, 0.5, 1.0, 2.0, 5.0, 10.0 and 20% against the nematode juveniles were evaluated in vitro. The extract, at 20% concentration was recorded to be effective in the reduction of nematode juveniles to 93.8 per cent. The more active non-polar and medium polar compounds which are having melting point less than 200o C were analysed by GC-MS. Eighteen compounds of the total extract were identified of which six compounds were reported to possess nematicidal properties.

Plant-parasitic nematodes, a looming threat to turmeric cultivation in India: results of recent surveys

Summary Turmeric (Curcuma longa) is a major spice of Indian origin. Turmeric is commonly used in Ayurvedic and Siddha medicine, and also in Indian cuisine. India produces nearly 1.2 million tonnes (Mt) of turmeric annually and is one of the world’s largest producers. Turmeric production is limited by a number of biotic and abiotic factors. Among the biotic factors, plant-parasitic nematodes (PPN) are important. They include Meloidogyne spp., Pratylenchus spp., Radopholus similis and Rotylenchulus reniformis. However, the information about the distribution, density and prominence of plant-parasitic nematodes and their interrelation with soil types is very scarce. Hence, the present comprehensive nematode survey was undertaken in the major turmeric-producing states of India: Tamil Nadu, Andhra Pradesh, Telangana and Odisha. The results indicated that Meloidogyne spp., R. reniformis, Pratylenchus spp., R. similis, Hoplolaimus spp., Helicotylenchus spp. and Tylenchorhynchus spp. were associated with turmeric. The most abundant nematodes were Meloidogyne spp. (115 individuals (100 cm3 soil)−1), followed by R. reniformis (68 (100 cm3 soil)−1) and Pratylenchus spp. (50 (100 cm3 soil)−1). The frequency of occurrence ranged from 0 to 60%, with Meloidogyne spp. (60%) and R. reniformis (51%) being the most common. Meloidogyne spp. (38%) and Pratylenchus spp. (19%) were the most prominent nematodes in plant samples. Overall, Meloidogyne spp. followed by Pratylenchus spp., R. reniformis and R. similis were the key nematodes associated with the turmeric crop in all the four states. Further, we have identified hotspot areas for the plant-parasitic nematodes, namely: Meloidogyne spp. (16), Pratylenchus spp. (16), R. reniformis (20), and R. similis (5) on the basis of the economic threshold level. The interrelationship of soil type and nematode distribution was also investigated.