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The predominant plant-parasitic nematodes associated with Pattawia pineapple-cultivated areas were investigated using combined molecular and morphological techniques. In total, 134 soil samples were collected for nematode extraction from the main pineapple crops in 3 districts (Sam Roi Yot, Mueang and Hua Hin) of Prachuap Khiri Khan, Thailand. Based on the morphology, 6 plant-parasitic nematode genera were identified: Rotylenchulus sp., Meloidogyne sp., Helicotylenchus sp., Hoplolaimus sp., Mesocriconema sp. and Pratylenchus sp. The main plant-parasitic nematodes that occurred in Sam Roi Yot and Mueang districts were Rotylenchulus sp. (70.27 and 97.01 %, respectively), while in Hua Hin district, Helicotylenchus sp. (37.73 %) was dominant. Based on molecular identification, nucleotide sequence comparisons and the phylogenetic tree analyses based on the 18S and 28S rRNA genes revealed the species of the nematodes were R. reniformis and H. dihystera, showing 99 % identity with the nematode populations from Japan and China, respectively. Notably, the morphometric and morphological characters also identified these 2 species correctly; however, this technique required more time and may be less accurate. While R. reniformis has been identified as a common species in pineapple fields in the USA, India, Kenya, the Philippines and Nigeria, the current study was the 1st to report H. dihystera isolated from soil in Pattawia pineapple crops in Thailand. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

Abstract 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.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Rotylenchulus reniformis (reniform nematode, RN) is among the most important nematodes affecting cotton. Cultural practices, such as rotation and soil amendment, are established methods for managing RN. Management may be enhanced if crop residue has biofumigant properties against RN. The objective was to evaluate the efficacy of winter crop amendments for managing RN in the greenhouse. Reniform nematode-infested soil was amended with dry or fresh organic matter (OM, 2% w/w) from winter crops – canola, carinata, hairy vetch, oat, or no crop. Cotton was subsequently grown in this soil. Independent of the crop, dry OM amendments were more effective than no amendment at managing RN, while fresh OM amendments were not. Soil and root RN abundances and reproduction factors were generally lower in Trials 1 and 3 for dry OM than fresh OM amendments or control without OM. In Trial 2, none of the OM treatments reduced RN parameters compared with no OM control. In general, when compared to plants without RN or OM, RN did not produce significant changes in growth parameters but did affect physiology (Soil Plant Analysis Development, or SPAD, values). In conclusion, dry OM amendments can help manage RN, crop growth does not always relate to RN abundances, and SPAD values could help indicate RN presence.

Rotylenchulus reniformis (reniform nematode, RN) is an important pathogen in cotton production. Cultural practices such as crop rotation and biofumigation—management of soil pathogens by biocidal compounds from crop residues—may help manage RN. The objective of this study was to evaluate the efficacy of winter crops for RN management through combinations of rotation and crop residue incorporation in a cotton greenhouse experiment. A total of 10 treatments were evaluated in soil inoculated with RN: three winter crops (carinata, oat, or hairy vetch) grown in rotation with no shoot organic matter (OM) incorporated (1–3), fresh shoot OM incorporated (4–6), or dry shoot OM incorporated (7–9), and a fallow control (10). Roots were re-incorporated in all treatments except fallow. Subsequently, cotton was grown. Oat and fallow were better rotation crops to lower soil RN abundances at winter crop termination than hairy vetch and carinata. After the OM incorporation treatments and cotton growth, oat was generally more effective at managing RN in cotton than carinata or hairy vetch. Within each crop, incorporation treatment generally did not affect RN management. Cotton growth was not consistently affected by the treatments.

A three-year rotation of cotton (Gossypium hirsutum) cultivars either resistant (R) or susceptible (S) to Rotylenchulus reniformis and fallow (F) was examined for effect on cotton yield and nematode density. In year 1, 2, and 3, the resistant cultivar (DP 2143NR B3XF) yielded 78, 77, and 113% higher than the susceptible cultivar (DP 2044 B3XF). Fallow in year 1 followed by S in year 2 (F1S2) improved yield in year 2 by 24% compared with S1S2, but not as much as R1S2 (41% yield increase over S1S2). One year of fallow followed by R (F1R2) had lower yield in year 2 (11% reduction) than R1R2. The highest yield after three years of these rotations occurred with R1R2R3, followed by R1S2R3 (17% less yield) and F1F2S3 (35% less yield). Rotylenchulus reniformis density in soil averaged 57, 65, and 70% lower (year 1, 2, 3, respectively) in R1R2R3 compared with S1S2S3. In years 1 and 2, LOG10 transformed nematode density (LREN) was lower in F1, and F1F2, than for all other combinations. In year 3, the lowest LREN were associated with R1R2R3, F1S2F3, and F1F2S3. The highest LREN were associated with F1R2S3, F1S2S3, S1S2S3, R1R2S3, and R1S2S3. The combination of higher yield and lower nematode density will be a strong incentive for producers to use the R. reniformis resistant cultivars continuously.

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.

Reniform nematode (Rotylenchulus reniformis) is a major pest of sweetpotato in many production regions in Southern United States. Applying soil fumigants and non-fumigant nematicides are the primary management strategies available to growers. This study compared the relative efficacy of nematicides (1,3-dichloropropene, fluopyram, oxamyl, fluazaindolizine, aldicarb, Majestene, and fluensulfone) for management of reniform nematode on sweetpotato. Fumigating soil with 1,3-dichloropropene consistently reduced soil population densities of reniform nematode at the time of planting in both trial years (31 – 36% reduction relative to the untreated control); however, the duration of suppression varied greatly by growing season. A similar trend was observed with fluopyram (56 – 67% reduction) and aldicarb (63 – 65% reduction), which provided season-long suppression of reniform nematode population development in 2021 but had no impact in 2022. In 2021, nematicide application had no impact on yield; however, in 2022, oxamyl and aldicarb increased the yield of U.S.#1 grade sweetpotato. Overall, soil fumigation with 1,3-dichloropropene and in-furrow application of fluopyram and aldicarb provided the most consistent suppression of reniform nematode on sweetpotato.

ABSTRACT Strategies for conserving natural resources and reducing agricultural inputs are the great challenge for agriculture, such as sustainable alternatives to control agricultural pests of high economic impact, e.g. plant-parasitic nematodes. This work aimed to evaluate phytonematode’s population dynamics in common bean cultivation grown under crop rotations and no-tillage system. The maize was seeded under pearl millet straw and intercropped with three different crops systems: i) exclusive maize system, ii) maize intercropped with brachiaria and, iii) maize intercropped with crotalaria. The experimental design was a randomized complete block with three treatments (crops systems) and 4 blocks (5 subsamples each block). The common bean was seeded on the straw of exclusive or intercropped maize. The phytonematode population was evaluated in the soil and in the roots in seven moments: (i) fallow; (ii) pearl millet flowering; (iii) pearl millet maturity; (iv) maize flowering; (v) maize maturity; (vi) common bean flowering; and (vii) common bean maturity. The greatest control of the phytonematodes species described in the area was in the maize intercropped with crotalaria treatment, as the phytonematodes population decreased 2.49-fold in this treatment when compared to exclusive maize, resulting in an increase of 11.27% in common bean yield. Therefore, maize intercropped with crotalaria is a viable alternative to reduce phytonematodes infestation in common bean crop.

Reniform nematode (Rotylenchulus reniformis, RN) is one of the most important yield-robbing pathogens in cotton (Gossypium hirsutum). In the southeast United States, carinata (Brassica carinata) is an emerging winter crop, but its host status for RN has not been studied. This information is foundational for the establishment of carinata as a crop and for RN management in the region. Therefore, the objective of this research was to determine the relative host suitability of carinata to RN when compared to poor hosts of RN--oat (Avena sativa), canola (B. napus), and peanut (Arachis hypogaea)--or good hosts of RN--hairy vetch (Vicia villosa) and cotton. This objective was investigated in a repeated greenhouse experiment with the first trial conducted in 2020 and the second in 2021. In both trials, carinata had reproduction factor values (final population density/initial population density) of less than one, and the abundance of RN per gram of roots and per root system was less for carinata than good hosts of RN. For other crops, results were consistent with the RN host status previously defined. Based on these results, carinata is a poor RN host, and therefore, it may be a useful management option for RN. [ABSTRACT FROM AUTHOR]

Root-knot (Meloidogyne incognita (Kofoid & White) Chitwood), reniform (Rotylenchulus reniformis Lindford & Oliveira), and lesion nematodes (Pratylenchus penetrans (Cobb) Filipjev & Schuurmans Stekhoven) are plant-parasitic nematodes that feed on soybean (Glycine max (L.) Merr.) roots, limiting seed production. The availability of resistance in soybeans to these nematodes is limited. However, new sources of resistance can be discovered in wild relatives of agronomic crops. Perennial Glycine species, wild relatives to soybean, are a source of valuable genetic resources with the potential to improve disease resistance in soybean. To determine if these perennials have resistance against nematodes, 18 accessions of 10 perennial Glycine species were evaluated for their response to M. incognita and R. reniformis, and eight accessions of six perennial Glycine species were evaluated for their response to P. penetrans. Pot experiments were conducted for M. incognita and R. reniformis in a growth chamber and in vitro experiments were conducted for P. penetrans. We found both shared and distinct interactions along the resistance-susceptible continuum in response to the three plant-parasitic nematode species. Ten and 15 accessions were classified as resistant to M. incognita based on eggs per gram of root and gall index, respectively. Among them, G. tomentella plant introductions (PIs) 446983 and 339655 had a significantly lower gall index than the resistant soybean check cv. Forrest. Of three R. reniformis resistant accessions identified in this study, G. tomentella PI 441001 showed significantly greater resistance to R. reniformis than the resistant check cv. Forrest based on nematodes per gram of root. In contrast, no resistance to P. penetrans was recorded in any perennial Glycine species.

Strategies for conserving natural resources and reducing agricultural inputs are the great challenge for agriculture, such as sustainable alternatives to control agricultural pests of high economic impact, e.g. plant-parasitic nematodes. This work aimed to evaluate phytonematode's population dynamics in common bean cultivation grown under crop rotations and no-tillage system. The maize was seeded under pearl millet straw and intercropped with three different crops systems: i) exclusive maize system, ii) maize intercropped with brachiaria and, iii) maize intercropped with crotalaria. The experimental design was a randomized complete block with three treatments (crops systems) and 4 blocks (5 subsamples each block). The common bean was seeded on the straw of exclusive or intercropped maize. The phytonematode population was evaluated in the soil and in the roots in seven moments: (i) fallow; (ii) pearl millet flowering; (iii) pearl millet maturity; (iv) maize flowering; (v) maize maturity; (vi) common bean flowering; and (vii) common bean maturity. The greatest control of the phytonematodes species described in the area was in the maize intercropped with crotalaria treatment, as the phytonematodes population decreased 2.49-fold in this treatment when compared to exclusive maize, resulting in an increase of 11.27% in common bean yield. Therefore, maize intercropped with crotalaria is a viable alternative to reduce phytonematodes infestation in common bean crop. [ABSTRACT FROM AUTHOR]

Reniform nematode (Rotylenchulus reniformis) is a parasite of cotton (Gossypium hirsutum) and crop rotation is commonly used for its management. One specific rotation system is a sod-based rotation, which uses two years of bahiagrass (Paspalum notatum) followed by one year each of peanut (Arachis hypogaea) and cotton, versus a conventional peanut-cotton-cotton rotation. High population densities of reniform nematode are found below plow depth in the soil profile, yet conventional chemical management is often not able to manage these deeper populations, nor is much known about other plant parasites such as ring nematode (Mesocriconema ornatum) and spiral nematode (Helicotylenchus dihystera) at these deeper depths. Our study aimed to investigate how long-term cropping history (since 2000) affects the vertical spatial distribution of plant-parasitic (reniform, ring, and spiral) nematodes under different irrigation regimes. Between March 2017 and January 2019, soil samples were collected to a depth of 120 cm before planting, after harvest, and in the winter using a hydraulic probe. Nematode abundances (including enumeration of all reniform nematode life stages) were analyzed in 30 cm-sections. There were no significant effects of irrigation on nematode abundances (P > 0.05). In each sampling date, all reniform nematode abundances decreased stepwise as soil depth increased, but spiral and ring nematodes were nearly absent below 30 cm. Sod-based rotation generally reduced reniform nematode abundances at all depths compared with conventional rotation, although differences were more pronounced in the shallower depths (0–30 and 30–60 cm). Conversely, at 0–30 cm soil depth, ring nematode abundances were generally greatest in the peanut phase of sod-based rotation. Similarly, spiral nematode abundances, at 0–30 cm soil depth, were generally significantly greater in bahiagrass phases than other phases and variously greater in first-year cotton (sod-based or conventional). Overall, sod-based rotation helped manage reniform nematodes up to 120 cm deep in the soil profile. Sod-based rotation was detrimental for managing minor plant-parasitic nematodes spiral and ring nematodes, and those nematodes were scarce below 30 cm deep in the soil profile. [ABSTRACT FROM AUTHOR]

Root-knot (Meloidogyne incognita (Kofoid & White) Chitwood), reniform (Rotylenchulus reniformis Lindford & Oliveira), and lesion nematodes (Pratylenchus penetrans (Cobb) Filipjev & Schuurmans Stekhoven) are plant-parasitic nematodes that feed on soybean (Glycine max (L.) Merr.) roots, limiting seed production. The availability of resistance in soybeans to these nematodes is limited. However, new sources of resistance can be discovered in wild relatives of agronomic crops. Perennial Glycine species, wild relatives to soybean, are a source of valuable genetic resources with the potential to improve disease resistance in soybean. To determine if these perennials have resistance against nematodes, 18 accessions of 10 perennial Glycine species were evaluated for their response to M. incognita and R. reniformis, and eight accessions of six perennial Glycine species were evaluated for their response to P. penetrans. Pot experiments were conducted for M. incognita and R. reniformis in a growth chamber and in vitro experiments were conducted for P. penetrans. We found both shared and distinct interactions along the resistance-susceptible continuum in response to the three plantparasitic nematode species. Ten and 15 accessions were classified as resistant to M. incognita based on eggs per gram of root and gall index, respectively. Among them, G. tomentella plant introductions (PIs) 446983 and 339655 had a significantly lower gall index than the resistant soybean check cv. Forrest. Of three R. reniformis resistant accessions identified in this study, G. tomentella PI 441001 showed significantly greater resistance to R. reniformis than the resistant check cv. Forrest based on nematodes per gram of root. In contrast, no resistance to P. penetrans was recorded in any perennial Glycine species. [ABSTRACT FROM AUTHOR]

Sorghum/sorghum–sudangrass hybrids (SSgH) have been used as a cover crop to improve soil health by adding soil organic matter, enhancing microbial activities, and suppressing soilborne pathogens in various cropping systems. A series of SSgH were screened for (1) allelopathic suppression and (2) improvement of soil edaphic factors and soil microbial profile against plantparasitic nematode (PPNs). The allelopathic potential of SSgH against PPNs is hypothesized to vary by variety and age. In two greenhouse bioassays, ‘NX-D-610 sorghum and the ‘Latte’ SSgH amendment provided the most suppressive allelopathic effect against the female formation of Meloidogyne incognita on mustard green seedlings when using 1-, 2-, or 3-month-old SSgH tissue, though most varieties showed a decrease in allelopathic effect as SSgH mature. A field trial was conducted where seven SSgH varieties were grown for 2.5 months and terminated using a flail mower, and eggplant was planted in a no-till system. Multivariate analysis of measured parameters revealed that increase in soil moisture, microbial biomass, respiration rate, nematode enrichment index, and sorghum biomass were negatively related to the initial abundance of PPNs and the root-gall index at 5 months after planting eggplant in a no-till system. These results suggested that improvement of soil health by SSgH could lead to suppression of PPN infection. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at the Odisha University of Agriculture and Technology (OUAT), Bhubaneswar, Odisha to evaluate the performance of intercropping of banana cv. Champa with elephant-foot yam, ginger, turmeric, arrow root, colocasia and mango ginger during 2011-16. Growth and yield characters of banana did not show any significant difference among each other, indicating that cultivation of intercrops does not have any significant effect on them. Yield of intercrops varied from 13.29 tonnes/ha in elephant-foot yam to as high as 54.84 tonnes/ha in mango ginger. However, arrow root recorded maximum returns of 3.54 lakh/ha. Banana + arrow root combination recorded maximum total returns (8.21 lakh/ha), net profit (5.29 lakh/ha) as well B:C ratio (2.09). The effect of intercropping on incidence of Eumusae leaf spot showed that except colocasia, other intercrop combinations had significantly higher PDI than growing banana alone (PDI 8.75). The maximum PDI was recorded in banana + turmeric (27.50), followed by banana + mango ginger (26.25). Banana + arrow root recorded a moderate leaf spot incidence of 17.50 necessitating the application of suitable systemic/contact fungicide while growing arrow root as an intercrop in banana. Two pathogenic nematode species, viz., reniform nematode, (Rotylenchulus reniformis) and root-knot nematode, (Meloidogyne incognita) were recorded. In none of the treatments, these two pathogenic nematodes were above the economic threshold level (ETL). The population of Rotylenchulus reniformis in banana + arrow root was 104 per 250 g soil, against ETL of 1000 young females per 250 g soil. Thus it is concluded that arrowroot can be taken as a remunerative intercrop in banana in Odisha.. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPN) are microscopic soil herbivores that cause damage to many economic crops. For the last century, it has been proposed that chemotaxis is the primary means by which PPN locate host plant roots. The identities and modes of action of chemoattractants that deliver host-specific messages to PPN, however, are still elusive. In this study, a unique multidimensional agar-based motility assay was developed to assess the impacts of root exudates on the short-range motility and orientation of PPN. Three PPN (Rotylenchulus reniformis, Meloidogyne incognita and Heterodera glycines) and root exudates from their respective host and non-host plants (cotton, soybean, and peanut) were used to validate the assay. As predicted, R. reniformis and M. incognita were attracted to root exudates of cotton and soybean (hosts), but not to the exudates of peanut (non-host). Likewise, H. glycines was attracted to soybean (host) root exudates. These results underpinned the intrinsic roles of root exudates in conveying the host specificity of PPN. In particular, PPN selectively identified and targeted to hydrophilic, but not hydrophobic, fractions of root exudates, indicating that groundwater should be an effective matrix for chemotaxis associated with PPN and their host plant interactions.

Three populations, two from Colombia and one from Brazil, of Rotylenchulus reniformis associated with banana and plantain, were characterized using morphological, morphometric, and molecular methods. Morphometric data from these populations were similar to type and reference populations of R. reniformis. Partial sequences of both D2-D3 rDNA and mitochondrial cytochrome oxidase subunit I (COI) regions had a strong affinity (99% similarity) to previously published sequences of R. reniformis. Phylogenetic analyses (maximum likelihood and Bayesian inference) suggested that the Colombian populations of R. reniformis corresponded to the previously described Type A of the species. This is the definitive first report in Colombia of R. reniformis associated with banana and plantain crops.

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Reniform nematode (Rotylenchulus reniformis) is a yield-limiting pathogen of soybean (Glycine max) in the southeastern region of the United States. A population of 250 recombinant inbred lines (RIL) (F2;8) developed from a cross between reniform nematode resistant soybean cultivar Forrest and susceptible cultivar Williams 82 was utilized to identify regions associated with host suitability. A genetic linkage map was constructed using single-nucleotide polymorphism markers generated by genotyping-by-sequencing. The phenotype was measured in the RIL population and resistance was characterized using normalized and transformed nematode reproduction indices in an optimal univariate cluster analysis. Quantitative trait loci (QTL) analysis using normalized phenotype scores identified two QTLs on each arm of chromosome 18 (rrn-1 and rrn-2). The same QTL analysis performed with log10(M transformed phenotype data also identified two QTLs: one on chromosome 18 overlapping the same region in the other analysis {rrn-1), and one on chromosome 11 (rrn-3). While rrn-1 and rm-3 have been reported associated with reduced reproduction of reniform nematode, this is the first report of the rrn-2 region associated with host suitability to reniform nematode. The resistant parent allele at rrn-2 showed an inverse relationship with the resistance phenotype, correlating with an increase in nematode reproduction or host suitability. Several candidate genes within these regions corresponded with host plant defense systems. Interestingly, a characteristic pathogen resistance gene with a leucine-rich repeat was discovered within rrn-2. These genetic markers can be used by soybean breeders in marker-assisted selection to develop lines with resistance to reniform nematode. [ABSTRACT FROM AUTHOR]

The upland cotton (Gossypium hirsutum L.) germplasm lines BARBREN-713, having the Renbarb1 and Renbarb2 quantitative trait loci (QTL), and LONREN, carrying the Renlon QTL, have introgressed resistance to reniform nematode (Rotylenchulus reniformis Linford and Oliveria). Stunting has been observed in the LONREN source of resistance when subjected to heavy nematode pressure but not for BARBREN-713. To investigate the potential to reduce stunting in the LONREN source of resistance, cotton lines were developed with different combinations of reniform nematode resistance QTL from LONREN and BARBREN-713. Marker assisted selection was conducted to identify the following QTL combinations: (1) Renbarb1 + Renbarb2, (2) Renbarb1 + Renbarb2 + Renlon, (3) Renbarb2 + Renlon, (4) Renbarb1 + Renlon, (5) Renbarb1 alone, (6) Renbarb2 alone, (7) Renlon alone, and (8) a Null susceptible genotype. QTL combinations were inoculated with 0, 2300, or 5000 reniform nematodes per 120 cm3 soil in growth chamber tests. Plants were harvested at 60 days after inoculation, plant growth measurements made, and the nematode reproduction factor calculated. In this study, the Renbarb1 genotype was scored as susceptible to reniform nematode. Combining Renlon with Renbarb2 did not improve resistance to reniform nematode; however, the Renbarb2/Renlon combination showed improved growth compared to LONREN-1, BARBREN-713, and the susceptible null check. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes (Rotylenchulus reniformis (reniform, RN), Helicotylenchus dihystera (spiral), and Mesocriconema ornatum (ring)) and yield were investigated in cotton phases of conventional (peanut–cotton–cotton) and sod-based (bahiagrass–bahiagrass– peanut–cotton) rotations with or without irrigation and fluopyram nematicide at a long-term research site, established in 2000, in Quincy, Florida, USA. Objectives were to determine impacts of nematicide application on cotton yield and evaluate effects of nematicide on plant-parasitic nematodes in these rotations in 2017 and 2018. Reniform nematode population densities were greater in conventional cotton than sod-based cotton. Ring and spiral nematode population densities were greater in sod-based cotton than conventional cotton. Plots receiving nematicide had increased RN population densities in preplant 2018 soil samples and spiral nematode population densities in preplant 2017, harvest 2017, preplant 2018, and harvest 2018 soil samples compared to untreated plots. Cotton seed yield in conventional rotation was increased by 18% following nematicide application in 2017 but decreased by 10% in sod-based rotation in 2018, relative to the untreated control. Sodbased rotation had greater cotton yield than conventional rotation in 2017 and 2018. Nematicide application did not improve cotton yield in sod-based rotation and was inconsistent in conventional rotation. [ABSTRACT FROM AUTHOR]

Breeding for reniform nematode (Rotylenchulus reniformis) resistance is hindered by the lack of resistance in upland cotton (Gossypium hirsutum) cultivars. Resistance has been frequently identified in accessions from the Gossypium arboreum germplasm collection with accession PI 529740 rated as highly resistant. Accession PI 529740 was crossed with the susceptible G. arboreum accession PI 529729 to develop an F2 population for genetic characterization. The population showed quantitative variation suggesting multiple genes conferred the resistant phenotype. Thirteen of the 216 F2 plants showed resistance similar to the resistant parent and these data supported a two recessive gene model. Sixty plants were classified as resistant or moderately resistant, indicating a single recessive gene conferred the moderately resistant phenotype. The classification of 24 F2:3 families for nematode resistance generally supported the classification of the corresponding F2 plants; however, most families were highly variable for infection with no families rated as resistant. This information will aid in the introgression of resistance into upland cotton as larger populations will be required to successfully recover resistance conferred by multiple recessive genes. [ABSTRACT FROM AUTHOR]

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., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

• Combination of cotton stalks, rice straw, sugarcane bagasse and wheat bran gave the highest yield (195.16 g Kg−1), biological efficiency (19.52%), protein (16.69%), polysaccharides (3.613%) and minerals (3433 mg/100 g). • Except polysaccharides, such values were increased at 10% biochar. • The higher the biochar level, the higher reduction in emitted CO2 and higher reduction in the crop cycle duration. • All tested GPMSs encouraged reproduction of reniform nematodes and improved plant growth. The in vitro growth of Ganoderma mycelia on six agro-wastes namely, broad bean stalks (BBS), cotton stalk (CS), maize straw (MS), rice straw (RS), sugarcane bagasse (SCB) and wheat straw (WS) supplemented with wheat bran (WB) or corn gluten (CG) was evaluated. Among the substrates used, CS appeared best followed by SCB and RS. WB showed best supplementation for mycelial growth. CO 2 emission values exhibited accurate measurements to decide the suitability of such agro-waste for growth rather than visual observations. CS+RS+SCB+WB in combination proven its superiority for in vitro growth and active spawn development substrate. In mushroom house, this particular formula proved its superiority and was on par with recommended EG formula; it gave the highest yield (195.16 g Kg−1), biological efficiency (19.52%), protein (16.69%), polysaccharides (3.613%) and minerals (3433 mg/100 g). Spawn running period was the shortest in treatments inoculated with agro-waste-based spawns. With 40% biochar, days required to the complete mycelium colonization and fructification were 10.60 and 23.00, respectively. At 10% biochar, highest yields (238.40 g Kg−1), biological efficiencies (23.84%), protein (19.58%) and minerals (4092 mg/100 g) were obtained. The higher the biochar level, the higher the reduction in emitted CO 2 , the loss in C and the increase in N of Ganoderma post mushroom substrates (GPMSs). Under greenhouse conditions, almost all the tested GPMSs, at 0.125 or 0.25%, encouraged the reproduction of reniform nematodes and improved plant growth criteria. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes (PPN) are microscopic soil herbivores that cause damage to many economic crops. For the last century, it has been proposed that chemotaxis is the primary means by which PPN locate host plant roots. The identities and modes of action of chemoattractants that deliver host-specific messages to PPN, however, are still elusive. In this study, a unique multidimensional agar-based motility assay was developed to assess the impacts of root exudates on the short-range motility and orientation of PPN. Three PPN (Rotylenchulus reniformis, Meloidogyne incognita and Heterodera glycines) and root exudates from their respective host and non-host plants (cotton, soybean, and peanut) were used to validate the assay. As predicted, R. reniformis and M. incognita were attracted to root exudates of cotton and soybean (hosts), but not to the exudates of peanut (non-host). Likewise, H. glycines was attracted to soybean (host) root exudates. These results underpinned the intrinsic roles of root exudates in conveying the host specificity of PPN. In particular, PPN selectively identified and targeted to hydrophilic, but not hydrophobic, fractions of root exudates, indicating that groundwater should be an effective matrix for chemotaxis associated with PPN and their host plant interactions. [ABSTRACT FROM AUTHOR]

Fusarium wilt [caused by the fungus Fusarium oxysporum f. sp. niveum (FON)] has been a consistent problem in watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] production worldwide. One method for combatting this pathogen in the field is to graft a susceptible, high-yielding scion on to a fusarium wilt-resistant rootstock. A concerning issue with rootstocks resistant to fusarium wilt is that they have not been tested for their susceptibility to plant pathogenic nematodes--specifically, root-knot nematodes (RKNs; Meloidogyne spp.) and the reniform nematode (Rotylenchulus reniformis). Preliminary findings have demonstrated that many of these Fusariumresistant rootstocks are highly susceptible to RKNs. Research was conducted during the Spring and Fall 2015 and 2016 to evaluate the resistance to RKN and reniform nematode in rootstocks with known resistance to fusarium wilt. Six rootstocks were evaluated over the course of four experiments. A nematode-susceptible interspecific hybrid [Cucurbitamaxima (Duchesne)×C.moschata (Duchesne)] rootstock 'Carnivor' was included as a susceptible control in both years. Results demonstrated that several Citrullus lanatus var. citroides (L.H. Bailey) rootstocks ('Carolina Strongback', USVL246-FR2, USVL252-FR2, and USVL-360) and 'SP-6' (a commercially available pollinizer cultivar) exhibited resistance to plant parasitic nematodes when compared with the susceptible control. Partial resistance was observed in USVL-482351. When compared with the control, these rootstocks also had fewer Meloidogyne spp. and R. reniformis in root tissue. These findings indicate that rootstocks may be available to manage both fusarium wilt and RKN in grafted cucurbit production system. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Agronematology is the property of Egyptian Society for Agronematology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Twenty-five breadfruit plantings on the islands of Kaua'i, Maui, and O'ahu were surveyed for plant-parasitic nematodes. Soil and breadfruit root samples were collected from plantings in residences, parks, schools, botanical gardens, and breadfruit orchards. Soil samples were processed by elutriation and centrifugation for nematode extraction. Roots were subjected to mist chamber extraction for 7 days. Seven different genera of plant-parasitic nematodes (Helicotylenchus, Meloidogyne, Mesocriconema, Paratylenchus, Pratylenchus, Rotylenchulus, and Tylenchorhynchus) and one unidentified taxon in Heteroderidae were found. Helicotylenchus dihystera, Rotylenchulus reniformis, Paratylenchus sp., Pratylenchus coffeae, Meloidogyne spp., and a Heteroderid were found on all islands surveyed. Helicotylenchus dihystera was the most frequent species encountered, occurring at 68% of sites surveyed and was the most widespread plant-parasitic nematode of breadfruit on Kaua'i. On Maui, H. dihystera, R. reniformis, and P. coffeae were found in 40% of the samples collected. Paratylenchus was the most common plant-parasitic nematode to the island of O'ahu and was detected in 86% of the samples. Meloidogyne spp. were found in 43% of breadfruit sites on Oah'u, and 23% and 20% of that on Kaua'i and Maui, respectively, but in low abundance on all islands. Soil samples yielded Mesocriconema at sites on Kaua'i and O'ahu, and Tylenchorhynchus on O'ahu. Plant-parasitic nematodes were absent from 12% of the locations surveyed. An unidentified nematode in the Heteroderidae was detected in samples from each island, all from botanical gardens. [ABSTRACT FROM AUTHOR]

The factors that influence the ability of cotton to minimize yield loss despite parasitism by Rotylenchulus reniformis (i.e., tolerance) were evaluated for 12 cotton genotypes. Reproduction of R. reniformis and total length of the root system were measured under greenhouse conditions, and the relationship of those variables to yield loss caused by R. reniformis in infested fields was evaluated. Values for nematodes per gram of root and root length were standardized by setting the genotype with greatest value as 100% and then calculating a percentage for each genotype. There was significant variability among genotypes in yield loss, resistance, and root length. Average yield loss for the genotypes ranged from 10.4% for IAC 26RMD to 43.2% for IMACD 5675B2RF. The least nematode reproduction was on IAC 26RMD, which had 49.6% of the reproduction on the susceptible check, Deltapine 16. The genotype with the shortest total root length was 34% less than the genotype with the greatest length. There was a significant linear relationship between percentage yield loss caused by R. reniformis and root length and nematodes per gram of root, both expressed as a percentage of the maximum, represented by the following equation: Yield loss (%) = 16.1258 - 0.1918*(% maximum root length) + 0.3728*(% maximum eggs + vermiform/g of roots). We conclude that tolerance to R. reniformis in cotton is influenced by the size of the root system and the parasitic load on the plant (nematodes per gram of root). Management approaches that increase root growth may lower the parasitic load, thereby reducing losses in cotton to R. reniformis. [ABSTRACT FROM AUTHOR]