Root Nematode Populations Research Articles

Análise multivariada como ferramenta na seleção de agroecossistemas sustentáveis de cultivo de meloeiro no Semiárido

ABSTRACT Soil management systems, including tillage and green manuring, are important for the control of nematodes and for the sustainable production. The objective was to select, through multivariate analysis, sustainable agroecosystems for yellow melon cultivated under irrigated conditions in the Brazilian semi-arid region. The long-term experiment is set up in Argissolo Vermelho- Amarelo (Ultisol) with six multifunctional agroecosystems, composed of the combination of three mixtures of cover crops (1 - 75% legumes + 25% grasses and oilseeds; 2 - 25% legumes + 75% grasses and oilseeds and 3 - spontaneous vegetation) and two types of soil management (no tillage-NT and tillage-T). The purpose was to evaluate the nutritional status of plants, soil fertility, nematode population in roots and soil, and the yield. Data were analyzed with multivariate techniques, allowing the grouping of the agroecosystems based on their similarities and complexity of functions. The incorporation of plant residues to the soil reduces nematode population, but their maintenance on the surface allows the improvement of fertility and yield, even under larger nematode populations. The agroecosystems that associate the nonincorporation of residues from cover crops with larger species diversity in composition constitute the most complex model, allowing different environmental functionalities. Thus, it is recommended not to incorporate the plant residues, planting the melon seedlings directly in the straw. However, considering that the results obtained with the non-incorporation of spontaneous vegetation were similar to those obtained with the incorporation of commercial cover crops, it is concluded that this practice is also viable and adapted to the semi-arid conditions.

Population of root knot nematode, Meloidogyne incognita and yield in tomato using various \bio agents under pot culture conditions

Tomato (Solanum lycopersicum) is one of the most important vegetable which has a great economic importance and also has a high processing value. Tomatoes are susceptible to root-knot nematode (Meloidogyne incognita) leading to a great economic loss. The life cycle of root-knot nematode takes about 25 days to complete. Second stage juveniles J2 initiate infection in the host. Root-knot nematodes constitute a major group of plant-parasitic nematodes causing extensive economic damage ton early all crop plants of economic importance in both tropical and sub-tropical crop production regions all over the world (Sikora and Fernandez, 2005). The efficacy of different bioagents like Trichoderma viride, Bacillus subtilis, Pochoniachlamy disporia, Purpureocillium lilacinum against Meloidogyn eincognita was estimated under four replications and assessment of plant morphometric characters and root knot index under pot culture conditions has been recorded. All the four bioagents were tested in vitro to study their efficacy against Meloidogyne incognita. Among all the bioagents tested, Purpureocillium lilacinum treatment showed significant increase in root length and shoot length (40.20cm and 76.20cm, respectively) and the untreated control plants recorded the least roo tlength and shoot length (19.11cm and 21.30cm). All the treatments were found to reduce nematode population in roots and highest reduction was noticed in Purpureocillium lilacinum treated plants (178.50 and 141.20) soil (250g) and root (5g), respectively. The untreated plants recorded the highest nematode population of 1314.14 and 1411.20 in soil (250g) and root (5g), respectively. Significant reduction in root knot index (1.2) were observed in the treatment Purpureocillium lilacinum and Carbofuran which recorded (2.0 ) per cent. The untreated control plant roots showed root knot index of 5.00 percent.

Assessment on population of root knot nematode, Meloidogyne incognita and yield in brinjal using various bio agents under pot culture conditions

Brinjal (Solanum melongena) is one of the most important vegetables which has a great economic importance and also has a high processing value. Brinjals are susceptible to root-knot nematode (Meloidogyne incognita) leading to a great economic loss. The life cycle of root-knot nematode takes about 25 days to complete. Second stage juveniles J2 initiate infection in the host.Root-knot nematodes constitute a major group of plant-parasitic nematodes causing extensive economic damage to nearly all crop plants of economic importance in both tropical and subtropical crop production regions all over the world (Sikora and Fernandez 2005). The efficacy of different bioagents like Trichoderma viride, Bacillus subtilis, Pochoniac, hlamydosporia, Purpureocillium lilacinum against Meloidogyne incognita was estimated under four replications and assessment of plant morpho metric characters and root knot index under pot culture conditions has been recorded. All the four bio agents were tested in vitro to study their efficacy against Meloidogyne incognita. Among all the bioagents tested, Purpureocillium lilacinum treatment showed significant increase in root length and shoot length (35.11cm and 59.11cm, respectively) and the untreated control plants recorded the least root length and shoot length (12.02 cm and 15.12cm). All the treatments were found to reduce nematode population in roots and highest reduction was noticed in Purpureocillium lilacinum treated plants (161.11 and 138.10) soil (250g) and root (5g), respectively. The untreated plants recorded the highest nematode population of 1129.11 and 1259.20 in soil (250g) and root (5g) respectively. Singnificant reductionin root knot index (1.0) were observed in the treatment Purpureocillium lilacinum and Carbofuran which recorded (2.2 ) per cent. The untreated control plant roots showed a root knot index of 5.00 percent.

Assessment on population of root knot nematode, Meloidogyne incognita and yield in brinjal using various bio agents under pot culture conditions

Brinjal (Solanum melongena) is one of the most important vegetables which has a great economic importance and also has a high processing value. Brinjals are susceptible to root-knot nematode (Meloidogyne incognita) leading to a great economic loss. The life cycle of root-knot nematode takes about 25 days to complete. Second stage juveniles J2 initiate infection in the host.Root-knot nematodes constitute a major group of plant-parasitic nematodes causing extensive economic damage to nearly all crop plants of economic importance in both tropical and subtropical crop production regions all over the world (Sikora and Fernandez 2005). The efficacy of different bioagents like Trichoderma viride, Bacillus subtilis, Pochoniac, hlamydosporia, Purpureocillium lilacinum against Meloidogyne incognita was estimated under four replications and assessment of plant morpho metric characters and root knot index under pot culture conditions has been recorded. All the four bio agents were tested in vitro to study their efficacy against Meloidogyne incognita. Among all the bioagents tested, Purpureocillium lilacinum treatment showed significant increase in root length and shoot length (35.11cm and 59.11cm, respectively) and the untreated control plants recorded the least root length and shoot length (12.02 cm and 15.12cm). All the treatments were found to reduce nematode population in roots and highest reduction was noticed in Purpureocillium lilacinum treated plants (161.11 and 138.10) soil (250g) and root (5g), respectively. The untreated plants recorded the highest nematode population of 1129.11 and 1259.20 in soil (250g) and root (5g) respectively. Singnificant reductionin root knot index (1.0) were observed in the treatment Purpureocillium lilacinum and Carbofuran which recorded (2.2 ) per cent. The untreated control plant roots showed a root knot index of 5.00 per cent.

Population of root knot nematode, Meloidogyne incognita and yield in tomato using various \bio agents under pot culture conditions

Tomato (Solanum lycopersicum) is one of the most important vegetable which has a great economic importance and also has a high processing value. Tomatoes are susceptible to root-knot nematode (Meloidogyne incognita) leading to a great economic loss. The life cycle of root-knot nematode takes about 25 days to complete. Second stage juveniles J2 initiate infection in the host. Root-knot nematodes constitute a major group of plant-parasitic nematodes causing extensive economic damage ton early all crop plants of economic importance in both tropical and sub-tropical crop production regions all over the world (Sikora and Fernandez, 2005). The efficacy of different bioagents like Trichoderma viride, Bacillus subtilis, Pochoniachlamy disporia, Purpureocillium lilacinum against Meloidogyn eincognita was estimated under four replications and assessment of plant morphometric characters and root knot index under pot culture conditions has been recorded. All the four bioagents were tested in vitro to study their efficacy against Meloidogyne incognita. Among all the bioagents tested, Purpureocillium lilacinum treatment showed significant increase in root length and shoot length (40.20cm and 76.20cm, respectively) and the untreated control plants recorded the least roo tlength and shoot length (19.11cm and 21.30cm). All the treatments were found to reduce nematode population in roots and highest reduction was noticed in Purpureocillium lilacinum treated plants (178.50 and 141.20) soil (250g) and root (5g), respectively. The untreated plants recorded the highest nematode population of 1314.14 and 1411.20 in soil (250g) and root (5g), respectively. Significant reduction in root knot index (1.2) were observed in the treatment Purpureocillium lilacinum and Carbofuran which recorded (2.0 ) per cent. The untreated control plant roots showed root knot index of 5.00 per cent.

Nematicidal Properties of Chitosan Nanoformulation.

Chitosan is the second most abundant bio-polymer available in the world, second only to cellulose. It is found in crustaceous shells, e.g., those of crabs, shrimps, prawns, and fungi, as well as insect exoskeletons. The use of nanoformulations for the management of pests and diseases is receiving increased interest with the advancement of nanotechnology. Here, chitosan nanospheres were obtained from chitosan using the ionic gelation technique. The nanoformulations obtained were characterized using a particle size analyzer, Fourier transform infrared spectroscopy, and a transmission electron microscope. The efficacy of chitosan nanospheres in suppressing the root-knot nematode Meloidogyne incognita was studied. The particle size of nanospheres formulated for this study was 380.2 nm, with a polydispersity index (PI) of 0.4 and Zeta potential of 45.7 or 50.9 mV at pH 5.2. The chitosan nanospheres were spherical and the particles did not agglomerate. FTIR spectra of the chitosan nanospheres peaked at 3334 cm-1, thereby indicating the stretching of the OH and NH group. In In-vitro studies, chitosan nanospheres showed significant nematicidal activity against M. incognita. Under pot culture conditions, chitosan nanospheres (1%- active compound chitosan) at 2ml/plant decreased the nematode population in roots or soil. Compared to the control, the number of galls was reduced by 83.68%, the number of egg masses by 83.85%, the number of adult females by 66.56%, and the number of second-stage juveniles by 73.20%. In a field experiment, application of chitosan nanospheres (1%) was followed by a 18.75% increase in fruit yield compared to the non-treated control.

Paecilomyces formosus MD12, a Biocontrol Agent to Treat Meloidogyne incognita on Brinjal in Green House.

The present study was carried out to analyze the potential of fungi isolated from the rhizosphere of soybean, brinjal, tomato, and potato plants. The density of fungi varied in the pot soil and rhizosphere after Paecilomyces formosus MD12 treatment. The P. formosus MD12 population was 6.3 ± 0.13 × 104 CFU g−1 in the pot planted with brinjal, and the population increased in the rhizosphere (6.72 ± 0.41 × 104 CFU g−1). P. formosus MD12 was cultured in the production medium, and the supernatant was used for egg inhibition studies on a root-knot nematode parasite, Meloidogyne incognita. It was revealed that maximum egg inhibition (94.7 ± 6.2%) was obtained at 100% concentration of extract. The culture supernatant from P. formosus MD12 affected the development of M. incognita juvenile, and the mortality rate was maximum after 96 h (95 ± 6%). Mortality was reduced when treated with 25%, 50%, and 75% supernatant. At 1 × 107 mL−1 of spore suspension, we found reductions of 71.6 ± 3.3% nematode populations in the soil, 60.7 ± 2.2% from the root, and 63.6 ± 2.4% egg mass compared with the control in the pot experiment. The culture supernatant applied at the 10% level showed a maximum mean reduction of the nematode population in roots (72.4 ± 2.2%), soil (77.9 ± 2.5%), and egg masses (73.2 ± 1.5%), respectively. The presence of P. formosus MD12 in a soil environment could antagonize nematode parasites and improve soil amendment. The P. formosus MD12 strain showed good biocontrol ability against the root-knot nematode, M. incognita, under in vitro and green house experimental condition.

Exploration of Potential Bacterial Endophytes against Root Knot Nematode, Meloidogyne incognita in Banana

A field survey was conducted in 12 districts of Assam viz., Jorhat, Golaghat, Nagaon, Marigaon, Goalpara, Dibrugarh, Tinsukia, Lakhimpur, Dhemaji, Sivsagar, Kamrup and Barpeta. A total of 92 root samples were collected and 37 bacterial isolates were isolated from commercial banana cultivars. The culture filtrates extracted from 37 endophytic bacterial isolates, were screened against southern root-knot nematode, Meloidogyne incognita in vitro and under pot culture studies. The five bacterial isolates viz., EB4, EB8, BC1, BC11 and BC12 showed 100% inhibition of egg hatching and juvenile mortality of M. incognita with an exposure period of 48 and 72h. On seed bacterization, with these five promising isolates, two isolates viz.EB4, BC1 significantly enhanced germination percentage (33.33, 25.31%) and vigour index (75.5, 64.39%) of paddy, receptively. The potential bacterial isolates viz., BC1 and EB4 were identified as Lysinibacillus sp. and Pseudomonas sp., respectively , based on the morphological phenotypic and biochemical characterization. The pot culture experiment revealed that the bacterial endophytes viz., Lysinibacillus sp. (BC1) Pseudomonas sp. (EB4) significantly reduced the soil (61.64, 56.71%) and root nematode population (77.29, 68.87%), number of adult females (73.97, 69.89%), egg masses (85.63, 80.11%) and root-knot index (1.33, 1.67) of M. incognita compared to untreated control. The bacterial endophytes viz., Pseudomonas sp. (EB4), Lysinibacillus sp. (BC1) were also significantly increased the growth parameters viz., shoot length (43.33, 39.18%), and root length (78.24, 59.26%) and pesudostem girth (58.38, 52.13%).

Yield Increases in Burrowing Nematode-infested Anthurium with Fluopyram and Trifloxystrobin Applications

Burrowing nematode (Radopholus similis) causes severe stunting and yield reduction in anthurium (Anthurium andraeanum) cut flower production. Two field trials were conducted at commercial grower farms to test the efficacy of fluopyram or fluopyram + trifloxystrobin for managing burrowing nematodes. Nematode population densities in roots and cinder media were evaluated during the trial in addition to cut flower yield and canopy cover. In the first trial, the nematode population in roots was reduced by 57% after two applications of fluopyram 3 months apart. As plant health improved, the increasing anthurium root weight supported higher nematode populations. After 14 months, fluopyram-treated plots had 43% more green canopy cover and a 53% increase in flower production compared with the untreated control plots. At a second location, population densities of burrowing nematode were reduced in roots after one application of fluopyram + trifloxystrobin and remained low with quarterly applications. Nematode populations were initially reduced in fluopyram-treated plots followed by a resurgence as demonstrated in the other trial. Ten months after the initial treatment, flower yield was greater in fluopyram + trifloxystrobin-treated plots with more large and extra-large flowers produced. Canopy cover was 45% and 22% greater with fluopyram + trifloxystrobin and fluopyram applications, respectively. Fluopyram shows potential for management of burrowing nematodes in anthurium by improving plant vigor and cut flower production.

Integrated control of Meloidogyne incognita in tomatoes using fluopyram and Purpureocillium lilacinum strain 251

The plant parasitic root-knot nematodes Meloidogyne spp. are a devastating threat to agriculture. The urgent need to search for alternative root-knot nematode control methods that are less environmentally toxic is a demanding challenge to secure the increasing global food demand. Therefore, we combined chemical and biological control strategies to evaluate their management potential on Meloidogyne incognita infested tomatoes. To determine the combined effect of the nematicides Velum and Purpureocillium lilacinum strain 251 formulated as wettable granulate (BioAct WG), we evaluated tomato yield parameters, gall index, soil and root nematode populations. Velum is a chemical nematicide with fluopyram as its active ingredient and BioAct is a biological nematicide based on the egg pathogenic fungus Purpureocillium lilacinum (strain 251). As a single treatment, the nematicide Velum showed better M. incognita reduction at-planting, while BioAct controlled the nematode population throughout the growing season. Greenhouse experiments in two consecutive years, showed that by combining the two nematicides, the M. incognita controlling effect was enhanced and the tomato yield increased compared to single nematicide treatments. The controlling effect of P. lilacinum was lower when M. incognita population increased, presumably based on its limiting ability to parasitize the increasing numbers of nematode eggs. To conclude, we have shown that combining chemical and biological nematicides can successfully control the root-knot nematode M. incognita and increase yields. Velum downregulated the nematode population at-planting and reinforced the biological efficacy of P. lilacinum throughout the growing season.

Pathogenicity of <i>Meloidogyne incognita</i> in selected groundnut varieties and its management with aqueous leaf extracts of wild sage (<i>Lantana camara</i> L.) and locust bean (<i>Parkia biglobosa</i> Jacq.)

Meloidogyne incognita , on four groundnut ( Arachis hypogaea L.) varieties. The efficacy aqueous leaf extracts of Lantana camara and Parkia biglobosa in the management of M. incognita infecting the groundnut varieties was also investigated. A preliminary study was first carried out from November 2014 – January 2015 in a screen house to access the pathogenicity of M. incognita on the four varieties of groundnut. Results obtained from soil and root nematode population led to field trials which involved the management of M. incognita using botanicals. The field experiment which was a 4x3 factorial fitted into Randomized Complete Block Design (RCBD) commenced in August, 2015. The effects of treatment on plants’ height, number of leaves, weight of fruits and on the population of root and soil nematodes were determined. Phytochemical screening of the active components in the test plant extracts was also conducted. Data collected were subjected to analysis of variance (ANOVA) and significant means were separated using Fisher’s protected LSD. Results from the study revealed that the growth parameters, yields and nematode population were significantly higher (p < 0.05) for the treatment combinations of L. camara and P. biglobosa than the control L. camara leaves extract at 100% performed better than P. biglobosa with respect to all the data measured. Phytochemical analysis revealed the presence of alkaloids, saponin, tannin, flavonoids, phenol and glycosides as the active chemical components in the test plants. This bio–active components were responsible for the nematotoxic effect of the leaf extracts. However results indicate that both aqueous extracts of L. camara and P. biglobosa can be used to manage the root-knot nematodes and increase the yield of groundnut without any toxic effects on the plants. Keywords: Lantana camara , Parkia biglobosa , Meloidogyne incognita , Aqueous leaf extract and Pathogenicity

Biological control of Meloidogyne javanica on tomato with Dazitol® and soil solarization.

Pot and greenhouse trials were conducted for the management of root-knot nematode, Meloidogyne javanica, infestation in tomato. Growth parameters, gall index, soil, and root nematode populations were measured to assess the effect of a novel bio-pesticide (Dazitol®), made from mustard oil and oleoresin of Capsicum, on plant growth and nematode reproduction. Data generated within the pot experiment showed that the tested bio-pesticide did not improve plant growth, but it reduced significantly root-knot nematode damage resulting in a decrease in gall index and root (91%) and soil (62%) population of M. javanica compared with untreated plants. The greenhouse experiment showed that Mocap® and Dazitol® decreased nematode incidence significantly (P < 0.05) on tomato. The result of this study suggested that the best nematode control was obtained by combining soil solarization with chemical or botanical nematicides as an integrated pest management approach.

Influência de manipueira sobre Meloidogyne javanica na soja

Searching alternatives for the control of plant parasitic nematodes, nematicide effect of secondary metabolites or plant residues has been studied. Thus, the manipueira, a liquid residue obtained from the industrialization of cassava (Manihot esculenta), has as its composition cyanogenic glycosides with antimicrobial properties. The objective of this study was to evaluate the potential of the manipueira applied to the soil, aiming at the control of Meloidogyne javanica in the soybean crop. The manipueira was applied at the concentrations of 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%. The experimental design was completely randomized, in an 11 × 2 factorial arrangement (concentrations of manipueira × forms of application - single and fractionated), with five replicates. Soybean plants were inoculated with 3000 eggs and J2 of M. javanica per pot. Sixty days after the first application of the manipueira, agronomic characteristics and parasitism were evaluated. The single application of the manipueira promoted greater growth and root development, as well as a reduction in the number of eggs and juveniles in the roots and in the reproduction factor of M. javanica, for all concentrations. The split application had more effect on reducing the number of galls and egg mass. The lethal manure concentrations for 50% of the soil and root nematode populations were 37.90% and 29.67%, respectively.

Susceptibility of Okra Accessions to Root Knot Nematode

ABSTRACTThe root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, is an important pest of okra [Abelmoschus esculentus (L) Moench], causing root galling and yield losses in commercial and local consumption cultivars. Use of expensive, toxic nematicides needs to be replaced with genetic improvement of plants for resistance to nematodes. A study was conducted to determine pathogenicity of root knot nematode on okra accessions and their degree of resistance to the nematode. Okra accessions obtained form the National Centre for Genetic Resources and Biotechnology, Ibadan, Oyo State, Nigeria, were exposed to 0 or 5000 eggs of M. incognita per plant. Two seeds from each accession were sown in pots containing a sterilized sandy loam soil and thinned to one plant per pot before inoculation with nematodes. Data were collected on plant height, shoot weight, fruit weight, numbers of galls, and nematode population in roots and soil. Reductions in plant height due to M. incognita infection ranged from 13.69% to 75.64%, shoot weight from 13.69% and 67.24%, and fruit weight from 12.96% to 53.29%. Accessions NG/TO/JUN/09/007, NHGB/10/048, NG/AA/SEP/09/040, NHGB/09/057, and NG/SA/DEC/07/0528 were tolerant to M. incognita. Accessions CEN/009, NG/AA/SEP/09/038, NG/SA/DEC/07/498, and NHGB/09/055 were susceptible to M. incognita infection. Resistance to root knot nematode may be able to be achieved through breeding.

Population dynamics of the citrus nematode, Tylenchulus semipenetrans, on navel orange as affected by some plant residues, an organic manure and a biocide

The population dynamics of the citrus nematode, Tylenchulus semipenetrans, on navel orange trees was studied from January 2012 to September 2012. The highest population of the citrus nematode appeared in May 2012 in the soil of navel orange trees, and the highest nematode population in roots appeared in August in the same year. Control of the citrus nematode by using smashed garlic cloves, powders of olive leaves and orange peels, an organic manure, chicken litter, either alone or in combination with a biocide, and sincocin compared to two nematicides, fenamiphos 10%G and oxamyl 24%L, was carried out in April 2012 .The best results for controlling the citrus nematode were obtained four months after the addition of the tested materials in soil; the highest nematode percentages reduction obtained were 90.9%, for smashed garlic cloves, and 72.8%, for chicken litter. On roots, the best results were 92.3% for garlic cloves and 92.0% for oxamyl, one month after application. The concomitant treatments of sincocin plus garlic clove or sicocin plus chicken litter were most effective in managing T. semipenetrans on navel orange trees after four and five months of application.

Melia azedarach controls Meloidogyne incognita and triggers plant defense mechanisms on cucumber

Melia azedarach fruit extracts have recently raised a substantial interest for their use in crop protection against phytoparasitic nematodes. The effect of M. azedarach on the root-knot nematode Meloidogyne incognita on cucumber, as well as the effect on the plant deference mechanism, is reported herein. Crushed fruits of M. azedarach, tested in the soil at the rates of 30 and 60 g kg−1, exhibited nematicidal activity similar to the one of fenamiphos (0.02 g a.i. kg−1) in terms of nematode population in roots and soil as well as reproduction rate. M. azedarach water extracts, rich in aldehydes, alcohols and carboxylic acids, showed nematicidal activity against M. incognita. Moreover, all M. azedarach treatments decreased the activities of catalase (CAT) and peroxidase (POX) involved in host H2O2 detoxification. Soil application of M. azedarach fruits could be favourably considered in the control of M. incognita on cucumber in a sustainable agriculture, since they act directly as nematicidals. Furthermore, M. azedarach elicits plant defence and helps the host to fight the nematodes infestation in an indirect way.

First Report of the Stubby Root Nematode, Paratrichodorus minor, in Mainland China.

The stubby root nematode, Paratrichodorus minor (Colbran, 1956) Siddiqi, 1974, is an economically important species. It not only causes direct damage to the meristemic tissues of plants, but also can be a vector of Tobacco rattle virus and Pepper ringspot virus (2). It has been documented in Afghanistan, Argentina, Australia, Brazil, Canary Islands, Cuba, Egypt, Fiji, India, Israel, Ivory Coast, Japan, Java, Mauritania, New Zealand, Nicaragua, Philippines, Puerto Rico, Senegal, South Africa, Taiwan, Upper Volta, the United States, the former USSR, and Venezuela (1). During a recent investigation on Trichodoridae occurring in China, eight stubby root nematode populations were detected in Hainan, Yunnan, and Fujian provinces in the rhizospheres of eggplant (Solanum melongena), Chinaberry (Melia azedarach), lettuce (Lactuca sativa), longan (Dimocarpus longan), peach (Prunus persica), pear (Pyrus sp.), and walnut (Juglans regia) in soils ranging from clay to sand. The eight populations had similar morphological and molecular characters. The females were cigar shaped with rod-shaped vaginal sclerotization parallel to the longitudinal body axis with a quadrangular vagina in side view having a short vulval slit. The key morphometrics of females were consistent with those of P. minor: body length, 631 to 757 μm; body diameter, 27 to 43 μm; onchiostyle, 35 to 36 μm; a, 18 to 24; b, 4.9 to 5.5; v%, 53 to 55; length of vagina, 10.8 to 11.1 μm; and size of vaginal pieces, 1.7 to 1.9 μm. Males in P. minor are rare and were not found in any of the eight populations. Partial sequences of the 18s RNA gene of each population were amplified with forward primer 5'-AAA GAT TAA GCC ATG CAT G-3' (2), and reverse primer 5'-AGT CAA ATT AAG CCG CAG-3' (3), which yielded a PCR fragment of 1,153 bp. PCR products from all eight populations were sequenced and submitted to GenBank and assigned Accession Nos. GQ995703, GQ995704, GQ995705, GQ995706, GQ995707, GQ995708, GQ995709, and GQ995710. The sequences exhibited 99.8 to 100% similarity with those of P. minor isolates DQ345526, AM269897, AJ438052, AJ438053, and AJ438058 from GenBank. Morphological and molecular identification confirmed that all populations were P. minor. To our knowledge, this is the first report of P. minor in mainland China.

SIMBA, a model for designing sustainable banana-based cropping systems

Banana monocultures (Musa spp., AAA, Cavendish sub-group cv. Grande Naine) can have a detrimental impact on the environment. In these agro-systems, pesticide treatments can lead to surface and groundwater pollution, as is the case in the tropical insular conditions of the French West Indies. Using models to design alternative cropping systems is of growing interest but most of the research work has been concentrated on annual crops and most often in temperate climate. A specific model called SIMBA was built to assess environmental risks under a large range of cropping techniques and to help design more sustainable cropping systems. SIMBA simulates banana-cropping systems at field level over several cropping cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield, and economic outputs with a sound balance between representing the major phenomena well and keeping the model simple to reduce the parameterization costs in a large range of conditions. Agro-environmental indicators generated by the model make it possible to assess the major potential environmental impacts. The model has been developed and calibrated in Guadeloupe and Martinique and is used to draw up practical recommendations for farmers and for virtual experiments of agro-technological innovations or field management strategies. The structure of SIMBA is presented and a methodology is proposed for designing sustainable banana-based cropping systems using the model. SIMBA has been evaluated in a broad range of cropping systems in Guadeloupe by comparing model estimates to data collected in field experiments and surveys. Simulations lead to trends in rotation-based cropping systems characterized by systems that can be considered as intensive for profit evaluation, and combinations of frequent replanting, low nematicide application, no ploughing, and low fertilization level, for environmental evaluation. Simulations performed to optimize the replanting decision rule showed that relatively frequent replanting is good for profit while low frequency replantations (over four banana cycles) give a better environmental evaluation.

Growth Response and Susceptibility of Telparia Occidentalis Hook Lines to the Root-knot Nematode Meloidogyne Incognita

The productivity and host suitability of fifteen lines of fluted pumpkin Telfairia occidentalis HOOK f. were evaluated in a root-knot nematode infested field in the early seasons of 2001 and 2002. The root systems of twelve week-old root-knot nematode-infected Celosia argentea L. cv. TLV-13 plants earlier grown on the plot were ploughed into the plot to serve as primary source of inoculum. Pre-planting soil nematode population (Pi) of the experimental plot was assessed from composited 200cm 3 soil. The experiment was laid out in a randomized complete block design with three replications. Growth response of line EN2000-4 was statistically outstanding when compared with the other tested lines. The vine lengths recorded for lines EN2000-4, EN2000-6, EN2000-11 and EN2000-12 were significantly longer than the other tested lines. The lower values however occurred in lines EN2000-1, EN2000-5, EN2000-7 and EN2000-8. Line EN2000-3 recorded the highest soil and root nematode populations, gall index as well as the highest number of egg-mass. Line EN2000-4 showed the highest level of resistance with significantly low nematode populations, gall index and number of egg-mass. Significant negative correlation was respectively observed between the growth characters and measured indices of nematode infection i.e. (nematode populations (soil and root), gall rating as well as number of egg-mass). Significant positive correlation was also observed between number of pods and plant vigour. Leaf fresh weight was significantly correlated with shoot fresh weight and number of pods. Similarly, number of leaf was correlated with shoot fresh weight. Correlation between soil nematode population, root nematode populations, gall rating and egg-mass were highly significant. Fresh shoot weight was negatively correlated with all the measured indices of nematode infection, but they were not significant.. Keywords : Growth, susceptibility, root-knot nematodes, Telfairia occidentalis Nigerian Journal of Horticultural Science Vol. 10 2005: pp. 52-58

Amelioration of root-knot disease of lady's finger plants by potentized Cina and Santonin

Lady's finger plants (Hibiscus esculentus), grown in pots, were inoculated with the second-stage larvae (76±6) of root-knot nematodes Meloidogyne incognita, starting 7 days later they were treated with Cina 30c, Santonin 30c or Ethanol 30c by foliar spray for 10 consecutive days. The drugs in 90% ethanol were diluted with distilled water 1:1000 before application on plants. Thirty days after the last treatment the plants were uprooted. Cina 30c and Santonin 30c reduced nematode infestation of plants significantly in terms of root-gall number, root-protein content and nematode population in roots. Santonin 30c reduced root water content. Santonin 30c may have influenced the water channel proteins of root tissues thereby altering the water contents of roots. The reduced water content in roots might have adversely affected the root-knot nematodes and thus reduced nematode infestation. Ethanol 30c also has some effect on treated plants.