Nematode Attack Research Articles

Phytohormones selectively affect plant parasitic nematodes associated with Arabidopsis roots.

Phytohormones may affect plant-nematode interactions directly as chemo-attractants or -repellents, or indirectly through the root-associated microbiome or through host defense mechanisms. However, the exact roles of phytohormones in these complex plant-soil-nematode interactions are not well understood. We used Arabidopsis thaliana mutants impaired in phytohormone synthesis or sensitivity to elucidate their role in root-nematode interactions. As root-associated microorganisms may modulate these interactions, we explored correlations between the relative abundances of root-associated nematodes, and bacteria and fungi using amplicon sequencing. We found distinct shifts in relative abundances of a range of nematode taxa in the A. thaliana phytohormone mutants. The root knot nematode Meloidogyne hapla, a sedentary endoparasitic species that is in intimate contact with the host, was highly enriched in JA-, SA- and SL-impaired lines, and in an ET-insensitive line. Positive or negative correlations between specific microbial and nematode taxa were observed, but, as the inference of causal relationships between microbiome responses and effects on nematode communities is premature, this should be studied in detail in future studies. In conclusion, genetic derailment of hormonal balances generally rendered plants vulnerable to endoparasitic nematode attack. Furthermore, preliminary data suggest that this effect may be partially modulated by the associated microbiome.

Nematode Attacks and their Influence on Farming Economics

Nematode attack is among the factors significantly reducing the world's rice production, to the extent of affecting farming economics and global food security. One of the factors involved in the decline in production is the prevalence of rice diseases and pests, among which are nematodes. Therefore, this study was conducted to identify the level of farmers’ knowledge on the symptoms of nematode infection in Pasir Panjang, which is situated in the rice cultivation area, namely Integrated Agricultural Development Area (IADA), of Northwest Selangor. The study also analyzed the effects of nematode attacks on farming economics. Descriptive analysis was performed on 86 randomly selected samples of farmers whose crops had often been attacked by nematodes. The results of the study found that the farming community had knowledge of the symptoms of nematode infestation in rice crop fields. Analysis of the study results showed that farmers were significantly affected by nematode attacks on their rice crops. The effects of attack could be seen from the reduced income and economic levels of the farmers and consequent increase in management costs, in addition to the increasing costs of purchasing pesticides and fertilizers. Production output and yield quality also declined. This situation has negatively impacted the quality of life of these farmers. The implications of this study inform the strategies for integrated and continuous disease and pest control to ensure that the country's food security is more stable.

Exogenous Peroxidase Mitigates Cadmium Toxicity, Enhances Rhizobial Population and Lowers Root Knot Formation in Rice Seedlings

Soil cadmium (Cd) causes toxicity and oxidative stress, alters biochemical processes and root knot formation in rice. Irrigation of exogenous peroxidase (POX) together with its co-substrate H2O2 (POXRice+H2O2), is likely to have protective effect upon the biochemical and nodular changes in rice grown in Cd-rich soil. Exposure to Cd concentration of 1.00mg/L increased oxidative stress, loss of cell viability, electrolyte leakage and root knot formation, whereas it significantly lowered the chlorophyll level and rhizobium growth in rice. Irrigation of exogenous POXRice+H2O2 to Cd-stressed rice seedlings reversed the Cd-induced alterations in rice to levels similar in control (non-stressed) seedlings. Results provided strong evidence of exogenous POXRice+H2O2-mediated reversal and restoration of physiological and biochemical processes as well as increased resistance of rice seedlings to root knot formation. Irrigation with POXRice+H2O2 appeared to contribute towards bringing normoxic conditions in the otherwise hypoxic soil environment by enhancing the O2 in pot-experiments due to reduced Cd uptake, enhanced mineral homeostasis of essential elements viz. P, Fe, Mo, Mg and Mn for maintenance of root architecture damaged by lipid peroxidation and reduction in oxidative stress by reducing Cd-induced reactive oxygen species generation. Therefore, the mitigation of Cd-toxicity in rice through this novel approach appeared to be a promising mode to limit Cd-uptake, modulate protective and tolerance mechanisms for sustainable rice yield in Cd-contaminated rice-croplands and prevent nematode attack in rice, however, more detailed studies are needed prior to large scale applications.

Impacts of Root-Lesion Nematode (Pratylenchus thornei) on Plant Nutrition, Biomass, Grain Yield and Yield Components of Susceptible/Intolerant Wheat Cultivars Determined by Nematicide Applications

Field experiments testing rates of various nematicides, with and without NPZn fertiliser, were analysed to investigate how root-lesion nematode (Pratylenchus thornei) affects growth and yield components of susceptible/intolerant wheat cultivars in a subtropical environment. Plant response to nematode attack was assessed by regression and principal components analyses of various plant parameters at different crop development stages, in relation to different nematode population densities in the roots and root-zone soil. Reduction in P. thornei population densities by nematicides resulted in increased numbers of tillers, plant biomass, N and P concentrations and uptakes, numbers of spikes and kernels, and grain yield. Grain yield was strongly correlated with number of kernels, biomass and number of spikes, and negatively correlated with number of P. thornei in the root-zone soil at stem elongation. This study showed that P. thornei damage to roots decreased wheat yield through limiting N and P concentrations and uptakes in plant tops causing poor growth that commenced early and continued through the life of the crop. Genetic, environmental and management factors that reduce population densities of P. thornei, and decrease the impact of the nematodes starting in early crop growth, will greatly increase spike and kernel numbers and grain yield.

A Phytochemical Perspective on Plant Defense Against Nematodes.

Given the large yield losses attributed to plant-parasitic nematodes and the limited availability of sustainable control strategies, new plant-parasitic nematode control strategies are urgently needed. To defend themselves against nematode attack, plants possess sophisticated multi-layered immune systems. One element of plant immunity against nematodes is the production of small molecules with anti-nematode activity, either constitutively or after nematode infection. This review provides an overview of such metabolites that have been identified to date and groups them by chemical class (e.g., terpenoids, flavonoids, glucosinolates, etc.). Furthermore, this review discusses strategies that have been used to identify such metabolites and highlights the ways in which studying anti-nematode metabolites might be of use to agriculture and crop protection. Particular attention is given to emerging, high-throughput approaches for the identification of anti-nematode metabolites, in particular the use of untargeted metabolomics techniques based on nuclear magnetic resonance (NMR) and mass spectrometry (MS).

Comparison of Metabolomics Expression in The Root and Leaf of Resistance and Susceptible Tomato against Root-Knot Nematode

The resistant tomato against nematode produces various biochemical compounds associated with the defense mechanisms for nematode attack. These compounds allegedly expressed in all cells not only in the infected area. These metabolites are useful for plant development program to point out the candidate traits based on specific metabolites. This study aimed to compare expression of metabolomics as defense mechanism in root and leaf of the plant. Four cultivars consisted of the resistant [GM2 and F1 (a cross GM2 and Hawaii 7996)] and susceptible (Gondol Putih and Gondol Hijau) were used as plant materials. Fifty mg of freeze-dried of root and leaf were taken for assessing 1H-NMR (Nuclear Magnetic Resonance) for metabolomic analysis. Tomato roots resulted in 16 metabolites, while in the leaf detected 15, including amino acid, sugar, and aromatic compounds. Both root and leaf showed the same metabolites that play an important role in nematode-resistant mechanism, these metabolites were α- and β-glucose, and caffeic acid. These compounds had the same concentration within the root and leaf. It is implied that the metabolites associated with defense mechanism of tomato plants against nematode not only expressed locally in the infected area but also produced by not infected tissues throughout the plant.

Efficacy of integrated microorganisms in controlling root-knot nematode Meloidogyne javanica infecting peanut plants under field conditions

BackgroundPeanut (Arachis hypogaea L.) is considered one of the most important legume and oil crops in Egypt. Root-knot nematodes Meloidogyne spp. is the most damaging nematodes of peanut. Losses can exceed 50% in severely infested soil. Application of nematicides is one of the primary strategies in controlling plant-parasitic nematodes. The nematicides are proven to be hazardous to the environment. A promising alternative is the use of microorganisms antagonistic to plant-parasitic nematodes. Some microorganisms that can grow in the rhizosphere such as Azotobacter and Bacillus bacteria and fungi, e.g., Tricoderma and Paecilomyces represent the front line of defense for roots against nematode attack and ideal for use as biocontrol agents.ObjectivesThe main aim of this study was to evaluate the efficacy of application of yeast fungus Saccharomyces cerevisiae singly or combined with fusant Bas 8; (Bacillus amyloliquefaciens and Lysinibacillus sphaericus Amira strain); Bacillus thuringiensis strain code K, Trichoderma harzianum, or Paecilomyces lilacinus to control the root-knot nematode Meloidogyne javanica infecting peanut plant cv. Giza 6, and to estimate their yield under field conditions.ResultsCompared to the untreated control, all treatments exhibited variable potential inhibitory activities against root-knot nematode M. javanica and enhanced peanut yield production. The most nematode suppressive treatment was the single treatment of Saccharomyces cerevisiae, followed by T. harzianum either singly or combined with the yeast. Moreover, data indicated that application of the combined treatment of yeast plus T. harzianum gave the best results in improving peanut production, plant growth parameters, and seed nutrient contents.ConclusionIt was concluded that integrated application of microorganisms could enhance peanut production and reduce the need for either chemical fertilizers or nematicides.

RESPUESTA A LA FERTILIZACION POTASICA DE TRES VARIEDADES DE FRIJOL CANARIO (Phaseolus vulgaris L), BAJO LAS CONDICIONES CLIMATICAS DE LOS ANITOS- BARRANCA

The Canario bean Phaseolus vulgaris L, is a food legume of economic importance in the Province of Barranca-Perú. In the last five years, the presence of the "balloon grain" has influenced the low productivity of the crop. The purpose of the present study was to identify which factors limit performance and determine which variety (s) have the best behavior or resilience under the edaphoclimatic conditions of the Fundo los Anitos, located in the Barranca district. The experiment was conducted at an altitude of 65 msnm, temperature oscillating between 13.9 to 29 °C and with an annual rainfall of 7-10 mm, FcoA soil, of alluvial origin. 03 Bean varieties were used, applying NPK with three levels of potassium fertilization. The experimental design used was a DBCA with 4 repetitions. The spacing of the culture was 0.8 mt. between grooves and 0.4 mt. between plants, 3 plants / blow. The hypothesis proposed refers to the fact that one or more Canario bean varieties, with balanced fertilization, are determining factors that influence the growth and accumulation of biomass, in addition to increasing the resilience capacity to unfavorable biotic and abiotic factors, caused by climate change. The results indicate that the Canario bean 2000, presented better behavior in biomass accumulation and resistance to rust and nematode attack, as well as better response to the 60N40P2O5-0K2O fertilization dose, compared to the other varieties under study. The centenario and common bean presented a response to fertilization 60N-40P2O5-60K2O and 60N-40P2O5- 120K2O, respectively. The results obtained in the present study are related to the growth habit of the varieties: Type I and II, being the Canario bean 2000, with a growth habit of type II, who presented the greatest accumulation of biomass at flowering, taking advantage of the residual potassium from the soil, resistance to rust and nematode attack. Key words: Potassium, fertilization, beans, variety, biomass, resilience

Can the plant immune system be activated against animal parasites such as nematodes?

Summary Plants have an immune system that can be exerted by every cell against a vast array of pathogens and parasites. This immune system has several levels of specialisation. A first level induces a general basal defence, after which specific pathogen-associated molecular patterns (PAMPs) are recognised by plant receptors. Normally, this basal defence is overcome by specialised pests by secreting specific effectors that suppress this first line of defence. Plant-parasitic nematodes have been found to secrete several such effectors through amphid and cuticle secretions or directly into the cells through their stylets. Many studies carried out on endoparasitic sedentary nematodes (ESN), in particular, reported the suppression of plant defence, especially in terms of down-regulation of the genes involved in salicylic acid (SA)-mediated defence, in the very first stages of plant-nematode interaction. However, plants can be immunised or primed against nematode attacks. Immunised plants respond to nematode infection more rapidly and efficiently and let a minor number of invasive juveniles become sedentary, develop to gravid females and reproduce. Immunisation of plants can be achieved by pre-treatments with chemicals that are functional analogues of the phytohormones that mediate defence reactions, such as salicylic acid (SA). Moreover, plants provided with the beneficial microorganisms commonly present in a healthy rhizosphere, such as arbuscular mycorrhizal fungi or opportunistic symbiotic fungi, have been found to be immunised against ESN. Immunisation is mainly mediated by up-regulation of SA-dependent defence genes, such as pathogenesis-related genes (PR-genes). Immunisation is systemic and can also work against herbivorous insects.

Interactions with ectoparasitic mites induce host metabolic and immune responses in flies at the expense of reproduction-associated factors.

Parasites cause harm to their hosts and represent pervasive causal agents of natural selection. Understanding host proximate responses during interactions with parasites can help predict which genes and molecular pathways are targets of this selection. In the current study, we examined transcriptional changes arising from interactions between Drosophila melanogaster and their naturally occurring ectoparasitic mite, Gamasodes queenslandicus. Shifts in host transcript levels associated with behavioural avoidance revealed the involvement of genes underlying nutrient metabolism. These genetic responses were reflected in altered body lipid and glycogen levels in the flies. Mite infestation triggered a striking immune response, while male accessory gland protein transcript levels were simultaneously reduced, suggesting a trade-off between host immune responses to parasite challenge and reproduction. Comparison of transcriptional analyses during mite infestation to those during nematode and parasitoid attack identified host genes similarly expressed in flies during these interactions. Validation of the involvement of specific genes with RNA interference lines revealed candidates that may directly mediate fly-ectoparasite interactions. Our physiological and molecular characterization of the Drosophila-Gamasodes interface reveals new proximate mechanisms underlying host-parasite interactions, specifically host transcriptional shifts associated with behavioural avoidance and infestation. The results identify potential general mechanisms underlying host resistance and evolutionarily relevant trade-offs.

The atypical E2F transcription factor DEL1 modulates growth\u2013defense tradeoffs of host plants during root-knot nematode infection

In plants, growth–defense tradeoffs are essential for optimizing plant performance and adaptation under stress conditions, such as pathogen attack. Root-knot nematodes (RKNs) cause severe economic losses in many crops worldwide, although little is known about the mechanisms that control plant growth and defense responses during nematode attack. Upon investigation of Arabidopsis thaliana infected with RKN (Meloidogyne incognita), we observed that the atypical transcription factor DP-E2F-like 1 (DEL1) repressed salicylic acid (SA) accumulation in RKN-induced galls. The DEL1-deficient Arabidopsis mutant (del1-1) exhibited excessive SA accumulation in galls and is more resistant to RKN infection. In addition, excessive lignification was observed in galls of del1-1. On the other hand, the root growth of del1-1 is reduced after RKN infection. Taken together, these findings suggest that DEL1 plays an important role in the balance between plant growth and defense responses to RKN infection by controlling SA accumulation and lignification.

Selection and validation of suitable reference genes for quantitative real time PCR analysis of gene expression studies in patchouli under Meloidogyne incognita attack and PGPR treatment

Patchouli (Pogostemon cablin) is an economically important aromatic plant and is often vulnerable to nematode attack (Meloidogyne incognita). The application of PGPR has tremendously changing disease management approach in plants and a systematic understanding the molecular mechanism behind it is needed to control over the disease more precisely. Since, qRT-PCR is the most frequently used molecular tools in studying molecular mechanism but is greatly dependent upon suitable reference or housekeeping genes. This study is aim to select suitable reference genes for qRT-PCR experiments in patchouli under the condition of nematode attack and PGPR treatments. Expression pattern of six reference genes (Actin, EF1, ACP, COX3, GAPDH and Pat18S) were statistically analyzed and validated using different algorithms viz., ΔCt, BestKeeper, GeNorm, NormFinder and RefFinder. The result showed that the Actin and ACP are the most suitable reference genes and the combination of ACP &GAPDH gene pairs can also be used whenever the experiment needed.

Occurrence and molecular characterization of Meloidogyne graminicola on rice in Central Punjab, Pakistan.

Meloidogyne graminicola threatens global rice production, yet is understudied for many areas where it is cultivated. To better understand the prevalence and incidence of M. graminicola in central Punjab, Pakistan, we carried out field surveys of rice fields in the districts of Faisalabad and Chiniot. M. graminicola isolates were recovered from soil and root samples and identified on the basis of perineal patterns and rDNA ITS-based sequencing. The severity of nematode attack on rice roots and infested fields at various locations was based on galling index, root-knot nematode juveniles per root system, juveniles per 100 ml of soil, and prevalence of stylet-bearing nematodes and non-stylet-bearing nematodes. Maximum prevalence (22.5 and 27.5%) and minimum prevalence (17.5 and 20%) of M. graminicola was observed in Chiniot and Faisalabad, respectively. Eleven alternate host-plant species were examined in this study revealing varying degrees of M. graminicola infestation. ITS sequencing and phylogenetic analysis indicated that isolates from this study form a well-resolved clade with others from Asia, while another isolate falls outside of this clade in an unresolved polytomy with those from Europe and South America. Though monophyletic with the other M. graminicola, the isolates from Pakistan are distinguished by their high genetic variability and long branch lengths relative to the other isolates of M. graminicola, suggesting Pakistan as a possible ancestral area. Our results indicate that rice is severely attacked by a genetically diverse and aggressive M. graminicola, necessitating the development of appropriate control measures for its management in rice and other graminaceous crops.

Variations in the level of resistance to root-knot nematodes (Meloidogyne spp.) infestation among ten cowpeas (Vigna unguiculata L. Walp.) genotypes

The cultivation of cowpea (Vigna unguiculata L. Walp.) cultivars that are tolerant to root-knot nematode attack is among the environmentally safe approach to managing the root-knot nematode menace in cultivated crops. In this study, the tolerance of 10 cowpea genotypes to root-knot nematodes infestation was evaluated in a pot experiment conducted in a Screenhouse, at the University for Development Studies, Nyankpala Campus. The experiment was laid out in a completely randomized design with three replications. The number of second stage juveniles (J2) per 250 cm3 of soil sample were counted while the severity of root-knot nematode damage (root galls) was assessed. The reproduction index (RI) was used to classify the varieties as resistant or susceptible. There was a significant difference (P < 0.05) in the number of second stage juveniles of root-knot nematode (RKN), galling index and RI among the genotypes tested. The study revealed that cowpea genotypes SARI 1-4-90, Padi tuya, Songotra, IT99K-1122, Sanzi and Apagbaala were moderately resistant whereas cowpea genotypes IT86D-610, Zaayura, SARI 5-5-5 and IT07K-299-6 were slightly resistant. Thus, the six moderately resistant cowpea genotypes were suggested to be used as a source of resistance to RKN in future breeding works.

Enhancing Greenhouse Tomato-Crop Productivity by Using Brassica macrocarpa Guss. Leaves for Controlling Root-Knot Nematodes

Tomato crops are affected in Mediterranean cold-greenhouse agrosystems by soilborne diseases, such as root-knot nematodes (Meloidogyne spp.), which represent a serious problem leading to losses in production. Agroecological soil management based on biocontrol agents and natural compounds has had increased grower interest in order to reduce chemical residues in the produce and to adopt environmentally friendly farming methods. In this frame, we evaluate and validate soil biofumigation by the use of glucosinolate (GLS) compounds. Among them, sinigrin showed biocontrol activities against several pests and diseases via nematotoxic action. Among the Brassicaceae species rich in sinigrin, we chose Brassica macrocarpa Guss. (BM) because its leaves show 90% of all GLSs, and we could better estimate the action of this single GLS. Different dosages of BM leaf flour, containing 200 to 300, 350, 400, 450, and 650 μmol m−2 of sinigrin, were inserted into soil already infected by Meloidogyne spp. for evaluating their effects on tomatoes grown in cold greenhouses in comparison to absolute control (CTRL) and to the chemical one, Vydate 5G® (CCTRL). The root disease index, caused by nematode attack, was the highest in CTRL, and a reduction of about 50% was observed with the 300 to 650 μmol m−2 sinigrin dosage. The CCTRL showed twofold marketable yield increase, and a fourfold increase was found in 650 μmol m−2 of sinigrin dosage, in comparison to the CTRL. Biofumigant applications improved tomato plant growth and development, and fruit quality, significantly for dry matter and soluble sugars (°Brix). BM leaf flour inserted into the soil, at a dose of 300 μmol m−2 of sinigrin, showed similar effects to the CCTRL on root disease index, root weight, and marketable yield. Data showed the nematotoxic effect of sinigrin for the biocontrol of Meloydogine spp. by the use of B. macrocarpa leaves, very rich in this GLS compound, which represents a new tool for agroecological soil management and for organic farming.

Genetic diversity and population structure of enset (Ensete ventricosum Welw Cheesman) landraces of Gurage zone, Ethiopia

Enset (Ensete ventricosum (Welw.) Cheesman), which feeds around 20 million Ethiopian people, is a unique crop; with all parts of the plant are utilizable. It is, arguably, less researched crop and the mode of production remained conventional. Understanding the extent of genetic diversity in the crop, especially making use of genotyping data, is a very important first step in the genetic improvement of the crop. Twelve polymorphic enset SSR markers were used to assess the genetic diversity and population structure of 79 cultivated landraces and four wild enset individuals collected from different enset growing locations of Ethiopia. The polymorphic information content of markers ranged from 0.62 to 0.77 with a mean value of 0.69. A total of 77 alleles were identified, and the average observed heterozygosity varied from 0.51 to 0.67. A mean gene diversity of 0.59 was recorded ranging from 0.55 to 0.62. The AMOVA revealed that within population allelic variations contributed more to the genetic diversity than among population variations. Discriminant Analysis of Principal Components and population structure analysis grouped the 83 enset germplasms into three major clusters, where the wild individuals clustered distinctly. Outcomes of this research provide valuable information for enset conservation and breeding strategies especially for development of resistance for bacterial wilt and nematode attacks.

Single-cell damage elicits regional, nematode-restricting ethylene responses in roots.

Plants are exposed to cellular damage by mechanical stresses, herbivore feeding, or invading microbes. Primary wound responses are communicated to neighboring and distal tissues by mobile signals. In leaves, crushing of large cell populations activates a long-distance signal, causing jasmonate production in distal organs. This is mediated by a cation channel-mediated depolarization wave and is associated with cytosolic Ca2+ transient currents. Here, we report that much more restricted, single-cell wounding in roots by laser ablation elicits non-systemic, regional surface potential changes, calcium waves, and reactive oxygen species (ROS) production. Surprisingly, laser ablation does not induce a robust jasmonate response, but regionally activates ethylene production and ethylene-response markers. This ethylene activation depends on calcium channel activities distinct from those in leaves, as well as a specific set of NADPH oxidases. Intriguingly, nematode attack elicits very similar responses, including membrane depolarization and regional upregulation of ethylene markers. Moreover, ethylene signaling antagonizes nematode feeding, delaying initial syncytial-phase establishment. Regional signals caused by single-cell wounding thus appear to constitute a relevant root immune response against small invaders.

Biochemical changes in Vegetable crops due to humic acid treatment for management of Nematodes

The aim of this study was to evaluate potassium humate against root-knot nematode infection and the biochemical changes which resulted in significant reduction on the rate of nematode build up and numbers of eggs/egg mass. Humic acid applied at the rate of 20 kg/ha appeared to be more suppressive to nematode buildup. The higher dose was more effective than the lower one. The phenol contents were found to be highest as the dosage increased. The study indicates a higher rate of protein synthesis during invasion of nematodes for initiation of early primary resistance mechanism by the plants to combat nematode attack. Sugar levels coincides with gall formation in the root tissue by the nematode and indicates greater sugars in the attacked tissue for providing nutrition to the nematodes for their growth and survival. In addition, potassium humate changes the physical as well as the tropic structure of soil which affects the nematode development and overall plant growth performance.

ACTIVITY OF CHESTNUT TANNINS AGAINST THE SOUTHERN ROOT-KNOT NEMATODE MELOIDOGYNE INCOGNITA

Studies on the effects of tannins on plant-parasitic nematodes are few. A new formulation of a hydrolysable tanninextracted from chestnut (SaviotaN®) was tested for efficacy in controlling Meloidogyne incognita. Therefore, in vitro andpot experiments on tomato were performed to investigate the nematicidal activity of tannin aqueous solutions at differentconcentrations on M. incognita. In the in vitro experiment the following concentrations of tannin at 0.30, 0.40, 0.50, 0.75,1.00, 1.25, 1.50 g L−1 were tested for their effect on the nematode. The second-stage juveniles (J2s) immobility increasedwith increasing concentration and exposure time. All tested tannin concentrations were effective to reduce viability fromabout 45 to 70% after 10 days of exposure, in comparison to the treated and untreated controls. The immobile J2s recoveredtheir mobility over time after rinsing and transferring them in water, showing a nematostatic activity of tannins. In the potexperiment, tannins, as aqueous solutions at rates from 0.30 to 1.50 g L−1, were applied to soil at three different applicationtimes (1: only at transplant; 2: at transplant, two weeks after transplant and repeated every seven days; 3: at transplant andtwo weeks later). The activity of tannins was compared to treated and untreated controls. Tested rates mostly repeated wereeffective to control nematode attack in comparison to untreated control. The height of treated plants was not significantlyinfluenced by the different applied rates of tannins, whereas nematode population density and root galling index wereaffected by repeated application times. No visual symptoms of phytotoxicity were detected. The use of SaviotaN®appearspromising for the control of M. incognitain sustainable agriculture of short-term crops and/or when nematode populationdensities are low and as a supplement to other chemical treatments.

The nematicidal property of aqueous crude extract of Calotropis procera on tomatoes (Lycoperscium esculentus)

The Efficacy of the aqueous crude extract from Calotropis procera Linn. on the growth and production of tomatoes Lycopersicum esculentus Mill. infested by Meloidogyne javanica was investigated. An aqueous crude extract of Calotropis procera Linn. was prepared by soaking 2kg of dried powdered leaf in the ratio of 1:5mg/ml for 24 hours; this was sieved and concentrated with water bath at a controlled temperature of not above 60°C also freeze dried to obtain 487g of the dried crude extract. The plant pot of tomatoes infested with Meloidogyne javanica was treated with different concentration of the extracts. Treatment with 50% concentration of the stock solution of C. Procera showed significant growth and yield of tomato. Plant height was 83.3cm whereas in control it was 68.3cm. Significant differences in all other parameters were also obtained. Plant height at final harvest was 89.6cm as compared to control (74.3cm). A positive effect was seen in reducing the number of nematodes both in the soil and in the root. The treatment showed a root gall index of 2.3 which was lowest as compared to control (7.3). Hence at adequate concentration of C. procera extract it is possible to inhibit the nematode attack in tomato.