A possible new approach for controlling root knot nematode,Meloidogyne incognita,infecting eggplant by certain insect growth regulators

Under greenhouse conditions, three insect growth regulators, buprofezin, flufenoxuron and pyriproxyfen, at field concentrations and other two lower concentrations were evaluated for controlling of root knot nematode, Meloidogyne incognita, infecting eggplant (Solanum melongena L.) cv. Baladi. Generally, the tested pesticides reduced the number of galls, egg masses, females and developmental stages in roots and juveniles in soil compared to untreated check. The percentages of reduction were positively proportional with the respective concentrations. Flufenoxuron at its highest concentration was the most effective pesticide in reducing galls, egg masses, females and developmental stages compared with pyriproxyfen and buprofezin. The percentages of reduction caused by flufenoxuron were 67.80, 69.57, 70.75 and 95.23% for the, respective nematode criteria, while buprofezin at the highest concentration was the most effective in reducing number of hatched juveniles in soil followed by flufenoxuron and pyriproxyfen. Data showed that the length and fresh and dry weights of root and shoot of egg plant were increased with the lowest concentrations than the highest ones.     

Antagonistic potential of certain legumes to Meloidgyne incognita on sugar beet

Under greenhouse conditions, a pot experiment was conducted to clarify the potential of using some legumes as intercropped plants for reducing the root-knot nematode Meloidogyne incognita infecting sugar beet (Beta vulgaris L.) cv. DS-9004 compared to non-legume plant, garlic and non-intercropped plants. The obtained results revealed that all legumes including chickpea, Egyptian clover, faba bean, fenugreek, lentil and lupin significantly (p ≤ 0.05) reduced nematode criteria on the roots of sugar beet at different degrees. Chickpea and Egyptian clover reduced the number of galls on the roots of sugar beet as the percentage of reductions were 54 and 50%, respectively, followed by lupin and fenugreek, while garlic achieved 72% reduction compared to non-intercropped plants. Lupin reduced the number of egg masses by 59% followed by Egyptian clover and fenugreek (32%), three months after the treatment. On the other hand, six months after the treatment, chickpea reduced the number of galls by 55.7% followed by lupin (53.4%) and Egyptian clover (52.3%) and the percentage of reduction of egg masses behaved the same trend. Also, the treatments improved plant growth criteria of sugar beet, weight of roots (tubers) and the percentage of total soluble solids (TSS).     

Pathogenicity of root knot nematode Meloidogyne incognita on okra and its management through botanicals

An investigation was carried out to study the pathogenicity of root knot nematode Meloidogyne incognita on okra and its management through various organic amendments. The inoculum level of 1000 juveniles per plant showed significant reduction in various plant growth parameters, which reveals that M. incognita is a potential pathogen of okra. With the increase in inoculums level of M. incognita (J₂), there was a progressive decrease in various plant growth parameters. The maximum reduction in plant growth parameters was observed at an inoculum level of 4000 juveniles per plant. The efficacy of five organic amendments viz. groundnut cake, castor cake, sunflower cake, linseed cake and sawdust was tested against root knot nematode M. incognita. Amending the soil with different oil cakes was found to be effective in reducing the nematode soil population, number of females, number of egg masses as well as root gall formation in okra. The highest increase in plant growth (13%) and maximum reduction in number of galls (54%), number of females (57%) and number of egg masses (55%) was recorded on application of groundnut cake.     

Host-Parasite Relationships of Meloidogyne arenaria and M. incognita on Susceptible Soybean

Pathogenicity and reproduction of single and combined populations of Meloidogyne arenaria and M. incognita on a susceptible soybean (Glycine max cv. Davis) were investigated. Significant galling and egg mass production were observed on roots of greenhouse-grown soybean inoculated with M. arenaria and M. incognita, in combination and individually. M. arenaria produced more galls and egg masses than M. incognita, whereas in combined inoculation with both nematode species, gall and egg production was intermediate. In growth chamber tests, inoculations with M. arenaria and M. incognita, singly or in combination, produced more galls and egg masses at 30 C than at 25 C. At 25 C, M. arenaria alone produced significantly more galls and egg masses than the combined M. arenaria plus M. incognita, while M. incognita produced the fewest. At 30 C, numbers of egg masses produced by M. arenaria did not differ significantly from combined M. arenaria and M. incognita. In temperature tank tests, M. incognita produced more galls and egg masses at 28 C than at 24 C soil temperature. In contrast, numbers of galls, egg masses, and eggs of M. arenaria were slightly higher at 24 C than at 28 C. Combined inoculum of both nematode species produced greater numbers of galls at 24 C than at 28 C.     

Susceptibility of different developmental stages of the root-knot nematode, Meloidogyne incognita, to the nematicide oxamyl

Oxamyl (6.25 μg ml^-1 soil water) was applied to cucumber roots containing Meloidogyne incognita at different stages of nematode development. Oxamyl was more effective in reducing the proportion of juveniles which developed into females when applied soon after infection to second stage juveniles than when applied later (to third and fourth stage juveniles). Early application of oxamyl also significantly reduced the proportion of females with egg masses, whereas late application had no such effect. However, the number of eggs per egg mass and the size of the young adult females was significantly reduced by all oxamyl treatments - the earlier the application the greater the effect. These results support the hypothesis that actively feeding second stage juveniles of Meloidogyne spp. are more susceptible to systemic nematicides than are the non-feeding third and fourth stage juveniles.     

Role of organic soil amendments with some non-conventional plant additives on the growth of eggplant and their role against Meloidogyne incognita infection

The effects of four waste residues from castor (Ricinus communis L.), rocket (Eruca sativa Mill.), linseed (Linum usitatissimum L.) and wheat germ (Triticum aestivum L.) crops oil extraction as soil amendments at three rates (on base lower rate, recommended rate and higher rate), in comparison with the nematicide Nemacur 10% G were evaluated in greenhouse conditions (25 ± 5°C) at the National Research Center, Egypt, during two successive seasons on the physiological influence on the eggplant and on the infection by the root-knot nematode Meloidogyne incognita. All the tested treatments significantly reduced the numbers of juveniles in soil or in roots, number of galls, egg-masses, gall and egg-mass indices and the rate of nematode build-up. Significant differences in the nematode stages were found within and between treatments. The percentage reduction in the nematode stages was greater with the use of wheat germ mill residues (WGMR) compound followed by castor seed mill residues (CAMR) compound, rocket seed mill residues (RSMR) and Nemacur 10% G. The application of linseed mill residues (LSMR) was the least effective in reducing the nematode stages. Regarding infected plants, all the evaluated amendments achieved significant increases in the almost shoot and root growth variables, total contents of photosynthetic pigments, phenolics and carbohydrates when compared with nematode inoculated and untreated plants. As for healthy plants, it is clear that all the doses of WGMR compound and the highest doses (3.75%, w/w) of the other additives had pronounced effect on the growth parameters and phenolic content of dry leaves of the eggplant. In addition, all the treatments increased photosynthetic pigments and carbohydrates content of the eggplant. These results indicate that some seed mill residues may be used as natural nematicides in controlling M. incognita nematode and improving the growth and some chemical composition of the eggplant.     

Interaction between Meloidogyne incognita and Pochonia chlamydosporia and their effects on the growth of Phaseolus vulgaris

An experiment was conducted to test the effect of different doses of 2, 4 and 8?g/2?kg of soil of Pochonia chlamydosporia against the root-knot nematode (Meloidogyne incognita) on Phaseolus vulgaris. It was observed that inoculation of plant with the nematode alone, and 15?days prior to fungal inoculation, reduced the plant growth when compared with the plant with fungal application followed by the nematode. Plant length, fresh and dry weight, chlorophyll, carotenoid, protein contents and nitrate reductase activity decreased in nematode-infested plants. Application of higher dose of 8?g/2?kg of soil of P. chlamydosporia increased all the plant growth parameters as well as biochemical parameters. Highest number of galls per root system was recorded on the plants infested with nematode but not treated with the fungus. However, application of fungus prior to nematode inoculation improved the plant growth and reduced the number of galls and the number of egg masses per root system.     

Biological control of Meloidogyne incognita and Fusarium solani in dry common bean in the field

Meloidoyne incognita (root-knot nematode) and Fusarium solani (root-rot pathogen) were the common soil-borne pathogens and cause severe damage to bean plants in newly reclaimed sandy soil in Nubaryia district, Behera Governorate, Egypt. The antagonistic effects of Trichoderma album and Trichoderma viride as well as three commercial products namely Rhizo-N^® (Bacillus subtilis), Bio-Arc^® 6% (Bacillus megaterium) and Bio-Zeid^® 2.5% (T. album) were tested against M. incognita and F. solani under naturally infected field conditions. T. album and T. viride highly reduced the frequency (%) population of pathogenic fungi such as Fusarium spp., F. solani and Rhizoctonia spp., than the commercial products. Results indicated that all the tested bio-control agents reduced, significantly, the nematode criteria as evidenced by the number of juvenile (J₂) in soil and number of galls and egg masses on roots of common bean and Fusarium root-rot incidence (%). Rhizo-N^® highly reduced the number of J₂ in soil, while T. album was the best in reducing the number of galls and egg masses in roots. The bio-control agents also increased the plant growth parameters of common bean plants i.e. plant height, plant weight, branch no./plant, pods no./plant, pod weight/plant, pod weight, seeds no./plant, fresh seeds weight/pod, dry seeds weight/pod and dry weight of 100 seeds.     

Isolation and screening of fungi associated with eggs and females of root-knot nematodes and their biocontrol potential against Meloidogyne incognita in Bangladesh

A total of 297 fungal isolates belonging to 20 genera and 33 species were isolated and identified from eggs and females of Meloidogyne spp. in Bangladesh. The predominant genera were Fusarium, Aspergillus and Penicillium; and the significant ones were Purpureocillium, Trichoderma and Pochonia. The 24 well tissue culture plate screening technique was applied for pathogenicity tests against Meloidogyne incognita in vitro. The average percentages of egg parasitism, egg hatch inhibition and juvenile mortality varied significantly and were ranged from 8.2 to 64.9% (p = 0.05), 24.8 to 72.4% (p = 0.05), and 2.3 to 33.1% (p = 0.05), respectively. Two isolates of Purpureocillium lilacinum (PLSAU 1 and PLSAU 2) and one isolate of Pochonia chlamydosporia (PCSAU 1) reduced more than 60% average root galls of tomato, eggplant and cucumber in greenhouse experiments. This is the first investigation of fungi associated with nematodes in the country and their biological control potential against M. incognita.     

Controlling of Portulaca oleracea and Meloidogyne incognita infecting sunflower using leaf extracts of Psidium guava

Experiments were conducted under laboratory and greenhouse conditions to investigate the allelopathic potential of aqueous extracts of dry and fresh leaves of Psidium guava on purslane weed growth and root-knot nematode, Meloidogyne incognita infecting sunflower plants cv. Giza 102. A Petri dish assay showed that the aqueous extracts significantly reduced seedling length of purslane (Portulaca oleracea), with the degree of inhibition being concentration dependent. Greenhouse studies (in 2008 and 2009) indicated greatest significant inhibition in purslane growth as well as number of galls and egg masses of infecting nematode. However, this inhibition was accompanied with increase in sunflower growth and yield. The studies indicated increase in the endogenous contents of total phenols in purslane tissues which correlated with growth inhibition. Chemical analysis indicated increase in the contents of carbohydrates, protein and oil in sunflower seeds. The studies involved analysis of fatty acid composition by GLC which indicated increasing in the percentage of oleic and linoeic acids in sunflower seeds by fresh and dry leaves extract of P. guava. The percentage of linoleic acid and linolenic acid was higher by fresh and dry leaves extract. A high-performance liquid chromatography analysis of P. guava extracts recorded that the ferulic, coumaric, vanelic, chlorogenic, caffiec acids were present.     

Effect of Meloidogyne incognita and Importance of the Inoculum on the Yield of Eggplant

The relationship between population densities of race 1 of Meloidogyne incognita and yield of eggplant was studied. Microplots were infested with finely chopped nematode-infected pepper roots to give population densities of 0, 0.062, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16, 32, 64, and 128 eggs and juveniles/cm³ soil. Both plant growth and yield were suppressed by the nematode. A tolerance limit of 0.054 eggs and juveniles/cm³ soil and a minimum relative yield of 0.05 at four or more eggs and juveniles/cm³ soil were derived by fitting the data with the equation y = m + (1 - m)z^P⁻T. Maximum nematode reproduction rate was 12,300. Hatch of eggs from egg masses in water or from sodium hypochlorite dissolved egg masses was similar (41% and 39%), but egg viability was significantly greater from egg masses in water (58%) than from sodium hypochlorite dissolved egg masses (12%) after 4 weeks. Greater numbers of nematodes were collected from roots of tomatoes from soil infested with entire egg masses than from tomato roots from soil infested with egg masses dissolved by sodium hypochlorite.     

Interaction between Pseudomonas fluorescens and Meloidogyne incognita on tomato plant as influenced by the different levels of phosphorus

A pot experiment was conducted on tomato (Solanum lycopersicum cv. Pusa Ruby) to assess the effect of different phosphorus (P) levels (0, 125, 250 and 500 mg/pot) and the plant growth promoting rhizobacterium, Pseudomonas fluorescens, on the growth of tomato and on the reproduction of Meloidogyne incognita. Maximum growth of tomato occurred at P rates of 125 mg/kg soil, irrespective of whether plants were uninoculated or inoculated with P. fluorescens or M. incognita or inoculated with both the agents. Nematodes per gram of roots, egg masses per root, eggs per egg mass and galls per root significantly increased by increasing levels of P. P. fluorescens performed better than other treatments and different P levels in improving tomato growth and reducing galling and multiplication of M. incognita.     

Effect of certain organic materials in controlling Meloidogyne incognita root-knot nematode infesting banana

Efficacy of certain plant wastes as onion bulb envelope, dry leaves of sugar beet, fleabane and jojoba, filter cake or mud as sugar cane industrial residue and nile fertile mineral bio-fertilisers were studied under field conditions for managing Meloidogyne incognita on banana Cv. Williams. All the tested treatments significantly (P ≤ 0.05 and 0.01) proved to be effective in reducing the studied nematode criteria during the growing season of banana. The highest percentage reductions of 87.5 and 85.5% were recorded in the number of second-stage juveniles caused by fleabane at vegetative and harvest stages, respectively. As for galls, the highest percentage reductions of 80.4 and 79.6% were achieved at harvest stage by sugar beet waste and filter cake residue, respectively. Also, sugar beet waste was the best at increasing banana fruit yield per feddan (77.0%), followed by jojoba (53.1%) and fleabane (50.4%). The number of fingers and hands per bunch increased by the different materials at various degrees.     

Root-knot Nematode Problem of Some Winter Ornamental Plants and Its Biomanagement

A microplot study under field conditions was carried out during 2 consecutive years to assess the effect of root-knot nematode infection (2,000 Meloidogyne incognita eggs/kg soil) on three winter ornamental plants: hollyhock (Althea rosea), petunia (Petunia hybrida), and poppy (Papaver rhoeas). Effects of root-dip treatment with the biocontrol agents Pochonia chlamydosporia, Bacillus subtilis, and Pseudomonas fluorescens and the nematicide fenamiphos were tested. The three ornamental species were highly susceptible to M. incognita, developing 397 and 285 (hollyhock), 191 and 149 (petunia), and 155 and 131 (poppy) galls and egg masses per root system, respectively, and exhibited 37% (petunia), 29% (poppy), and 23% (hollyhock) (P = 0.05) decrease in the flower production. Application of fenamiphos, P. chlamydosporia, P. fluorescens, and B. subtilis suppressed nematode pathogenesis (galls + egg masses) by 64%, 37%, 27%, and 24%, respectively, leading to 14% to 29%, 7% to 15%, 14% to 36%, and 7% to 33% increase in the flower production of the ornamental plants, respectively. Treatment with P. fluorescens also increased the flowering of uninfected plants by 11% to 19%. Soil population of M. incognita was decreased (P = 0.05) due to various treatments from 2 months onward, being greatest with fenamiphos, followed by P. chlamydosporia, B. subtilis, and P. fluorescens. Frequency of colonization of eggs, egg masses, and females by the bioagents was greatest by P. chlamydosporia, i.e., 25% to 29%, 47% to 60%, and 36% to 41%, respectively. Colonization of egg masses by B. subtilis and P. fluorescens was 28% to 31% and 11% to 13%, respectively, but the frequency was 0.3% to 1.3% in eggs. Rhizosphere population of the bioagents was increased (P = 0.05) over time, being usually greater in the presence of nematode.     

Interactive effect of root-knot nematode,Meloidogyne incognita and root-rot fungus,Rhizoctonia solani,on okra [Abelmoschus esculentus L.]

The individual, concomitant and sequential inoculation of second stage juveniles (at 2000 J₂/kg soil) of Meloidogyne incognita and Rhizoctonia solani (at 2 g mycelial mat/kg soil) showed significant reduction in plant growth parameters viz. plant length, fresh weight and dry weight as compared to control. The greatest reduction in plant growth parameters was recorded in the plants simultaneously inoculated with M. incognita and R. solani followed by sequential and individual inoculation. In sequential inoculation, plant inoculated with M. incognita 15 days prior to R. solani shows more reduction in comparison to plant inoculated with R. solani 15 days prior to M. incognita. Moreover, the multiplication of nematode and number of galls/root system were significantly reduced in concomitant and sequential inoculation as compared to individual inoculation, whereas the intensity of root-rot/root system caused by R. solani was increased in the presence of root-knot nematode M. incognita as compared to when R. solani was inoculated individually.     

Glucosinolate content and nematicidal activity of Brazilian wild mustard tissues against Meloidogyne incognita in tomato

The wild mustard (Brassica juncea L.), an invasive weed of winter crops in Brazil, was evaluated for glucosinolate content of its plant tissues and nematicidal activity of its dry leaf meal (LM), whole seed meal (WSM) and hexane defatted seed meal (DSM) against Meloidogyne incognita on tomato plants. Sinigrin was the major glucosinolate in LM, WSM and DSM, occurring at concentration of 0.11, 12.2 and 21.9 mg/gdw, respectively. Allyl isothiocyanate (AITC) was the major degradation product and its concentration was highest in DSM followed by WSM and LM. The number of galls, egg masses and eggs on tomato plants was reduced by over 90% by amending soil with 1.6% LM, 0.2% WSM, or 0.05% DSM. Exposure to the volatiles from the amended soils reduced egg eclosion. The soil amendment with LM, WSM and DSM killed the second stage juveniles of M. javanica, M. enterolobii (=M. mayaguensis) and Heterodera glycines. The efficacy of the LM, WSM and DSM for nematode suppression was related to the amount of AITC released in soil.     

Soil fumigation and oxamyl drip applications for nematode and insect control in vegetable plasticulture

A series of experiments were conducted to evaluate the effect of oxamyl in combination with the soil fumigants 1,3-D, metam sodium and methyl bromide on nematode damage and fruit yield in vegetables. Experiments were conducted in Tifton, GA, USA over five seasons, between 2000 and 2002, using four different vegetables: squash (Cucurbita pepo), cucumber (Cucumis sativus), pepper (Capsicum annuum) and eggplant (Solanum melongend). In the eggplant experiment, insect populations were monitored. Soil fumigation alone, irrespective of application method or formulation, gave acceptable control of root-knot nematode in all experiments, except in the spring 2001 pepper experiment. Oxamyl by itself did not provide control of root-knot nematode (Meloidogyne incognita), but insect populations on eggplant were reduced. Out of three experiments that included oxamyl by itself, root galling caused by Meloidogyne spp. was reduced only on eggplant when nematode pressure was low (five nematodes per 150 cm³ soil). When oxamyl was applied in combination with pre-plant soil fumigation, small but consistent reductions in root galling were observed. Greatest reductions in galling due to oxamyl were found when fumigation provided less than optimal nematode control. The timing of application of oxamyl did not have much impact on nematode infection, but applications early in the season, preferably starting at planting, appear to be beneficial. Stubby root nematode (Paratrichodorus spp.) populations were low and variable in most experiments, but neither fumigation nor post-plant nematicide applications seemed to have any effect on soil populations at harvest. Crop yields were often significantly greater when oxamyl followed fumigation, as compared to fumigation only, which could be due to a reduction in root-knot nematode damage (and in the case of eggplant also reduced foliar damage by insects), and/or to a carbamate growth stimulant response. These experiments indicate the potential of oxamyl to reduce root-knot nematode infection and increase yields of vegetables when combined with soil fumigation by 1,3-D and/or metam sodium. More research is required to understand the effect of crop type, pest pressure, preceding fumigant (1,3-D or metam sodium) and injection timing of oxamyl.     

Detection and biocontrol potential of <Emphasis Type="Italic">Verticillium leptobactrum</Emphasis> parasitizing <Emphasis Type="Italic">Meloidogyne</Emphasis> spp.

Three isolates of Verticillium leptobactrum proceeding from egg masses of root-knot nematodes (RKN) Meloidogyne spp. and soil samples collected in Tunisia were evaluated against second-stage juveniles (J2) and eggs of M. incognita, to determine the fungus biocontrol potential. In vitro tests showed that V. leptobactrum is an efficient nematode parasite. The fungus also colonized egg masses and parasitized hatching J2. In a greenhouse assay with tomato plants parasitized by M. incognita and M. javanica, V. leptobactrum was compared with isolates of Pochonia chlamydosporia and Monacrosporium sp., introducing the propagules into nematode-free or naturally infested soils. The V. leptobactrum isolates were active in RKN biocontrol, improving plants growth with a significant increase of tomato roots length, lower J2 numbers in soil or egg masses, as well as higher egg mortalities. In a second assay with M. javanica, treatments with three V. leptobactrum isolates reduced egg masses on roots as well as the density of J2 and the number of galls. To evaluate the fungus capability to colonize egg masses a nested Real-time polymerase chain reaction (PCR) assay, based on a molecular beacon probe was used to assess its presence. The probe was designed on a V. leptobactrum ITS region, previously sequenced. This method allowed detection of V. leptobactrum from egg masses, allowing quantitative DNA and fungal biomass estimations.     

Suppression of Meloidogyne incognita and M. javanica by Pasteuria penetrans in Field Soil

The role of Pasteuria penetrans in suppressing numbers of root-knot nematodes was investigated in a 7-year monocuhure of tobacco in a field naturally infested with a mixed population of Meloidogyne incognita race 1 and M. javanica. The suppressiveness of the soil was tested using four treatments: autoclaving (AC), microwaving (MW), air drying (DR), and untreated. The treated soil bioassays consisted of tobacco cv. Northrup King 326 (resistant to M. incognita but susceptible to M. javanica) and cv. Coker 371 Gold (susceptible to M. incognita and M. javanica) in pots inoculated with 0 or 2,000 second-stage juveniles of M. incognita race 1. Endospores of P. penetrans were killed by AC but were only slightly affected by MW, whereas most fungal propagules were destroyed or inhibited in both treatments. Root galls, egg masses, and numbers of eggs were fewer on Coker 371 Gold in MW, DR, and untreated soil than in AC-treated soil. There were fewer egg masses than root galls on both tobacco cultivars in MW, DR, and untreated soil than in the AC treatment. Because both Meloidogyne spp. were suppressed in MW soil (with few fungi present) as well as in DR and untreated soil, the reduction in root galling, as well as numbers of egg masses and eggs appeared to have resulted from infection of both nematode species by P. penetrans.     

Assessment of Predacity and Efficacy of Arthrobotrys dactyloides for Biological Control of Root Knot Disease of Tomato

Five isolates of Arthrobotrys dactyloides were isolated from different locations of India and their in vitro predacity was tested against Meloidogyne incognita (J₂), Tylenchorhynchus brassicae and Hoplolaimus indicus. All isolates of A. dactyloides captured and killed M. incognita and T. brassicae but not H. indicus. The isolates also differed in their predacity of the first two nematode species. The application of mass culture of A. dactyloides in soil infested with 2000 juveniles of M. incognita per ‘kg’ before planting of tomato seedlings reduced the number of root knots by 5.6–45.6%, of females by 44.7–72.9%, of egg masses by 44.5–51.3% and of juveniles by 37.9–81.8% and increased the plant growth in a pot experiment. The effect of this fungus as biocontrol agent was enhanced when its mass culture was applied with cow dung manure, which reduced the number of root knots by 61.7–66.6%, of females by 80.6–94.7%, of egg masses by 80.3–89.6% and of juveniles by 68.1–88.0%.