Effect of organic fertiliser and Chromolaena odorata residue on the pathogenicity of Meloidogyne incognita on maize

Pot experiments laid out in a complete randomised design were conducted in the screen house of the Department of Crop Protection, University of Agriculture, Abeokuta, Ogun State, Nigeria to determine the effects of organic fertiliser and Chromolaena odorata residue at 1% w/w on the pathogenicity of Meloidogyne incognita infecting maize. M. incognita significantly reduced the plant height, number of leaves per plant, leaf area, cob weight and grain yield of maize by 6.89, 15.18, 20, 63.92 and 56.16% respectively. C. odorata residue and organic fertiliser significantly suppressed M. incognita galling, inhibited the nematode fecundity and reduced the number of eggs and juveniles on maize. A remarkable increase in plant height, number of leaves per plant, leaf area, cob weight and grain yield were observed on maize plants treated with the mixture of C. odorata and organic fertiliser despite the nematode infection. The observation from this study suggests that C. odorata in combination with organic fertiliser is a viable option for the control of M. incognita on maize.     

Chitinolytic microbes confer Meloidogyne incognita resistance and augment secondary metabolites in Bacopa monnieri (L.) Pennell

Meloidogyne incognita (Kofoid and White) Chitwood a calamitous plant pathogen affects almost all the commercial crops, especially medicinal plants viz. Bacopa monnieri L. In this study, the efficacy of indigenous chitinolytic microbes against M. incognita in B. monnieri was evaluated under sterilised and natural soil conditions. The plant growth was observed for various parameters viz. nutrient uptake, phytochemical activities and secondary metabolites (bacoside). In the natural soil under green house conditions, the isolates significantly (P ≤ 0.05) reduced M. incognita infestation (1.38–2.78-folds) with significant increase in secondary metabolites (1.28–1.88-fold) over the untreated control. The potential strains were identified through 16S-rRNA as Streptomyces sp., Microbacterium arabinogalactanolyticum, Cellulosimicrobium cellulans, Actinomycetales bacterium, Chitiniphilus sp. and Flavobacterium johnsoniae. These findings thus highlight the potential of indigenous chitinolytic microbes that can be utilised for overall fitness of the plant along with the reduced root-knot nematode infestation in B. monnieri.     

Achieving improved control of foliar diseases of sesame (Sesamum indicum L.) intercropped with maize (Zea mays L.) through foliar spray of plant extracts

Field trials were conducted to evaluate the effect of foliar spray of aqueous extracts of Tithonia diversifolia or Ocimum gratissimum on Cercospora leaf spot (CLS) and Alternaria leaf blight (ALB) diseases of sesame intercropped with maize. Spraying regime was at 2 weeks interval from 3 weeks after planting (WAP) until 12 WAP. Extracts of T. diversifolia or O. gratissimum reduced the incidence and severity of both diseases. CLS incidence and severity as well as defoliation was significantly (p < 0.05) reduced below what obtained in the unsprayed intercrop. ALB lesion size was significantly (p < 0.05) reduced by T. diversifolia extract at 8.0% (w/v) from 154.7 mm² (sole crop) or 13.4 mm² (unsprayed intercrop) to 4.9 mm² (sprayed intercrop). T. diversifolia extract at 8.0% (w/v) enhanced higher values of grain yield/plant and incidence of normal seeds, and lower incidence of fungal infection of seeds than in the unsprayed intercrop.     

Phenology of Tick weed (Cleome viscosa L.) and its interaction with okra (Abelmoschus esculentus (L.) Moench) and Melodoigyne incognita

Cleome viscosa is an emerging weed with the potential of interfering with okra and influencing pests of okra. Screen house studies were conducted on the phenology of C. viscosa, its interference with okra and its interaction with root-knot nematode-infected okra. Seedlings of C. viscosa were monitored in pots for growth, yield and dry matter accumulation for 14 weeks. C. viscosa was planted with okra at densities 0, 2, 4, 6, 8 and 10 weeds per okra plant and observed for 11 weeks. Data were collected on growth, yield and dry matter of okra. Plants were inoculated with 2,500 M. incognita eggs per pot while control plants were not inoculated. C. viscosa attained 91.7 cm height and accumulated 7.8 g/plant biomass at 14 weeks after planting. The percentage reduction in okra plant height, plant dry weight and fruit yield due to interference at lowest cleome density (2 plants/pot) was 33.7, 83.6 and 82.1%, respectively. Nematode reproductive factor was significantly lower for okra alone (4.9) compared to okra with cleome (7.6). This study shows that C. viscosa is a fast-growing weed that suppressed the performance of okra even at low density, is a good host to M. incognita and increased the population of the nematode in soil.     

Penetration and Development of Meloidogyne incognita in Roots of Resistant and Susceptible Corn Genotypes

Rates of penetration and development ofMeloidogyne incognita race 4 in roots of resistant (inbred Mp307, and S4 lines derived from the open-pollinated varieties Tebeau and Old Raccoon) and susceptible (Pioneer 3110) corn genotypes were determined. Seedlings grown in styrofoam containers were inoculated with 5,000 eggs of M. incognita. Roots were harvested at 3-day intervals starting at 3 days after inoculation (DAI) to 27 DAI and stained with acid fuchsin. Penetration of roots by second-stage juveniles (J2) at 3 DAI was similar for the four corn genotypes. Meloidogyne incognita numbers in Tebeau, Old Raccoon, Mp307, and Pioneer 3110 peaked at 12, 12, 15, and 27 DAI, respectively. Nematode development in the resistant genotypes was greatly suppressed compared to Pioneer 3110. Resistance to M. incognita in these genotypes appears to be expressed primarily as slower nematode development rather than differences in J2 penetration.     

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.     

Biological activity of tree marigold, Tithonia diversifolia, on cowpea seed bruchid, Callosobruchus maculatus (Coleoptera: Bruchidae)

The powder and ethanol extract of Tithonia diversifolia leaves were tested for their efficacy at five different concentrations (0.0%, 0.5%, 1.0%, 1.5% and 2.0%) on bruchid mortality, oviposition and adult emergence of cowpea seed beetle Callosobruchus maculatus at ambient tropical storage conditions of temperature and relative humidity. Results showed that the leaf extract had a higher bioactivity on oviposition, adult emergence and mortality of C. maculatus. The mean number of eggs laid on seeds treated with extract was reduced from 20.7 in the solvent-treated to 4.7 at 2%Tithonia extract concentration while adult emergence reduced from a mean of 92.2 in the solvent-treated seeds to 72.2 at 2.0% extract treatment. Mortality was 100% at higher concentrations of 3%, 4% and 5% within 24 h of extract application but at lower concentrations mortality was 73.3% and 93.3% at 1% and 2%, respectively after 24 h. Fourty-eight hours after application, 100% mortality of adult C. maculatus was obtained at all concentrations. The mean number of eggs laid was reduced from 41.3 in the untreated to 17.3 at 2.0% powder concentration while adult emergence dropped from 98.5% in the control to 74.2% at the highest powder concentration. The powder was effective at higher concentrations and longer exposure time. At 3%, 4% and 5%, 63–75% mortalities occurred within 24 h of application while at 48 h, mortality was 76–98% at 3–5% powder application rates. The results of this study revealed T. diversifolia as a potential candidate for bioinsecticide preparations because of antiovipositional, ovicidal and knockdown properties of its products, which have some volatile components.     

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.     

Effects of Tithonia diversifolia (Hemsl.) A. Gray Extract on Adipocyte Differentiation of Human Mesenchymal Stem Cells

Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) is widely used in traditional medicine. There is increasing interest on the in vivo protective effects of natural compounds contained in plants against oxidative damage caused from reactive oxygen species. In the present study the total phenolic and flavonoid contents of aqueous, methanol and dichloromethane extracts of leaves of Tithonia diversifolia (Hemsl.) A. Gray were determined; furthermore, free radical scavenging capacity of each extract and the ability of these extracts to inhibit in vitro plasma lipid peroxidation were also evaluated. Since oxidative stress may be involved in trasformation of pre-adipocytes into adipocytes, to test the hypothesis that Tithonia extract may also affect adipocyte differentiation, human mesenchymal stem cell cultures were treated with Tithonia diversifolia aqueous extract and cell viability, free radical levels, Oil-Red O staining and western bolt analysis for heme oxygenase and 5''-adenosine monophoshate-activated protein kinase were carried out. Results obtained in the present study provide evidence that Tithonia diversifolia (Hemsl.) A. Gray exhibits interesting health promoting properties, resulting both from its free radical scavenger capacity and also by induction of protective cellular systems involved in cellular stress defenses and in adipogenesis of mesenchymal cells.     

Nematicidal effect of an Amaranthus hypochondriacus L. cystatin (AhCPI) on the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood

The root-knot nematode Meloidogyne incognita is one of the most damaging plant parasitic nematodes in the world. In this study, the effect of cystatin from Amaranthus hypochondriacus (AhCPI) as a potential control agent for M. incognita was explored. In vitro bioassays demonstrated that AhCPI affects the growth and development of eggs and the infectivity of juveniles (J2) of M. incognita, such as mortality and slower development, showing characteristic tissue damage. Mortality levels were quantified by Probit analysis, estimating LC₅₀s of 1.4 mg/mL for eggs and 0.028 mg/mL for J2. In planta bioassays showed that infected tomato seedlings treated with 0.056 mg/mL of AhCPI showed a 60% reduction in the number of galls, as compared with untreated J2-inoculated seedlings. Under greenhouse conditions, three applications of 10 mL of AhCPI (1.4 mg/mL) in the soil around the stem of M. incognita-infected tomato plants, reduced the number of galls by 93 ± 8%, as compared to the control M. incognita-infected plants. The application of AhCPI to the infected plants increased the yield (10.7%) of harvested tomato fruits, as compared to infected plants. These results show the potential of AhCPI for the control of M. incognita in tomato plants.     

Bio-efficacy of some leaf extracts on the inhibition of egg hatching and mortality of Meloidogyne incognita

Nematicidal activities of extracts from plants were assayed against Meloidogyne incognita in vitro. Leaves of six different plants were collected in and around Aligarh Muslim University Campus. Aqueous extracts of six plants were screened for egg hatchability and nematicidal activity against second stage juveniles of M. incognita in the plant pathology and nematology laboratory, AMU Aligarh. The nematode egg and juveniles were exposed 12, 24 and 48 h in (S, S/2, S/10, S/100) concentrations of plant extracts. The plant extracts of leaves of six plants species viz. Jatropha pandurifolia, Polyalthia longifolia, Wedelia chinensis, Nerium indicum, Duranta repens and Cassia fistula exhibited highly promising mortality of 99.00–72.00% after 48 h of exposure. Aqueous extracts of leaves of J. pandurifolia, P. longifolia, W. chinensis were recorded to be highly effective for inhibition of egg hatching and increasing juvenile mortality of M. incognita. There was a gradual decrease in egg hatching and increase in mortality rate of juveniles of M. incognita with increase in the concentration of leaf extract and exposure time.     

Pre-release evaluation of absolute spillover impact risk of Physonota maculiventris (Chrysomelidae: Cassidinae) on non-target plant species Helianthus annuus (Asteraceae) and Zea mays (Poaceae) in South Africa

The tortoise beetle, Physonota maculiventris (Coleoptera: Chrysomelidae), a candidate biological control agent of Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) was screened for spillover risks on non-target plant species in South Africa. Studies were conducted to measure the absolute feeding damage and reproductive performance of P. maculiventris on non-target plant species, Helianthus annuus L. (Asteraceae) and Zea mays L. (Poaceae). The influence of spillover on generational build-up performance on the non-target plant species was also investigated. Adult female beetles were switched from T. diversifolia at 14 (actively feeding colony) or 24 (gravid colony) days to the non-target species. Likewise, as a backup or control, female beetles were exposed to H. annuus in a no-choice situation and switched to T. diversifolia and Z. mays. Feeding damage, adult longevity and egg production of P. maculiventris were significantly lower on H. annuus, compared to those metrics on T. diversifolia. Gravid P. maculiventris adults switched from T. diversifolia on the 14th day after emergence laid a few egg batches on the leaf surfaces of Z. mays, but no signs of feeding were observed. Furthermore, the population of P. maculiventris significantly increased by 11.7 fold (26.8–312.5 adults) between the first (F1) and second (F2) generations on T. diversifolia, while on the non-target, H. annuus, it decreased from 6.3 to zero (0). The study concludes that P. maculiventris will sustain its populations entirely on the target, T. diversifolia population stands associated with or without H. annuus and Z. mays cultivations at different scales in South Africa.     

Pathogenicity of Pratylenchus coffeae,Scutellonema bradys,Meloidogyne incognita,and Rotylenchus reniformis on Dioscorea rotundata

Low populations (200 specimens per plant) of Pratylenchus cofl''eae, Scutellonema bradys, Meloidogyne incognita, and Rotylenchulus reniformis stimulated the development of tops, roots, and tubers of Dioscorea rotundata "Guinea" yam. We demonstrated experimentally that P. coffeae was responsible for the deterioration in quality of the yam tuber in Puerto Rico, a condition known as a dry rot of yam. Initial populations of 600 P. coffeae, S. bradys, or M. incognita, and populations of 1,000 P. coffeae or S. bradys per plant were high enough to induce dry rot of the yam tubers. P. coffeae and S. bradys were pathogenic to yam cultivar Guinea, but M. incognita and R. reniformis did not cause necrosis or cracking of the tuber cortex in our experiments.     

Evaluation of Asteraceae Plants for Control of Meloidogyne incognita

Of the 56 species and 43 genera of Asteraceae tested, 9 were highly resistant or immune to Meloidogyne incognita and did not form root galls. Twenty-six species and six cultivars had 25% or fewer roots galled and were considered moderately resistant to M. incognita. Pre-planting Cosmos bipinnatus (F190), Gaillardia pulchella, Tagetes erecta, Tithonia diversifolia, or Zinnia elegans (F645) reduced root galling and M. incognita J2 in and around Ipomoea reptans. Amendment of soils with roots, stems, or leaves of G. pulchella was effective in controlling M. incognita on I. reptans. Tissue extracts of G. pulchella were lethal to various plant-parasitic nematodes but were innocuous to free-living nematodes. Root exudates of G. pulchella were lethal to J2 of M. incognita and were inhibitory to the hatch of eggs at the concentration of 250 ppm or higher. Gaillardia pulchella could be used to manage M. incognita as a rotation crop, a co-planted crop, or a soil amendment for control of root-knot 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.     

Alginate films for delivery of root-knot nematode inoculum and evaluation of microbial interactions

A method was developed for utilizing alginate films to deliver inoculum into soil and evaluate microbial antagonistic activity against nematode eggs. Eggs of Meloidogyne incognita were harvested from galled tomato roots (Lycopersicon esculentum), surface disinfested, suspended in 2% (w/v) aqueous sodium alginate, and applied to 2.5 × 5.0 cm polyvinyl chloride coated fiberglass screens (1.5 mm² mesh size) at a uniform thickness of 0.5 mm. The alginate solution was gelled by dipping in 0.25 M CaCl₂. Films containing eggs were observed in vitro and egg development was evaluated. The number of immature eggs and eggs with first stage juveniles declined linearly over time while the number of empty eggs shells, and hatched juveniles increased over time, indicating that the alginate gel did not inhibit development and motility of M. incognita juveniles. In a greenhouse experiment using cucumber (Cucumis sativus) the number of galls g^-1 root was correlated with the number of eggs in alginate films placed in each pot at planting. Films containing M. incognita eggs were buried in field soil containing organic amendments, incubated, removed from soil, rinsed with water, and observed. The number of immature eggs in grids from soil amended with chitin or flax seed meal were lower than in untreated soil; percent parasitized eggs was also greater in films from amended soil than from untreated soil.     

Effects of varying environmental factors on the biological control of Meloidogyne incognita in tomato by Bacillus cereus strain BCM2

The root-knot nematode (Meloidogyne spp.), which represents a global threat to agricultural production, can cause serious losses in both the yield and quality of many crops. Endophytic bacteria are known to have great potential against Meloidogyne incognita. The colonisation ability of endophytic Bacillus cereus BCM2 in tomato roots and its biological control efficacy of M. incognita were investigated. By the end of the growth period of tomato plants, the population of BCM2 in the rhizosphere soils and roots of the tomato were 5.86 and 3.38 log CFU g^?1, respectively, indicating that BCM2 can colonise tomato roots for long periods of time. Pre-inoculation with BCM2 resulted in a significant reduction in the population of M. incognita and the gall index of tomato compared to the untreated control, and there was an increase in the tomato yield of 47.4%. Colony counts showed that the population of BCM2 in tomato roots was affected by soil type and pH, and the colonisation of BCM2 in tomato rhizosphere soils was influenced by soil water and organic matter contents. We observed that the biocontrol effects of BCM2 were best when soil pH was 7. Pre-inoculation with BCM2 can inhibit the formation of tomato galls more effectively when soil water content is 25%, and rich organic matter content was conducive to a reduction in the number of M. incognita second stage juveniles (J2s) in soil. These results demonstrated that B. cereus BCM2 has great potential for controlling M. incognita in tomato plants.     

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.     

The role of root-knot nematode on the wilt disease of Telfairiaoccidentalis in northern Nigeria

Cultivation of Telfairia occidentalis, an important vegetable grown in central and southern Nigeria, has gradually diffused to northern Nigeria where it has gained an economic importance. Its cultivation is, however, threatened by wilt disease occurring in farmers’ fields. A preliminary survey of farmers’ fields indicated that the disease was severe in fields with high root-knot population compared to the fields with less root-knot. Using Koch's postulate, the wilt causative organism was identified as Fusarium spp. The objective of this study was to determine therole of Meloidogyne incognita and its interaction with Fusarium oxysporum onwilt development in T. occidentalis. Four-week-old seedlings, raised in heat sterilised soil, were inoculated with Fusarium spp. and M. incognita under screenhouse condition. Seedlings were either inoculated with M. incognita and/or F.oxysporum as sole infection and as combined infection in a complex. Combined infection with both pathogens produced wilt symptom on the plant and gave significantly lower vegetative yield (p = 0.05) than sole inoculation with either M.incognita or F. oxysporum, except where the seedlings were mechanically inoculated with F. oxysporum. Results from the screenhouse studies were consistent with the field observations.     

A global assessment using PCR techniques of mycorrhizal fungal populations colonising<Emphasis Type="Italic"> Tithonia diversifolia</Emphasis>

Tithonia diversifolia (Mexican sunflower) is a shrub commonly used as a green manure crop in Central and South America, Asia and Africa as it accumulates high levels of phosphorus and other nutrients, even in depleted soils. In root samples collected from the global distribution of Tithonia, we examined the degree of mycorrhizal colonisation and estimated the families of associated arbuscular mycorrhizal (AM) fungi. No colonisation by ectomycorrhizas was found. The degree of colonisation by AM fungi was on average 40%, but ranged between 0 and 80%. No mycorrhizal colonisation was found in the samples collected from the Philippines or in one each of the Rwandan and Venezuelan samples. Throughout its global distribution (Costa Rica, Nicaragua, Indonesia, Honduras, Mexico, Kenya and Rwanda), Tithonia forms mainly associations with Glomaceae. Only in one location in Nicaragua were associations with another family (Acaulosporaceae) found.