Influence of growth medium on antifungal activity of neem oil (<Emphasis Type="Italic">Azadirachta indica</Emphasis>) against <Emphasis Type="Italic">Lagenidium giganteum</Emphasis> and <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis>

The inhibition of mycelial growth of Lagenidium giganteum by neem oil was lower than that of Metarhizium anisopliae in PYG and Emerson’s YpSs agar media. However, neem oil did not inhibit the mycelial growth of L. giganteum in sunflower seed extract agar medium, but did it inhibit the mycelial growth of M. anisopliae. The minimum inhibitory concentration of neem oil for L. giganteum was higher than that for M. anisopliae. The minimum fungicidal concentration of neem oil in PYG medium was lower than in YpSs for both fungi. The spores of L. giganteum grown in SFE medium could be used with neem oil for vector control.     

Starter culture for the production of ‘soyiru’

Bacillus subtilis or licheniformis facilitated production of soyiru with the best results being given by using both together. Fermentation employing Streptococcus enterococcus was unsuccessful.H.A. Suberu is with the Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria. J.A. Akinyanju is with the Department of Biological Sciences, University of Ilorin, P.M.B. 1515, Ilorin, Nigeria.     

Rhizobacterial bioformulation for the effective management of Macrophomina root rot in mungbean

Abstract

Fluorescent pseudomonads based bioformulation was evaluated for their ability to control Macrophomina root rot disease in mungbean (Vigna mungo). P. fluorescens isolate Pf1 showed the maximum inhibition in mycelial growth of Macrophomina phaseolina under in vitro conditions. Bioformulation of Pf1 with chitin was effective in reducing the root rot incidence in green gram both under glasshouse and field conditions. The rhizosphere colonization of P. fluorescens was observed appreciable with the green gram plants. However, Pf1 amended with chitin colonized effectively. Furthermore, the induction of defence-related enzymes and chemicals in plants by Pf1 amended with or without chitin and neem were tested. Increased accumulation of defence enzymes viz., phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenol oxidase (PPO), chitinase, β-1,3-glucanse and phenolics were observed in Pf1 bioformulation amended with chitin, pre-treated plants challenge inoculated with M. phaseolina under glasshouse conditions. The present study reveals that in addition to direct antagonism and plant-growth promotion, PGPR strains amended with chitin bioformulation induced defence-related enzymes and pathogenesis related (PR) proteins which collectively enhance the resistance in green gram against the infection of M. phaseolina.     

Potential bio-control agent for management of post-flowering stalk rot complex and maize plant health

The of aim of this study was to evaluate the potentiality of the native isolate of Trichoderma harzianum from IARI farm for the management of post-flowering stalk rot of maize and improvement of plant health. The treatment was tried as a seed treatment with the potent commercial formulation Kalisena SD (Aspergillus niger), neem kernel powder and effective fungicides (Thiram, Carbendazim, Captan) for comparison of its efficacy. The minimum disease was recorded in plots treated with native isolate both due to Fusarium moniliforme and Macrophomina phaseolina. The fungicides Carbendazim and Thiram ranked second in controlling the disease due to F. moniliforme and M. phaseolina, respectively. Plant health with respect to vigour and plant stand were found to be better than those of all the other treatments. It is concluded that the native isolate of T. harzianum may be used for maintaining good plant health and managing post-flowering stalk rot of maize.     

Macrophomina phaseolina – Meloidogyne javanica disease complex in balsam (Impatiens balsamina): a new report

Balsam seedlings were inoculated with root-knot nematode Meloidogyne javanica Race-2 and Macrophomina phaseolina either individually or concomitantly, as well as sequentially with an interval of 15?days between the nematode or fungal inoculations to determine whether the interaction was concomitant or sequential. The greater reduction in plant growth characters was observed in the plants inoculated with M. javanica and M. phaseolina, either concomitantly or sequentially as compared to their individual inoculation. However, the highest reduction in plant growth characters were recorded in the plants inoculated with M. javanica Race-2 15?days prior to M. phaseolina followed by concomitant-inoculated M. javanica Race-2 and M. phaseolina, and M. phaseolina 15?days prior to M. javanica. The number of galls/root system and the reproduction factor of the root-knot nematode was reduced in the presence of root-rot fungus. The intensity of root-rot caused by M. phaseolina increased in the presence of root-knot nematode M. javanica as compared to when M. phaseolina was inoculated individually. Moreover, stem and collar-rot symptoms caused by M. phaseolina appeared only in the presence of root-knot nematode.     

Detection,identification and morphological characteristic of Macrophomina phaseolina: the charcoal rot disease pathogens isolated from infected plants in Northern Jordan

This is the first report about charcoal rot disease in Jordan. Twenty-five Macrophomina phaseolina isolates were collected from infected plants showing typical symptoms of charcoal rot disease. All of the 25 M. phaseolina isolates were pathogenic to cucumber plants under green house effect. The amplification of the isolated DNA from the 25 pathogenic fungal cultures using ITS specific primers (ITS 1?+?ITS 4) showed a single band of 580?bp. There was a significant variation of their mycelial linear growth rate on PDA medium. The 25 M. phaseolina isolates showed a wide heterogeneity in their mycelium colour, microsclerotia distribution, pycnidia formation and chlorate phenotypes. Based on the morphological characterisation, the 25 isolates were grouped into seven different groups as indicated in a dendrogram of their morphological variation. The overall means similarity matrix of the 25 M. phaseolina recovered isolates were 0.58. The means of similarity matrix of the 25 M. phaseolina was in between 0.83 and 0.14. The similarity coefficient between the 25 isolates varies between 0.27 and 1.0.     

Effect of organic soil amendments on the incidence of stalk rot of maize

Five organic materials, Calopogonium sp. leaves, rice straw, mixed wood saw dust of Terminalia sp. Triplochyton sp. and Kaya sp., fresh guinea grass and poultry manure were added to soil with a recent history of high stalk rot of maize caused by Macrophomina phaseolina and Fusarium moniliforme. The two stalk rot organisms reacted differently to the organic amendments. All the amendments produced significantly less Fusarium stalk rot disease than the unamended control. Amendment of soil with fresh Calopogonium leaves was almost ineffective in controlling the incidence of Macrophomina phaseolina. Organic amendment with poultry manure increased the disease casued by M. phaseolina. The other amendments appeared to be equally effective in checking the disease. Increased microbial population due to amendment may play some role in disease suppression.     

Integrated approach for the management of Meloidogyne javanica on eggplant using oil cakes and biocontrol agents

Investigations were carried out to evaluate the efficacy of biocontrol agents (Paecilomyces lilacinus and Cladosporium oxysporum) and/or oil cakes of castor, linseed, groundnut, mahua and neem in the management of root knot nematode, Meloidogyne javanica infecting eggplant under glasshouse conditions. All the treatments effectively suppressed the nematode population and kept the infection at significantly low level. Individual treatment of P. lilacinus was more effective than C. oxysporum in controlling M. javanica, whereas among oil cakes individual treatment of neem was more effective in the management of M. javanica followed by linseed cake, castor cake, groundnut cake and mahua cake. However, the efficacy of biocontrol agents increased in the presence of oil cakes. The highest improvement in plant growth and best protection against M. javanica was obtained by the integration of P. lilacinus with groundnut cake followed by neem cake, linseed cake, castor cake and mahua cake. On the other hand the integration of C. oxysporum with neem cake followed by groundnut cake, linseed cake, castor cake and mahua cake gave the best results in managing M. javanica on eggplant.     

Incidence of charcoal rot of sorghum and soil populations of Macrophomina phaseolina associated with sorghum and native vegetation in Somalia

Studies were conducted in the Bay Region of Somalia to determine the incidence of charcoal rot in sorghum incited by Macrophomina phaseolina and the soil population of M. phaseolina in sorghum fields and areas of native vegetation. Charcoal rot was detected in 34 of 40 sorghum fields. Incidence (percent sorghum hills with diseased plants) in the four regional districts was 21, 70, 20 and 35% (mean of 15 hills/field and 10 fields/district) for Baidoa, Burhakaba, Dinsoore and Quansadhere, respectively. Soil collected from the 40 sorghum fields and from 40 native vegetation sites (10 in each district) all contained M. phaseolina. Mean soil populations for sorghum fields and native vegetation sites were 25.2 and 2.5 microsclerotia g^–1 soil, respectively. Soil populations of M. phaseolina in sorghum fields were significantly (p=0.05) different from populations in native vegetation sites and ranged from 7 to 107 and 0.1 to 14.0 microsclerotia g^–1 soil, respectively. Incidence of charcoal rot in sorghum was positively correlated with soil populations of M. phaseolina (r=0.53, p= 0.01). Correlation between ratoon failure and disease incidence was also highly significant (r=0.48, p=0.01). Correlation between ratoon failure and soil population of M. phaseolina was not significant (r=0.17, p=0.10). Only one out of 30 seed lots of sorghum grown in the Bay Region contained seed infected with M. phaseolina.     

Population dynamics of Macrophomina phaseolina in relation to disease management: A review

Macrophomina phaseolina (Tassi) Goid. causes seedling blight, charcoal rot, leaf blight, stem and pod rot on over 500 plant species in different parts of the world. The pathogen survives as sclerotia formed in host tissues which are released into the soil as tissue decay. Low soil moisture is considered the more important predisposing factor for M. phaseolina-induced diseases than high temperature. The intensity of the disease on a crop is related to the population of viable sclerotia in the soil and abiotic factors. The influence of various management strategies in reducing the number of viable propagules of the pathogen in the soil has been studied in order to minimize the impact of the disease. Any management approach that reduces inoculum density in the soil may reduce disease incidence on the host. However, to reduce inoculum density, quantitative determination of viable propagules from soil is necessary in order to understand the effect of management strategies on the population dynamics of this pathogen. Considerable work has been done on organic amendments, changing crop sequences with tolerant crops, fumigants, herbicides and tillage in managing M. phaseolina populations in the soil and the resulting disease. Solarization has been used in controlling M. phaseolina in different countries where this pathogen is causing disease on economically valuable crops. However, this method of soil disinfestation was effective in eliminating viable populations at the top soil layer although by combining other approaches its effectiveness was improved at lower soil depth. Use of biological control agents with or without organic amendments or after solarization has emerged to be a practical management approach in the control of M. phaseolina. In this paper, an attempt has been made to review those research findings where the influence of various management approaches on survival of M. phaseolina mainly sclerotia have been investigated.     

Assessment of nodulation of Mucuna pruriens by promiscuous indigenous rhizobia in the moist savanna zone of Nigeria

Leucaena leucocephala failed to nodulate effectively with promiscuous indigenous rhizobia with which Mucuna pruriens nodulated effectively. Mucuna pruriens was adequately established and well nodulated due to the presence of favourable climatic and edaphic factors which enhanced its establishment in the humid/moist savanna zone of Nigeria. The microsymbiont for M. pruriens seems to thrive more in an alkaline rhizosphere. Introduction of M. pruriens into the farming system in Nigeria may serve as a low input agricultural system, which is not only sustainable but also economically viable.     

Toxicity of Essential Oil from a New Strain of Ocimum gratissimum (Clocimum) against Betelvine Pathogenic Fungi

The leaves of Ocimum gratissimum (Clocimum) exhibited strong volatile fungitoxicity against betelvine (Piper betle L.) pathogens—Alternaria alternata, Colletotrichum capsici and Sclerotium rolfsii. Fifteen compounds could be identified from the fungitoxic constituents—the essential oil. The oil at its minimum inhibitory concentrations of 50, 250 and 500 ppm against S. rolfsii, A. alternata and C. capsici, respectively, was fungistatic, although, fungicidal at higher concentrations. Eugenol was found to be the major fungitoxic principle in the oil. The oil was either equally effective or superior to synthetic commercial fungicides and was non-phytotoxic to the host plants. Thus, the oil can be used as a valuable indigenous and biodegradable agent against fungi that cause losses to the betelvine industry.     

Effect of Macrophomina phaseolina Infection on the Physico-Chemical Components of Groundnut Seed

Various aspects of groundnut seed deterioration due to M. phaseolina infection were studied. Fungal infection caused both quantitative and qualitative damage to the seed. It resulted in characteristic discoloration of pod and kernel. There was marked reduction in the pod and kernel yield, shelling percentage and oil content. The oil extracted from healthy kernels was barium yellow, whereas, oil from diseased kernels was amber yellow in color. The diseased kernels contained lesser amounts ofstearic and behenic acids but higher quantities of palmitic, oleic, linoleic and arachidic acids. Four fatty acids, namely, lauric, myristic, palmitoleic and eicosenoic acids were absent in diseased kernels.     

Morphological and pathogenic variability in Macrophomina phaseolina isolates of pigeonpea (Cajanus cajan L.) and their relatedness using principle component analysis

Sixty-one isolates of Macrophomina phaseolina were characterised on the basis of different morphological characters to study the variability in the population. PCA analysis extracted three main components, microsclerotia, texture and colour, from the population that described the variability in the population most appropriately. Colour of the isolates and the presence of the microsclerotia have a significant effect on the area under disease progress curve. Isolates with the production of microsclerotia (M⁺) were more aggressive as compared to isolates with no production of microsclerotia (M^?). The study has brought out pathogenic variation in M. phaseolina, thus better understanding of host pathogen relationship to identify physiologic races in the breeding programme.     

Control of charcoal root rot in <Emphasis Type="Italic">Pinus radiata</Emphasis> nurseries with antagonistic bacteria

The objective of this study was to determine the potential of antagonistic bacteria to control charcoal root rot of coniferous seedlings caused by Macrophomina phaseolina (Tassi) Goid. in forest nurseries. Bacterial isolates were collected from nurseries located between Region Metropolitana and the VIII Region of Chile. Antagonists were initially evaluated in in vitro assays based on the ability to inhibit mycelial growth of M. phaseolina, and subsequently in two trials in a Pinus radiata nursery with a natural infestation of the pathogen. For nursery trials, the isolates were selected according to in vitro and field trial pathogen controls. The bacteria were applied as seed treatments and via water irrigation. The trials were conduced in a completely randomized block design. Among 568 bacterial isolates tested in vitro, 19.8% displayed some capacity to inhibit the mycelial growth of M. phaseolina, with inhibition between 1.7% and 67.6%. In the first nursery trial, Bacillus amyloliquefaciens VII 015, Bacillus pumilus IX 030, Bacillus stearothermophilus TM 008 and other two Bacillus sp. (VI 009 and IX 049) strains, significantly reduced the total, pre- and post-emergency mortality of seedlings, but no isolate reduced the incidence of M. phaseolina in seedlings. In the second trial, Bacillus sp. IX 049, VI 099, B. subtilis (IX 007) and a non-identified isolate V 005, decreased the incidence of charcoal root rot. It is concluded that the best of these bacterial antagonists have the potential to control M. phaseolina in P. radiata nurseries.     

Plant defense approach of Bacillus subtilis (BERA 71) against Macrophomina phaseolina (Tassi) Goid in mung bean

This study was aimed to elucidate the mitigation mechanism of an endophytic bacterium, Bacillus subtilis (BERA 71) against Macrophomina phaseolina (Tassi) Goid disease in mung bean. M. phaseolina reduced the plant growth by inducing disease, hydrogen peroxide (H₂O₂) and lipid peroxidation. The inoculation of B. subtilis to diseased plants increased chlorophyll, ascorbic acids, and superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities, and while inhibited H₂O₂ and lipid peroxidation for enhancing plant growth. In addition, B. subtilis association in plants mitigated the M. phaseolina infection due to increase of indole acetic acids and indole butyric acid, and also a decrease of abscisic acid. However, the nutrients (N, K, Ca, Mg, Zn, Cu, Mn and Fe) were increased, except Na in M. phaseolina diseased plants treated with B. subtilis. The result of this study suggests that B. subtilis interaction with plants can modulate the metabolism of pigments, hormones, antioxidants and nutrients against M. phaseolina to induce disease resistance in mung bean.     

Diversity and distribution of murid rodent populations between forest and derived savanna sites within south western Nigeria

Southward encroachment of the derived savanna zone with its attendant denudation of the rainforest in Nigeria adversely affects the diversity and distribution of mammals, particularly murid rodents. This study was carried out to establish the identities of murid rodent populations and to compare their diversity between forest and derived savanna sites within south western Nigeria. Identification of captured specimens was carried out by multivariate statistics of body and skull measurements, and also by analysis of certain discrete characters. Six species were identified: Praomys tullbergi, Hylomyscus stella, Mastomys natalensis, Arvicanthis rufinus, Lemniscomys striatus and Lophuromys sikapusi. Forest sites possessed a higher Shannon’s diversity index (1.685) than the derived savanna sites (0.978), containing a higher number of taxa and larger abundance of murid rodents. This underscores the negative impact that encroachment of the derived savanna has upon diversity of animals in areas that were once forest.     

Integrating sub-lethal heating with Brassica amendments and summer irrigation for control of Macrophomina phaseolina

Effects of varying intensities of sub-lethal heating were ascertained in improving the efficiency of Brassica amendments and summer irrigation on survival of Macrophomina phaseolina, a dry root rot pathogen. Sub-lethal heating (45–55°C) of M. phaseolina infested dry soil reduced the viable propagules by only 12.8% in a period of 90 days. One summer irrigation without sub-lethal heating caused 33.9% reduction in M. phaseolinapropagules, which improved to 43.3% when it was combined with 60 days of sub-lethal heating. Addition of the Brassicaamendments to irrigated soil resulted in significant reduction (60.4–71.6%) in counts of M. phaseolinabut this reduction improved (89.4–96.1%) when sub-lethal heating was combined with amendments. Mustard oil-cake (0.18% w/w) was found to be the most effective with reduction but a 94% inoculum reduction by mustard pod straw (0.36% w/w) was also achieved at 0–30 cm soil depth under similar conditions. Moderate heat level could not exert detectable weakening effect on M. phaseolinapropagules. These results suggest a practical cultural control of soil-borne pathogens by combining sub-lethal heating, Brassica amendments with one summer irrigation.     

Bacillus thuringiensis and neem seed oil (Azadirachta indica) effects on the potato tuber moth Phthorimaea operculella zeller in the field and stores

A comparative evaluation for the efficacy of Bacillus thuringiensis and neem seed oil on Phthorimaea operculella has been carried out in the field and store. These two preparations were almost equally effective on the potato tuber moth infestation. The percentage of infestation was reduced through successive application of either preparations in the field up to harvest. No synergism was observed upon using combination of the two preparations. In the store, neem seed oil (500 ppm) was highly protective and was as effective as sevin. A combination of both neem and B.t. (Delfin) significantly protects the tubers. This suggests the possible use of either neem seed oil or B.t. in combating the insect pest in the field or during storage.     

Growth and insect assays of Beauveria bassiana with neem to test their compatibility and synergism

Beauveria bassiana is being used as a biopesticide for many insect pests. Neem oil (azadirachtin) is an eco-safe popular botanical pesticide. A biopesticde with a neem compatible isolate of B. bassiana will enable their simultaneous use in pest management. A sample of 30 isolates of B. bassiana from culture collections was screened for compatibility with a commercial formulation of neem oil (Margoside®) at the field recommended dose (0.3%, v/v). Compatibility was tested in vitro through germination and growth assays. In all isolates, conidial germination was delayed but not significantly decreased by neem. In the growth assays, 23 isolates were found compatible with neem. In the neem sensitive isolates, growth was decreased but not totally inhibited. The effect of combined treatment with B. bassiana and neem in comparison to single treatments with either of them on Spodoptera litura Fabricius was tested in laboratory bioassays. The combined treatment was found to have synergistic effect on insect mortality when a B. bassiana isolate compatible with neem was used, while, with an isolate sensitive to neem, an antagonistic effect was observed.