Management Of Plant Parasitic Nematodes Research Articles

Conjoint effect of oil-seed cakes and Pseudomonas fluorescens on the growth of chickpea in relation to the management of plant-parasitic nematodes

Soil application of organics has been explored as an alternative means of organic management of plant-parasitic nematodes. Efficiency of different oil-seed cakes of neem (Azadirachta indica), castor (Ricinus communis), groundnut (Arachis hypogaea), linseed (Linum usitatissimum), sunflower (Helianthus annuus) and soybean (Glycine max) were evaluated in field conditions with association of Pseudomonas fluorescens in relation to growth parameters of chickpea and population of plant-parasitic nematodes. Their efficacious nature was highly effective in reducing the population of these dominant soil nematodes. Significant improvement was observed in plant-growth parameters such as plant weight, percent pollen fertility, pod numbers, root-nodulation and chlorophyll content of chickpea, seemed to be due to reduction in disease incidence and might be due to growth promoting substances secreted by P. fluorescens. The multiplication rate of nematodes was less in the presence of P. fluorescens as compared to its absence. Most effective combination of P. fluorescens was observed with neem cake.

Mean Dosage Stimulation Range of Allelochemicals from Crude Extracts of Cucumis africanus Fruit for Improving Growth of Tomato Plant and Suppressing Meloidogyne incognita Numbers

Successful utilisation of allelochemicals in management of plant-parasitic nematodes depends on their degree of phytotoxicity. Conventional methods of determining phytotoxicity are tedious, with inconsistent results. Plants respond to increased dosages of allelochemicals in a density-dependent growth pattern, which allows the use of the Curve-fitting Allelochemical Response Data computer-based model to determine the mean dosage stimulation range of used allelochemicals. The CARD modelling was used to determine the stimulation range of fermented dried crude extracts of wild cucumber (Cucumis africanus) fruit for improving growth of tomato (Solanum lycopersicon) plants, each infested with 1500 eggs and juveniles of the southern root-knot (Meloidogyne incognita) nematode. Dilutions at 0, 2, 4, 8, 16, 32 and 64% were applied weekly through irrigation system. At 56 days after treatment, CARD demonstrated density-dependent growth patterns as dosages increased. The mean dosage stimulation range of diluted fermented crude extracts, computed from CARD biological indices, was 2.64% dilution for tomato plant. Since at 2% dilution, the material reduced final nematode population density of M. incognita by 90%. The 2.64% was suitable for stimulation of tomato plant and suppression of nematode numbers.

Nematicidal activities of Cannabis sativa L. and Zanthoxylum alatum Roxb. against Meloidogyne incognita

Because of being costly and pernicious to the environment and human health, the use of nematicides has become prohibitive in many countries and the management of plant parasitic nematodes using antagonistic plants can be a very attractive alternative. In the present studies the effectiveness of aqueous extracts of Cannabis sativa and Zanthoxylum alatum was assessed on hatching, mortality and infectivity of Meloidogyne incognita at different concentrations viz. S, S:1, S:5, S:10, S:25, S:50 and S:100. Both the plants had significant effects on juvenile mortality and hatching inhibition in a dose-dependent manner. Mortality and hatching inhibition caused by C. sativa were significantly higher than that of Z. alatum. Time duration also affected mortality and hatching inhibition significantly. Significant inhibition in invasion of M. incognita juveniles on cucumber cv. Royal Sluis was observed by different treatments with extracts. M. incognita juveniles exposed to ‘S’ extracts of C. sativa and Z. alatum for 24 and 48h caused no infection. Exposure for 12 and 6h caused more than 95 and 90% reductions in infectivity of M. incognita juveniles respectively. Similarly, soil drench and root dip treatments also caused significant reductions in infection. Reduction in infectivity was found to be significantly higher with extracts of C. sativa as compared to Z. alatum and decreased in a dose-responsive manner. The results of the studies showed that the extracts of test plants, commonly found locally, possess high potentials for the control of root-knot nematodes and could be the possible replacement for synthetic nematicides.

Cloning and characterization of two neuropeptide genes from cereal cyst nematode, Heterodera avanae from India.

The cereal cyst nematode, Heterodera avenae (Wollenweber, 1924) is one of the most important plant parasitic nematodes of cereals. It is an obligate sedentary endo parasite causing considerable crop losses in wheat, barley and oats worldwide. FMRFamide-like peptides (FLPs) play critical role as neurotransmitters or neuromodulators in the nervous system and proposed as one of the important targets for the plant parasitic nematode management. Therefore, for the first time we have cloned and characterized two neuropeptide genes (flp-12 and flp-16) from the cDNA library of feeding female of H. avenae. Sequence analysis of FLPs revealed that both the neuropeptides are closely related with the parasitic as well as free-living nematodes. The flp-12 contains putative 22 residue long signal peptide at N-terminal suggesting its association with extra-cellular functions, while flp-16 does not contain signal peptide. Besides this, we have found highly conserved motif KFEFIRF in flp-12 and RFGK motif in flp-16. These two flp genes could be interesting and potential targets for functional validation to explore their utility for designing management strategies.

Effects of N fertilisation, organic matter, and biofertilisers on the growth and yield of chilli in relation to management of plant-parasitic nematodes

An experiment was conducted at the University Agricultural Research Farm to study the effect of inoculation with biological nitrogen fixers on growth and yield of chilli (Capsicum annum L.) cv. "Pusa Jawala" in relation to disease incidence caused by plant-parasitic nematodes. The growth, yield, and quality parameters of chilli increased significantly with the inoculation of biological nitrogen fixers using Azospirillum and Azotobacter. Performance of Azospirillum was found better as compared to Azotobacter. Simultaneous inoculation with biofertilisers (100% recommended dose of N-fertiliser 100 kg N per ha and farmyard manure 15 t per ha) resulted the maximum growth, yield, and quality parameters. Thus, the associative nature of the above biofertilisers helps to save 25% nitrogenous fertiliser in chilli crop. There was increased content in plant nitrogen, phosphate and potash, leaf chlorophyll and residual available soil nitrogen, phosphate and potash with dual inoculation with the biological nitrogen fixers along with recommended full dose of nitrogen fertiliser. Disease intensity was recorded in decreasing order in all the treatments but more pronounced in those where biofertilisers were added.

Effect of some botanicals for the management of plant-parasitic nematodes and soil-inhabiting fungi infesting chickpea

A field experiment was conducted during 2009-2011 at the University Agricultural Research Farm to evaluate the efficacious nature of some botanicals such as Argemone mexicana, Calotropis procera, Solanum xanthocarpum, and Eichhornia echinulata in combination with normal as well as deep ploughing against plant-parasitic nematodes and soil-inhabiting fungi infesting chickpea (Cicer arietinum L.) cultivar K-850 in relation to its growth characteristics. Significant reduction was observed in the multiplication of plant-parasitic nematodes Meloidogyne incognita, Rotylenchulus reniformis, Tylenchorhynchus brassicae, and Helicotylenchus indicus and in the frequency of parasitic fungi such as Macrophomina phaseolina, Fusarium oxysporum, Rhizoctonia solani, Phyllosticta phaseolina, and Sclerotium rolfsii by the application of botanicals to soil. However, the frequency of saprophytic fungi Aspergillus niger, Trichoderma viride, and Penicillium digitatum was significantly increased. Much improvement was observed in growth parameters like plant weight, per cent pollen fertility, pod numbers, root nodulation, nitrate reductase activity, and chlorophyll content in leaves. Depth of ploughing also influenced the population of plant-parasitic nematodes and the frequency of soil-inhabiting fungi in chickpea crop.

Use of indigenous Cucumis technologies as alternative to synthetic nematicides in management of root-knot nematodes in low-input agricultural farming systems: A review

The ”Indigenous Cucumis Technologies” (ICTs) were researched and developed for the management of plant-parasitic nematodes, particularly Meloidogyne species, in an attempt to alleviate the void created by the withdrawal of synthetic nematicides from the agro-chemical markets and the drawbacks associated with the use of conventional organic matter as a nematode management practice. Currently, ICTs comprises of four technology types, namely (1) ground leaching, (2) nematode resistance, (3) inter-generic grafting and (4) fermented crude extracts. ICTs, in their various forms, consistently suppressed the nematode numbers and improved crop yields in experimental trials carried out in Limpopo Province, Republic of South Africa. The present paper reviews a decade of successful research and development in ICTs for the management of root-knot nematodes in low-input agricultural farming systems. Key words: Cucumis species, fermented crude extract, ground leaching technology, inter-generic grafting, nematode resistance.

Arbuscular Mycorrhizal Fungi and Opportunistic Fungi: Efficient Root Symbionts for the Management of Plant Parasitic Nematodes

Arbuscular mycorrhizal fungi (AMF) and opportunistic fungi (OP) are the important groups of efficient root symbionts, which play a key role in the management of plant parasitic nematodes (PPN). The AM fungi have the ability to increase plant growth by nutrient uptake and water absorption while opportunistic fungi produced some biologically active metabolites. In recent years, these root symbionts have been widely used for management of plant diseases caused by PPN in various crops because they not only have the capability to modify the quality and abundance of rhizosphere microflora but also alter the overall rhizosphere microbial activity. Beside this, these symbionts may also induce changes in the host root exudation pattern. Concerning the high cost of inorganic fertilizers and the negative effect of chemical pestides on the environment and human health, the mycorrhizal and opportunistic fungi are used as a potential tool for the management of plant diseases caused by plant parasitic nematodes. This review presents a cumulative effect of PPN on plant health and the interaction takes place between the PPN, AM and opportunistic fungi on various host systems. Recent cost effective technologies for mass propagation of these efficient symbionts at commercial scale for the field application are also discussed.

Subsurface drip application of alternative fumigants to methyl bromide for controlling nematodes in replanted grapevines

Many California grape growers use preplant fumigation to ensure uniform and healthy grapevine establishment in replant situations. A field study was conducted to evaluate the performance of subsurface drip-applied chemical alternatives to methyl bromide on plant-parasitic nematodes, plant vigor and fruit yield during the 6 year period following replanting. Subsurface drip fumigation with 1,3-dichloropropene plus chloropicrin and with iodomethane plus chloropicrin had generally similar nematicide activity as methyl bromide in three grape types, while sodium azide was less effective. The combination of 1,3-dichloropropene plus chloropicrin enhanced vine vigor similarly to methyl bromide. However, all plots treated with alternative fumigants produced less fruit yield than methyl bromide over the 4 years of evaluation. Subsurface drip fumigation with alternative chemicals to methyl bromide generally provided adequate management of plant-parasitic nematodes during the vine establishment period. However, further research is required to increase the performance of alternative chemicals against other components of the replant problem, as grape yield in vines grown in the alternative treatments was lower than in methyl bromide.

Organic amendments and their influences on plant-parasitic and free-living nematodes: a promising method for nematode management?

Abstract The use of organic soil amendments, such as green manures, animal manures, composts or slurries, certainly has many advantageous aspects for soil quality and is suggested as a promising tool for the management of plant-parasitic nematodes. However, during a recent literature survey we also found numerous studies reporting an increase of plant-parasitic nematodes after the use of organic amendments. Therefore, we critically re-evaluated the usefulness of organic amendments for nematode management and suggest possible mechanisms for a stimulation of plant-parasitic nematodes, as well as mechanisms that might be causing a reduction of plant-parasitic nematodes. In addition, we also elucidate a possible mechanism that might be responsible for the observed overall positive effects of organic amendments on crop yields. It is likely that a significant part of this is, inter alia, due to the proliferation of non-pathogenic, free-living nematodes and their overall positive effects on soil microbial populations, organic matter decomposition, nutrient availability, plant morphology and ecosystem stability.

IN PLANTA SUPPRESSIVENESS TO NEMATODES AND LONG TERM ROOT HEALTH STABILITY THROUGH BIOLOGICAL ENHANCEMENT - DO WE NEED A COCKTAIL?

It is taken for granted that plants grow in a very complex soil environment harboring diverse microorganisms and are constantly exposed to numerous complex biological interactions that either positively or negatively affect root health and growth. Some scientists believe the soil environment is not complex, and that biological interactions are rare and seldom affect plant growth significantly. Plant pathologists frequently adhere to the low complexity school of thought and therefore often target their research work to a single pest/disease interaction. Similarly biologists studying microbial-based biological control also tend to study one antagonist and one pest, a concept that has been reasonably successful, for example, in biological enhancement of banana planting material with endophytic microorganisms. Good control has been attained regardless of the antagonist involved: mutualistic endophytic fungi or bacteria, arbuscular mycorrhizal fungi, plant health-promoting rhizobacteria or entomopathogenic fungi. There are many practical reasons for a single antagonist approach, but in planta suppressiveness in the field is not an industrial-based phenomenon but is based on unique interrelationships between the microbial community and plants, which result in a healthy root system. Success has been achieved with biological enhancement of plant material for the management of plant-parasitic nematodes in Musa. Practical application is no longer a question of if, but a question of when and where. However, a number of questions still confront those working with the biological enhancement concept: 1) can we increase the levels of control presently attained? 2) can we extend the spectrum of target pests affected? and 3) can in planta suppressiveness be established for long term control? Since in planta suppressiveness is clearly related to the activity of microbial communities and not to a single organism, the question that requires answering is - do we need a cocktail?

Differential effect of hot water treatment on whole tubers versus cut setts of yam (Dioscorea spp.)

The use of thermotherapy or hot water treatment (HWT) is recommended for the management of plant-parasitic nematodes and other pathogens for a range of planting material, especially vegetatively propagated crops including yams, Dioscorea spp. The sprouting (germination) and consequent viability of yam following HWT, however, appear to be influenced by the post-treatment method of planting (whole or cut setts) and cultivar. The present study was established to evaluate the sensitivity of the most popular yam cultivars in Benin and Nigeria, West Africa, to HWT at 50-53 degrees C for 20 min. Sprouting of both setts and whole tubers of most cultivars was affected by HWT. Across experiments, 47% of HWT material, compared with 61% of non-HWT material, sprouted over 8 weeks. When cut into setts, 41% of HWT or untreated tubers sprouted, compared with 72% of whole tubers. Whole, untreated tubers had highest sprouting rates (84%), and setts following HWT had the lowest (38%). Yam planting material was also not completely free of parasitic nematodes following HWT. The reaction to HWT or cutting was highly cultivar specific. Yam cultivars vary in their sensitivity to hot water therapy. Care is therefore advised in selecting yam cultivars for HWT, especially when using cut setts.

THE BURROWING NEMATODE OF BANANA: STRATEGIES FOR CONTROLLING THE UNCONTROLLABLE

The burrowing nematode of banana, Radopholus similis, is difficult, if not impossible, to control effectively. The lack of resistance in commercially acceptable cultivars and the perennial nature of the crop limit management options. Multiplecycle treatment with systemic nematocides is presently the only effective tool available for reducing damage and sustaining yield. Most of these compounds are not toxic to the burrowing nematode, but only inhibit nematode activity for short periods of time. The repetitive application of non-fumigant nematocides has led to an increase in the rapidity of their biodegradation. From environmental, toxicological and consumer viewpoints, this type of pest management is unacceptable. Many attempts have been made to improve the situation with little or no impact to date. Many nematocides have been or are being removed from the market, and new replacement compounds have not been developed. Resistance has never been detected in commercial banana cultivars, and genetically modified cultivars are still unacceptable to a large number of banana consumers. Microbialbased strategies are considered to be a promising alternative approach to nematode management in banana. Progress can only be made if research and crop production systems are streamlined to support new management concepts. The following are discussed: 1) biological enhancement of planting material with fungal endophytes; 2) treatments with multiple nematode antagonists with diverse modes of action; 3) importance of induced systemic resistance in biological control systems; and 4) use of molecular tools to detect effective antagonists. INTRODUCTION There are a large number of effective plant protection technologies available for the management of plant-parasitic nematodes. However, most, if not all, are not adaptable to commercial production systems and less so to subsistence banana and plantain farming. Most people are not aware that Radopholus similis is not controlled by nematocides currently used to secure yield and prevent toppling of the banana plant. Nematocides do not kill nematodes. The majority of systemic nematocides only inhibit movement of R. similis for 2 to 5 weeks. Therefore, nematocides only ensure healthy root growth for a short period. Nematocides are either biodegraded, diluted by rainfall or washed out of the rhizosphere shortly after their application. In addition, microbially enhanced biodegradation of nematocides increases with repeated applications over time (Ou et al., 1994; Karpouzas and Walker, 2000; Pattison et al., 2000; Moens et al., 2004). Microbial degradation also leads to increases in the number of nematocide applications/year, which aggravates the overall situation and disturbs the biological balance in the soil. More importantly, most of the nematocides presently being used are highly toxic to almost all organisms having a nervous system. Most banana crops are grown with nematocides that, for environmental and toxicological reasons, should not be on the market. If R. similis is to be managed without nematocides, new and effective management tools, that actually achieve control without environmental side effects, are needed. Proc. IS on Banana Crop Prot., Sust. Prod.

Effects of pyrrolizidine alkaloids on the performance of plant‐parasitic and free‐living nematodes

Chemical nematicides such as methyl bromide have for decades played a significant role in the management of plant-parasitic nematodes. Their application is problematic because of negative environmental impacts, and therefore methyl bromide was phased out in Europe in 2005. A possible alternative to synthetically derived nematicides is seen in the use of plants and/or their secondary metabolites. These plants could either be used as nematicidal green manure or as a source for nematicidal extracts. This study aimed to evaluate the effects of 1,2-dehydropyrrolizidine alkaloids (PAs), a group of secondary plant metabolites found in hundreds of plant species throughout the world, on the performance of plant-parasitic and free-living nematodes. PAs induced nematicidal, ovicidal and repellent effects on different plant-parasitic and free-living nematodes. There was no conclusive ranking in toxicity for the different structural types of PAs tested. However, the effects were often more pronounced for the tertiary than for the oxidised form of PAs. Further, large differences were observed in the susceptibility of different nematode species to PAs. PAs do affect several performance parameters and developmental stages of nematodes. Therefore, PA-producing plants such as species of Crotalaria, Ageratum or Senecio might be promising candidates for nematode management strategies. [Correction made here after initial online publication].

Management of crotalaria and pigeon pea for control of yam nematode diseases

Management of plant-parasitic nematodes with the use of nematicides has not been recommended for small farmers that grow yam in the Northeastern region of Brazil, due to its high cost and residue toxicity. The use of plants with antagonistic effect to nematodes and green manure which improves soil chemical, physical and biological characteristics can be a viable and low cost alternative to control parasitic nematodes. This work aimed to evaluate the effect of crotalaria (Crotalaria juncea) and pigeon pea (Cajanus cajan) plants on the control of yam nematodes. Three experiments were carried out. The first was conducted under in vitro conditions to evaluate the nematostatic and nematicide effect of extracts from fresh and dry matter of the above ground parts of crotalaria, pigeon pea, and the combination of both. The second experiment was carried out under greenhouse conditions to evaluate the effect of soil amendment with crotalaria, pigeon pea, and the combination of both in the infectivity of Scutellonema bradys, using tomato plants as the host plant. The third experiment was conducted under field conditions to evaluate the effect of crotalaria, pigeon pea, and the combination of both, cultivated between yam planting rows and incorporated to soil surface, on yam nematodes. The aqueous extract obtained form fresh matter of crotalaria had a nematicide effect of 100% for S. bradys. Extracts from dry matter of both crotalaria and pigeon pea did not have any nematicide effect, but had a nematostatic effect. Incorporation of crotalaria to soil inhibited infectivity of S. bradys in tomato seedlings. These results showed that planting crotalaria alone or in combination with pigeon pea, between the yam planting rows, is an efficient method for controlling S. bradys and Rotylenchulus reniformis associated with yams. Crotalaria can be used for controlling these plant-parasitic nematodes in soil.

Mutualistic endophytic fungi and in-planta suppressiveness to plant parasitic nematodes

This paper reviews the development of the concept of biological enhancement of plants with mutualistic fungal endophytes for the management of plant parasitic nematodes. The vast majority of the research conducted to date on biological enhancement of plants with fungal endophytes involves the use of nonpathogenic strains of Fusarium oxysporum and, to a lesser extent, species of Trichoderma, for biological control of nematodes. The main crops thus far studied for biological enhancement with endophytes have been banana, tomato and rice. Because the concept of using nonpathogenic fungi that colonize the endorhiza for biological control is still relatively new, information on this subject in the form of published literature is scare, in the form of Ph.D. theses or in unpublished form. Taking this limitation into account, it is nevertheless hoped that this review will be useful to those working or planning to work with mutualistic fungal endophytes for biological enhancement of plants for nematode management.

Host status of green manures for two isolates of Pratylenchus brachyurus in Brazil

Abstract Due to the complexity of management of plant-parasitic nematodes in cash crops, the use of non-chemical methods, such as rotation with green manures, has increased in recent years. However, data about the host status of green manures for lesion nematodes are scarce. Thus, two glasshouse trials were carried out to evaluate the host status of some green manures for two isolates of Pratylenchus brachyurus, a root-lesion nematode often found attacking soybean, maize and cotton in Brazil. Green manures tested were pigeon pea (Cajanus cajan) cultivars Fava Larga and Iapar 43, Crotalaria juncea, C. spectabilis, C. mucronata, C. breviflora, C. ochroleuca, C. paulina, velvetbean (Mucuna pruriens) cvs Black, Dwarf and Gray. Soybean cv. Pintado and French marigold (Tagetes patula) were included as standard good and poor hosts for P. brachyurus. In a separate glasshouse experiment, a naturally infested soil was used to evaluate the suitability of two green manures to P. brachyurus in comparison with two gramineaceous cover crops. In addition, morphometric studies were carried out with the two isolates of P. brachyurus used in experiments in order to confirm the species. Among the 11 green manures tested, at least two, C. spectabilis and C. breviflora, can be useful as rotation crops to reduce population densities of P. brachyurus, irrespective of the origin of the nematode. By contrast, all velvetbean cultivars and C. juncea must be avoided in infested areas as they are good hosts for the nematode.

A review on the role of predatory soil nematodes in the biological control of plant parasitic nematodes

Predatory nematodes feed on soil microorganisms including plant parasitic nematodes. They reduce populations of plant parasitic nematodes in virtually all soils because of their constant association with plant parasitic nematodes in the rhizosphere, and also release nutrients in plant-available forms, which may enable plants to better withstand nematode burden on their roots. Predation by nematodes of the orders Mononchida, Diplogasterida, Dorylaimida and Aphelenchida, has been studied but the data available in field/natural conditions are insufficient to conclude whether they are effective biocontrol agents of plant parasitic nematodes. However, among the different types of predators, diplogasterids are the most suited for biocontrol of nematodes, because of their short life cycles, easy culture, prey-specificity, chemotaxis sense and resistance to adverse conditions. This article summarizes progress to date and suggests ways to encourage the use of predatory nematodes as biocontrol agents in the management of plant parasitic nematodes.

Manejo integrado de nematóides na cultura da bananeira

O manejo integrado é uma exigência dos mercados importadores, sobretudo da Comunidade Européia (CE), rigorosa em requisitos de qualidade e sustentabilidade, que enfatiza primordialmente a proteção do meio ambiente, segurança alimentar, condições de trabalho, saúde humana e viabilidade econômica. Neste contexto, a utilização da matéria orgânica no manejo dos solos é uma das estratégias que mais benefícios traz à biodiversidade e conservação dos solos. É prática conhecida desde os primórdios da civilização. Contudo, sua utilização de forma efetiva depende ainda do conhecimento de muitas interações que ocorrem no agroecossistema. São apresentados alguns estudos de sua utilização no manejo integrado de fitonematóides e perspectivas de validação, com enfoque na cultura da bananeira e possibilidades de sua adoção para atender à demanda de sustentabilidade.

Microbial control of plant-parasitic nematodes: a five-party interaction

Plant-parasitic nematodes cause significant economic losses to a wide variety of crops. Chemical control is a widely used option for plant-parasitic nematode management. However, chemical nematicides are now being reappraised in respect of environmental hazard, high costs, limited availability in many developing countries or their diminished effectiveness following repeated applications. This review presents progress made in the field of microbial antagonists of plant-parasitic nematodes, including nematophagous fungi, endophytic fungi, actinomycetes and bacteria. A wide variety of microorganisms are capable of repelling, inhibiting or killing plant-parasitic nematodes, but the commercialisation of these microorganisms lags far behind their resource investigation. One limiting factor is their inconsistent performance in the field. No matter how well suited a nematode antagonist is to a target nematode in a laboratory test, rational management decision can be made only by analysing the interactions naturally occurring among “host plant–nematode target–soil–microbial control agent (MCA)–environment”. As we begin to develop a better understanding of the complex interactions, microbial control of nematodes will be more fine-tuned. Multidisciplinary collaboration and integration of biological control with other control methods will␣also contribute to more successful control practices.