Plant-parasitic Nematode Populations Research Articles

Interactions between nematodes and their microbial enemies in coastal sand dunes

European foredunes are almost exclusively colonised by Ammophila arenaria, and both the natural succession and the die-out of this plant have been linked to populations of plant-parasitic nematodes (PPN). The overarching aim of this study was to investigate top-down control processes of PPN in these natural ecosystems through comparative analyses of the diversity and dynamics of PPN and their microbial enemies. Our specific aims were, first, to identify and quantify PPN microbial enemies in European sand dunes; second, to assess their life history traits, their spatial and temporal variation in these ecosystems, and third, to evaluate their control potential of PPN populations. This was done by seasonal sampling of a range of sites and making observations on both the nematode and the microbial enemy communities in rhizosphere sand. Nine different nematode microbial enemies belonging to different functional groups were detected in European sand dunes. Their high diversity in these low productivity ecosystems could both result from or lead to the lack of dominance of a particular nematode genus. The distribution of microbial enemies was spatially and temporally variable, both among and within sampling sites. Obligate parasites, either with low host-specificity or having the ability to form an environmentally resistant propagule, are favoured in these ecosystems and are more frequent and abundant than facultative parasites. Three microbial enemies correlated, either positively or negatively, with PPN population size: Catenaria spp., Hirsutella rhossiliensis and Pasteuria penetrans. Microbial-enemy supported links in the food-web may be involved in the control of PPN populations through indirect effects. The endospore-forming P. penetrans was the most successful top-down control agent, and was implicated in the direct control of Meloidogyne spp. and indirect facilitation of Pratylenchus spp. Overall, our findings suggest strong and diverse top-down control effects on the nematode community in these natural ecosystems.

Impact of anaerobic soil disinfestation combined with soil solarization on plant–parasitic nematodes and introduced inoculum of soilborne plant pathogens in raised-bed vegetable production

A two-year field study was established in August 2008 at the USDA-ARS, U.S. Horticultural Research Laboratory in Fort Pierce, FL to examine the impact of anaerobic soil disinfestation (ASD) combined with soil solarization as an alternative to methyl bromide (MeBr) fumigation for control of plant–parasitic nematodes and introduced inoculum of soilborne plant pathogens. A complete factorial experiment in a split-split plot was established to evaluate three levels of applied initial irrigation (10, 5, or 0cm), two levels of partially-composted poultry litter (CPL; amended or unamended), and two levels of molasses (amended or unamended) in combination with solarization in a raised-bed bell pepper-eggplant double crop production system. Untreated and MeBr controls were established in each block for comparison to ASD treatments. Survival of Phytophthora capsici inoculum, introduced prior to ASD treatment, was equal to that with MeBr and less than the untreated control for all solarized treatments regardless of applied soil amendments during both seasons. Survival of introduced inoculum of Fusarium oxysporum f. sp. lycopersici was least (and equivalent to the MeBr control) in treatments with applied molasses during the second season. While endemic plant-parasitic nematode populations were generally low throughout the first season, by the end of the second eggplant double crop, root-knot nematode (Meloidogyne incognita) populations in treatments not receiving molasses and/or CPL (solarization only) or not receiving irrigation at treatment averaged more than 200 nematodes per 100cm3 of soil compared to an average of 10 nematodes per 100cm3 in ASD treatments where molasses or molasses+CPL was applied and irrigated with 5 or 10cm of water. Anaerobic soil disinfestation combined with solarization may provide an alternative to chemical soil fumigation for control of soilborne plant pathogens and plant–parasitic nematodes in Florida raised-bed vegetable production systems.

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.

KEANEKARAGAMAN NEMATODA DALAM TANAH PADA BERBAGAI TIPE TATAGUNA LAHAN DI ASB-BENCHMARK AREA WAY KANAN

The soil nematode diversity in several land-use types in Way Kanan ASB-Benchmark Area. The conversion of forest to intensive agroecosystem such as monoculture system reduces biodiversity of the plant, herbivore, and decomposer subsystems. Those changes affected the litter and plant root quality. Consequently, few soil nematode species could be dominant and cause of disturbance of the stability of the below ground community. The increasing populations of plant parasitic nematodes usually occur on monoculture system . The research was conducted to study the effect of forest changes in several land use types on soil nematode diversity in Way Kanan Benchmark Area. Soil sampling on five land use types (secondary forest, agroforest or tree based agriculture, plantation, cassava field, and Imperata grass land) was conducted in November1996 and December 1997. Nematodes were extracted by decantation-centrifugation with sugar method. The soil nematodes were grouped into order and generic level including plant parasitic and non- parasitic. The results show that the order of Rhabditida, Dorylaimida, and Tylenchida were found from those five land-use types. The total genera of plant parasitic nematodes in Imperata grass land were the highest among the other four land use types. The total number of non-plant parasitic nematodes in secondary forest (28.0 individual per 300 cc of soil) was higher than total number in the plantation ( 2.6 individual per 300 cc of soil), cassava field (4.0 individual per 300 cc of soil) or Imperata grass land (6.6 individual per 300 cc of soil). The total number of plant parasitic nematodes in Imperata grass land (59.8 individual per 300 cc of soil), agroforest (59.0 individual per 300 cc of soil), secondary forest (48.2 individual per 300 cc of soil), and plantation (17.6 individual per 300 cc of soil) were not significantly different, but total number in Imperata grass land and agroforest were significantly higher than that in cassava field (11,6 individual per 300 cc of soil).

Effects of organic amendments on plant-parasitic nematode populations, root damage, and banana plant growth

Nematodes are major pests for crops, including banana. Environmentally friendly methods for managing plant-parasitic nematodes have to be developed, such as organic material application. Our study focuses on the impacts of several organic amendments on banana plants, considering mainly their effect on soil nitrogen supply and soil microbial biomass, and the consequences on plant-parasitic nematode impacts on the plants. A microcosm experiment for 13 weeks was conducted to evaluate four organic materials: sugarcane bagasse, sugarcane sludge, plant residues, and sewage sludge, compared to a control without organic amendment. Input of organic materials led to an important change on nitrogen resource, and plants grew better when the N availability was the highest, but better growth conditions did not necessarily reduce parasitic nematodes impacts on the roots. Damage on the roots depended on plant-parasitic nematode abundance. Three of four tested amendments exhibited a regulator effect on plant-parasitic nematode populations (bagasse, sugarcane sludge, and plant residues). Root growth was not the explanatory factor for this regulation. Only sugarcane sludge led to an overall positive effect on the plant, increasing its growth and reducing its parasitism pressure. The other organic materials exhibited an antagonism between the promoted plant growth and the reduced nematode populations.

Parasitic Nematodes on Polish Tulip Plantations

Soil samples were collected from 10 plantations of tulip. The most often found plant-parasitic nematode was Pratylenchus neglectus, of which 80 species were found. But P. neglectus was usually not over 10% of the individuals in the samples.Among ectoparasitic nematodes, the most often found was Bitylenchus dubius. The occurrence of Bitylenchus dubius was not dependent on the acidity of the soil. Facultative parasites were the most numerous group, especially Filenchus vulgaris and Basiria graminophila. The plant-parasitic nematode populations which occurred on plantations of tulip did not cause severe damage.

Sampling for Plant-parasitic Nematodes in Corn Strip Trials Comparing Nematode Management Products

Protectant seed treatments are a new management option for plant-parasitic nematodes that feed on corn. Many growers and agribusiness personnel are conducting strip-trial comparisons of nematode seed treatments in growers' fields. Yield monitors in combines and weigh wagons can be used to collect yield data from multiple-row strips that stretch across an entire field. But some growers and agribusiness personnel also want to assess plant-parasitic nematode populations in these strip trials to gauge whether the seed treatments are affecting nematode population densities (numbers). Drawing conclusions about the effects of treatments on numbers of plant-parasitic nematodes in strip trials is problematic because of the natural variability of nematode populations and their densities in the field. This guide discusses various points to consider about collecting samples to assess possible effects of treatments on population densities of plant-parasitic nematodes in strip trials. Accepted for publication 15 July 2011. Published 1 September 2011.

Spatial and temporal variability of plant-parasitic nematodes population in sugarcane

Nematodes are important pests of sugarcane crop in Brazil. However, no studies have been reported on the spatial and temporal variability of nematodes population in sugarcane fields and such studies are indispensable for the development of sampling plans, aimed at their application in integrated management programs. This work was carried out in two commercial fields of approximately 1 ha, both of them infested by Meloidogyne javanica and Pratylenchus zeae. In each area, samples represented by about 50 g of roots, were collected every two months, within a grid measuring 10.5 × 10 m (experiment 1) and 9.8 × 10 m (experiment 2). The highest nematodes populations were obtained during the rainy season, when high temperatures and moistures were favorable to root development. For this reason the rainy season was considered the best time to collect samples to identify areas with nematodes problem. Among the 52 calculated semivariograms (28 for M. javanica or P. zeae populations in area 1 and 24 for M. javanica or P. zeae populations in area 2), 22 could not be fitted to any model and presented a pure nugget effect. The spherical model showed the best fit to the semivariograms of data observed in the other 30 conditions. In those cases, values of range in semivariogram varied from 22 to 77 m, with 47 m on average and suggesting that, to obtain a reliable estimate for the population of these plant parasites in a given area, samples should be collected 47 m apart, which is equivalent to 1.5 sampling points per hectare.

Brassica Biofumigants Improve Onion (Allium cepa L.) and Celery (Apium graveolens) Production Systems

Four experiments evaluated effects of brassica cover crops on onion and celery. Treatments included oilseed radish (Raphanus sativus L.), oriental mustard (Brassica Juncea L. Czerniak), brown mustard (Brassica Juncea L. Czerniak), yellow mustard (Sinapis alba L.), and a bare ground control. All brassica cover crops increased celery yield, while only oilseed radish increased onion marketable yield. The brassica cover crops enhanced the population of beneficial microorganisms in the soil of both celery and onion fields. At the same time, the population of plant-parasitic nematodes was reduced, but only in the commercial field that was in continuous celery for many years.

Evaluation of Low-Input Management Methods for Plant Parasitic Nematodes in Plantain CV. Agbagba in Southwestern Nigeria

Field trial was conducted at the National Horticultural Research Institute’s experimental field between July 2003 and January 2005 to determine the effect of some cultural practices on the populations and control of plant parasitic nematodes infestation and their effect on some growth and yield attributes of plantain cv. Agbagba. The treatments included corm paring / hot water root dip, Tithonia diversifolia leaf mulch and combination of Tithonia leaf and hot water root dip. The untreated plantlets served as the control. Results showed that in all the assayed soil and root samples, the control plots recorded the highest populations of plant parasitic nematodes. They include Meloidogyne incognita, Helicotylenchus multicintus and Radopholus similis while the lowest populations occurredin plots with the treatment combination of hot water root dip and T. diversifolia mulch. Plant height, number of leaves and sucker production were significantly enhanced. in Tithonia mulch + hot water root dip- treated plantain followed by Tithonia mulch and hot water dip treatment respectively, Early flowering and fruiting as well as significant increasein bunch weight were observed in Tithonia mulch + hot water root dip - treated plantain. Similarly, the highest cumulative yield values occured in Tithonia mulch + hot water root dip - treated plantain. This practice is recommended for plantain producers in organic agriculture production system

Food web diagnostics and functional diversity of soil inhabiting nematodes in a natural woodland

Abstract Functional diversity and detritus soil food web of soil inhabiting nematodes in natural woodland dominated by Acacia nilotica L. was studied. Functional diversity was studied in terms of trophic groups assessed by Trophic diversity index (TDI) and Shannon-Weaver index (H′), while food web was diagnosed by channel index (CI). The plant parasitic channel was determined by plant parasitic index (PPI). The stability of the soil ecosystem was measured in terms of maturity index (MI), structure index (SI) and enrichment index (EI). Shannon-Weaver index of the area was recorded as 2.1 ± 0.3 while trophic diversity index 2.6 ± 0.7, maturity index (MI) 3.1 ± 0.2, channel index 62.4 ± 28.1 and structure and enrichment indices 68.1 ± 18.5 and 15.4 ± 13.7 respectively. A high degree of positive correlation was recorded between population of dorylaims and MI while some degree of negative correlation existed between population of plant parasitic nematodes and MI. Population of other nematodes showed a positive correlation with SI and EI. The faunal profile was found to be tilted towards quadrat C giving the idea of relatively undisturbed ecosystem with moderate enrichment and fungal decomposition channel.

The effect of two compost soil amendments, based on municipal green and penicillin production wastes, on plant parasitic nematodes

Abstract Suppressive effect of two composts, applied at five doses (0 %, 1 %, 2.5 %, 5 % and 10 % w/w), was studied on spring barley to control different genera of plant parasitic nematodes in potting mixtures. Amendment of soil with these materials resulted in a significant decreasing effect of plant parasitic nematode populations. The best reduction of number of plant parasitic nematodes was found for the nematode genera Bitylenchus, Helicotylenchus, Heterodera, Paratylenchus and Rotylenchulus by a municipal green compost (C1) and nematode genera Bitylenchus, Geocenamus, Helicotylenchus, and Rotylenchulus by a compost derived from penicillin production residues (C2). The compost C1 with a lower C:N ratio was more effective in the nematode control than the compost C2. The analysis of variance showed a significant interaction among all factors involved in the experiment: type of compost, different doses and nematode genera. Relationship between applied doses and number of nematodes showed a significantly high negative correlation.

Impact of floor vegetation on the abundance of nematode trophic groups in vineyards

This study examined the effect of two floor vegetation management strategies on the abundance of nematode trophic groups in two Australian vineyards (one cool and one warm climate) for three consecutive years. Throughout the grape growing season floor vegetation was managed either as a perennial sward by regular mowing/snipping (permanent sward) or eliminated by spraying herbicide (spray/bare soil). Soil from both treatments was inhabited by five nematode trophic groups namely bacteria feeders, predators, omnivores, fungal feeders and plant parasites. Of these, bacteria feeder nematodes were predominant, comprising 60–70% of the total population in each site. Predators and plant parasites comprised ca. 3% and 17% of the total population respectively at Wagga Wagga, and ca. 17% and 4% at Tumbarumba. In the sward plots by the end of the experiment, the populations of non-plant parasitic ‘beneficial’ nematodes (bacteria feeders, predators, omnivores and fungal feeders) had generally increased linearly with time whereas plant parasitic nematode populations had decreased. On the last sampling date, the total bacteria feeder nematode populations were ca. 3–4-fold and ca. 2–3-fold greater in the sward than the spray plots at Wagga Wagga and Tumbarumba vineyard respectively. Over three years, the omnivore nematode (primarily Dorylaimidae) populations were also significantly increased by ca. 2–6-fold and 3-fold in the sward plots compared to the spray plots at Wagga Wagga and at Tumbarumba vineyard respectively. Similarly, predatory nematodes in the sward plots were ca. 32–57% higher at Wagga Wagga and ca. 60–164% at Tumbarumba compared to the spray plots. In contrast, plant parasitic nematodes were ca. 4-fold greater in inter-row sward plots than the spray plots at Wagga Wagga but 3-fold lower at Tumbarumba. The plant parasitic nematode populations were decreased consistently over time for both treatments and soil layers until at the termination of the experiment when its populations were reduced below 100 m −2 in undervine soil in the Tumbarumba vineyard. Therefore, the overall results from this study showed that non-plant parasitic ‘beneficial’ nematodes were increased generally in plots with permanent swards, which in turn suppressed pest nematodes.

Survey of Plant-Parasitic Nematodes Associated with Yams in Ogun and Osun States of Nigeria

Survey of Plant-Parasitic Nematodes Associated with Yams in Ogun and Osun States of NigeriaA survey was conducted to determine the types, frequency and population of plant parasitic nematodes associated with the soils and roots of Yam (Dioscoreaspecies) in all the Local Government Areas of Ogun and Osun States of Nigeria using random sampling soil and root and pie pan modification of Baerman funnel for plant parasitic nematode extraction. Ten and nine genera of plant parasitic nematodes were encountered both from the soils and root samples from the two States. Plant parasitic nematodes recovered includedScutellonemaspp.,Meloidogynespp.,Pratylenchusspp.,Trichodorusspp.,Helicotylenchusspp.,Radopholusspp.,Longidorusspp.,Xiphinemaspp.,Rotylenchulusspp andAphelenchoidesspecies.Scutellonemaspp.,Meloidogynespp., andPratylenchusspp were most widely distributed with frequency ratings of 70, 65 and 60% respectively in soil samples from Ogun State and in the root samples the three genera predominated with 60, 55 and 45% frequency ratings respectively.Meloidogynespp.,Scutellonemaspp., andPratylenchusspp were most widely distributed with frequency ratings of 65, 45 and 35% respectively in soil samples from Osun State and in the root samples the three genera predominated with 55, 35 and 35% frequency ratings respectively.

Spatio-temporal consideration of soil conditions and site-specific management of nematodes

Site-specific (precision) management (SSM) has potential for application in managing nematodes and soil conditions in environmentally meaningful ways. Successful application of SSM, however, may be dependent on how agronomically, biologically, and ecologically integrated the plan in question is. Otherwise, SSM risks falling into the “Tried but did not last” category. With this background and in addition to describing the concepts and principles of SSM, this presentation discusses the following interrelated points: (1) Case studies of spatio-temporal analysis of soybean cyst nematode (Heterodera glycines) infestations, soil conditions and crop yield in managed ecosystems. Among the critical factors to an accurate and sustained application of SSM are understanding (i) the temporal structure and (ii) the spatial structure of the attribute in question, and (iii) establishing cause-and-effect relationships in the prevailing conditions. New approaches to temporal structure analysis when balancing the purpose of SSM application and nematode biology (as it relates to life stages), population density in soil and root tissue (to determine threshold), and damage functions (physiological stress of the plant during the growing season) are outlined. (2) Application of the concept of fertiliser use efficiency (FUE) to identify soil conditions when managing soil fertility. Defined as increase in host productivity and/or decrease in plant-parasitic nematode population density in response to a given fertiliser treatment, the FUE model recognizes variable responses and identifies four categories of interactions necessary for integrated management decision-making options that account for agronomic, economic, ecological and environmental and pest management issues. (3) Approaches to changing soil conditions in agro-biologically integrated ways. By incorporating nematode community structure (an excellent indicator of soil bio-ecological changes), soil nutrient amendments and crop yield, we have described a modification of the FUE model to identify and monitor changes in soil conditions, thereby creating the necessary bridges to disciplinary and cross-disciplinary gaps and interactions.

Fitonematóides associados à rizosfera e raízes da mandioca cultivada em rotação com inhame cultivar da Costa

O trabalho teve o objetivo de avaliar as populações de fitonematóides associados à cultura da mandioca, plantada em sucessão à cultura do inhame, em 22 propriedades rurais do Recôncavo da Bahia. Adicionalmente, foram feitos testes de hospedabilidade com as variedades de mandioca 'Cigana' e 'Talo Roxo', ao nematóide Scutellonema bradys. Foram constatadas as presenças dos seguintes nematóides: Pratylenchus brachyurus, Scutellonema bradys, Meloidogyne incognita e Rotylenchulus reniformis, nas raízes e amostras de solo. Além dos nematóides, Tylenchus sp., Aphelenchus sp., Meloidogyne incognita, Mesocriconema sp., Aphelenchoides sp., Helicotylenchus presente apenas nas amostras de solos. O teste de hospedabilidade demostrou que as variedades de mandioca estudadas não são hospedeiras de Scutellonema bradys.

First field release of a predatory nematode, Mononchoides gaugleri (Nematoda: Diplogastrida), to control plant-parasitic nematodes

Predatory nematodes are an important entity of the soil food web with biological control potential against plantparasitic nematodes (Bilgrami, 1997). Low fecundity, long life cycle, difficult culture conditions, cannibalism and susceptibility to changing environmental conditions restrict the use of mononchs and stylet-bearing predators as biological control agents. The possibility of using nematodes as biological control agents of plant-parasitic nematodes lies with diplogastrid predators (Diplogastrida). Among the advantages of diplogastrids over mononchs and stylet-bearing predators, Siddiqi et al. (2004) and Bilgrami et al. (2005) have listed ease of in vitro culture, high rates of reproduction and predation, short life cycle, and ability to detect and respond to prey attractants and rare cannibalism. Diplogastrids possess greater tolerance to unfavourable environmental conditions (Bilgrami, 1997), density-dependent predation (Bilgrami et al., 2005), ability to reduce root galling (Fauzia et al., 1998) and decrease in parasitic nematode populations in pots (Osman, 1988). This is the first report of a predatory nematode being field-released to control plant-parasitic nematodes. Our goal was to evaluate the effects of Mononchoides gaugleri (Nematoda: Diplogastrida) on naturally occurring plantparasitic and non-parasitic nematode populations in a turfgrass field. A field experiment was conducted at Rutgers University Turfgrass Station, New Brunswick, NJ, USA. The experiment was laid out in a completely randomised design within a 260 × 170 cm plot. Forty 10 cm long sections of PVC pipe (10 cm internal diam.) were driven into the ground in five vertical rows; each row was 20 cm apart and contained eight PVC pipes. The area encircled by the pipe is referred to as a microplot. Thirty-nine microplots were divided into three groups, i.e., controls I and II, and

Effects of long-term turfgrass management practices on soil nematode community and nutrient pools

The impact of long-term turfgrass management practices on soil nematode population and community structure and nutrient pools were studied in replicated Kentucky bluegrass ( Poa pratensis) plots managed under 9 different organic- and mineral-fertilizer regimes for 15 years in Delaware, Ohio. Soil samples were collected in September 2003, July 2004 and October 2004. Nematodes were extracted using the Baermann funnel technique, identified to genus level, and populations of total, free-living (FLN), bacterivorous, fungivorous, predatory, omnivorous, and plant-parasitic (PPN) nematodes, were counted. FLN/PPN ratio, total number of genera, genus diversity, richness, evenness, Maturity Index, Plant-Parasitic Index, and Combined Maturity Index were calculated. In addition, soil nematode faunal profile analysis was conducted to determine soil food web condition using Enrichment Index and Structure Index. Concentrations of NH 4-N, NO 3-N, dissolved organic nitrogen, microbial biomass nitrogen, and soil organic matter (SOM) were measured in soil samples to describe soil nutrient status. Results from repeated measures analysis of variance showed that in general, nematode populations and food web indices were not differently affected by the 9 turfgrass management regimes but microbial biomass nitrogen and SOM were different. Further group analysis revealed that nematode community indices, Maturity Index and Combined Maturity Index, were significantly lower and Enrichment Index was significantly higher under high (223 kg N ha −1 year −1) and medium (171 kg N ha −1 year −1) N-input compared to low N-input (98 kg N ha −1 year −1) management group, indicating disturbance of the nematode food web. In addition, organic-fertilizer based turf management resulted in significantly higher soil microbial biomass compared to mineral-fertilizer management or the control, but no differences were found in the nematode community between the two fertilizer types. Herbicide, insecticide, or fungicide applications had no significant negative effect on soil nematode community, microbial biomass and SOM. We conclude that the amount of N fertilizer influences the soil nematode food web and nutrient pools in turfgrass while pesticides have no effect. Our results also show that irrespective of the management regime, the soil nematode food webs under turfgrass are more enriched but less structured than those under natural grassland ecosystems, indicating an overall food web disturbance.

Seasonal fluctuation in nematode population associated with mango, Mangifera indica L.

Mango, Mangifera indica L. Family – Anacardiaceae, an economically important fruit tree, was selected to study the effect of seasonal changes of the population of plant parasitic nematodes viz., Hoplolaimus indicus, Helicotylenchus indicus, Rotylenchulus reniformis, Tylenchorhynchus mashoodi, Tylenchus filiformis and Hemicriconemoides mangiferae around the roots. The population was investigated at 10, 20 and 40 cm depths. It was observed that seasonal fluctuations have a direct effect on the nematode population. The population was larger at 10 cm depth followed by 20 and 40 cm depths. The largest nematode population was observed when the percent soil moisture was high. Both soil temperature and soil moisture were equally important. The soil pH also affected indirectly the nematode population densities.

Effect of some land clearing practices on plant parasitic nematode populations in soils of farmed lands in the moist semi-decidous rain forest zone of Ghana

Effect of some land clearing practices on plant parasitic nematode populations in soils of farmed lands in the moist semi-decidous rain forest zone of Ghana