Meloidogyne Incognita Eggs Research Articles

TOXICITY AND BIOCHEMICAL EFFECT OF ORGANOPHOSPHATES AND BIOPESTICIDES AGAINST ROOT-KNOT NEMATODE, Meloidogyne incognita

This study was carried out to investigate the toxicity and biochemical effects of two (biopesticides) biofly, abamectin and two organophosphates pesticides cadusafos and fenitrothion against root-knot nematode, Meloidogyne incognita egg filtrates and second stage juveniles (J2) as well as on laboratory experiment, also the inhibitory effect of the tested pesticides to acetylcholenesterase (AChE) and adenosine triphosphatase (ATPase) were determined. Results indicated that the tested pesticides have toxic action against Meloidogyne incognita second-stage juveniles (J2) and egg filtrates after 24 hrs from application to 72 hrs and the toxicity increased with the time. Abamectin was the most toxic followed by ,fenitrothion cadusafos and biofly was least in its toxicity to M. incognita second stage juveniles (J2 )and egg filtrates while the toxicity was depending on dose. The tested pesticides have inhibitory effect on AChE and ATPase activity and the inhibitory effect increased with AChE in case of abamectin and cadusafos while the potency of the organophosphate pesticides to inhibit ATPase was limited refers to its mode of action

Isolation of nematophagous fungi from eggs and females of Meloidogyne spp. and evaluation of their biological control potential

Fungi were isolated from Meloidogyne spp. eggs and females on 102 field-collected root samples in China. Of the 235 fungi isolated (representing 18 genera and 26 species), the predominant fungi were Fusarium spp. (42.1% of the isolates collected), Fusarium oxysporum (13.2%), Paecilomyces lilacinus (12.8%), and Pochonia chlamydosporia (8.5%). The isolates were screened for their ability to parasitise Meloidogyne incognita eggs in 24-well tissue culture plates in two different tests. The percentage of eggs parasitised by the fungi, the numbers of unhatched eggs and alive and dead juveniles were counted at 4 and 7 days after inoculation. The most promising fungi included five Paecilomyces isolates, 10 Fusarium isolates, 10 Pochonia isolates and one Acremonium isolate in test 1 or test 2. Paecilomyces lilacinus YES-2 and P. chlamydosporia HDZ-9 selected from the in vitro tests were formulated in alginate pellets and evaluated for M. incognita control on tomato in a greenhouse by adding them into a soil with sand mixture at rates of 0.2, 0.4, 0.8 and 1.6% (w/w). P. lilacinus pellets at the highest rate (1.6%) reduced root galling by 66.7%. P. chlamydosporia pellets at the highest rate reduced the final nematode density by 90%. The results indicate that P. lilacinus and P. chlamydosporia as pellet formulation can effectively control root-knot nematodes.

Effects of catechins and low temperature on embryonic development and hatching in Heterodera glycines and Meloidogyne incognita

Mimics of two natural influences, a chemical similar to one present in cyst nematodes and low temperature exposure of nematode eggs, were evaluated for their effects on quantitative and qualitative features of embryonic development and hatching. The polyphenol epigallocatechin gallate (EGCG), an analogue of a compound found in nematode cysts, reduced hatch from both Heterodera glycines and Meloidogyne incognita eggs. Reduction was by 22.7% in H. glycines and 68.5% in M. incognita at 14 days after exposure to 1.0 mM EGCG. Significant reductions in hatch were observed at 7 days after exposure in H. glycines eggs, and as early as 5 days in M. incognita. Half-maximal percentage hatch was delayed by 0.6 days in H. glycines and 1.1 days in M. incognita (16.2 and 18.3%, respectively). Decreased hatch was associated primarily with an increase in unhatched, but viable, second-stage juveniles (J2). Hatch levels could be completely restored by day 14 in both species if EGCG was replaced with water on day 3. Replacement on day 7 partially restored hatch in M. incognita but was not effective in H. glycines. Inhibition of chitinase activity by EGCG suggests one factor in J2 retention in the egg. Exposure to low temperature decreased hatch by ca 50% in both species but without accumulation of unhatched J2. This stage peaked on day 3 in H. glycines-treated eggs, and on day 7 in M. incognita. However, response to low temperature in each species was characterised by developmental arrest at the first-stage juvenile.

Winter survival of Meloidogyne incognita juveniles and eggs in Kyushu, Japan.

Winter survival of Meloidogyne incognita juveniles and eggs in Kyushu, Japan.

Effect of some organic waste extracts on hatching of Meloidogyne incognita eggs.

Plant parasitic nematodes significantly hinder food production particularly in the developing world where peasant farmers have little knowledge of these pests. Currently, synthetic pesticides which are highly detrimental to man and the environment are the principal means of nematode control. However, plant products might provide a sustainable control option as nematicidal properties have been identified in many higher plants. An in vitro experiment involving five organic waste extracts; citrus waste, cocoa bean testa, compost, poultry manure and oil palm bunch waste were therefore evaluated for their hatching inhibitory potential to the southern root-knot nematode, Meloidogyne incognita eggs. Three concentration levels (w/v) that is 4, 8 and 10% of cold aqueous extracts of the organic waste compounds were filtered into 9 cm Petri dishes and infested with 100 eggs each. Hatching of eggs was monitored over a three time period; 24, 48 and 72 h after infestation of the eggs into the cold aqueous extracts of the five candidates in Petri dishes. The best result was obtained with citrus waste extract in which 5 eggs hatched while 73 eggs hatched in the distilled water (the control treatment) representing a hatching reduction of 93% at the highest time and concentration of 72 h and 10% respectively. Key words: Hatching, Meloidogyne incognita, organic waste extracts, plant parasitic nematodes.

Transcriptome analysis shows differential gene expression in the saprotrophic to parasitic transition of Pochonia chlamydosporia

Expression profiles were identified in the fungus Pochonia chlamydosporia, a biological control agent of plant parasitic nematodes, through a cDNA-amplified fragment length polymorphism approach. Two isolates with different host ranges, IMI 380407 and IMI 331547, were assayed in conditions of saprotrophic-to-parasitic transition, through in vitro assays. Gene expression profiles from three different nutritional conditions and four sampling times were generated, with eggs of host nematodes Globodera pallida and Meloidogyne incognita. Expression of transcripts changed in RNA fingerprints obtained under different nutritional stresses (starvation in presence/absence of eggs, or rich growth media). Transcript derived fragments (TDFs) obtained from the expression profiles corresponded to 6,800 products. A subset was sequenced and their expression profile confirmed through RT PCR. A total of 57TDFs were selected for further analysis, based on similarities to translated or annotated sequences. Genes expressed during egg parasitism for both IMI 380407 and IMI 331547 were involved in metabolic functions, cellular signal regulation, cellular transport, regulation of gene expression, DNA repair, and other unknown functions. Multivariate analysis of TDF expression showed three groups for IMI 380407 and one for IMI 331547, each characterized by expression of genes related to eggs parasitism. Common amplification profiles among TDF clusters from both isolates also reflected a pool of constitutive genes, not affected by the nutritional conditions and nematode associations, related to general metabolic functions. The differential expression of parasitism related genes suggest a network of induced/repressed products, playing a role in fungal signaling and infection, with partial overlaps in host infection and parasitism traits.

Toxicity of Kaempferia galanga rhizome constituents to Meloidogyne incognita juveniles and eggs

AbstractThe toxicity of Kaempferia galanga rhizome constituents to second-stage juveniles (J2) and eggs of Meloidogyne incognita was examined in vitro and in container experiments. Results were compared with those of three nematicides: carbofuran, fosthiazate and metam sodium. Ethyl cinnamate (EC) and ethyl p-methoxycinnamate (EMC) were the nematicidal and hatch inhibitory principles. In direct-contact mortality bioassays, EC 0.037 mg ml–1) and EMC (0.041 mg ml–1) were more toxic than carbofuran (0.092 mg ml–1) but less toxic than fosthiazate (0.002 mg ml–1) towards J2 based upon 48 h LC50 values. EC and EMC treatments resulted in 100% and 93 and 81% inhibition of hatch at 125.0 and 62.5 μg ml–1, respectively. Inhibition of these compounds was higher than carbofuran and metam sodium but significantly lower than fosthiazate. In contact +fumigant mortality bioassays with J2, EC and EMC applied at 0.25 and 0.125 mg (g soil)–1resulted in 81 and 80% and 77 and 73% mortality, respectively, while carbofuran and metam sodium treatments resulted in 86 and 96% and 57 and 73% mortality, respectively. Fosthiazate resulted in 92% mortality at 0.063 mg (g soil)–1. In vapour-phase mortality bioassays with J2, EC and EMC were more effective in a closed container than in an open one, indicating that mode of delivery was, in part, a result of vapour action. Global efforts to reduce the level of highly toxic synthetic nematicides in the agricultural environment justify further studies on K. galanga rhizome-derived materials, particularly ethyl cinnamate and ethyl p-methoxycinnamate, as potential nematicides and hatching inhibitors for the control of M. incognita as fumigants with contact action.

Fusarium oxysporum f. sp. phaseoli and Meloidogyne incognita interaction in common bean

To verify a possible relationship between resistance to nematodes and to Fusarium oxysporum (Fop) in common bean, 18 lines (eight resistant and eight susceptible to Fop plus two controls) were evaluated for resistance to the nematode Meloidogyne incognita. This evaluation was conducted in a greenhouse in a randomized block design with five replications. The plot consisted of one pot with two bean plants and a nematode-susceptible tomato plant. Two weeks after sowing, plants were infested in the rhizosphere with 5000 eggs of Meloidogyne incognita, race 3. The number of egg masses was assessed, about 45 days after inoculation. Only lines ESAL 522, ESAL 519 and 'Aporé' were resistant to the nematode. Only 'Aporé' was resistant to both pathogens. The correlation between grades of Fop severity and mean egg mass was practically zero (r = 0.0252, P < 0.9293).

Nematicidal influence of <i>P.tuberreguim</i> and neem extract on the incidence of root-knot nematode on hausa potato (<i>Solenostemon rotundifolius Poir</i>).

Efficacy of Pleurotus tuberregium, Neem-leaf ash, carbofuram and combination of the three above were tested in the control of root-knot nematode (Meloidogyne incognita) on Hausa potato. In the green house, twenty-five polythene bags were filled with 10kg of steam-sterilized sandy loam soil and Hausa potato seedlings were planted in each of them. Four weeks after planting 5000 eggs of (Meloidogyne incognita) were inoculated round the plants in each of the bag. The treatments which included Pleurotus tuberregium, Neem-leaf ash, Carbofuran (a synthetic nematicide), and a combination of the three treatments above as a combined approach treatment were applied into the bags around the plants to ascertain the nematicidal influence of each. A control plot where nematode eggs were not inoculated and no treatment application was maintained and observed. Influence of these treatment were further observed in the field which is naturally infested with nematode (Meloidogyne incognita.) The field study was laid out in a Randomized Complete Block Design (RCBD) replicated five times. Both the green house study and the field study shows that all the materials used as treatments in this study have nematicidal influence as they significantly (P=0.05) reduced nematode population and their damaging effects. Combined approach treatment (i.e. P. tuberregium, plus Neem-leaf ash, plus carbofuran) gave better result than the single treatments.Keywords: Root-Knot nematode, control, Hausa potato.

Enhancing the virulence of Paecilomyces lilacinus against Meloidogyne incognita eggs by overexpression of a serine protease

To enhance the virulence of Paecilomyces lilacinus against Meloidogyne incognita eggs, a serine protease was overexpressed in P. lilacinus 9410 (PL9410). The cDNA of a mature serine protease gene was cloned from PL9410 and integrated into the genomes of PL9410 transformants through Agrobacterium tumefaciens-mediated transformation. Our results confirmed that the serine protease gene was overexpressed at the transcriptional level, and that the serine protease activities were enhanced in the transformants when compared to the parent strain. The bioassay results indicated that the relative parasitizing rates of the transformants against M. incognita eggs increased by about 20% in both conidial suspension and mycelium treatment groups.

Short interfering RNA-mediated knockdown of drosha and pasha in undifferentiated Meloidogyne incognita eggs leads to irregular growth and embryonic lethality

Micro-(mi)RNAs play a pivotal role in the developmental regulation of plants and animals. We reasoned that disruption of normal heterochronic activity in differentiating Meloidogyne incognita eggs may lead to irregular development, lethality and by extension, represent a novel target for parasite control. On silencing the nuclear RNase III enzyme drosha, a critical effector of miRNA maturation in animals, we found a significant inhibition of normal development and hatching in short interfering (si)RNA-soaked M. incognita eggs. Developing juveniles presented with highly irregular tissue patterning within the egg, and we found that unlike our previous gene silencing efforts focused on FMRFamide (Phe-Met-Arg-Phe-NH 2)-like peptides (FLPs), there was no observable phenotypic recovery following removal of the environmental siRNA. Aberrant phenotypes were exacerbated over time, and drosha knockdown proved embryonically lethal. Subsequently, we identified and silenced the drosha cofactor pasha, revealing a comparable inhibition of normal embryonic development within the eggs to that of drosha-silenced eggs, eventually leading to embryonic lethality. To further probe the link between normal embryonic development and the M. incognita RNA interference (RNAi) pathway, we attempted to examine the impact of silencing the cytosolic RNase III enzyme dicer. Unexpectedly, we found a substantial up-regulation of dicer transcript abundance, which did not impact on egg differentiation or hatching rates. Silencing of the individual transcripts in hatched J2s was significantly less successful and resulted in temporary phenotypic aberration of the J2s, which recovered within 24 h to normal movement and posture on washing out the siRNA. Soaking the J2s in dicer siRNA resulted in a modest decrease in dicer transcript abundance which had no observable impact on phenotype or behaviour within 48 h of initial exposure to siRNA. We propose that drosha, pasha and their ancillary factors may represent excellent targets for novel nematicides and/or in planta controls aimed at M. incognita, and potentially other parasitic nematodes, through disruption of miRNA-directed developmental pathways. In addition, we have identified a putative Mi-eri-1 transcript which encodes an RNAi-inhibiting siRNA exonuclease. We observe a marked up-regulation of Mi-eri-1 transcript abundance in response to exogenously introduced siRNA, and reason that this may impact on the interpretation of RNAi-based reverse genetic screens in plant parasitic nematodes.

Toxicity of Kaempferia galanga rhizome-derived extract and steam distillate to Meloidogyne incognita juveniles and eggs, and their effects on Lycopersicon esculentum germination and growth

Abstract The toxicity of Kaempferia galanga rhizome-derived methanol extract (RME), powder (RP) and steam distillate (RSD) to Meloidogyne incognita second-stage juveniles (J2) and eggs, and their effects on Lycopersicon esculentum germination and growth were examined in vitro and in pot experiments. Results were compared with those of three nematicides: carbofuran, fosthiazate and metam sodium. In contact + fumigant bioassays with J2, RME applied at 1, 0.5 and 0.25 mg (g soil)–1 resulted in 92, 88 and 73% mortality, respectively. The lethality of RME was almost the same as carbofuran but lower than that of either fosthiazate or metam sodium. RSD and RP were less active than RME. In vapour-phase mortality bioassays with J2, the test materials were more effective in a closed container than in an open one, indicating that mode of delivery was, in part, a result of vapour action. In direct-contact mortality bioassays with M. incognita eggs, RME, RSD and fosthiazate treatments resulted in 91, 100 and 95% inhibition of hatch at 250 μg ml–1 and 82, 88 and 81% inhibition of hatch at 100 μg ml–1, respectively. In filter paper bioassays with L. esculentum seed, 8.8 μg cm–2 RME and RP did not cause germination inhibition, while RSD and fosthiazate treatments resulted in 84 and 13% germination inhibition. In pot tests, RME and RSD applied at 8 mg (g soil)–1 reduced galling caused by M. incognita significantly, and fosthiazate at 0.02 mg (g soil)–1 stopped galling completely. Kaempferia galanga rhizome-derived materials, particularly a methanol extract, merit further study as potential nematicides and hatching inhibitors for the control of M. incognita as fumigants with contact action.

Characterization of Egyptian Fluorescent Rhizosphere Pseudomonad Isolates with High Nematicidal Activity against the Plant Parasitic Nematode Meloidogyne Incognita

A total of 52 Egyptian rhizosphere fluorescent pseudomonad isolates (ERFP) were screened for their nematicidal activity in vitro. The screening results showed an inhibitory effect on hatching of Meloidogyne incognita eggs ranging from 57 % to 100 %. Similar to the chemical nematicide Videt in vitro experiment, cultures or cell-free supernatants (CFS) of the ERFP isolates showed complete inhibition of egg hatching and killed 100 % of the J2. In glasshouse pot experiments, cultures of these isolates, CFS and the chemical nematicide showed reduction in root galling ranging from 81.0-95.4, 61.3-84.5, 97.3%, respectively. Also, the reduction in nematode multiplication in soil was 91.9-95.7, 83.5-84.5 and 96.5% for cultures, CFS and the chemical nematicide, respectively, compared to the positive control (nematode only). Furthermore, these isolates showed significant increases in plant growth characters, phenolic content and activities of the plant defense-related enzymes. Based on 16S rDNA sequences and API NE kits, two major clusters were observed; strains Ps 36 and Ps 54 appeared to fall within the variability range of P. putida, while Ps 21, Ps 22 and Ps 14 are likely to be strains of P. aeruginosa. The distinctness of Ps 36 and Ps 54 from Ps 14, Ps 21 and Ps 22 was supported by their physiological characteristics, such as the ability of Ps 14 and Ps 21 and Ps 22 to utilize mannitol, N-acetyl-glucose amine and adipate.

Potentiality of different isolates of wilt fungus Fusarium oxysporum collected from rhizosphere of tomato against root-knot nematode Meloidogyne incognita

This investigation was undertaken to determine the effect of culture filtrates of different isolates of Fusarium oxysporum f. sp. lycopersici on mortality of Meloidogyne incognita juveniles and egg hatching. It was observed that different concentrations including standard extract (S.E), 1:10 and 1:100 dilutions of all fungal filtrates inhibited egg hatch when compared with control. Minimum mortality and maximum hatching was observed in BRT (showing least mortality) isolate of F. oxysporum, while maximum mortality and minimum egg hatching was recorded in BGT (showing maximum mortality) isolate. Larval mortality was decreased with a decrease in concentration and the least mortality was observed in 1:100 when compared with SE and 1:10. The potentiality of both the isolates (BRT and BGT) against root-knot nematode M. incognita was confirmed by the pathogenicity test on tomato. These observations confirmed that F. oxysporumisolates possesses variability in pathogenicity ranging from pathogenic to bio-control agent. The plants inoculated with BRT isolate failed to show wilt symptoms while plants inoculated with BGT isolate showed wilt indices.

Purification and characterization of chitinases from Paecilomyces variotii DG-3 parasitizing on Meloidogyne incognita eggs

Two extracellular chitinases were purified from Paecilomyces variotii DG-3, a chitinase producer and a nematode egg-parasitic fungus, to homogeneity by DEAE Sephadex A-50 and Sephadex G-100 chromatography. The purified enzymes were a monomer with an apparent molecular mass of 32 kDa (Chi32) and 46 kDa (Chi46), respectively, and showed chitinase activity bands with 0.01% glycol chitin as a substrate after SDS-PAGE. The first 20 and 15 N-terminal amino acid sequences of Chi32 and Chi46 were determined to be Asp-Pro-Typ-Gln-Thr-Asn-Val-Val-Tyr-Thr-Gly-Gln-Asp-Phe-Val-Ser-Pro-Asp-Leu-Phe and Asp-Ala-X-X-Tyr-Arg-Ser-Val-Ala-Tyr-Phe-Val-Asn-Trp-Ala, respectively. Optimal temperature and pH of the Chi32 and Chi46 were found to be both 60 degrees C, and 2.5 and 3.0, respectively. Chi32 was almost inhibited by metal ions Ag(+) and Hg(2+) while Chi46 by Hg(2+) and Pb(2+) at a 10 mM concentration but both enzymes were enhanced by 1 mM concentration of Co(2+). On analyzing the hydrolyzates of chitin oligomers [(GlcNAc)( n ), n = 2-6)], it was considered that Chi32 degraded chitin oligomers as an exo-type chitinase while Chi46 as an endo-type chitinase.

The role of chitinase from Lecanicillium antillanum B-3 in parasitism to root-knot nematode Meloidogyne incognita eggs

B-3 fungal isolate was isolated from soil samples of Gwangju in Korea. Based on morphological and phylogenetic analysis, it was designated as Lecanicillium antillanum B-3 (syn. Verticillium antillanum B-3). The fungus was a chitinolytic-nematophagous microorganism. B-3 chitinase activity from 0.5% swollen chitin broth medium reached the highest level on the sixth day and then plateaued until 12 days. B-3 isolate showed the high rate of parasitism on Meloidogyne incognita eggs with more than 90% infection rate on the third day after treatment. B-3 crude chitinase damaged the eggshell structures more than 78% based on lactoglycerol staining data at a final protein concentration of 14.6 µg mL−1 on the fourth day following treatment. Partially purified chitinase with molecular 37 kDa from DEAE-Sephadex chromatography also showed damaging effect on the eggs. These results suggested that chitinase from B-3 isolate was responsible for degradation of M. incognita eggshell structures.

Cloning of the gene Lecanicillium psalliotae chitinase Lpchi1 and identification of its potential role in the biocontrol of root-knot nematode Meloidogyne incognita

The nematophagous fungus Lecanicillium psalliotae (syn. Verticillium psalliotae) is a well-known biocontrol agent. In this study, a chitinase gene Lpchi1 was isolated for the first time from L. psalliotae using degenerate primers and DNA-walking technique. The cloned gene Lpchi1 encoding 423 amino acid residues shares a high degree of homology with other pathogenicity-related chitinases from entomopathogenic and mycoparasitic fungi. The complementary DNA sequence of the mature chitinase was amplified via reverse transcription polymerase chain reaction and expressed well in Pichia pastoris GS115. Through gel filtration, the recombinant chitinase was purified as a protein of ca. 45 kDa with an optimal activity at pH 7.0 and 37.6 degrees C. The purified chitinase LPCHI1 was found degrading chitinous components of eggs of the root-knot nematode Meloidogyne incognita and significantly influence its development. Moreover, our results also demonstrate that the protease Ver112 and the chitinase LPCHI1 from the same fungus interacted on the egg infection.

Effect of Some Plant Extracts on the Hatch of Meloidogyne incognita Eggs

Effect of Some Plant Extracts on the Hatch of Meloidogyne incognita Eggs

Velvetbean (Mucuna pruriens) extracts: impact on Meloidogyne incognita survival and on Lycopersicon esculentum and Lactuca sativa germination and growth.

Velvetbean (Mucuna spp.) is a summer annual that has been used as a cover crop to reduce erosion, fix nitrogen and suppress weeds and plant-parasitic nematodes. Crude aqueous extracts (1:15 dry weight plant/volume water) were made from velvetbean plant parts, and various concentrations of the extracts were evaluated in vitro for toxicities to different stages of Meloidogyne incognita (Kofoid and White) Chitwood and for suppression of hypocotyl and root growth and inhibition of germination of tomato (Lycopersicon esculentum L.) and lettuce (Lactuca sativa L.). Germination was only affected by the full-strength extract from leaf blades. Lettuce root growth was the most sensitive indicator of allelopathic activity of the plant part extracts. Lettuce and tomato root growth was more sensitive to the extract from main roots than to extracts of other plant parts, with lethal concentration (LC50) values of 1.2 and 1.1% respectively. Meloidogyne incognita egg hatch was less sensitive to extracts from velvetbean than the juvenile (J2) stage. There was no difference among LC50 values of the extracts from different plant parts against the egg stage. Based on LC50 values, the extract from fine roots was the least toxic to J2 (LC50 39.9%), and the extract from vines the most toxic (LC50 7.8%). The effects of the extracts were nematicidal because LC50 values did not change when the extracts were removed and replaced with water.

Fertiliser use efficiency of soybean cultivars infected with Meloidogyne incognita and Pratylenchus penetrans

AbstractThe most appropriate use of fertilisers to offset damage caused by nematode infestations can benefit greatly from determining fertiliser use efficiency (FUE). FUE is defined as increase in host productivity and/or decrease in nematode population density in response to a given fertiliser treatment. This study describes new and integrated approaches to identify FUE in nematode-infected plants. In two consecutive experiments, Heterodera glycines-resistant 'Bryan', susceptible-tolerant 'G88-20092', and susceptible-intolerant 'Tracy M' soybean cultivars were inoculated with 0 or 15 000 eggs of Meloidogyne incognita or mixed stages of Pratylenchus penetrans per 800 cm3 of sandy loam soil and maintained under glasshouse conditions (28 ± 2°C) for 25 and 26 days. Plants received 83 ± 21 and 89 ± 19 ml either full-strength Hoagland solution (HS), HS without N (HS-N), or tap water daily in Experiments 1 and 2, respectively. Photosynthesis and nematode population dynamics were chosen to test FUE because the relationship between these two parameters, for the most part, determines the outcome of crop yield in the presence of nematodes. Although the FUE varied by fertiliser source, cultivar and nematode, the data were conclusive in identifying the interactions. FUE was high for photosynthesis in all three cultivars, and more so in HS than in HS-N. FUE was high for suppressing population densities of both nematodes and increasing photosynthesis in cv. Tracy M and for M. incognita in cv. G88-20092. Fertiliser application against P. penetrans in cv. Bryan was unproductive because nematode population density increased. FUE for P. penetrans in cv. G88-20092 and for M. incognita in cv. Bryan was less conclusive because there was some increase in nematode population density. Overall, these new approaches to identifying FUE for host productivity in the presence of nematodes provide quantitative data that should be of great interest to plant breeders, soil scientists, agronomists and plant protection specialists.