PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (67)
 

Clipboard (0)
None
Journals
Year of Publication
Document Types
issn:0022-300
2.  Diversity Among a Heterodera glycines Field Isolate and Derived Inbreds Based on RAPD Analysis and Reproduction on Soybean Genotypes 
Journal of Nematology  1998;30(4):477-484.
A field population of Heterodera glycines was inbred by a combination of controlled male-female matings and inoculation of soybean with second-stage juveniles (J2) from single cysts. The initial and four F₆ inbred populations were subjected to random amplified polymorphic DNA analysis and were also tested for their ability to reproduce on race differentials. The RAPD patterns of the inbred populations had a lower number of total bands and a lower percentage of polymorphic bands among individual cysts than the initial population. The estimated number of polymorphic loci detected by RAPD analysis was about 25% for the initial population and 4% to 7% for the inbred lines. Reproduction of H. glycines decreased for 6 of 24 inbred-soybean combinations. In particular, reproduction of three inbred populations on PI 90763 was greatly reduced. Inbreeding did not decrease variance of cyst number on soybean genotypes. The inbreeding coefficient calculated from RAPD data was greater than that derived from the known inbreeding pedigree.
PMCID: PMC2620319  PMID: 19274241
cyst; diversity; genetics; Glycines max; Heterodera glycines; inbreeding; isolate; nematode; PCR; population; RAPD; resistance; soybean; soybean cyst
3.  Managing Soybean Resistance to Heterodera glycines 
Journal of Nematology  1998;30(4S):525-529.
Heterodera glycines is an economically important pest of soybean in the United States. The steps necessary to manage this nematode are to sample for inoculum density, identify the race present, and then select appropriate control measures. Planting resistant cultivars is the most widely used management practice, and this tactic has provided enormous economic benefits. However, the nematode has adapted to each source of resistance deployed. The time required for the nematode to adapt to resistant cultivars is lengthened by including nonhost crops and susceptible cultivars in rotations with resistant cultivars. Searching for new sources of resistance and developing more techniques to prolong the effectiveness of resistance genes are necessary to maintain profitability for soybean producers.
PMCID: PMC2620337  PMID: 19274242
Glycine max; management; nematode; race; resistance; rotation; soybean; soybean cyst nematode; yield loss
4.  Esterase Allozymes of Soybean Cyst Nematode, Heterodera glycines, from China, Japan, and the United States 
Journal of Nematology  1998;30(4):468-476.
Individual females from 19 populations of Heterodera glycines from China, Japan, and the United States were analyzed for esterase allozyme polymorphism. Eight esterase electrophoretic phenotypes were resolved. Four putative loci, est-1, est-2, est-3, and est-4, were identified, having one, one, two, and one allele, respectively. The four loci expressed six genotypes in the four Chinese populations. Loci est-2, est-3, and est-4 were identified in five Japanese populations and expressed five genotypes, whereas only loci est-2 and est-3 were identified in 10 populations from the United States and expressed four genotypes. Putative alleles at each locus were defined as characters for data analysis. Phylogenetic analysis using parsimony (PAUP) was utilized to determine relationships among the 19 populations. More loci and alleles in populations from China and phylogenetic similarities among populations from Japan and the United States are consistent with a founder effect resulting from dissemination of progenitor H. glycines from China to Japan and subsequent introductions of founder populations from Japan to the United States.
PMCID: PMC2620317  PMID: 19274240
allozyme; biogeography; colonization; esterase polymorphism; founder effect; Heterodera glycines; parsimony; phylogenetic analysis; soybean cyst nematode
5.  Schistonchus africanus n. sp. (Aphelenchida: Aphelenchoididae) Associated with Ficus thonningii (Moraceae) and its Pollinator Wasp Elisabethiella stuckenbergi (Chalcidoidea: Agaonidae) 
Journal of Nematology  1998;30(4):404-410.
Syconia ("figs") from Ficus thonningii and adults of its pollinator wasp Elisabethiella stuckenbergi were dissected to elucidate their association with a new species of Schistonchus (Aphelenchoididae). Schistonchus africanus n. sp. is characterized by a short stylet (13-16 μm long); position of the excretory pore opening in both sexes at a level just behind the stylet knobs; and short post-uterine branch, one body-width long. Schistonchus africanus n. sp. parasitizes F. thonningii florets and is transported by the winged females of E. stuckenbergi. Juveniles, females, and males of the nematode were found in the female and male fig florets and in the abdomen of the vector. Nematode populations extracted from female wasps or fig floret tissues did not differ in their morphology. No association was observed with the wingless males of the pollinator wasp.
PMCID: PMC2620320  PMID: 19274232
Agaonidae; Aphelenchoididae; Elisabethiella stuckenbergi; Ficus thonningii; fig; life history; nematode; Schistonchus africanus n. sp.; South Africa
6.  Competition Between Tylenchorhynchus annulatus and Mesocriconema xenoplax on Grain Sorghum as Influenced by Macrophomina phaseolina 
Journal of Nematology  1998;30(4):423-430.
Greenhouse experiments were conducted to examine competition between Tylenchorhynchus annulatus and Mesocriconema xenoplax on grain sorghum roots that were colonized by the fungus Macrophomina phaseolina or free from fungus colonization. An incomplete factorial treatment design consisted of two levels of M. phaseolina (0 or 10 colony-forming units/g soil) and 12 T. annulatus:M. xenoplax ratios: 1,000:0; 750:0; 500:0; 250:0; 0:0; 0:250; 0:500; 0:750; 0:1,000; 750:250; 500:500; and 250:750. Plants were harvested after 105 days. Despite similar feeding habits, competition between these ectoparasitic nematode species was limited. Tylenchorhynchus annulatus was more susceptible to antagonism by M. xenoplax than the reverse, but susceptibility depended on initial inoculum ratio. Root colonization by M. phaseolina reduced competitive effects of T. annulatus on M. xenoplax but not the reverse. Both nematode species reduced shoot dry weight but only T. annulatus reduced root dry weight. Both plant weight parameters were reduced by M. phaseolina.
PMCID: PMC2620311  PMID: 19274235
charcoal rot fungus; community ecology; competition; interaction; Macrophomina phaseolina; Mesocriconema xenoplax; nematode; ring nematode; Sorghum bicolor; stunt nematode; Tylenchorhynchus anulatus
7.  Fungi Parasitic on Juveniles and Egg Masses of Meloidogyne hapla in Organic Soils from New York 
Journal of Nematology  1998;30(4S):632-638.
Fungi associated with egg masses and juveniles of Meloidogyne hapla were isolated from organic soil samples obtained from five fields planted to lettuce or onion in NewYork. The soil samples were placed in sterilized clay pots, infested with M. hapla, and planted to lettuce. After 4 months, egg masses and juveniles were surface-disinfested, plated on water agar, and examined for fungal infection. Depending on the soil sample, fungal isolates were recovered from 13% to 30%, and from 5% to 24% of the egg masses and juveniles, respectively. A total of 24 and 16 isolates collected from egg masses and juveniles, respectively, were selected for further characterization. Fifteen of the isolates were considered as egg-mass pathogens as they were able to infect healthy assay egg masses and could be succesfully reisolated. These fungi included species of Fusarium, Alternatia, and Verticillium psalliotae. Six of the egg-mass-parasitizing fungi could not be identified. Nine fungal isolates were found to be pathogenic to juveniles of M. hapla; six were identified as Monacrosporium sp., two as Arthrobotrys sp., and one as Hirsutella rhossiliensis. The remaining 16 fungal isolates were unable to infect egg masses or juveniles, and thus were considered nonparasitic to M. hapla.
PMCID: PMC2620331  PMID: 19274258
Alternaria; antagonist; Arthrobotrys; biological control; Fusarium; Hirsutella; Meloidogyne hapla; Monacrosporium; nematode; nematophagous fungus; northern root-knot nematode; Verticillium
8.  Possible Transfer of Resistance to Heterodera glycines from Glycine tomentella to Glycine max 
Journal of Nematology  1998;30(4S):547-552.
Eight wild perennial Glycine species (G. argyrea, G. canescens, G. curvata, G. cyrtoloba, G. latifolia, G. microphylla, G. tabacina, and G. tomentella) were evaluated for resistance to isolates of races 1, 3, and 14 of Heterodera glycines. In a second experiment, reproduction of isolates of races 3, 5, and 14 of H. glycines on five of the wild perennial species was determined. Seventy-one derived fertile lines (2n = 40) that were hybrids between G. max cv Clark 63 and G. tomentella also were evaluated for resistance to isolates of races 3, 5, and 14. All of the wild perennial Glycine species were resistant (Female Indices [FI] less than 10) to all of the isolates that were tested on them. In most cases no females matured. The soybean cvs. Clark 63 and Altona, which were tested at the same time as the hybrids, were susceptible to all isolates of H. glycines tested. When the tests were combined and a single FI calculated with the average number of females on Lee 74, one derived fertile line was resistant to race 3, three derived fertile lines were resistant to race 5, and five derived fertile lines were resistant to race 14. Thus, transfer of resistance to H. glycines from G. tomentella to G. max apparently occurred.
PMCID: PMC2620338  PMID: 19274245
Glycine species; Heterodera glycines; interspecific hybrids; nematode; resistance; soybean; soybean cyst nematode
9.  Foliar Sprays with Steinernema carpocapsae against Early-season Apple Pests 
Journal of Nematology  1998;30(4S):599-606.
Persistence and field efficacy of the entomopathogenic nematode Steinernema carpocapsae A11 strain applied by foliar sprays were evaluated against the apple sawfly Hoplocampa testudinea and the plum curculio Conotrachelus nenuphar, two early-season pests in Quebec apple orchards. From 1992 to 1995, bioassays with Galleria mellonella larvae were conducted to assess the persistence of S. carpocapsae on leaves, flower clusters, and twigs up to 4 days after evening application. S. carpocapsae juveniles remained infective on apple leaves 24, 42, 98, and 24 hours after application in 1992, 1993, 1994, and 1995, respectively. In bioassays, the percentage of G. mellonella mortality was consistently higher on leaves (average = 84%), intermediate on flower clusters (73%), and lower on twigs (43%) for all application dates. In 1992 and 1993, single nematode sprays applied every 2 to 3 days from early May to mid-June on apple tree limbs reduced primary damage caused by H. testudinea by 98% and 100%, respectively, but none of the treatments was effective in 1994. In 1993 and 1994, multiple border-row sprays were applied against C. nenuphar adults with a commercial hand-gun applicator in an insecticide-free orchard. At harvest, plum curculio damage in the nematode-treated orchard reached 5% and 55% in 1993 and 1994, respectively, as compared to 80% and 85% in an adjacent insecticide-free orchard. In a second experiment performed in 1994, multiple broadcast sprays with a commercial orchard sprayer caused no significant effect on plum curculio damage (nematode = 28%; control = 31%). Although some efficacy of canopy sprays of nematodes was detected against early-season apple pests, the inconsistent results and high application costs preclude their use as a sole control tactic against these pests in commercial apple orchards.
PMCID: PMC2620325  PMID: 19274253
apple; biological control; Coleoptera; Conotrachelus nenuphar; Curculionidae; European apple sawfly; field persistence; foliar application; Hoplocampa testudinea; Hymenoptera; nematode; plum curculio; Steinernema carpocapsae; Tenthredinidae
10.  Colonization of Soybean Cyst Nematode Females, Cysts, and Gelatinous Matrices by the Fungus Verticillium lecanii 
Journal of Nematology  1998;30(4):436-450.
Heterodera glycines was grown in monoxenic culture on soybean roots and then inoculated with the antagonistic fungus Verticillium lecanii. Use of root explant cultures allowed evaluation of the fungus-nematode interaction with the nematode attached to roots or removed from the host, and avoided contamination with other fungi. From 16 hours to 14 days following inoculation, female and cyst samples were examined with the light microscope, or prepared for either conventional or low-temperature scanning electron microscopy. Within 16 hours, hyphae had begun colonizing the gelatinous matrices (GM). The fungus proliferated in the GM of some specimens within a week, but was rarely seen in unhatched eggs. Fungus penetration holes in female and cyst walls were observed 3 days after inoculation; penetration through nematode orifices was not seen at that time. More cysts than females were colonized at the earliest sampling dates. Specimens associated with external hyphae exhibited variable internal colonization, ranging from no fungal penetration to extensive mycelial growth.
PMCID: PMC2620316  PMID: 19274237
biocontrol; colonization; fungus; Heterodera glycines; light microscopy; nematode; scanning electron microscopy; soybean; Verticillium lecanii
11.  Soil Infestation Density Affects the Results of Heterodera glycines Race Tests 
Journal of Nematology  1998;30(4S):553-562.
Production of females by stock populations of races 1, 2, 3, 4, 5, 6, 9, and 14 of Heterodera glycines on 'Lee 74', 'Pickett', 'Peking,' PI 88788, and PI 90763 soybean cultivars and lines at inoculum densities of 100, 1,000, 4,000, 5,000, and 10,000 eggs and second-stage juveniles/pot (2.2, 21.8, 87.1, 108.9, and 217.9/cm³ soil) was tested to determine the effects of soil population density on race identification using the 16-race scheme. Tests of all races were repeated 1 to 3 times during the year, except for the race 9 test, which was conducted once. Only races 3 and 9 had the same race designation at all infestation densities in repeated tests. Races 2 and 4 consistently were identified at all except the lowest infestation densities. Race 5 was identified as race 15 at the 100 infestation density in one test, and as race 1 at the 1,000 density in another test. Race 6 had significant numbers of females on Peking and P190763 that resulted in female indices of 34 on Peking and 14 on P190763 when the infestation density was 10,000. Race 14 was consistently identified between infestation densities of 4,000 and 10,000 but was identified as race 6 or 9 at the 100 infestation density and as race 4 or 14 at the 1,000 infestation density. Race 1 was identified as race 5 in a few instances because Pickett was not resistant to this population. The results of this series of experiments suggest that an infestation density of 4,000 eggs and second-stage juveniles/pot is best for race identification. Races were very poorly differentiated at the lowest density, differentiation was inconsistent at the 1,000 infestation density, and densities higher than 4,000 had reduced numbers of females on Lee 74 and relatively high numbers on the differentials which resulted in poor race differentiation with some races.
PMCID: PMC2620333  PMID: 19274246
Glycine max; Heterodera glycines; races; soybean; soybean cyst nematode
12.  Effect of Castor and Velvetbean Organic Amendments on Meloidogyne arenaria in Greenhouse Experiments 
Journal of Nematology  1998;30(4S):624-631.
Effectiveness of castor (Ricinus communis) and velvetbean (Mucuna deeringiana) amendments was tested for suppression of the root-knot nematode (Meloidogyne arenaria) and growth of okra (Hibiscus esculentus) in three greenhouse experiments. Regression analysis was used to relate nematode population data or plant growth responses to various rates (0, 1, 2, 4, or 8 g/560 cm³ soil pot) of each amendment in separate experiments. In general, plant growth parameters responded positively to the amendment rate until a level of about 4 g to 5 g of velvetbean or castor amendment/pot. Similar trends were observed for nematode galls, egg masses, and second-stage juveniles extracted from root systems. In most circumstances, quadratic equations best expressed the relationships between plant or nematode parameters and rates of velvetbean or castor amendment, leading to the assumption that a best rate of the amendment for plant growth or nematode suppression can be predicted. In a third experiment, in which both amendments were compared directly, velvetbean amendment was more efficient than castor in suppressing nematodes as well as in improving plant growth.
PMCID: PMC2620327  PMID: 19274257
Hibiscus esculentus; Meloidogyne arenaria; Mucuna deeringiana; nematode; nematode management; okra; Ricinus communis; root-knot nematode
13.  Strawberry Cultivars Vary in their Resistance to Northern Lesion Nematode 
Journal of Nematology  1998;30(4S):577-580.
The genetic diversity of commercial cultivars of strawberry Fragaria x ananassa from various parentages, as expressed by their resistance to the northem lesion nematode Pratylenchus penetrans, was evaluated in nematode-infested field plots for two growing seasons. Data taken for each plant in each season included soil nematode Pi and Pf, end-of-season nematode numbers in each entire root system, and end-of-season fresh and dry top weight and whole root system weight. Resistance was estimated using an index of the nematode load on the plant: Nematode load = {n(root) + (200 × n[soil])}/{root dry weight} where n (root) = number of nematodes in the root, n [soil] = number of nematodes in 50 g of nonfumigated soil, and 200 is a multiplier to convert the soil nematode count to a 10-kg basis. Nineteen strawberry cultivars varied in their resistance to the northern lesion nematode, from a mean load of 382 nematodes/plant for Pajaro to 1,818 nematodes/plant for Veestar. This variability could be related to the original family groupings, with the most resistant cultivars related to Lassen and the least resistant to Sparkle x Valentine.
PMCID: PMC2620340  PMID: 19274249
Fragaria x ananassa; nematode; nematode load; northern lesion nematode; Pratylenchus penetrans; resistance; strawberry; tolerance
14.  Host Status of Herbaceous Perennials to Meloidogyne incognita and M. arenaria 
Journal of Nematology  1998;30(4S):607-610.
Twenty-two different herbaceous perennials were studied for their reaction to separate inoculations of Meloidogyne arenaria and M. incognita under greenhouse conditions. Perennial taxa that did not develop root-galls following inoculation, and therefore are considered as nonhosts of both nematode species, included species and cultivars of Aethionema, Fragaria, Phlox, and Polygonum. Echinacea, Monarda, and Patrinia developed only a few galls. Root-galls developed on species and cultivars of Achillea, Geranium, Heuchera, Heucherella, Linaria, Nepeta, Nierembergia, Penstemon, and Salvia. There was no difference in the number of root-galls caused by M. arenaria or M. incognita on most plants except for Penstemon cultivars. Plant heights and dry weights varied between species and nematode density.
PMCID: PMC2620339  PMID: 19274254
Meloidogyne arenaria; Meloidogyne incognita; nematode; ornamentals; resistance; susceptibility
15.  Survey of Heterodera glycines Races and Other Plant-parasitic Nematodes on Soybean in North Carolina 
Journal of Nematology  1998;30(4S):569-576.
A survey of soybean-production areas in the Piedmont, Coastal Plain and Tidewater regions of North Carolina was conducted from 1994 to 1996. Heterodera glycines was detected in 55 of 77 fields sampled in 15 counties. The host race of H. glycines was determined for 39 of the populations collected. Of all populations collected, 4% were race 1, 40% race 2, 16% race 4, 7% race 5, and 4% race 9; the remaining 29% could not be accurately categorized. None of the populations evaluated had high levels of reproduction on the resistant cultivar Hartwig. The southern root-knot nematode Meloidogyne incognita was detected in 26% of the fields. Helicotylenchus spp. were detected in all fields sampled, Tylenchorhynchus spp. were found in 62%, Paratrichodorus spp. in 56%, and Pratylenchus spp. in 72% of fields sampled. Mesocriconema spp., Xiphinema spp., and Hoplolaimus spp. were detected in less than 20% of the fields sampled.
PMCID: PMC2620330  PMID: 19274248
Distribution; Glycine max; Helicotylenchus; Heterodera glycines; Hoplolaimus columbus; Hoplolaimus galeatus; host race; Meloidogyne incognita; Mesocriconema; nematode; Paratrichodorus; populations; Pratylenchus; race; soybean; soybean cyst nematode; survey; Tylenchorhynchus; Xiphinema
16.  Pathogenicity Tests on Nine Mosquito Species and Several Non-target Organisms with Strelkovimermis spiculatus (Nemata Mermithidae) 
Journal of Nematology  1998;30(4):411-414.
Nine species of mosquitoes and several species of non-target aquatic organisms were tested for susceptibility to the mernaithid nematode, Strelkovimermis spiculatus. All species of Anopheles, Aedes, Culex, and Toxorhynchites exposed to S. spiculatus were susceptible. Of the nine mosquito species tested, C. pipiens quinquefasciatus had the greatest tolerance to initial invasion and the highest percent infection of those that survived. High levels of infection were also achieved with Aedes taeniorhynchus and A. albopictus, but these mosquitoes were significantly less tolerant to parasitism than C. pipiens quinquefasciatus. Strelkovimermis spiculatus did not infect or develop in any of the non-target hosts tested.
PMCID: PMC2620315  PMID: 19274233
Aedes aegypti; Aedes albopictus; Aedes taeniorhynchus; Aedes triseriatus; Anopheles albimanus; Anopheles quadrimaculatus; biological control; Chironomus sp.; Copepoda; Corethrella brakeleyi; Corixidae; Culicidae; Culex pipiens quinquefasciatus; Culex restuans; Diptera; Dytiscidae; entomopathogenic nematodes; Ephydridae; host range; Mermithidae; mosquito; nematode; Odonata; non-target organisms; safety testing; Strelkovimermis spiculatus; Toxorhynchites rutilus septentrionalis
17.  Interaction Between Meloidogyne incognita and Thielaviopsis basicola on Cotton (Gossypium hirsutum) 
Journal of Nematology  1998;30(4):415-422.
The effects of Meloidogyne incognita and Thielaviopsis basicola on the growth of cotton (Gossypium hirsutum) and the effects of T. basicola on M. incognita populations were evaluated in a 2-year study. Microplots were infested with M. incognita, T. basicola, or a combination of M. incognita and T. basicola. Uninfested plots served as controls both years. Seedling survival was decreased by the M. incognita + T. basicola treatment compared to the control. Meloidogyne incognita alone and M. incognita + T. basicola reduced plant height-to-node ratio for seedlings in both years. Seed cotton yield was reduced, and the length of time required for boll maturation was lengthened by M. incognita + T. basicola in 1994 and M. incognita both alone and with T. basicola in 1995. Position of the first sympodial node on the main stem was increased by M. incognita in both years and was higher for plants treated with M. incognita + T. basicola in 1995 in comparison to the control. The number of sympodial branches with bolls in the first and second fruiting position and the percentage of bolls retained in the second position were reduced both years by M. incognita + T. basicola compared to either the control or T. basicola alone. Orthogonal contrasts indicated that effects on height-to-node ratio, number of days to first cracked boll, and yield were significantly different for combined pathogen inoculations than with either pathogen alone. Meloidogyne incognita eggs at harvest were reduced by T. basicola in 1994 and 1995 compared to M. incognita alone. The study demonstrated a significant interaction between M. incognita and T. basicola on cotton that impacted the survival and development of cotton and the reproduction of M. incognita on cotton.
PMCID: PMC2620314  PMID: 19274234
black root rot; Chalara elegans; cotton; Gossypium hirsutum; interaction; Meloidogyne incognita; nematode; root-knot; Thielaviopsis basicola
18.  Horizontal and Vertical Distribution of Longidorus africanus in a Bermudagrass Field in the Imperial Valley, California 
Journal of Nematology  1998;30(4S):592-598.
The horizontal and vertical distribution of the needle nematode Longidorus africanus was studied in a bermudagrass field in the Imperial Valley in southern California. A geostatistical method involving the use of semi-variograms was used to quantify the relationship between sampling distance and variation in L. africanus population levels. Semi-variance between nematode numbers from different samples was very low when samples were taken close together, increased with sampling distances up to ca. 15 m, and fluctuated around a sill value at distances greater than 15 m. At very large sampling distances the semi-variance increased further. It was concluded that patches with fairly similar numbers of L. africanus were elongated and up to 15 m long. Seasonal fluctuations over a 2-year period, in total numbers of L. africanus extracted from three depths, were large and highly correlated with soil temperature. Population densities were greatest during the summer months and lowest during the winter. Averaged over the 2-year period, L. africanus population densities increased with increasing depth. Chances for detecting this nematode are greatest in summer at depths of 60 to 90 cm.
PMCID: PMC2620335  PMID: 19274252
distribution; geostatistics; horizontal distribution; Longidorus africanus; nematode; sampling; temperature; vertical distribution
19.  Velvetbean and Bahiagrass as Rotation Crops for Management of Meloidogyne spp. and Heterodera glycines in Soybean 
Journal of Nematology  1998;30(4S):563-568.
Soybean (Glycine max) yield often is limited by the phytoparasitic nematodes Meloidogyne spp. and Heterodera glycines in the southeastern United States. We studied the effects of rotation with bahiagrass (Paspalum notatum), velvetbean (Mucuna pruiens), or continuous soybean, aldicarb, and soybean cultivar on yield and population densities in two fields infested with a mixture of Meloidogyne spp. and H. glycines. Velvetbean and bahiagrass reduced population levels of both nematode species to near zero prior to planting soybean. At harvest, both nematode populations were equal in soybean following bahiagrass and continuous soybean but were lower following velvetbean. Both bahiagrass and velvetbean as previous crops were equal in producing significantly (P < 0.003) higher yield than continuous soybean. Velvetbean increased subsequent soybean yield by 98% and bahiagrass increased subsequent soybean yield by 85% as previous crops compared to continuous soybean. The major differences between the two rotation crops were yield response of the nematode-susceptible cultivars and at-harvest nematode populations. Velvetbean tended to mask genetic differences among cultivars more so than bahiagrass. Velvetbean also produced a more long-term effect on nematode populations, with numbers of both Meloidogyne spp. and H. glycines lower in soybean following velvethean than following bahiagrass or continuous soybean.
PMCID: PMC2620328  PMID: 19274247
aldicarb; bahiagrass; biodiversity; crop rotation; Glycine max; Heterodera glycines; host-plant resistance; Meloidogyne; Mucuna pruiens; nematode; Paspalum notatum; root-knot nematode; soybean; soybean cyst nematode; velvetbean
20.  An Alternative Field Method for Screening Soybean Genotypes for Resistance to Heterodera glycines 
Journal of Nematology  1998;30(4S):542-546.
The soybean cyst nematode (Heterodera glycines) has become an increasingly severe problem in soybean production areas in Brazil. The development and use of resistant cultivars is the most efficient method of minimizing losses due to this pathogen. Our objective was to test the efficiency of an alternative method for screening soybean genotypes for resistance to H. glycines in field plots. The alternative method was compared to the standard method of sowing the test genotypes in fields found to be infested during the previous crop season. In the alternative method, the test genotypes are sown in the furrow following the uprooting of 45-day-old infected plants. The alternative method resulted in twice the cyst population and fewer escapes, and more consistent results than the standard method. The major advantage of the alternative method is that it permits screening in a more homogeneous distribution of H. glycines in the soil.
PMCID: PMC2620322  PMID: 19274244
Heterodera glycines; resistance; screening; soybean; soybean cyst nematode
21.  Management of Plant-parasitic Nematodes on Peanut with Selected Nematicides in North Carolina 
Journal of Nematology  1998;30(4S):643.
Field experiments were conducted to determine peanut growth and yield responses to selected fumigant and nonfumigant nemaficide treatments in 1988 and 1989. All treatments with the fumigant 1, 3-D significantly suppressed nematode reproduction (Meloidogyne arenaria, M. hapla, and Mesocriconema ornatum) and enhanced peanut yields over the other treatments in four tests in 1988. Yield increases with the fumigant ranged from about 20% to 100% over the untreated control. Test sites in 1989 had lower nematode levels than those for 1988, and fewer positive plant and nematode responses were detected. Treatments with 1,3-D improved peanut quality but not yield in one experiment with low levels of M. hapla and M. ornatum in 1988. The 1,3-D + chloropicrin treatments at another site gave higher peanut yields than 1,3-D alone.
PMCID: PMC2620329  PMID: 19274260
Arachis hypogaea; chemical control; management; Meloidogyne arenaria; Meloidogyne hapla; Mesocriconeraa ornatum; nematicides; nematode; peanut
22.  Problems Associated with Crop Rotation for Management of Pratylenchus penetrans on Easter Lily 
Journal of Nematology  1998;30(4S):581-589.
In Humboldt and Del Norte counties of California and Curry County, Oregon, Easter lilies (Lilium longiflotum) are grown commercially in a 3- to 6-year rotation with pasture for cattle and sheep. Bulbs are sold to greenhouse operations to produce flowering plants. The lesion nematode, Pratylenchus penetrans, is a serious detriment to Easter lily production. Both soil and planting stock are often infested; typically, a dual nematicide application is used consisting of a preplant soil fumigation followed by an at-planting application of an organophosphate or carbamate. Nematicide usage has resulted in ground-water contamination. Several factors that could lead to an improved crop rotation program were examined in five field trials in Oregon. Examining the relative nematode host status of crops for feeding cattle and sheep indicated differences in host suitability among clovers and fescues that could prove useful in development of pasture mixes. Populations of P. penetrans under continuous fallow and pasture were monitored for 4 years following harvest of Easter lilies. Populations fluctuated in both situations but generally increased on pasture plants and decreased under fallow. Nematodes were still detectable at the end of 4 years of weed-free fallow. Populations of P. penetrans on Easter lilies were followed over two successive crops. Numbers in soil peaked in July and then decreased while numbers within roots continued to increase until harvest in October.
PMCID: PMC2620334  PMID: 19274250
crop rotation; Easter lily; lesion nematode; Lilium longiflorum; nematode; Pratylenchus penetrans
23.  The Lance Nematode, Hoplolaimus magnistylus, on Cotton in Arkansas 
Journal of Nematology  1998;30(4S):590-591.
The population density of Hoplolaimus magnistylus, a lance nematode, in cotton was determined at planting, mid-season, and harvest during the 1995 and 1996 growing seasons for a Poinsett County, Arkansas field. Nematode populations increased from planting to harvest in 1995 but declined in 1996. Application of aldicarb at planting at rates of 0.59 or 0.84 kg a.i./ha did not influence either nematode population density or cotton yield. This study indicates that H. magnistylus is not a serious pest of irrigated cotton in Arkansas.
PMCID: PMC2620326  PMID: 19274251
aldicarb; control; cotton; Gossypium hirsutum; Hoplolaimus magnistylus; nematode; pathogenicity
24.  Ultrastructure of Spermatozoa in the Nematode Halalaimus dimorphus (Nemata: Oxystominidae) 
Journal of Nematology  1998;30(4):391-403.
The ultrastructure of spermatozoa in the free-living marine nematode Halalaimus dimorphus was studied with transmission electron microscopy. Spermatozoa in the posterior testis of the male had a large cavity filled with cellular processes, which contained a variable number of small tubules. Mitochondria and small tubules were the only cell structures observed in the cytoplasm. The spermatozoa had a bipolar structure. The anteriorly situated nucleus, which was electron-dense and homogeneous, was surrounded by a single membrane. The size of the small tubules in the cytoplasm (diam. 12-13 nm) and their relatively thick wall structure suggested that they were not normal microtubules (diam. 25 nm). The material of the small tubules was assumed to be major sperm protein (MSP). The cavity appeared to open on the surface of the spermatozoon at the posterior extremity of the cell, and also medially, at the level of the anterior end of the cavity. The pores apparently were closed by a special plug-like structure, which was an evagination of the cell. The wall of the cavity was characterized by longitudinal folds, which were mushroom-shaped in transverse section. Spermatids in the anterior testis of H. dimorphuswere characterized by fibrous bodies packed with small tubules and by cellular processes also containing small tubules. H. dimorphus sperm seem to perform swimming movements based on liquid currents commonly present in turbin-like systems. Spermatogenesis resembled that found in ticks.
PMCID: PMC2620318  PMID: 19274231
Halalaimus dimorphus; marine nematode; nematode; reproduction; sperm; spermatogenesis; tick; ultrastructure
25.  Resistance to Root-knot, Reniform, and Soybean Cyst Nematodes in Selected Soybean Breeding Lines 
Journal of Nematology  1998;30(4S):530-541.
Soybean breeding lines and reported sources of nematode resistance were evaluated in repeated greenhouse tests for resistance to North Carolina populations of the soybean cyst nematode Heterodera glycines, reniform nematode Rotylenchulus reniformis, and the root-knot nematode species Meloidogyne incognita, M. arenaria, and M. arenaria. Lines from the soybean breeding program in Missouri that had 'Hartwig' soybean as a parent were the most resistant to races 1-4 of the soybean cyst nematode and the population of reniform nematode evaluated here. Numerous cysts of an inbred soybean cyst nematode race 4 population were produced on several of these Hartwig descendants, however, and accession $92-1603 had a cyst index of 29.2%. These accessions were also susceptible to M. arenaria and M. arenaria. Soybean lines N87-539 and N91-245 from the breeding program in North Carolina had strong resistance to an inbred soybean cyst nematode race 1 population and to M. arenaria, respectively. Soybean germplasm from the Georgia breeding program demonstrated the strongest resistance to the root-knot nematode species tested. Lines from the Georgia program, including G80-1515, G83-559, G93-9106, and G93-9223, that incorporated both root-knot and soybean cyst nematode resistance had the best overall resistance to the nematode populations evaluated. Resistance reported in the soybean lines was generally upheld. In a few cases, differences in the origin and culture of the nematode populations used in this study may have led to discrepancies between reported and observed resistance.
PMCID: PMC2620336  PMID: 19274243
Glycine max; Heterodera glycines; Meloidogyne arenaria; Meloidogyne incognita; Meloidogyne javanica; nematode; reniform nematode; resistance; root-knot nematode; Rotylenchulus reniformis; soybean cyst nematode

Results 1-25 (67)