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2.  Population Dynamics of Plant Nematodes in Cultivated Soil: Effect of Sod-based Rotations in Cecil Sandy Loam 
Journal of Nematology  1969;1(4):309-312.
In a 6-year study of four nematode species in sod-based corn (Zea mays) rotations, population densities varied with different cropping systems. Continuous corn, with or without a winter rye (Secale cereale) or vetch (Vicia villosa) cover, favored an increase of Pratylenchus zeae and suppressed Trichodorus christiei, Helicotylenchus dihystera, and Xiphinema americanum. A four-year sod-based rotation (3 years sod, 1 year corn) of 'Coastal' bermudagrass (Cynodon dactylon) and fescue (Festuca arundinacea) was less favorable for P. zeae than was monocultured corn but was more favorable for T. christiei. Alfalfa (Medicago sativum) and rescue favored an increase of T. christiei but suppressed the other three species. 'Coastal' bermudagrass and 'Pensacola' bahiagrass (Paspalum notaturn) were not favorable for extensive development of any nematode species present. In longer term studies, of which these are a part, all four species survived for 10 years in relatively low numbers in bermudagrass and bahiagrass sods.
PMCID: PMC2617847  PMID: 19325691
3.  Morphology and Morphometrics of Six Species of Pratylenchus 
Journal of Nematology  1969;1(4):363-386.
Six species of Pratylenchus (P. penetrans, P. vulnus, P. coffeae, P. scribneri, P. zeae and P. brachyurus) were propagated aseptically on alfalfa callus tissue at 27 C and in greenhouse pot culture on suitable hosts. Morphological and morphometric comparisons revealed a high degree of variability of most taxonomic characters studied. The number of annules in the lip region, the number and arrangement of incisures in the lateral field, the shape of stylet knobs and tail varied considerably within most of the species. Of 20 morphometric characters, vulva percent and stylet length had the lowest coefficients of variability and were found to be of diagnostic value. A slightly greater morphometric variability was encountered in P. vulnus females and males from greenhouse than from callus cultures. A small spermatotheca containing no spermatozoa was present in the monosexual species P. scribneri, P. zeae and P. brachyurus. A few males were found only in P. brachyurus. The distal part of the uterus was composed of 12 cells arranged in three rows of four cells each (tricolumella). A detailed description of each species is given.
PMCID: PMC2617846  PMID: 19325698
4.  Oogenesis and Embryology of Two Plant-parasitic Nematodes, Pratylenchus penetrans and P. zeae 
Journal of Nematology  1969;1(4):352-356.
The process of oogenesis was studied in the bisexual species, Pratylenchus penetrans, and the monosexual species, P. zeae. The nucleus of the oocyte of P. penetrans underwent two divisions after sperm penetration. The chromosome number of P. penetrans observed at metaphase of the first maturation division was 2n = 10 and the reduced chromosome number observed at anaphase of the first maturation division was n = 5. Two polar bodies were found within the egg, indicating that this species reproduces by amphimixis. The nucleus o f the oocyte of P. zeae underwent one mitotic division and the chromosome number was 2n = 26. The presence of only 1 polar body indicates that this species reproduces by mitotic parthenogenesis. The development of the embryo was similar in P. penetrans and P. zeae. Unsegmented eggs were usually deposited by females. Following the 9-celled stage, the number of cells increased rapidly until a blastula was formed. Cell differentiation immediately followed, as evidenced by the formation of darker and larger inner endodermal cells and smaller ectodermal cells. Six to 7 days after egg deposition, the first stage larva was coiled three to f o u r times within the egg shell. During the first molt, the styler apex was formed first, then the larva moved frequently and vigorously and the styler was repeatedly thrust into the egg shell. Finally, the shell was broken and the second stage larva emerged. It took 10 days from the unsegmented egg to hatching at 23 C.
PMCID: PMC2617845  PMID: 19325696
5.  Peanut Pod Invasion by Aspergillus flavus in the Presence of Meloidogyne hapla 
Journal of Nematology  1969;1(4):318-320.
'Argentine', 'Early Runner' and 'Florigiant' peanut cultivars were grown in methyl bromide treated soil in field microplots inoculated with: (i) Aspergillus flavus or (ii) A. flavus + Meloidogyne hapla. Nematode infection produced heavy root galling and light pod galling equally on all cultivars. A. flavus, A. niger, Cephalosporium spp., Colletotrichum sp., Curvularia spp., Fusarium spp., Penicillium spp. and Trichoderma viride were isolated from shells and kernels. A significantly greater incidence and density of A. flavus was obtained from kernels of plants inoculated with both organisms than from kernels of plants receiving only the fungus. Differences were not significant, however, for incidence and density of A. flavus in shells or for the total of all fungal propagules in shells and kernels. Shells of 'Early Runner' contained significantly greater incidence and density of A. flavus than the other two cultivars; also, kernels of this cultivar contained more fungal propagules than kernels of 'Argentine.' A significantly larger number of total fungi was isolated from kernels of 'Argentine' than from 'Florigiant.' Aflatoxins were found only in two shell samples and not in kernels.
PMCID: PMC2617844  PMID: 19325693
6.  Gametogenesis and Reproduction of Seven Species of Pratylenchus 
Journal of Nematology  1969;1(4):357-362.
Three bisexual Pratylenchus species, P. penetrans, P. vulnus and P. coffeae have n = 5, 6 and 7 chromosomes, respectively, and reproduce by cross-fertilization. The monosexual P. scribneri comprises two chromosomal and reproductive forms. One has n = 6 chromosomes and reproduces by meiotic parthenogenesis, the other has a somatic chromosome number of approximately 25 and reproduces by mitotic parthenogenesis. The monosexual species P. zeae, P. brachyurus and P. neglectus have somatic chromosome numbers of approximately 21 to 26, 30 to 32, and 20, respectively, and reproduce by mitotic parthenogenesis. All mitotic parthenogenetic forms probably are polyploid. The phyletic relationships of some species are discussed briefly.
PMCID: PMC2617843  PMID: 19325697
7.  Taxonomy and Morphology of Axonchium (Nematoda: Belondiroidea), and a description of A. thornei n. sp. 
Journal of Nematology  1969;1(4):321-348.
Useful diagnostic characters in the nematode genus A xonchium include: lip shape, styler length, shape of the esophageal constriction, presence or absence of spiral musculature in the esophageal sheath, proportion of the esophageal length occupied by the esophageal expansion, length and shape of cardia, shape of the vulva and vaginal cuticularization, development of the anterior gonad, shape of the posterior uterus, subcuticle thickness at mid-body, tail shape, number and arrangement of supplements and caudal pores, and body measurements. A. thornei n. sp. is separated from A. choristum by its thinner subcuticle at mid-body, number of supplements, and shorter spicules, from A. solitare by presence of males, and from both species by the female tail shape and shorter stylet. A. saccatum is synonymized with A. gossypii and A. nitidum is synonymized with A. bulbosum. A. leptocephalum, A. Iongicollis, A. magnicollis, and A. tenuicollis are made species inquirendae. A key to 25 species of Axonchium is given.
PMCID: PMC2617842  PMID: 19325694
8.  Sexual Attraction and Mating Patterns in Cylindrocorpus longistoma and C. curzii (Nematoda: Cylindrocorporidae) 
Journal of Nematology  1969;1(4):313-317.
Females of Cylindrocorpus longistoma and C. curzii excrete attractants which probably function to bring the sexes together before mating. Intraspecific and interspecific heterosexual and homosexual pairing experiments showed the attractants to be species specific as well as sex specific. Observations on mating behavior support the hypothesis that sexual attraction and copulation require independent stimuli.
PMCID: PMC2617840  PMID: 19325692
9.  Criconemoides ornatus Parasitic on Peanuts 
Journal of Nematology  1969;1(4):349-351.
Roots, pods, and pegs of 'Argentine' and 'Starr' peanut cultivars inoculated with Criconemoides ornatus were severely discolored with brown necrotic lesions. Nematodes were attached to roots, pods, and pegs often in large numbers. Small necrotic lesions were often superficial, but necrosis in large lesions usually extended deep into the tissues. Lesions were present on roots of all ages. Many lateral root primordia, and young roots were killed resulting in reduced numbers of laterals. Pod yields from nematode infected plants were reduced about one-half.
PMCID: PMC2617839  PMID: 19325695
12.  A Comparison of Preparation Techniques in Taxonomic Studies of Longidorus africanus Merny 
Journal of Nematology  1969;1(3):193-200.
A comparison was made of ten different techniques for killing, fixing, and mounting Longidorus africanus Merny for microscopic study. The most satisfactory specimens were those killed by Seinhorst's method, fixed in FAA and mounted in glycerin by the slow method. Specimens killed by "gentle heat," fixed in FAA and mounted in glycerin were also acceptable as were those killed by hot formalin and mounted in glycerin or processed by Baker's method. Less satisfactory were: nematodes killed by "gentle heat," fixed in formalin and mounted in glycerin and specimens killed by vapor phase perfusion or by Hopper's lethal stain, both latter groups were mounted in glycerin after fixation in formalin. Killing with cold formalin, gradual heat (60 C for 15 min), or by storage in distilled water produced poorly defined specimens. Nematodes killed by hot formalin, and processed to glycerin by the slow method, maintained their live dimensions. Reduction in length occurred in specimens killed by cold formalin, by storage, or treated with solutions containing acetic or propionic acids. Nematodes processed by Baker's method increased in size. Other minor modifications occurred in specimens processed by the different methods. Esophageal definition was best in nematodes killed with formalin, hot or cold. There is no correlation between position of the posterior part of the esophagus and position of the onchiostyle.
PMCID: PMC2617836  PMID: 19325676
13.  The Histochemical Localization of Several Enzymes of Soybeans Infected with the Root-knot Nematode Meloidogyne incognita acrita 
Journal of Nematology  1969;1(3):265-276.
The sites of activity of alkaline phosphatase, acid phosphatase, esterase, peroxidase, adenosine triphosphatase, and cytochrome oxidase were demonstrated histochemically in fresh sections of 'Lee' soybeans infected by the root-knot nematode Meloidogyne incognita acrita. Each of the six enzymes was more active at the sites of infection than in adjacent non-infected tissue. During the early stages of infection, an increase in enzyme activity was observed in several cells in the proximity of the lip region of the nematode. However, when definite syncytia were observed, increased enzyme activity was confined primarily within the limits of the syncytium. Increased activity paralleled syncytial development and nematode maturation.
PMCID: PMC2617835  PMID: 19325688
14.  The Relationship of Meloidogyne incognita acrita to the Incidence of Cabbage Yellows 
Journal of Nematology  1969;1(3):219-222.
Three inoculum level combinations of Meloidogyne incognita acrita and Fusariurn oxysporurn f. conglutinans did not affect the incidence of cabbage yellows in the moderately-resistant 'Greenback' or the highly-resistant 'Marion Market' varieties. The susceptible 'Early Round Dutch' variety was more susceptible to low levels of fungus inoculum in the presence of the nematode.
PMCID: PMC2617834  PMID: 19325680
15.  The Influence of Temperature on Development and Sex Differentiation of Meloidogyne graminis 
Journal of Nematology  1969;1(3):212-215.
Meloidogyne grarninis (Sledge and Golden) Whitehead on Cynodon sp. (var. 'Tifgreen' bermudagrass) was studied at four temperatures; 16, 21, 27, and 32 C. Both mode and rate of development were temperature dependent. Females developed more rapidly and in greater numbers at 27 C: saccate females exuding matrices were present 14 days following inoculation, eggs were laid after 21 days and newly-hatched larvae were present in the matrix at 25 days. Sex differentiation to males was 80% at 32 C and 4% at 27 C. No males were observed at 21 or 16 C. Developing males were present 14 days following inoculation and emerged from roots after 21 days at 32 C. In populations pre-exposed to 27 C then transferred to 32 C, the percentage of males ranged from 0 for 1 day exposure at the initial temperature to 45.5% after 5 days. After 11 days pre-exposure the recovery of males was 4.3%. Individuals interpreted to be male sex reversals and male intersexes were noted. Pre-exposure at 32 C for 1 or 2 days followed by 27 C produced 1-2% males, while exposure for 3 or more days at 32 C followed by 27 C produced 90% males.
PMCID: PMC2617833  PMID: 19325678
16.  Saprozoic Nematodes as Carriers and Disseminators of Plant Pathogenic Bacteria 
Journal of Nematology  1969;1(3):216-218.
The plant pathogenic bacteria Agrobacterium tumefaciens (Smith and Townsend) Conn. (strain 5-14 Deep), Erwinia amylovora (Burill) Winslow et al., E. carotovora (Jones) Holland and Pseudornonas phaseolicola (Burk.) Dows. (ICPB-PM3) and the red-pigmented non-pathogen Serratia marcescens Bizio were hosts for the saprozoic nematode Pristionchus Iheritieri (Maupas, 1919) Paramonov. Viable bacteria survived passage through the nematode and produced typical colonies on nutrient agar plates. Female nematodes ingested more bacterial cells and retained them longer than did males. It was hypothesized saprozoic nematodes may disseminate pathogenic bacteria to new infection courts.
PMCID: PMC2617832  PMID: 19325679
17.  Seasonal Population Dynamics of Selected Plant-parasitic Nematodes as Measured by Three Extraction Procedures 
Journal of Nematology  1969;1(3):232-239.
Seasonal fluctuations in field populations of Meloidogyne spp. (M. incognita and M. hapla), Pratylenchus zeae, Criconemoides ornatum, Tylenchorhynchus claytoni, Belonolaimus longicaudatus, and Helicotylenchus dihystera were determined monthly for 1 year by three extraction procedures. Baermann funnel method (BF) gave highest recoveries of Meloidogyne spp. and P. zeae during summer and fall, but centrifugal-flotation (CF) and sugar-flotation-sieving (SFS) usually yielded higher numbers of these nematodes during winter and spring. CF was t h e only effective method for recovery of C. ornatum with maximum numbers occurring in September. Recoveries of T. claytoni were similar with all methods in summer and fall. However, BF gave low numbers in winter and spring, whereas population peaks with the flotation methods occurred in January and February. All methods gave similar recoveries of B. longicaudatus with highest numbers occurring in November and December. This species declined drastically in late winter and spring. Yields of H. dihystera were similar for all three methods with CF consistently higher and the major peaks occurring in August.
PMCID: PMC2617831  PMID: 19325683
18.  Effects of Storage Temperature and Extraction Procedure on Recovery of Plant-parasitic Nematodes from Field Soils 
Journal of Nematology  1969;1(3):240-247.
Storage of nematodes in soil at -15 C for 1 to 16 weeks greatly increased nematode recovery by a sugar-flotation-sieving procedure. One week of exposure to -15 C killed all nematodes except Pratylenchus zeae and Tylenchorhynchus claytoni which were recoverable in decreasing numbers up to 10 weeks by the Baermann funnel method. Optimum storage temperature for survival of most nematode species was 13 C. The numbers of Meloidogyne incognita, T. claytoni, Belonolaimus Iongicaudatus, and P. zeae recoverable by either extraction method remained constant or increased when stored at 13-24 C for 16 weeks. This was also true for Helicotylenchtts dihystera and Xiphinema americanum extracted by the Baermann funnel technique, whereas the numbers retrieved by the sugar-flotation-sieving method decreased slightly. All species except T. claytoni decreased appreciably in soil stored at 36 C.
PMCID: PMC2617830  PMID: 19325684
19.  Interrelationships between Root-nodule Bacteria, Plant-parasitic Nematodes and their Leguminous Host 
Journal of Nematology  1969;1(3):201-211.
The effect of infection by Meloidogyne javanica and Heterodera trifolii on number, size, structure and efficiency of nodules formed by Rhizobiurn trifolii on white clover roots was investigated. Introduction of nematodes one week before, simultaneously, or one week following inoculation with Rhizobium bacteria did not hinder nodule formation. Nodule size did not differ between nematode-infected and nematode-free plants. Formation of nodules on M. javanica galls and gall formation on the nodules have been reported. The structure of nodular tissues was not disturbed by nematode infection, even though giant cells were formed inside the vascular bundles. The nitrogen-fixation efficiency of nematode-infected nodules was not impaired; however, earlier disintegration of nodules as a result of M. javanica infection ultimately deprived the plants of nitrogenous materials. The drastic reduction of the total-N in H. trifolii-infected plants reflected stunting of the entire plant due to nematode infection. Both nematodes invaded the entire root system, uniformly showing preference for nodules.
PMCID: PMC2617829  PMID: 19325677
20.  Improving Seedling Growth in Longleaf Pine Plantations with Nematicidal Soil Fumigants 
Journal of Nematology  1969;1(3):248-253.
In-row, preplanting fumigation with DD and DBCP in a longleaf pine plantation was evaluated for nematode control, improved seedling survival, and early and uniform release of seedlings from the grass stage. Only DD significantly lowered the nematode population during the first growing season. DBCP not only failed to control nematodes, but was phytotoxic. Fumigation had little effect on seedling survival. Seedlings in rows fumigated with DD started height growth earlier and produced taller trees after 5 years than those in nonfumigated rows.
PMCID: PMC2617828  PMID: 19325685
21.  Pratylenchus penetrans (Cobb) Populations as Influenced by Microorganisms and Soil Amendments 
Journal of Nematology  1969;1(3):260-264.
Numbers of Pratylenchus penetrans in sterilized soil decreased significantly 2 weeks after the addition of 1% w/w (700 ppm N) nonsterile soybean meal (SBM), or sterilized SBM in combination with selected microorganisms. Sterilized SBM had no effect on nematode populations in steamed soil. Bacteria and fungi in the presence of SBM were more effective than the actinomycetes tested, causing up to 96-100% reduction in nematode populations. Simpler nitrogenous compounds included KNO₂, Ca(NO₃)₂, NH₄NO₃, (NH₄)₂CO₃, urea, and peptone, decreased nematode populations with variable effectiveness when added to steamed soil at 700 ppm N; KNO₂ was the most nematicidal.
PMCID: PMC2617827  PMID: 19325687
22.  Effect of Liquid Nutrient Culture, Vacuum Distillation and Dialysis on Hatching Activity of Sugar Beet Root Diffusate for Heterodera schachtii 
Journal of Nematology  1969;1(3):223-226.
Roots of sugar beets grown in liquid culture excrete substances that stimulate egg hatch and emergence of larvae from cysts of Heterodera schachtii. Their hatching effect is comparable to that of sugar beet root diffusate leached from soil-grown sugar beet plants. Consequently, liquid culture provides a way of obtaining H. schachtii hatch-stimulant free of contaminants from soil. Root diffusate, concentrated 50-fold or dried by vacuum distillation, retained hatching activity. The active principle of diffusate is dialyzable with a diffusion rate between those of inorganic salts and compounds with molecular weights greater than 15,000.
PMCID: PMC2617826  PMID: 19325681
23.  Praecocilenchus rhaphidophorus n. gen., n. sp. (Nematoda: Aphelenchoidea) Parasitizing Rhynchophorus bilineatus (Montrouzier) (Coleoptera: Curculionidae) in New Britain 
Journal of Nematology  1969;1(3):227-231.
Praecocilenchus rhaphidophorus n. gen., n. sp. is described as a new endoparasitic aphelenchoid nematode parasitizing adults of the palm weevil, Rhynchophorus bilineatus (Montrouzier). P. rhaphidophorus is unusual in that juveniles develop to maturity within the female uterus and thin, needle-shaped crystals form in the intestines of mature parasitic females. Hundreds of parasitic female nematodes were found in the body cavity of infected hosts. The role of this parasite as a biological control agent of Rhynchophorus weevils is discussed.
PMCID: PMC2617825  PMID: 19325682
24.  Amino Acids from Heterodera glycines 
Journal of Nematology  1969;1(3):254-259.
Amino acids emitted and extracted from surface-sterilized larvae and adults of Heterodera glycines were identified by paper chromatography and quantitatively analyzed by column chromatography. Five amino acids (alanine, aspartic acid, glutamic acid, glycine and serine) were emitted by H. glycines larvae and eight others (asparagine, glutamine, leucine/isoleucine, lysine, methionine sulfoxide, threonine, tyrosine, valine/methionine) were found in extracts from crushed larvae.
In addition to the amino acids emitted or extracted from larvae, four others were emitted by adults (γ-aminobutyric acid, histidine, phenylalanine, and proline). Four different amino acids (arginine, cystathionine, hydroxyproline, and ornithine) were found only in the extract from crushed adults. Greater quantities of alanine, aspartic acid and glycine were emitted than could be detected in nematode extracts suggesting selective emission.
Subsamples of nematode populations were taken from growing plants 19, 26, 33, and 40 days after inoculation and extracted to determine whether changes in specific amino acid content correlated with aging. Proline content shifted most, increasing from 4.1% to 21.5% of the total amino acid complement from the 19th to the 40th days.
PMCID: PMC2617824  PMID: 19325686

Results 1-25 (54)