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4.  Integrated Approach to the Control of the Golden Nematode, Heterodera Rostochiensis 
Journal of Nematology  1974;6(4):185-186.
Under high population densities of Heterodera rostochiensis, control is impossible by one method alone, whether by chemical means, crop rotation, or the use of resistant potato varieties. Integrated control using thiazone (DMTT) in autumn, resistant potato hybrid 61-8/1, or Solanum andigenum cultivars 'Antinema' and 'Specula', followed by cereal and clover reduced the population below the detection level in the upper 18-cm on small plots on sandy loam soil.
PMCID: PMC2620070  PMID: 19308119
Solarium andigenum; thiazone; DMTT; rotations
5.  Biochemical Changes in Root Exudate and Xylem Sap of Tomato Plants Infected with Meloidogyne incognita 
Journal of Nematology  1974;6(4):194-202.
Under two monoxenic culture techniques of growing plants (filter paper and silica sand cultures), sugar in root exudate from Meloidogyne incognita-infected tomato increased 133 to 836% over controls. In contrast, amino acids were moderately reduced 52 to 56%. Chromatographic analysis showed that galled root exudate contained three sugars, twelve amino acids, and three organic acids, whereas healthy root exudate contained four sugars, fifteen amino acids, and four organic acids. Polysaccharide was responsible for the large increase of sugars in galled root exudates. The concn and the absolute amount of total sugars in the infected plant xylem sap were greater than in healthy plant xylem sap up to 6 wk after inoculation, whereas amino acids were moderately lower than in controls throughout the test period. Chromatographic analysis showed that xylem sap from both healthy and infected plants at 4 wk after inoculation contained four sugars and five organic acids. We identified 18 and 17 amino acids in the healthy and infected plant xylem sap, respectively. The concn of sugar increased as the nematode inoculum increased at 2, 4 and 6 wk after inoculation. The amino acids in all samples from the infected plant moderately decreased with an increase of nematode inoculum. We suggest that changes in total sugars and amino acids, of infected plant xylem sap and root exudate are a probable mechanism by which tomato plants are predisposed to Fusarium wilt.
PMCID: PMC2620069  PMID: 19308122
root-knot; Lycopersicon esculentum; disease physiology; disease complex; Fusarium wilt
8.  Seasonal Population Dynamics of Selected Plant-Parasitic Nematodes on Four Monocultured Crops 
Journal of Nematology  1974;6(4):187-190.
Seasonal fluctuations in field populations of Meloidogyne incognita, Pratylenchus zeae, P. brachyurus, Criconemoides ornatus, Trichodorus christiei, and Helicotylenchus dihystera on monocultured corn, cotton, peanut, and soybean were determined monthly for 4 yr. Population densities of M. incognita were greater in corn and cotton plots than in peanut and soybean plots from July until January. Those of Pratylenchus spp. were greater on corn and soybean than on cotton and peanut during all months except May and June. C. ornatus populations were greater on corn and peanut than on cotton and soybean during all months. C. ornatus on corn and peanut was more numerous in July than in other months. There was no significant increase in populations of T. christiei, except on corn in June. H. dihystera was greater in cotton and soybean plots than in corn and peanut plots from August through December.
PMCID: PMC2620065  PMID: 19308120
Zea mays; Arachis hypogaea; Gossypium hirsutum; Glycine max
9.  Dynamics of Concomitant Field Populations of Hoplolaimus columbus and Meloidogyne incognita 
Journal of Nematology  1974;6(4):190-194.
From the fall of 1968 through the summer of 1973, a Georgia cotton field with a lengthy history of the Cotton Stunt Disease Complex was sampled for the presence of plant parasitic nematodes. Although Meloidogyne incognita was recovered on all sampling dates, concomitant populations of Hoplolaimus columbus were not recovered until the spring of 1970. During the succeeding four growing seasons, the population density and horizontal distribution of H. columbus increased, and H. columbus replaced M. incognita as the predominant phytopathogenie species. A second Georgia cotton field containing concomitant populations of H. columbus and M. incognita was observed from the fall of 1971 through the summer of 1973. In this case the horizontal distribution of both species remained relatively constant and the population density of H. columbus increased steadily. In both locations, the presence of either H. columbus or M. incognita significantly inhibited the presence of the concomitant species. In general, however, the initial spring or final fall population densities of H. columbus or M. incognita had no significant influence on the population density of the concomitant species, The data are also discussed in relation to the biological significance of H. columbus in the southeastern coastal plain.
PMCID: PMC2620064  PMID: 19308121
cotton; soybean; Gossypium hirsutum; Glycine max; evolutionary biology
10.  Nature and Inheritance of Nematode Resistance in Cereals 
Journal of Nematology  1974;6(4):165-174.
Resistance to a number of nematodes is present in varieties of temperate and tropical cereals. The occurrence, nature, and inheritance of varietal resistance in cereals is reviewed. Evaluation of the practical significance of nematode resistance in a particular host-nematode combination is discussed in relation to host efficiency, host sensitivity, genetic control of resistance, and presence of virulence in the nematode population.
PMCID: PMC2620063  PMID: 19308117
11.  Seasonal Fluctuations in the Spatial Distribution of Nematode Populations in a California Vineyard 
Journal of Nematology  1974;6(4):203-210.
Distribution of Xiphinema americanum and four Meloidogyne spp, was studied in a vineyard over a 13-mo. period. The X. arnericanum population was concd in the upper 60-cm of undisturbed soil in the vine row, whereas the Meloidogyne species were distributed both in and between rows and to greater depths, similar to the distribution of the root system. Samples for assessment of X. americanum densities had least variation when taken in the vine row from the upper 60-cm of soil. Sampling error is reduced in Meloidogyne populations by sampling within 40 cm of the vine both within and/or between rows.
PMCID: PMC2620062  PMID: 19308123
population dynamics; sampling; Xiphinema americanum; Meloidogyne spp.; population management
12.  Discocriconemella inaratus n. sp. and Criconemoides inusitatus n. sp. (Nematoda) from Iowa 
Journal of Nematology  1974;6(4):210-214.
Discocriconemella inaratus n. sp. from Iowa prairies is characterized by a single offset disk-shaped head annule which is often discontinuous, a sigmoid vagina, a stylet length of 51-61 μm, and 77-100 smooth body annules. Criconemoides inusitatus n. sp. from Iowa woodlands is characterized by two offset head annules, a "closed" vulva, a straight vagina, no overlapping anterior vulva lip, a stylet length of 42-50 μm, and 71-86 smooth body annules.
PMCID: PMC2620061  PMID: 19308124
Criconematinae; ring nematodes; taxonomy
14.  Population Dynamics of Plant Nematodes in Cultivated Soil: Effects of Combinations of Cropping Systems and Nematicides 
Journal of Nematology  1974;6(3):103-107.
The population density of Meloidogyne incognita was significantly reduced in land that was fallowed or cropped to crotalaria, marigold, bermudagrass, or bahiagrass. The rate of population decline caused by different cropping systems was influenced by initial population densities. Crotalaria, marigold, and bare fallow were about equally effective in reducing the density of M. incognita below dctectable lcvels, usually requiring 1-3 yr. Bahiagrass and bcrmudagrass required 4-5 yr or longer to reduce M. incognita below a detectable level. A high population density of Trichodorus christiei developed in land cropped 5 yr to bermudagrass, bahiagrass, okra, and marigold. Population densities of Pratylenchus brachyurus and Xiphinema americanum increased in land cropped to crotalaria or bermudagrass. Belonolabnus Iongicaudatus was detected only in land cropped to bermudagrass, The effectiveness of nematicides in reducing M. incognita infection was rclatcd to nematode population density resulting from 5 yr of different cropping systems. Treatment with aldicarb reduced M. incognita below detectable levels following all cropping systems; treatment with ethoprop following all cropping systems except okra, treatment wflh ethylene dibromide following bahiagrass or fallow; and treatment with DBCP only after 5 yr of fallow. Tomato transplant growth was affected .by both cropping systems and nematicide treatment. Transplants grown after crotalaria and bahiagrass were significantly larger than those grown after other crops. Also, treatment with aldicarb and ethoprop significantly increased transplant size.
PMCID: PMC2620059  PMID: 19308109
crop rotation; chemical control; tomato transplants
15.  A Pest Management Approach to the Control of Pratylenchus thornei on Wheat in Mexico 
Journal of Nematology  1974;6(3):107-1165.
The lesion nematode, Pratylenchus thornei, was clearly demonstrated as a parasite of wheat. It reduced plant stands and stunted plants in the field under the environmental conditions found in Sonora, Mexico. Other soil organisms also may have contributed to the problem. The nematode is widely distributed throughout the wheat-growing region, and may be a problem each growing season. Nematicides controlled the nematode and increased yields, but they were not economical. No resistance was found in existing commercial wheat cultivars. A pest management approach using variety selection, nitrogen fertilizer, planting in cool soil (15 C) and a crop rotation avoiding wheat after wheat was the most practical solution to this problem on a commercial scale.
PMCID: PMC2620058  PMID: 19308110
lesion nematode; resistance; crop rotation; chemical control; fertilizer; temperature; nematicides
16.  Mass Culturing of Ditylenchus dipsaci to Yield Large Quantities of Inoculum 
Journal of Nematology  1974;6(3):126-129.
Methods are described for rearing large quantities of Ditylenchus dipsaci on alfalfa tissues. Nematodes and alfalfa seed were disinfected and nematodes were reared in quantities sufficient to provide a continuous supply of inoculum for our alfalfa-breeding program. Nematodes reproduced best in darkness at 20-25 C. Cultures reached maximum numbers in 3-6 wk.
PMCID: PMC2620057  PMID: 19308113
tissue culture; alfalfa; stem nematode; Medicago sativa
18.  A Description of Males of Hoplolaimus columbus 
Journal of Nematology  1974;6(3):116-118.
The male of the Columbia lance nematode, Hoplolaimus columbus, is described and illustrated from a harvested soybean field in Holly Hill, South Carolina. It is morphologically similar to the female, except for reproductive structures.
PMCID: PMC2620055  PMID: 19308111
lance nematode; males; soybean
19.  Nematode Community Structure of Forest Woodlots: III. Ordinations of Taxonomic Groups and Biomass 
Journal of Nematology  1974;6(3):118-126.
Nematode communities of 18 Indiana mixed hardwood stands were comprised of an average of 23% tylenchid species, 31% dorylaimid species, and 46% species of six other orders. Based on total numbers of individuals present the stands averaged 42% tylenchids, 20% dorylaimids, and 38% individuals of other orders. Ordination of the sites using data only for tylenchid species gave an even distribution of sites, indicating little effect of site disturbances on tylenchid populations. By contrast an ordination using data for dorylaimid species showed a high degree ofd issimilarity between reference sites indicating that disturbances at some sites had drastically affected the dorylaimid fauna. An ordination utilizing biomass of all species present was very similar to the ordination based on data for dorylaimid species only.
PMCID: PMC2620054  PMID: 19308112
Indiana hardwood stands; Tylenchida; Dorylaimida; Rhabditida; Teratocephalida; Araeolaimida; Monhysterida; Chromadorida; Enoplida
20.  Variation among Populations of Belonolaimus longicaudatus 
Journal of Nematology  1974;6(2):87-94.
Three North Carolina populations of Belonolairnus longicaudatus differed significantly from three Georgia populations in stylet measurements, the c ratio, the distance of the excretory pore from the anterior end for both sexes; the a ratio for females only; and the total body length, tail length, and spicule length for males only. The Georgia nematodes were stouter, and the females possessed sclerotized vaginal pieces. The distal portion of the spicules of North Carolina males had an indentation and hump lacking in those of the Georgia males. The haploid number of chromosomes was eight for males from all populations of B. longicaudatus and a North Carolina population of B. maritimus. Interpopulation matings of the Tarboro, N.C. and Tifton, Ga. populations indicated that the offspring produced were infertile. Morphological differences and reproductive isolation suggest that the North Carolina and the Georgia populations belong to different species.
PMCID: PMC2620052  PMID: 19319373
morphology; cytology; hybridization; Belonolairnus maritimus; populations
21.  Distribution of Selected Plant Parasitic Nematodes Relative to Vegetation and Edaphic Factors 
Journal of Nematology  1974;6(2):81-86.
The occurrence of selected plant-parasitic nematodes in the hemlock-hardwood-white pine, boreal forest, tundra, and oak-hickory associations in some northern states was compared. Helicotylenchus platyurus and Xiphinema americanum were not found in the boreal forest and tundra, and occurred infrequently in the hemlock-hardwood-white pine areas. They were found frequently, however, in the oak-hickory forest of Iowa. It is questioned that vegetational differences among the areas account directly for the major differences in nematode occurrence. Presence and absence of nematodes and their numbers in the oak-hickory association were clustered by similarity coefficients by sites and correlated with soil pH, percentage organic matter, percentage sand-silt-clay, and field capacity. Of the soil factors measured, pH gave the strongest correlations with nematode numbers. Xiphinema chambersi was found only in soils with a pH between 4.5 and 6.4 while the largest numbers of H. platyurus, H. pseudorobustus, and X. americanum occurred in soil above pH 6.0.
PMCID: PMC2620051  PMID: 19319372
forests; soil texture
22.  Suppression of Embryogenesis and Hatching in Meloidogyne javanica by Thermal Stress 
Journal of Nematology  1974;6(2):95-99.
Embryogenes is and hatching of eggs of Meloidogyne javanica were suppressed by brief heat treatment (46 C for 10 min). The period of suppression or arrested development differs according to the stage of development of the nematode when heat treatment is applied. The effect on hatching is much more pronounced than on embryogenesis.
PMCID: PMC2620050  PMID: 19319374
root-knot nematode; biology; gastrula; temperature
24.  The Effect of Soil Type on Movement and Infection Rate of Larvae of Tylenchulus semipenetrans 
Journal of Nematology  1974;6(2):60-62.
Most of the Tylenchulus semipenetrans larvae applied on the surface of four soils in pots 14.5-cm deep moved no further downward than 6.5 crn, and remained in the upper half of the pot. The percentage of second-stage larvae that developed into adult females on 'Homosassa' sweet orange in the soils were: sandy loam, 6.8% in the same soil with inoculation holes, 8.6%; loamy sand, 5.4%; coarse sand, 0.2%; and in sand-peat (2:1, v/v)mixture 0.04%. Low percentage infection in coarse sand and sand-peat mixture may have been caused by restriction of larval migration in the coarse sand, and by low pH or toxic organic acids in the sand-peat mixture. Good root development occurred throughout all soils.
PMCID: PMC2620048  PMID: 19319368
citrus nematode; soil type; infection; sweet orange seedlings
25.  Four Biotypes of Tylenchulus semipenetrans in California Identified, and Their Importance in the Development of Resistant Citrus Rootstocks 
Journal of Nematology  1974;6(2):63-66.
Four biotypes (pathotypes) of the citrus nematode, Tylenchulus semipenetrans, occurring in California, U.S.A. were differentiated on the basis of differences of infectivity on 'Homosassa' sweet orange, 'Troyer' citrange, 'Pomeroy' and 'Rubidoux' Poncirus trifoliata, 'Thompson Seedless' grape, and 'Manzanillo' olive. A method for differentiating biotypes of T. semipenetrans is described. Field observations indicate that biotypes of this nematode are very stable. The importance of using highly infective biotypes in the development and selection of satisfactory citrus-nematode-resistant rootstocks is emphasized.
PMCID: PMC2620047  PMID: 19319369
Tylenchulus semipenetrans biotypes

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