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effect on meloidogyne hapla of excised tomato roots treated with alpha-methoxyphenylacetic acid. 195617736439
nematode-trapping fungi: evaluation of axenic healthy and galled roots as trap inducers.larvae of meloidogyne hapla chit. induced abundant trap formation in the predaceous fungus arthrobotrys conoides drechs. under similar aseptic conditions, neither healthy roots of lycopersicon esculentum mill, nor roots parasitized by the root-knot nematode induced traps.196414190248
plant parasitic nematodes: a new mechanism for injury of hosts.pathological effects of ditylenchus dipsaci and meloidogyne hapla are related to the disturbance of the auxin balance in the host by the nematode. the parasites produce an auxin inactivator, apparently enzymatic, that enables ditylenchus dipsaci to stunt host stem apices and meloidogyne hapla to reduce its galling potential.196517790829
polyploidy and reproductive patterns in the root-knot nematode meloidogyne hapla. 19665927453
peanut pod invasion by aspergillus flavus in the presence of meloidogyne hapla.'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 incid ...196919325693
attraction of ditylenchus dipsaci and meloidogyne hapla by resistant and susceptible alfalfa seedlings.ditylenchus dipsaci kühn were equally attracted to and equally invaded resistant ('lahontan') and susceptible ('ranger') germinating alfalfa (medicago sativa l.) seedlings exposed singly in moist sand except at a distance of 12.5 mm at 20 c when the susceptibles proved more attractive than the resistants. larvae hatching from egg-masses of meloidogyne hapla chitwood were also attracted equally to germinating seedlings of resistant ('m-9') and susceptible ('lahontan') alfalfa offered singly. when ...197119322372
occurrence, parasitism, and pathogenicity of nematodes associated with sycamore (platanus occidentalis l.).ten species of stylet-bearing nematodes were recovered in a survey of sycamore (platanus occidentalis l. ) stands in georgia. helicotylenchus, xiphinema, and criconemoides were the genera found most frequently. populations of hoplolaimus galeatus, scutellonema brachyurum, helicotylenchus dihystera and h. pseudorobustus increased on greenhouse-grown sycamore, but trichodorus christiei, xiphinema americanum, meloidogyne hapla, m. arenaria and m. incognita did not. hoplolaimus galeatus and s. brach ...197119322367
effects of temperature and inoculation timing on the meloidogyne hapla/corynebacterium insidiosum complex in alfalfa. 197219319247
relative dna content and chromosomal relationships of some meloidogyne, heterodera, and meloidodera spp. (nematoda: heteroderidae).the relative dna content of hypodermal nuclei of preparasitic, 2nd-stage larvae was determined cytophotometrically in 19 populations belonging to 13 species of meloidogyne, heterodera and meloidodera. in meloidogyne hapla, m. arenaria, m. incognita and m. javanica, total dna content per nucleus is proportional to their chromosome number, indicating that chromosomal forms with high chromosome numbers are truly polyploid. m. graminicola, m. grarninis and m. ottersoni have a dna content per chromos ...197219319282
the effects of selected antimetabolites and antibiotics on reproduction, embryonic development and hatch of meloidogyne hapla.meloidogyne hapla egg-laying was unaffected by a 3-day immersion in 40 ppm concentrations of 6-azauracil, 5-bromodeoxyuridine, or streptomycin sulfate in physiological saline. comparable exposure to 1-20 ppm cycloheximide irreversibly inhibited egg-laying, but with exposures of 1, 3, or 9 hr, the effect was partly reversible. of the few eggs laid after the nematodes were transferred to physiological saline, many were abnormally developed. most of the unlaid eggs extracted from the uteri of cyclo ...197219319271
effect of plant age on resistance of alfalfa to meloidogyne hapla.meloidogyne hapla-resistant plants grown from cuttings and inoculated with m. hapla larvae were free of galls. however, 35 to 48% of the seedling intercross progeny of resistant genotypes that were inoculated in the germinated seed stage were galled. there was an inverse relationship between the age of plants grown from seed and the percentage of plants galled by m. hapla; the older the plants at inoculation, the greater the percentage of gall-free plants. the per cent of galled plants was signi ...197219319252
interaction of meloidogyne hapla and m. javanica infecting tomato.a soil temperature of 20 c was equally suitable for the invasion and development of m. hapla and m. javanica. however, m. javanica predominated in a mixed species infection at this temperature. predominance increased with increasing mixed-species inoculum levels. invasion by m. hapla was more density-dependent than m. javanica. m. hapla produced a greater incidence of terminal galls and lateral roots.197219319239
resistance to meloidogyne hapla in peanut.two hundred thirty-five cultivated varieties, breeding lines and plant introductions of arachis hypogaea and 12 accessions of wild arachis spp. were tested for resistance to meloidogyne hapla. eight of the cultivated peanut lines were only moderately susceptible and four of the wild peanuts exhibited resistance. no resistance-breaking m. hapla populations were found among 10 geographical isolates tested.197319319351
effect of temperature on growth, development and reproduction of meloidogyne hapla in lettuce.temperature was an important factor in growth, development and reproduction of meloidogyne hapla in lettuce. growth, as measured by increase in diameter of females, was not appreciably different at the intermediate (21.1 c night and 26.7 c day) and high (26.7 c night and 32.2 c day) temperature regimes, but was considerably less at the low temperature regime (15.5 c night and 21.1 c day) than at the two higher temperature regimes. second-stage female larvae developed into adults 14 days after in ...197319319319
meloidogyne hapla in organic soil: effects of environment on hatch, movement and root invasion.using new techniques, hatch and movement of meloidogyne hapla and nematode invasion o f lettuce roots growing in organic soil were studied under controlled soil conditions of temperature, moisture, o and co. when o levels of 2.7, 5, 10, 21 and 40% with co maintained at 0.03% were used, o below 21% or at 40% reduced nematode activities compared with those at 21%. when co levels of 0.03, 0.33, 2.8, 10 and 30% with o maintained at 21% were used, all levels above 0.03% co resulted in less activity t ...197319319318
pathogenicity of meloidogyne hapla to lettuce as affected by inoculum level, plant age at inoculation and temperature.pathogenicity of meloidogyne hapla to lettuce was influenced by inoculum level, age of plant at inoculation and temperature. top weight of 'minetto' lettuce was reduced 32% when 2-week-old lettuce plants were each inoculated with five egg masses. higher inoculum levels did not further decrease top weight significantly. inoculation at seeding reduced top growth more than inoculation of 1-, 2- or 3-week-old seedlings. m. hapla reduced growth more at the intermediate (21.1 c night and 26.7 c day), ...197319319317
survival and reproduction of some nematodes as affected by muck and organic acids.fulvic, humic, acetic, n-bulyric, formic, lactic, and propionic acids were inhibitory to the survival or reproduction of aphelenchus avenae, aphelenchoides goodeyi, helicotylenchus pseudorobustus, meloidogyne hapla or xiphinema americanum. reproduction of h. pseudorobustus and m. hapla significantly increased with increasing amounts of muck added to sand, and with the initial amount of nematode inoculum. all acids except humic and fulvic were lethal, in vitro, to all nematode species tested. whe ...197319319297
correlations of field populations of nematodes with crop growth responses for determining relative involvement of species.treated and nontreated field plots were assayed, and the population density of each plant-parasitic nematode present was compared with crop growth and yield and with the population densities of other nematode species in the same plots. the strongest correlations between nematode population densities and growth responses occurred when soil assays for nematodes were made 55-73 days after planting. belonolairnus longicaudatus was the most damaging parasite on peanut, arachis hypogaea, as evidenced ...197519308153
temperature-induced phase transitions in nematode lipids and their influence on respiration.temperature-induced phase transitions estimated by electron spin resonance (esr) technique were ohscrved in the lipids of several nematode species. in both meloidogyne javanica and caenorhahditis elegans, there was a phase transition in their phospholipids from a liquid-crystalline state to a solid gel state at about 10 c. aphelenchus avenae also had a phase transition, but at about 20 c. with this species, the spin-label motion parameters indicated the transition was from the liquid-crystalline ...197519308140
influence of pratylenchus vulnus and meloidogyne hapla on the growth of rootstocks of rose.pratylenchus vulnus is involved in a desease of rosa noisettiana 'manetti' rose rootstock characterized by darkening of roots, death of feeder roots, and stunting of entire plants. the disease is more severe when plants are grown in silt loam soil than when they are grown in sandy loam soil. the nematodes reproduce best in silt loam soil at 20 c. meloidogyne hapla did not affect the growh of manetti. rosa sp. 'dr. huey', manetti, and r. odorata rose rootstocks were found to be goos hosts for p. ...197619308189
influence of nematodes and light sources on growth and nodulation of soybean.the influence of nematodes on nodulation of soybean varied according to their modes of parasitism. in the greenhouse, nodule formation was stimulated by the endoparasites, meloidogyne hapla and pratylenchus penetrans, but was inhibited slightly by the ectoparasite, belonolaimus longicaudatus. in an experiment under controlled conditions in a phytotron, heterodera glycines severely inhibited nodule formation, whereas plants inoculated with b. longicaudatus and p. penetrans had more nodules per g ...197619308196
histopathology of beta vulgaris to individual and concomitant infections by meloidogyne hapla and heterodera schachtii.histological changes in roots of beta vulgaris cultivar 'ush9a' resulting from infection of meloidogyne hapla alone, heterodera schachtii alone, or infection by both species on one feeding site were studied. anatomical changes caused by m. hapla infection were characterized by regions of hypertrophy and hyperplasia. giant cells were formed within the stele and varied in numbers from 4-7/feeding site; hyperplasia occurred in the form of a large number of relatively small compacted cells generally ...197619308244
parasitism of beta vulgaris by meloidogyne hapla and heterodera schachtii alone and in combination.interrelationships of meloidogyne hapla and heterodera schachtii in combinations of several population levels and different inoculation periods were studied. results indicated suppression of gall development of m. hapla in any treatment in which inoculations of h. schachtii preceded those of m. hapla by 10 days. this interrelationship was characterized by amensalism with m. hapla serving as an amensat and h. schachtii serving as an inhibitor. conversely, when inoculations of m. hapla preceded h. ...197619308223
self-interactions of meloidogyne hapla and of heterodera schachtii on beta vulgaris.double inoculations of sugar beet with larvae of meloidogyne hapla resulted in a higher galling incidence in only one treatment than did a single inoculation using the same number of larvae. double inoculations with larvae of heterodera schachtii, however, resulted in three- to five-fold more cysts in most cases than did single inoculations using the same number of larvae. in general, plants died more quickly after double inoculations than after single inoculations of the same total number of ei ...197619308195
predicting on-set of egg production by meloidogyne hapla on lettuce from field soil temperatures. 197619308203
effects of population densities of meloidogyne hapla on growth and yield of tomato.growth and yield of 'veebrite' tomato were studied in 20-cm (i.d.) clay-tile microplots containing initially 260, 1,840, 6,120, or 27,950 meloidogyne hapla larvae/kg of soil. low nematode numbers stimulated, and the highest nematode population suppressed, vegetative plant growth. more tomatoes, with a higher total weight, were harvested from plants infested with 260 and 1,840 nematode larvae at planting than from those with initial densities of 6,120 and 27,950 larvae. at the two highest densiti ...197719305611
penetration and development of meloidogyne hapla in resistant and susceptible alfalfa under differing temperatures.studies were conducted to examine under differing temperatures (12, 16, 20, 24, 28, and 32 c) the penetration anti development of meloidogyne hapla in resistant lines '298' and 'nev. syn xx', and susceptible 'lahontan' and 'ranger' hardy-type alfalfas. the results indicated that resistance to m. hapla was similar to that previously described for m. incognita in nonhardy alfalfa. although initial penetration in resistant seedlings was similar to that of susceptible seedlings, nematode larvae fail ...197719305571
phytoparasitic nematodes adjacent to established strawberry plantations.plant-nematode populations associated with uncultivated vegetation, adjacent strawberry plants, and alternate crop sites were studied at three locations in minnesota. at one site (forest lake), paratylenchus projectus, meloidogyne hapla, and pratylenchus tenuis were frequently associated with the roots of native vegetation. these nematode species were also present in adjacent strawberry beds. among alternate crops observed, oats and muskmelon usually supported the fewest nematodes although moder ...197819305841
ontogeny of daucus carota infected with meloidogyne hapla.the ontogeny of carrots (daucus carota cv. 'spartan premium') grown under greenhouse conditions in pots of organic soil infected with meloidogyne hapla was influenced detrimentally as early as 4 days after seeding, as determined through analysis of plant surface area, dry weight, fresh weight, net assimilation rate, relative growth rate, and leaf-area ratio. only 58% of the diseased carrots were suitable for fresh market, compared with 97% of those grown in nematode-free soil. growth and develop ...197819305837
root-knot nematodes and the process of ageing in plants.infection of plants by root-knot nematodes is often accompanied by physiological changes characteristic of ageing. ultra-low tissue luminescence of infected plants indicated oxidation of cell-membrane lipids. cells with membranes subjected to oxidation lose some of their capacity for water retention. treating tomato and radish with lidocaine hydrochloride, an inhibitor of lipid oxidation, retarded above-ground symptoms of root-knot nematode infection and of ageing.197819305822
effects of oxamyl on the reproduction of meloidogyne hapla and heterodera schachtii. 197819305874
scanning electron microscopy of perineal patterns of three species of meloidogyne.the perineal pattern of meloidogyne graminicola is oval, characterized by the anastomosing of cuticular striae converging, and elevating at the tail terminus. a deep lateral incisure forming a low arch traverses the rounded perineal pattern of meloidogyne hapla. punctations at the tail region of m. hapla are not observed with the scanning electron microscope. minute crosslines invaginate with the vulvar lips of meloidogyne incognita. punctate indentations around the anal opening and bordering th ...197819305825
interacting effects of soil temperature and type on reproduction and pathogenicity of heterodera schachtii and meloidogyne hapla on sugarbeets. 197919300649
nonfumigant nematicides for control of root-knot nematode to protect carrot root growth in organic soils.greenhouse tests were conducted to determine the effects of two kinds of meloidogyne hapla inoculum on the growth and quality of carrot roots, and the protection afforded in each case by nonfumigant nematicides in organic soils. for all treatments the percentage of carrots damaged was greater with larvae alone as inoculum than with larvae and eggs, indicating that most of the damage occurs early during formation of the taproot. fosthietan, aldicarb, and oxamyl at 4 and 6 kg ai/ha protected the r ...197919300652
influence of plant age, light intensity, nematode inoculum level, and their interactions on tomato growth and reproduction of meloidogyne hapla. 197919305557
effects of dcpa, eptc, and chlorpropham on pathogenicity of meloidogyne hapla to alfalfa.treatments wilh the herbicides chlorpropham (isopropyl m-chlorocarbinilate), dcpa (dimethyl tetrachloroterephthalate), and el'tc (s-ethyl dipropylthiocarbamate), alone or in combination with meloidogyne hapla chilwood, significantly reduced the growth of both nemalode-resistant 'nev syn xx' atttt susceptible 'ranger" alfalfa (medicago saliva l.) seedlings. m. hapla infection of both alfalfas was reduced by all herbicides because of fewer available infective courts in the treated plants. eptc, ho ...197919305525
morphological comparison of second-stage juveniles of six populations of meloidogyne hapla by sem.external morphology of second-stage juveniles of six populations of meloidogyne hapla, hclonging to two cytological races (a and b), and one population each of m. arenaria, m. incognita, and m. javanica was compared by scanning electron microscopy (sem). race a of m. hapla included three facultatively parthenogenetic populations with haploid chromosome numbers of 15. 16, and 17; race b consisted of three mitotically parthenogenetic populations with somalic chromosome numhers of 45, 45, and 48. t ...197919305521
morphological comparison of meloidogyne female head structures, perineal patterns, and stylets.the external morphology of female heads of three populations of each of two cytological races of meloidogyne hapla (race a-meiotic, race b-mitotic) and single populations of m. arenaria, m. incognita, and m. javanica was compared by light (lm) and scanning electron microscopy (sem). perineal patterns of all nine populations were observed with a lm and then examined with a sem. in addition, female stylets of each population were excised, viewed with a sem, and compared with observations made with ...198019300707
the ultrastructure of sperm development in the plant-parasitic nematode meloidogyne hapla. 19807381988
reproduction and pathogenicity of three isolates of meloidogyne hapla race a on concord grapes. 198019300676
morphological comparison of meloidogyne males by scanning electron microscopy.males of five populations of meloidogyne hapla were compared by scanning electron microscopy (sem). three populations of race a had haploid chromosome numbers of 15, 16, and 17 and reproduced by facultative parthenogenesis. race b consisted of two mitotically parthenogenetic populations with somatic chromosome numbers of 45 and 48. males of one population each of m. arenaria, m. incognita, and m. javanica were also examined to delineate species differences. the populations of m. arenaria, m. inc ...198019300666
interrelationship of meloidogyne hapla and ditylenchus dipsaci on resistant and susceptible alfalfa.simultaneous inoculations of alfalfa with meloidogyne hapla larvae and ditylenchus dipsaci at 16, 20, 24, and 28 c did not depress penetration of either nematode in 'nev syn xx' -a selection resistant to m. hapla and d. dipsaci, 'vernal 298' -a selection resistant to m. hapla and susceptible to d. dipsaci, 'lahontan' -a cultivar resistant to d. dipsaci and susceptible to m. hapla, and 'ranger' -a cultivar susceptible to both m. hapla and d, dipsaci. infection with d. dipsaci depressed growth of ...198019300705
pachytene karyotype analysis of tetraploid meloidogyne hapla females by electron microscopy.pairing of homologous chromosomes results in the formation of 34 synaptonemal complexes (sc) at pachytene, corresponding to the 34 bivalents at metaphase i. no multivalent associations were observed and pairing occurs two-by-two. the modified sc, which lacks a central element, does not affect the pairing process. only one end of the sc is attached to the nuclear envelope, although either end can attach. total sc length and the number of recombination nodules in the tetraploid were about 1.5 time ...19817327051
influence of volcanic ash on infectivity and reproduction of two species of meloidogyne.mount st. helens volcanic ash was incorporated into a loamy sand greenhouse soil mix to produce concentrations of 0, 0.5, 1.0, 2.0, 4.0, 8.0, 25, 50 and 100% ash. chemical and physical properties of the various mixtures were determined. three experiments were conducted in a greenhouse to determine if volcanic ash had any influence on root-knot nematode survival and infectivity. tomato, lycoperscion esculentum, seedlings cv. columbia, susceptible to meloidogyne hapla and m. chitwoodi were planted ...198119300784
observations on the cuticle ultrastructure of meloidogyne hapla males. 198119300753
influence of photoperiod and temperature on migrations of meloidogyne juveniles.photoperiod influences the migration of m. incognita juveniles toward tomato roots. approximately 33% migrated vertically 20 cm in 7 days to roots when 12 h dark were alternated with 12 h light. only 7% migrated when light was constant for 24 h. vertical migration of m. incognita juveniles was studied at 14, 16, 18, 20, and 22 c. the migration of m. incognita juveniles begins at about 18 c and reaches its maximum at 22 c. the migration of m. hapla and m. incognita juveniles were compared at 14, ...198119300748
development of four populations of meloidogyne hapla on two cultivars, of cucumber at different temperatures.the infectivity and development of four populations of meloidogyne hapla were compared, at three temperatures, on tomato and two varieties of cucumber. a population from canada produced few root-galls on cucumber and, except at 24 c, no larvae developed into adult females and produced egg masses. in contrast, a population with 45 chromosomes from america produced many galls on cucumber and small proportions of larvae became females and produced egg masses at 20 and 24 c. at 18 c this population ...198219295751
relationship between meloidogyne hapla density and damage to carrots in organic soils.field and growth chamber experiments were conducted to determine the effect of five initial densities (pi - 20 - 240/100 cm(3) soil) of meloidogyne hapla on carrot development and yield of storage roots at maturity. carrots growing in infested and noninfested organic soil were harvested after 15, 29, 44, 59, and 106 days of growth in controlled environment chambers and after l l 0 days in field plots. nematodes affected weight of roots and foliage, weight and length of the storage portion of tap ...198219295674
interactions among selected endoparasitic nematodes and three pseudomonads on alfalfa.meloidogyne hapla, pratylenchus penetrans, and helicotylenchus dihystera, reduced the growth of 'saranac ar alfalfa seedlings when applied at concentrations of 50 nematodes per plant. all except p. penetrans reduced seedling growth when applied at 25 per seedling. m. hapla reduced growth when applied at 12 per seedling. nematodes interacted with three pseudomonads to produce greater growth reductions than were obtained with single pathogens, suggesting synergistic relationships. ditylenchus dips ...198219295682
pathological interaction of a combination of heterodera schachtii and meloidogyne hapla on tomato.increased culturing of a tomato population of heterodera schachtii (ut1c) on tomato for 480 days (eight inoculation periods of 60 days each) significantly increased virulence to 'stone improved' tomato. a synergistic relationship existed between meloidogyne hapla and h. schaehtii on tomato. a combination of h. schachtii (utic) and m. hapla significantly reduced tomato root weights by 65, 64, and 61% below root weights of untreated controls, and single inoculations of m. hapla and h. schachtii, r ...198219295694
influence of meloidogyne hapla chitwood, 1949 on development and establishment of heterodera schachtii schmidt, 1871 on beta vulgaris l.influence of meloidogyne hapla on estahlishnrent and maturity of heterodera schachtii in sugarbeet was studied. results indicated that when the majority of m. hapla were in second, third, or fourth larval stages within plants prior to h. schachtii inoculation, growth and development of the latter was retarded. however, when m. hapla reached the young female stage prior to inoculation of h. schachtii, establishment and development of the latter was greatly enhanced. as m. hapla reached maturity b ...198319295848
histopathology of selected cultivars of tobacco infected with meloidogyne species.rates of nematode penetration and the histopathology of root infections in fluecured tobacco cultivars 'mcnair-944,' 'speight g-28,' and 'nc-89' with either meloidogyne arenaria, m. incognita, m. hapla, or m. javanica were investigated. penetration of root tips by juveniles of all species into the m. incognita-resistant nc-89 and g-28 was much less than that on the susceptible mcnair-944. few juveniles of m. incognita were detected in resistant cultivars 7 and 14 days after inoculation. infectio ...198319295823
response of two alfalfa cultivars to meloidogyne hapla. 198319295860
effect of time of application on the action of foliar sprays of oxamyl on meloidogyne hapla in tomato.foliar sprays containing 3,000 or 4,000 ppm oxamyl applied before inoculation with meloidogyne hapla completely protected tomato plants from intection for up to 36 days but sprays containing 1,000 or 2,000 ppm provided only partial protection. postinoculation sprays were less effective than preinoculation sprays but they decreased the numbers of females and their rate of development and increased the numbers of males. similar amounts of oxamyl applied to the soil as a drench or as granules contr ...198319295771
relationship between heterodera schachtii, meloidogyne hapla, and nacobbus aberrans on sugarbeet.heterodera schachtii, meloidogyne hapla, and nacobbus aberrans either alone, or in various combinations with each other, can, when inoculated at a concentration of 12 second-stage juveniles/ cm(3) of soil, cause a significant (p = 0.01) suppression of growth of sugarbeet (cv. tasco ah14) seedlings. m. hapla and h. schachtii decreased growth of sugarbeet more than n. aberrans over a 60-day period. the adverse effect of n. aberrans on the final population/initial population (pf/pi) ratio for eithe ...198419295890
control of meloidogyne spp. on russet burbank potato by applying metham sodium through center pivot irrigation systems.metham sodium applied in october through center pivot irrigation systems was evaluated for control of meloidogyne hapla at 374, 468, and 701 liters/ha and for control of m. chitwoodi at 468 liters/ha on potato. metham sodium at the high rates effectively controlled m. hapla. no females were detected in the tubers at the high rates of nematicide application, whereas a mean of 19 and 69% of the tubers were infected at the low rate and in the nontreated controls, respectively. in the m. chitwoodi t ...198419295894
interrelationship of heterodera schachtii and meloidogyne hapla on tomato.invasion of tomato (lycopersicon esculentum l.) roots by combined and sequential inoculations of meloidogyne hapla and a tomato population of heterodera schachtii was affected more by soil temperature than by nematode competition. maximum invasion of tomato roots, by m. hapla and h. schachtii occurred at 30 and 26 c, respectively. female development and nematode reproduction (eggs per plant) of m. hapla was adversely affected by h. schachtii in combined inoculations of the two nematode species. ...198519294113
influence of meloidogyne hapla on alfalfa yield and host population dynamics.self-thinning in alfalfa, a dynamic process involving the progressive elimination of the weakest plants, was enhanced by meloidogyne hapla. alfalfa stand densities decreased exponentially with time and were reduced 62% (p = 0.05) in the presence of m. hapla. as stand densities decreased over time, mean plant weights increased at a rate 2.59 times faster in the absence of m. hapla. in a stepwise multiple regression analysis, 65% of the total variation in yield could be explained by changes in sta ...198519294119
influence of glomus fasciculatum on meloidogyne hapla infecting allium cepa.the impact of glomus fasciculatum on meloidogyne hapla associated with allium cepa was evaluated in two experiments. nematode density was not different in mycorrhizal and nonmycorrhizal plants 10 weeks after the joint inoculation of m. hapla and g. fasciculatum. differences in the age structure of m. hapla populations reared on mycorrhizal and nonmycorrhizat plants were noted. g. fasciculatum enhanced leaf and bulb growth of a. cepa in the absence of m. hapla, but did not affect plant weight whe ...198519294114
population trends and vertical distribution of plant-parasitic nematodes associated with vitis labrusca l. in michigan.nematode population trends and vertical distribution were monitored in a southwest michigan vineyard (vitis labrusca cv. concord) from 1976 through 1983. shallow (20 cm) and deep (90 cm) applications of 1,3-dichloropropene applied at 281 (shallow) plus 658 or 1,122 (deep) liters/ ha provided excellent control of xiphinema americanum, criconemella xenoplax, and meloidogyne hapla. populations of x. americanum remained below detectable levels for the entire 8-year experimental period where the fumi ...198519294066
influence of glomus fasciculatum and meloidogyne hapla on allium cepa in organic soils.the influence of meloidogyne hapla and glomus fasciculatum on allium cepa (onion) grown in organic soil was evaluated under greenhouse conditions. in the absence of g. fasciculatum, m. hapla significantly retarded the growth of a. cepa cv. krummery special and msu 8155 x 826, but had no detrimental influence on downing yellow globe, spartan banner, or spartan sleeper. all five cultivars maintained populations of m. hapla, final root population densities of m. hapla associated with spartan banner ...198519294058
influence of alfalfa plant growth on the multiplication rates and ceiling population density of meloidogyne hapla.the rates of reproduction and multiplication of meloidogyne hapla decreased as a result of self-regulatory, density-dependent processes with time and nematode population increase in the soil and roots of medicago sativa cv. cuf 101. juvenile, egg, and mature female population densities increased at a maximum rate until damage to the host resulted in alfalfa yield reductions. temporal differences in multiplication and reproduction rates of m. hapla were observed to be a function of initial popula ...198619294220
interaction of vesicular-arbuscular mycorrhizae and cultivars of alfalfa susceptible and resistant to meloidogyne hapla.the interaction between vesicular-arbuscular mycorrhizal (vam) fungi and the root-knot nematode (meloidogyne hapla) was investigated using both nematode-susceptible (grasslands wairau) and nematode-resistant (nevada synthetic xx) cultivars of alfalfa (medicago sativa) at four levels of applied phosphate. mycorrhizal inoculation improved plant growth and reduced nematode numbers and adult development in roots in dually infected cultures of the susceptible cultivar. the tolerance of plants to nema ...198619294155
differential reaction of alfalfa cultivars to meloidogyne hapla and m. chitwoodi populations.meloidogyne hapla reproduced and suppressed growth (p < 0.05) of susceptible lahontan and moapa alfalfa at 15, 20, and 25 c. at 30 c, resistant nevada syn xx lost resistance to m. hapla. m. hapla invaded and reproduced on rhizobium meliloti nodules of lahontan and moapa, inducing giant cell formation and structural disorder of vascular bundles of nodules without disrupting bacteroids. at 15, 20, and 25 c a m. chitwoodi population from utah reproduced on lahontan, moapa, and nevada syn xx alfalfa ...198619294189
control of pratylenchus penetrans and meloidogyne hapla and yield response of alfalfa due to oxamyl seed treatments.alfalfa (medicago sativa l. cv. saranac) seed were soaked for 20 minutes in water, acetone, or methanol containing 10 or 50 mg/ml of oxamyl (vydate l) or coated with a 2% aqueous cellulose solution containing the same amounts of oxamyl. seed were analyzed for oxamyl by hplc immediately after treatment and after 9 and 26 months of storage. oxamyl content of alfalfa seed did not decline after 26 months of storage. the effects of seed treatment on growth of alfalfa and nematode control were examine ...198719290170
evaluation of cultivars, experimental lines and plant introduction collection of sainfoin for resistance to meloidogyne hapla chitwood.stands of several cultivars and experimental lines of sainfoin (onobrychis viciifolia) were severely reduced (92% average loss) in a field naturally infested with meloidogyne hapla. stands of two alfalfa cultivars included in the test were unaffected. in studies conducted in the greenhouse with plants inoculated at the time of seeding, average mortality was 55% for sainfoin entries and 7% for ladak alfalfa. little mortality occurred when plants were inoculated after establishment. three months a ...198719290103
interaction of ditylenchus dipsaci and meloidogyne hapla on resistant and susceptible plant species.numbers ofditylenchus dipsaci or meloidogyne hapla invading ranger alfalfa, tender crop bean, stone improved tomato, ah-14 sugarbeet, yellow sweet clover, and wasatch wheat from single inoculations were not significantly different from numbers by invasion of combined inoculations. d. dipsaci was recovered only from shoot and m. hapla only from root tissue. combined inoculations did not affect reproduction of either d. dipsaci or m. hapla. d. dipsaci suppressed shoot growth of all species at 15-3 ...198719290168
usefulness of egg assays in nematode population-density determinations. 198719290117
parasitism of woody ornamentals by meloidogyne hapla.meloidogyne hapla is the dominant root-knot nematode found in tennessee woody ornamental nurseries. in greenhouse tests, m. hapla produced galls and formed egg masses on roots of abelia x grandiflora, comus florida, hydrangea paniculata grandiflora, photinia x fraseri, spiraea x bumalda, spiraea x vanhouttei, and viburnum carlesii. galls on h. grandiflora and v. carlesii were mostly large and fusiform. galls on c. florida were spherical and usually terminal, whereas those on the other species we ...198719290273
nematode-degree days, a density-time model for relating epidemiology and crop losses in perennials.the impact of meloidogyne hapla on alfalfa (medicago sativa) yield was described by a multiple point damage model as a function of current plant status, cumulative pest stress, and crop history. nematode-degree days (ndd(female symbol)), calculated on a physiologic time scale as total area under the adult female population density curve, were used to express m. hapla parasitism as cumulative nematode dosage. ndd(female symbol) increased exponentially over physiological time at rates relative to ...198719290114
susceptibility of nevada synthetic xx germplasm to a california race of meloidogyne hapla. 198919287611
pathogenicity of two populations of meloidogyne hapla chitwood on alfalfa and sainfoin.the pathogenicity of two populations of the northern root-knot nematode, meloidogyne hapla chitwood, population 1 (p1) from alfalfa and population 2 (p2) from sainfoin, was studied on both alfalfa and sainfoin for 25 weeks. alfalfa and sainfoin plants inoculated with p2 had significantly (p </= 0.05) higher mortality than plants inoculated with p1. plant stands over all weeks for the uninoculated control, p1, and p2 were 90.5, 78.5, and 64.0% for alfalfa and 84.5, 51.0, and 41.0% for sainfoin, r ...198919287580
biological control of meloidogyne hapla on alfalfa and tomato with the fungus meria coniospora.this study was to determine whether arthrobotrys flagrans, a. oligospora, and meria coniospora would control the root-knot nematode meloidogyne hapla on alfalfa and tomato. alfalfa seeds were coated with a fungus-rye powder in 2% cellulose and were planted in infested soil. three-week-old seedlings from seed treated with m. coniospora had 60% and 58% fewer galls in two experiments than did seedlings from untreated seeds. numbers of j2 in the soil were not reduced. plant growth did not improve. w ...198919287596
efficacy of oxamyl coated on alfalfa seed with a polymer sticker in pratylenchus and meloidogyne infested soils.a polymer sticker was used as a coating in which oxamyl was applied to seeds of alfalfa cultivar saranac for the control of pratylenchus penetrans and meloidogyne hapla. the sticker, diluted 1:1 (sticker:water) to 1:5, delayed seedling emergence during the first 4 days after planting. by day 13, however, emergence from all sticker treatments was comparable to the control. shoot growth of seedlings at day 21 was less than that of the control only from seeds coated with a 1:1 dilution; root growth ...198919287603
plant-parasitic nematodes and fungi associated with root rot of peas on prince edward island.eight commercial pea fields on prince edward island were sampled in june and july over a 2-year period (1986-87) to determine soil population densities and the incidence of nematodes and fungi associated with root rot of peas. root lesion nematodes (pratylenchus spp.) were the dominant endoparasitic nematodes recovered from roots and soil. low populations of the northern root-knot nematode (meloidogyne hapla) were also present. tylenchorhynchus spp. and paratylenchus spp. were recovered frequent ...199019287779
host range and ecology of isolates of pasteuria spp. from the southeastern united states.isolates of pasteuria penetrans were evaluated for ecological characteristics that are important in determining their potential as biological control agents. isolate p-20 survived without loss of its ability to attach to its host nematode in dry, moist, and wet soil and in soil wetted and dried repeatedly for 6 weeks. some spores moved 6.4 cm (the maximum distance tested) downward in soil within 3 days with percolating water. the isolates varied greatly in their attachment to different nematode ...199019287753
plant-parasitic nematodes in maine agricultural soils.in a survey of plant-parasitic nematodes associated with agricultural crops in nine maine counties, 744 soil samples from 26 potential host plants were analyzed between november 1987 and january 1989. the most commonly encountered nematode genus was pratylenchus, occurring in 85% of the samples from most crops, except blueberries and onions. pratylenchus penetrans and p. crenatus were found commonly as species mixtures, with p. penetrans composing 40-80% of the mixture. meloidogyne hapla was enc ...199019287791
resistance in lycopersicon peruvianum to isolates of mi gene-compatible meloidogyne populations.root-knot nematode resistance of f progeny of an intraspecific hybrid (lycopersicon peruvianum var. glandulosum acc. no. 126443 x l. peruvianum acc. no. 270435), l. esculentum cv. piersol (possessing resistance gene mi), and l. esculentum cv. st. pierre (susceptible) was compared. resistance to 1) isolates of two meloidogyne incognita populations artificially selected for parasitism on tomato plants possessing the mi gene, 2) the wild type parent populations, 3) four naturally occurring resistan ...199019287762
growth of carrot and tomato from oxamyl-coated seed and control of meloidogyne hapla.oxamyl was coated on carrot (daucus carota l. cv. spartan fancy-80) and tomato (lycopersicon esculentum mill. cv. glamour) seeds with a polymer sticker for the control of meloidogyne hapla. the sticker diluted in water 1:1 delayed carrot seedling emergence. oxamyl at 40 mg/ml in a 1:5 dilution of sticker lowered the rate of carrot seedling emergence until day 13 and plant growth until day 28. oxamyl at 20 or 40 mg/ml in a 1:5 dilution of sticker on carrot seeds planted in m. hapla-infested muck ...199019287706
cold hardening of meloidogyne hapla second-stage juveniles.the effect of previous exposure to low temperatures on freezing tolerance was determined for second-stage juveniles of meloidogyne hapla. juveniles in 5% polyethylene glycol 20,000 were exposed to 0-24 c for 12-96 hours, and then freezing tolerance was assessed by freezing samples at -4 c for 24 hours, thawing, and determining survival. freezing tolerance was inversely related to prefreeze temperatures of 4-24 c. prefreeze exposure to 4 c resulted in fourfold greater freezing tolerance than did ...199019287695
effects of incorporation method of ethoprop and addition of aldicarb on potato tuber infection by meloidogyne hapla.the efficacy of controlling meloidogyne hapla on potato with water incorporation of ethoprop was compared to physical incorporation before planting. the standard practice of aldicarb application for insect control was also evaluated for m. hapla suppression with and without ethoprop. physical incorporation before planting by rototilling or discing reduced (p </= 0.05) tuber infection. postplant water incorporation of ethoprop was not as effective as physical incorporation of ethoprop or postplan ...199119283186
further studies on the role of polyploidy in the evolution of meloidogyne.two tetraploid isolates of meloidogyne hapla, 86p and e289p, with haploid chromosome numbers of 34 and 28, respectively, were studied cytogenetically and biologically in relation to the diploid populations, 86-va (n = 17) and e289-taiwan (n = 14), from which they had been originally isolated. both isolates were quite stable, converting to diploidy at the low rate of about 2.5%. the tetraploid isolate 86p maintained itself in competition with its diploid counterpart in mixed cultures, although an ...199119283121
efficacy of ethoprop on meloidogyne hapla and m. chitwoodi and enhanced biodegradation in soil.responses of egg masses, free eggs, and second-stage juveniles (j2) ofmeloidogyne hapla and m. chitwoodi to ethoprop were evaluated. the results indicated that j2 were the most sensitive, followed by free eggs and egg masses. in general, m. chitwoodi was more susceptible to ethoprop than m. hapla. ethoprop at 7.2 mug a.i./g soil protected tomato roots from upward migrating m. chitwoodi for 5 weeks. the zone of protection was extended to 10 and 20 cm below the root zone when 3.6 and 7.2 cm water ...199119283141
resistance to root-knot nematodes in cucumber and horned cucumber.two experiments were conducted in the greenhouse. in one experiment, cucumber (cucumis sativus) and horned cucumber (c. metuliferus) cultigens were evaluated for resistance to four root-knot nematode species (meloidogyne arenaria, m. hapla, m. incognita, and m. javanica), and, in a second experiment, a standard (12-week) test was compared with a rapid (6-week) test. in the first experiment, horned cucumber cultigens varied in response to the meloidogyne species. 'sumter' cucumber was more suscep ...199119283171
predisposition of broadleaf tobacco to fusarium wilt by early infection with globodera tabacum tabacum or meloidogyne hapla.in greenhouse experiments, broadleaf tobacco plants were inoculated with tobacco cyst (globodera tabacum tabacum) or root-knot (meloidogyne hapla) nematodes 3, 2, or 1 week before or at the same time as fusarium oxysporum. plants infected with nematodes prior to fungal inoculation had greater fusarium wilt incidence and severity than those simultaneously inoculated. g. t. tabacum increased wilt incidence and severity more than did m. hapla. mechanical root wounding within 1 week of f. oxysporum ...199219283018
relative damage functions and reproductive potentials of meloidogyne arenaria and m. hapla on peanut.the reproductive potential and damage functions for meloidogyne hapla and m. arenaria race 1 on virginia-type peanuts (arachis hypogaea cv. florigiant) were determined over 2 years in microplot experiments in north carolina. peanut yield suppression and damage to pods as a result of galling were greatest in response to m. arenaria (p = 0.01). damage functions for the two species were adequately described by the quadratic models: yield (g/plot) = 398 - 17.1 (log[pi + 1]) - 17.0(log[pi + 1])(2); ( ...199219283222
host suitability and response of asparagus cultivars to meloidogyne species and races.the host-parasite relationships of asparagus and meloidogyne spp. were examined under greenhouse and microplot conditions. meloidogyne species and races differed greatly in their ability to reproduce on asparagus seedlings. meloidogyne hapla generally failed to reproduce, and m. javanica, m. arenaria race 1, and m. incognita race 3 reproduced poorly, with a reproduction factor (rf = final population/initial population) usually < 1.0. only m. arenaria race 2 and m. incognita races 1 and 4 reprodu ...199219283211
distribution of heterodera carotae and meloidogyne hapla in michigan carrot production.during 1986 and 1988, selected farms in all of the major carrot-growing counties of michigan were surveyed to determine the extent of infestation by heterodera carotae and meloidogyne hapla. both species were found in all eight counties surveyed, but not on all farms. heterodera carotae was recovered from 67.4% of the fields surveyed. meloidogyne hapla was detected in 24.8% of the samples and from 69.8% of the fields. in most cases, h. carotae and m. hapla occurred in the same field.199219283061
resistance of lathyrus species and accessions to the northern root-knot nematode, meloidogyne hapla.the leguminous plant genus lathyrus contains many species useful for soil conservation and reclamation. some of these species may also have vaiue in the united states for forage production. the extent of genetic variation among lathyrus populations in reaction to most disease pathogens is not known. we examined 28 usda agricultural research service plant introduction accessions representing 16 lathyrus species for their ability to tolerate attack by the northern root-knot nematode, meloidogyne h ...199219283053
effects of cropping sequences on population densities of meloidogyne hapla and carrot yield in organic soil.the influence of various cropping sequences on population densities of meloidogyne hapla and carrot yield was studied in organic soil under microplot-and field conditions. spinach, radish, barley, oat, and wheat were poor or nonhosts for m. hapla. population densities of m. hapla were maintained or increased on cabbage, celery, lettuce, leek, marigold, and potato. marketable percent-age and root weight of carrots were greater following spinach, oat, radish, and fallow-onion than those following ...199219283022
impact of thermal history on tolerance of meloidogyne hapla second-stage juveniles to external freezing.low temperature induced physiological changes that increased the ability of second-stage juveniles of meloidogyne hapla to survive external freezing. second-stage juveniles in polyethylene glycol solution were exposed to -4 , 0, 4, or 24 c, and then their survival was determined after ice-induced freezing of the suspensions at - 4 c for 24 hours. survival was greatest for juveniles exposed to 4 c before freezing. some juveniles were killed by exposure to - 4 c before freezing of the suspensions. ...199219282993
isolates of meloidogyne hapla with distinct mitochondrial genomes.because two conflicting reports of the structure of the meloidogyne hapla mitochondrial genome exist, we compared the mitochondrial dna (mtdna) purified from two isolates of m. hapla: one from san bernardino county in southern california (brdo) and the other from england. the authenticity of the brdo isolate in particular was confirmed by examination of morphological characters, isoenzyme analysis, and differential host range tests. restriction analysis revealed that mtdna from the brdo and engl ...199319279763
hermaphroditism in meloidogyne hapla.hermaphrodites were detected in diploid and polyploid isolates of population 86-va of meloidogyne hapla. young hermaphrodites are indistinguishable from normal females. initially, hermaphrodite ovaries are filled with oocytes at various stages of development. hermaphroditism is expressed later when young oocytes in the early pachytene region of the growth zone suddenly advance to diakinesis and proceed with maturation divisions, resulting in spermatid production. spermatogenesis may be initiated ...199319279736
suppression of meloidogyne chitwoodi with sudangrass cultivars as green manure.meloidogyne chitwoodi race 1 reproduced on piper sudangrass (sorghum bicolor (l.) moench), 332 (sudangrass hybrid), and p855f and p877f (sorghum-sudangrass hybrids), but failed to reproduce efficiently on trudan 8, trudex 9 (sudangrass hybrids), and sordan 79, ss-222, and bravo ii (sorghum-sudangrass hybrids). meloidogyne chitwoodi race 2 behaved similarly and reproduced more efficiently on piper, p855f, and p877f than on trudan 8, trudex 9, or sordan 79. the mean reproductive factor for m. chit ...199319279773
reproduction of plant-parasitic nematodes on winter rapeseed (brassica napus ssp. oleiferas).the reproduction of isolates of five plant-parasitic nematode species on the winter rapeseed cultivars bridger, gorzanski, h-47, lindora, and viking was evaluated. each cultivar was a good host for helicotylenchus pseudorobustus, meloidogyne hapla, and m. incognita, all rapeseed cultivars were poor hosts for pratylenchus scribneri, in comparison with a susceptible reference host. heterodera glycines females rarely developed on any cultivar, but low numbers of juveniles invaded roots and males oc ...199319279854
differential sensitivity of meloidogyne spp. and heterodera glycines to selected nematicides.differential sensitivity of meloidogyne arenaria, m. hapla, m. incognita, m. javanica, and heterodera glycines races 1 and 5 to the nonfumigant nematicides aldicarb, ethoprop, and fenamiphos was evaluated using a 48-hour root-penetration bioassay. generally, h. glycines was more tolerant of the nematicides, especially ethoprop, than were the meloidogyne species. among meloidogyne species, m. incognita was most sensitive to aldicarb and fenamiphos, but its reaction to ethoprop was similar to the ...199319279834
cloning and characterization of two satellite dnas in the low-c-value genome of the nematode meloidogyne spp.two highly reiterated styi satellite dnas have been cloned from two nematode species: one from meloidogyne hapla and another from m. incognita. the monomeric units of these two satellites have a repeat length of 169 and 295 bp, respectively. these styi repeated element families constitute 5% of the m. hapla and 2.5% of the m. incognita haploid genomes. the a + t content is elevated in both families (i.e., 68% and 77%, respectively). nucleotide methylation and transcriptional activity are negativ ...19948125299
response of perennial herbaceous ornamentals to meloidogyne hapla.sixty-nine herbaceous perennial ornamentals in 56 genera were evaluated for root galling after 2 months in soil infested with meloidogyne hapla under greenhouse conditions. plants were rated susceptible or resistant based on the number of galls present on the root system. thirty-six percent had more than 100 galls on the roots (similar to 'rutgers' tomato controls) and were rated susceptible. thirty percent of the plants tested did not have galls or egg masses present on the root system and were ...199519277335
induced resistance to meloidogyne hapla by other meloidogyne species on tomato and pyrethrum plants.advance inoculation of the tomato cv. celebrity or the pyrethrum clone 223 with host-incompatible meloidogyne incognita or m. javanica elicited induced resistance to host-compatible m. hapla in pot and field experiments. induced resistance increased with the length of the time between inoculations and with the population density of the induction inoculum. optimum interval before challenge inoculation, or population density of inoculum for inducing resistance, was 10 days, or 5,000 infective nema ...199519277310
satellite dna as a target for pcr-specific detection of the plant-parasitic nematode meloidogyne hapla.the polymerase chain reaction was evaluated for its ability to amplify dna sequences specific for the root-knot nematode meloidogyne hapla, using oligonucleotides whose sequence was deduced from the satellite dna previously cloned in this species as primers. as expected, ladder patterns of monomers and multimers of an approximate 150-170-bp repeat were amplified from purified genomic dna of all the m. hapla isolates studied, while no amplification was detected with the five other meloidogyne spe ...19958593688
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