| 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 ... | 1993 | 19279773 |
| 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 ... | 1991 | 19283141 |
| 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 ... | 1984 | 19295894 |
| morphological and molecular evaluation of a meloidogyne hapla population damaging coffee (coffea arabica) in maui, hawaii. | an unusual population of meloidogyne hapla, earlier thought to be an undescribed species, was found causing large galls, without adventitious roots, and substantial damage to coffee in maui, hawaii. only in brazil had similar damage to coffee been reported by this species. unlike m. exigua from south and central america, this population reproduced well on coffee cv. mokka and m. incognita-susceptible tomato but poorly on tomato with the mi resistance gene. characterization included sem images, e ... | 2005 | 19262853 |
| the complex hybrid origins of the root knot nematodes revealed through comparative genomics. | root knot nematodes (rkn) can infect most of the world's agricultural crop species and are among the most important of all plant pathogens. as yet however we have little understanding of their origins or the genomic basis of their extreme polyphagy. the most damaging pathogens reproduce by obligatory mitotic parthenogenesis and it has been suggested that these species originated from interspecific hybridizations between unknown parental taxa. we have sequenced the genome of the diploid meiotic p ... | 2014 | 24860695 |
| rapid, simple and direct detection of meloidogyne hapla from infected root galls using loop-mediated isothermal amplification combined with fta technology. | the northern root-knot nematode (meloidogyne hapla) is a damaging nematode that has caused serious economic losses worldwide. in the present study, a sensitive, simple and rapid method was developed for detection of m. hapla in infested plant roots by combining a flinders technology associates (fta) card with loop-mediated isothermal amplification (lamp). the specific primers of lamp were designed based on the distinction of internal transcribed spacer (its) sequences between m. hapla and other ... | 2017 | 28368036 |
| identification of two meloidogyne hapla genes and an investigation of their roles in the plant-nematode interaction. | root-knot nematodes are soil-borne pathogens that invade and establish feeding sites in plant roots. they have an extremely broad host range, including most vascular plants. during infection of a susceptible host, root-knot nematodes secrete molecules called effectors that help them establish an intimate interaction with the plant and, at the same time, allow them to evade or suppress plant immune responses. despite the fact that meloidogyne hapla is a significant pest on several food crops, no ... | 2017 | 28301312 |
| assessing attraction of nematodes to host roots using pluronic gel medium. | nematodes and other organisms perceive and respond to plant root exudates. these exudates are affected by the condition and genetic makeup of the plant. attraction of the root-knot nematode meloidogyne hapla to roots is altered in plants with mutations affecting ethylene signaling, suggesting that the root exudates to which the nematode responds are modulated by ethylene signaling. nematode interactions with roots have been difficult to observe directly due to the opaqueness of soil. a medium ba ... | 2017 | 28293853 |
| detection of invertebrate suppressive soils, and identification of a possible biological control agent for meloidogyne nematodes using high resolution rhizosphere microbial community analysis. | white clover (trifolium repens) is the key legume component of new zealand pastoral agriculture due to the high quality feed and nitrogen inputs it provides. invertebrate pests constrain white clover growth and this study investigated rhizosphere-associated fungal controls for two of these pests and attempts to disentangle the underpinning mechanisms. the degree of suppressiveness of 10 soils, in a latitudinal gradient down new zealand, to added meloidogyne hapla and costelytra zealandica scarab ... | 2016 | 28082997 |
| impact of grapevine (vitis vinifera) varieties on reproduction of the northern root-knot nematode (meloidogyne hapla). | one of the most commonly encountered plant-parasitic nematodes in eastern washington vitis vinifera vineyards is meloidogyne hapla; however, limited research exists on the impact of this nematode on v. vinifera. the objectives of this research were to determine the impact of m. hapla on chardonnay and cabernet sauvignon vine establishment and to determine the host status of v. vinifera varieties/clones predominantly grown in washington to m. hapla. in a microplot experiment, chardonnay and caber ... | 2015 | 26170476 |
| development of abamectin loaded plant virus nanoparticles for efficacious plant parasitic nematode control. | plant parasitic nematodes are one of the world's major agricultural pests, causing in excess of $157 billion in worldwide crop damage annually. abamectin (abm) is a biological pesticide with a strong activity against a wide variety of plant parasitic nematodes. however, abm's poor mobility in the soil compromises its nematicide performance because of the limited zone of protection surrounding the growing root system of the plant. in this study, we manipulated abm's soil physical chemistry by enc ... | 2015 | 25906360 |
| first report of northern root-knot nematode, meloidogyne hapla, parasitic on oaks, quercus brantii and q. infectoria in iran. | root-knot nematodes (rkn) are the most serious plant parasitic nematodes having a broad host range exceeding 2,000 plant species. quercus brantii lindl. and q. infectoria oliv are the most important woody species of zagros forests in west of iran where favors sub-mediterranean climate. national botanical garden of iran (nbgi) is scheduled to be the basic center for research and education of botany in iran. this garden, located in west of tehran, was established in 1968 with an area of about 150 ... | 2015 | 25861121 |
| spatial distribution of plant-parasitic nematodes in semi-arid vitis vinifera vineyards in washington. | the most commonly encountered plant-parasitic nematodes in eastern washington vitis vinifera vineyards are meloidogyne hapla, mesocriconema xenoplax, pratylenchus spp., xiphinema americanum, and paratylenchus sp.; however, little is known about their distribution in the soil profile. the vertical and horizontal spatial distribution of plant-parasitic nematodes was determined in two washington v. vinifera vineyards. others variables measured in these vineyards included soil moisture content, fine ... | 2014 | 25580024 |
| above- and belowground herbivory jointly impact defense and seed dispersal traits in taraxacum officinale. | plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. the str ... | 2014 | 25473483 |
| evaluation of 31 potential biofumigant brassicaceous plants as hosts for three meloiodogyne species. | brassicaceous cover crops can be used for biofumigation after soil incorporation of the mowed crop. this strategy can be used to manage root-knot nematodes (meloidogyne spp.), but the fact that many of these crops are host to root-knot nematodes can result in an undesired nematode population increase during the cultivation of the cover crop. to avoid this, cover crop cultivars that are poor or nonhosts should be selected. in this study, the host status of 31 plants in the family brassicaceae for ... | 2014 | 25276003 |
| improved structural annotation of protein-coding genes in the meloidogyne hapla genome using rna-seq. | as high-throughput cdna sequencing (rna-seq) is increasingly applied to hypothesis-driven biological studies, the prediction of protein coding genes based on these data are usurping strictly in silico approaches. compared with computationally derived gene predictions, structural annotation is more accurate when based on biological evidence, particularly rna-seq data. here, we refine the current genome annotation for the meloidogyne hapla genome utilizing rna-seq data. published structural annota ... | 2014 | 25254153 |
| segregation and mapping in the root-knot nematode meloidogyne hapla of quantitatively inherited traits affecting parasitism. | the root-knot nematode meloidogyne hapla can reproduce on a wide range of crop species but there is variability in host range and pathogenicity both within and between isolates. the inbred strain vw9 causes galling but does not reproduce on solanum bulbocastanum clone sb22 whereas strain vw8 causes little galling and reproduces poorly on this host. comparison of reproduction on sb22 of nematode f2 lines generated from hybrids between strains vw8 and vw9 revealed that, whereas over half the lines ... | 2013 | 23758293 |
| diversity and evolution of root-knot nematodes, genus meloidogyne: new insights from the genomic era. | root-knot nematodes (rkns) (meloidogyne spp.) are obligate endoparasites of major worldwide economic importance. they exhibit a wide continuum of variation in their reproductive strategies, ranging from amphimixis to obligatory mitotic parthenogenesis. molecular phylogenetic studies have highlighted divergence between mitotic and meiotic parthenogenetic rkn species and probable interspecific hybridization as critical steps in their speciation and diversification process. the recent completion of ... | 2013 | 23682915 |
| a gene encoding a peptide with similarity to the plant ida signaling peptide (atida) is expressed most abundantly in the root-knot nematode (meloidogyne incognita) soon after root infection. | small peptides play important roles in intercellular signaling. inflorescence deficient in abscission (ida) is an arabidopsis mutant that does not abscise (shed) its flower petals. the ida gene encodes a small, secreted peptide that putatively binds to two redundant receptor-like kinases (haesa and haesa-like2) that initiate a signal transduction pathway. we identified ida-like (idl) genes in the genomic sequence for meloidogyne incognita and meloidogyne hapla. no orthologous sequences were foun ... | 2013 | 23538028 |
| the 8d05 parasitism gene of meloidogyne incognita is required for successful infection of host roots. | parasitism genes encode effector proteins that are secreted through the stylet of root-knot nematodes to dramatically modify selected plant cells into giant-cells for feeding. the mi8d05 parasitism gene previously identified was confirmed to encode a novel protein of 382 amino acids that had only one database homolog identified on contig 2374 within the meloidogyne hapla genome. mi8d05 expression peaked in m. incognita parasitic second-stage juveniles within host roots and its encoded protein wa ... | 2013 | 23294405 |
| a sequence-anchored linkage map of the plant-parasitic nematode meloidogyne hapla reveals exceptionally high genome-wide recombination. | root-knot nematodes (meloidogyne spp.) cause major yield losses to many of the world's crops, but efforts to understand how these pests recognize and interact with their hosts have been hampered by a lack of genetic resources. starting with progeny of a cross between inbred strains (vw8 and vw9) of meloidogyne hapla that differed in host range and behavioral traits, we exploited the novel, facultative meiotic parthenogenic reproductive mode of this species to produce a genetic linkage map. molec ... | 2012 | 22870404 |
| ethylene signaling pathway modulates attractiveness of host roots to the root-knot nematode meloidogyne hapla. | infective juveniles of the root-knot nematode meloidogyne hapla are attracted to the zone of elongation of roots where they invade the host but little is known about what directs the nematode to this region of the root. we found that arabidopsis roots exposed to an ethylene (et)-synthesis inhibitor attracted significantly more nematodes than control roots and that et-overproducing mutants were less attractive. arabidopsis seedlings with et-insensitive mutations were generally more attractive whe ... | 2013 | 22712507 |
| root-knot nematodes exhibit strain-specific clumping behavior that is inherited as a simple genetic trait. | root-knot nematodes are obligate parasites of a wide range of plant species and can feed only on the cytoplasm of living plant cells. in the absence of a suitable plant host, infective juveniles of strain vw9 of the northern root-knot nematode, meloidogyne hapla, when dispersed in pluronic f-127 gel, aggregate into tight, spherical clumps containing thousands of worms. aggregation or clumping behavior has been observed in diverse genera in the phylum nematoda spanning free-living species such as ... | 2010 | 21151553 |
| effects of biosolid amendment on populations of meloidogyne hapla and soils with different textures and phs. | temperate vegetable and nursery industries face significant challenges in managing meloidogyne hapla, a plant-parasite for which few resistant cultivars and/or viable alternatives to methyl bromide exist. n-viro soil(r) (nvs), an alkaline-stabilized biosolid product, has soil nutrition enrichment capacity and potential for plant-parasitic nematode suppression. in three sets of experiments, we investigated the effects of nvs on m. hapla populations from rhode island (ri), connecticut (ct), new yo ... | 2010 | 20427181 |
| determination of preferred ph for root-knot nematode aggregation using pluronic f-127 gel. | root-knot nematodes (meloidogyne spp.) are obligate endoparasites of a wide range of plant species. the infective stage is attracted strongly to and enters host roots at the zone of elongation, but the compounds responsible for this attraction have not been identified. we developed a simple assay to investigate nematode response to chemical gradients that uses pluronic f-127, a synthetic block copolymer that, as a 23% aqueous solution, forms a liquid at low temperature and a gel at room temperat ... | 2009 | 19838866 |
| characterization of a putative endoxylanase in the migratory plant-parasitic nematode radopholus similis. | plant-parasitic nematodes have developed an arsenal of enzymes to degrade the rigid plant cell wall. in this article, we report the presence of a putative endoxylanase in the migratory endoparasitic nematode radopholus similis. this enzyme is thought to facilitate the migration of the nematode, as it breaks down xylan, the major component of hemicellulose. the corresponding gene (rs-xyl1) was cloned and the sequence revealed three small introns. interestingly, the position of all three introns w ... | 2009 | 19400841 |
| the genomes of root-knot nematodes. | plant-parasitic nematodes are the most destructive group of plant pathogens worldwide and are extremely challenging to control. the recent completion of two root-knot nematode genomes opens the way for a comparative genomics approach to elucidate the success of these parasites. sequencing revealed that meloidogyne hapla, a diploid that reproduces by facultative, meiotic parthenogenesis, encodes approximately 14,200 genes in a compact, 54 mpb genome. indeed, this is the smallest metazoan genome c ... | 2009 | 19400640 |
| sequence and genetic map of meloidogyne hapla: a compact nematode genome for plant parasitism. | we have established meloidogyne hapla as a tractable model plant-parasitic nematode amenable to forward and reverse genetics, and we present a complete genome sequence. at 54 mbp, m. hapla represents not only the smallest nematode genome yet completed, but also the smallest metazoan, and defines a platform to elucidate mechanisms of parasitism by what is the largest uncontrolled group of plant pathogens worldwide. the m. hapla genome encodes significantly fewer genes than does the free-living ne ... | 2008 | 18809916 |
| meiotic parthenogenesis in a root-knot nematode results in rapid genomic homozygosity. | many isolates of the plant-parasitic nematode meloidogyne hapla reproduce by facultative meiotic parthenogenesis. sexual crosses can occur, but, in the absence of males, the diploid state appears to be restored by reuniting sister chromosomes of a single meiosis. we have crossed inbred strains of m. hapla that differ in dna markers and produced hybrids and f(2) lines. here we show that heterozygous m. hapla females, upon parthenogenetic reproduction, produce progeny that segregate 1:1 for the pr ... | 2007 | 17483427 |
| damage and management of meloidogyne hapla using oxamyl on carrot in new york. | the northern root-knot nematode (meloidogyne hapla) is a major pathogen of processing carrot in new york, significantly reducing marketable yield and profitability. severely infected carrots are stubby, galled and forked and therefore unmarketable. in field microplot trials in 1996 and 1998, the incidence and severity of root-galling increased and the marketable yield of carrot decreased as the initial inoculum density of m. hapla was increased from 0 to 8 eggs/cm(3) soil, in mineral or organic ... | 2006 | 19259467 |
| host-specific pathogenicity and genome differences between inbred strains of meloidogyne hapla. | five isolates of m. hapla originating from the netherlands and california were inbred by sequential transfer of single egg masses to produce six strains. cytological examination showed that oocytes of these strains underwent meiosis and had n = 16 chromosomes. strains were tested for ability to infect and to develop on several hosts by in vitro assays. the two strains from california infected tomato roots at a higher rate than those from the netherlands, but no difference among strains was seen ... | 2006 | 19259441 |
| relationship between levels of cyanide in sudangrass hybrids incorporated into soil and suppression of meloidogyne hapla. | sudangrass cv. trudan 8 has been demonstrated to suppress infection of vegetables by meloidogyne hapla (mh). hydrogen cyanide, released from the degradation of the cyanogenic glucoside (dhurrin) during decomposition of trudan 8, was the primary factor involved in suppression of mh on vegetables. the cyanide ion level in leaf tissue of 14 hybrids of sudangrass varied between 0.04 (cv. sx-8) to 1.84 parts per million (cv. 840f). the suppressive activity of the sudangrass hybrids against mh was ass ... | 2002 | 19265902 |
| fungi parasitic on juveniles and egg masses of meloidogyne hapla in organic soils from new york. | fungi associated with egg masses and juveniles of meloidogyne hapla were isolated from organic soil samples obtained from five fields planted to lettuce or onion in newyork. the soil samples were placed in sterilized clay pots, infested with m. hapla, and planted to lettuce. after 4 months, egg masses and juveniles were surface-disinfested, plated on water agar, and examined for fungal infection. depending on the soil sample, fungal isolates were recovered from 13% to 30%, and from 5% to 24% of ... | 1998 | 19274258 |
| management of meloidogyne hapla in herbaceous perennial ornamentals by sanitation and resistance. | meloidogyne hapla can be spread in bare-root herbaceous perennial propagation material and may be difficult to control once established in new fields or in the landscape. root pruning of bare-root plants was investigated as a means of reducing spread and establishment of m. hapla. plants previously inoculated with 10,000 eggs/plant were root-pruned to remove either a portion or most of the fibrous root system without removing underground stems, buds, tubers, or tuberous roots. root pruning of ac ... | 1997 | 19274274 |
| effects of meloidogyne spp. and rhizoctonia solani on the growth of grapevine rootings. | a disease complex involving meloidogyne incognita and rhizoctonia solani was associated with stunting of grapevines in a field nursery. nematode reproduction was occurring on both susceptible and resistant cultivars, and pot experiments were conducted to determine the virulence of this m. incognita population, and of m. javanica and m. hapla populations, to v. vinifera cv. colombard (susceptible) and to v. champinii cv. ramsey (regarded locally as highly resistant). the virulence of r. solani is ... | 1997 | 19274149 |
| host suitability of 32 common weeds to meloidogyne hapla in organic soils of southwestern quebec. | thirty-two weeds commonly found in the organic soils of southwestern quebec were evaluated for host suitability to a local isolate of the northern root-knot nematode meloidogyne hapla under greenhouse conditions. galls were observed on the roots of 21 species. sixteen of the 21 had a reproduction factor (pf/pi = final number of m. hapla eggs and juveniles per initial number of m. hapla juveniles per pot) higher than carrot (pf/pi = 0.37), the major host crop in this agricultural area. tomato cv. ... | 1996 | 19277189 |
| response of additional herbaceous perennial ornamentals to meloidogyne hapla. | twenty-nine herbaceous perennial ornamentals were evaluated for root galling after 2 months in soil infested with meloidogyne hapla u n d e r greenhouse conditions. plants such as asclepias, epimedium, liriope, lithospermura, myosotis, penstemon, sidalecea, and solidago did not have galls or egg masses present on the root system and were rated as resistant. astrantia, boltonia, centranthus, and miscanthus had more than 100 galls on the roots (similar to 'rutgers' tomato controls) and were rated ... | 1996 | 19277187 |
| damage threshold of meloidogyne hapla to lettuce in organic soil. | lettuce was seeded in pots in the greenhouse and in field microplots in 1991 and 1992. pots and microplots were filled with untreated or fumigated organic soil infested with meloidogyne hapla at seven initial population densities (pi) (0 to 32 eggs/cm(3) soil). lettuce weight, severity of root galling, and number of eggs per root system (pf) were determined after 8 weeks. at the highest pi, m. hapla caused yield losses up to 64% in the microplots and plant death in the greenhouse tests. the sein ... | 1996 | 19277172 |
| identification of stable plant cystatin/nematode proteinase complexes using mildly denaturing gelatin/polyacrylamide gel electrophoresis. | the biochemical interactions between two cystatins from rice seeds, oryzacystatin i (oci) and oryzacystatin ii (ocii), and the cysteine proteinases from three plant parasitic nematodes, meloidogyne hapla, m. incognita and m. javanica, were assessed using standard protease assays and mildly denaturing gelatin/polyacrylamide gel electrophoresis (gelatin/page). activity detected in extracts of preparasitic second-stage larvae (j2) from m. hapla was optimal at ph 5.5 and was inhibited in vitro by th ... | 1996 | 8874065 |
| 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 ... | 1995 | 19277335 |
| 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 ... | 1995 | 19277310 |
| 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 ... | 1995 | 8593688 |
| biological relationship of meloidogyne hapla populations to alfalfa cultivars. | greenhouse and growth chamber studies were established to determine if there are pathological and physiological differences among meloidogyne hapla populations from california (ca), nevada (nv), utah (ut), and wyoming (wy) on alfalfa cultivars classified as resistant or susceptible to root-knot nematodes. in the greenhouse, plant survival was not consistent with resistance classifications. while all highly resistant nevada synthetic germplasm (nev syn xx) plants survived inoculation with all nem ... | 1995 | 19277299 |
| 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 ... | 1994 | 8125299 |
| 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 ... | 1993 | 19279763 |
| 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 ... | 1993 | 19279736 |
| 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 ... | 1992 | 19283053 |
| 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 ... | 1992 | 19283022 |
| 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. ... | 1992 | 19282993 |
| 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 ... | 1991 | 19283186 |
| 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 ... | 1991 | 19283121 |
| 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 ... | 1990 | 19287706 |
| 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 ... | 1990 | 19287695 |
| susceptibility of nevada synthetic xx germplasm to a california race of meloidogyne hapla. | | 1989 | 19287611 |
| 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 ... | 1989 | 19287580 |
| 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 ... | 1987 | 19290273 |
| 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 ... | 1987 | 19290114 |
| 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 ... | 1986 | 19294220 |
| 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 ... | 1986 | 19294155 |
| 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 ... | 1985 | 19294119 |
| 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 ... | 1985 | 19294114 |
| 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 ... | 1985 | 19294066 |
| 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 ... | 1985 | 19294058 |
| response of two alfalfa cultivars to meloidogyne hapla. | | 1983 | 19295860 |
| 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 ... | 1983 | 19295771 |
| 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 ... | 1982 | 19295751 |
| 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 ... | 1982 | 19295674 |
| 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 ... | 1981 | 19300784 |
| observations on the cuticle ultrastructure of meloidogyne hapla males. | | 1981 | 19300753 |
| 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, ... | 1981 | 19300748 |
| 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 ... | 1981 | 7327051 |
| 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 ... | 1980 | 19300707 |
| the ultrastructure of sperm development in the plant-parasitic nematode meloidogyne hapla. | | 1980 | 7381988 |
| reproduction and pathogenicity of three isolates of meloidogyne hapla race a on concord grapes. | | 1980 | 19300676 |
| 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 ... | 1980 | 19300666 |
| 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 ... | 1979 | 19300652 |
| influence of plant age, light intensity, nematode inoculum level, and their interactions on tomato growth and reproduction of meloidogyne hapla. | | 1979 | 19305557 |
| 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 ... | 1979 | 19305525 |
| 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 ... | 1979 | 19305521 |
| 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 ... | 1978 | 19305841 |
| 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 ... | 1978 | 19305837 |
| 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. | 1978 | 19305822 |
| 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 ... | 1977 | 19305611 |
| 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 ... | 1977 | 19305571 |
| predicting on-set of egg production by meloidogyne hapla on lettuce from field soil temperatures. | | 1976 | 19308203 |
| 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. | 1973 | 19319351 |
| 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 ... | 1973 | 19319319 |
| 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 ... | 1973 | 19319318 |
| 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), ... | 1973 | 19319317 |
| 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 ... | 1972 | 19319282 |
| 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 ... | 1972 | 19319271 |
| 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 ... | 1972 | 19319252 |
| 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. | 1972 | 19319239 |
| polyploidy and reproductive patterns in the root-knot nematode meloidogyne hapla. | | 1966 | 5927453 |
| effect on meloidogyne hapla of excised tomato roots treated with alpha-methoxyphenylacetic acid. | | 1956 | 17736439 |