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survey of crop losses in response to phytoparasitic nematodes in the united states for 1994.previous reports of crop losses to plant-parasitic nematodes have relied on published results of survey data based on certain commodities, including tobacco, peanuts, cotton, and soybean. reports on crop-loss assessment by land-grant universities and many commodity groups generally are no longer available, with the exception of the university of georgia, the beltwide cotton conference, and selected groups concerned with soybean. the society of nematologists extension committee contacted extensio ...199919270925
factors influencing emergence of juveniles from cysts of heterodera zeae.several factors were studied to determine their effects on hatch and emergence of second-stage juveniles (j2) from cysts of heterodera zeae. the optimum temperature for emergence of j2 from cysts of h. zeae was 30 c. no juveniles emerged from cysts at 10 or 40 c. immersion of cysts in 4 mm zinc chloride solution stimulated 10% greater emergence of j2 than occurred in tap water controls during 28 days. fresh corn rhizosphere leachates from 25-day and older plants growing in sand or sandy field so ...199519277300
survival of heterodera zeae in soil in the field and in the laboratory.eggs and (or) second-stage juveniles (j2) inside cysts of heterodera zeae survived over winter in the field with no detectable mortality at all six depths to 30 cm from which soil samples were collected between corn stubble in the row at 4-8-week intervals. few or no free j2 were recovered from soil collected in january-april from the top 5 cm, but some were recovered at all samplings from soil collected at greater depths. emergence of j2 from cysts and numbers of females developing on corn root ...198919287619
temperature and the life cycle of heterodera zeae.development of the corn cyst nematode, heterodera zeae, was studied in growth chambers at 20, 25, 29, 33, and 36 +/- 1 c on zea mays cv. pioneer 3184. the optimum temperature for reproduction appeared to be 33 c, at which the life cycle, from second-stage juvenile (j2) to j2, was completed in 15-18 days; at 36 c, 19-20 days were required. juveniles emerged from eggs within 28 days at 29 c and after 42 days at 25 c. although j2 were present within eggs after 63 days at 20 c, emergence was not obs ...199019287738
molecular and morphological characterization of the corn cyst nematode, heterodera zeae, from greece.the corn cyst nematode heterodera zeae was detected in soil from an organic maize field in northern greece. in greenhouse studies, reproduction of h. zeae was detected on maize plants (zeae mays) using soil high in organic matter; the field was under winter fallow at the time of sampling. maize plants were grown in a greenhouse with soil from the affected field used as inoculum. females appeared after six weeks incubation, and abundant cysts were present after 12 weeks. morphological and molecul ...201223482617
redescription of heterodea zeae, the corn cyst nematode, with sem observations.heterodera zeae, the corn cyst nematode, is redescribed and illustrated with comparative details and measurements of females, cysts, and larvae from maryland, usa; and india. scanning electron micrographs o f specimens from the united states are also presented. revised measurements for the larval stylet and new diadnostic characters, especially in the cyst cone, for h. zeae are given. the relationship of h. zeae to close species is discussed.198319295765
description of males of heterodera zeae.the male ofheterodera zeae, the corn cyst nematode, is described and illustrated for the first time. specimens were obtained from a culture originating from cysts collected in kent county, maryland, at the site of the first known infestation of h. zeae in the united states.198419295879
life cycle of heterodera zeae koshy, swarup, and sethi on zea mays l. axenic root explants.monoxenic cultures of heterodera zeae, the corn cyst nematode (ccn), were established on root explants of corn zea mays l., cv. kenworthy. the life cycle of h. zeae was determined from light anti scanning electron microscopic observations of the root explants grown in the dark at 29.5 +/- .5 c under gnotobiotic conditions. the life cycle, from the time the explants were inoculated with second-stage larvae (l2) to the first appearance of newly hatched second-generation l2, required 22 days. the o ...198319295775
isolation of nematicidal compounds from tagetes patula l. yellow flowers: structure-activity relationship studies against cyst nematode heterodera zeae infective stage larvae.bioassay guided isolation studies on the extracts of yellow flowers of tagetes patula l. against the heterodera zeae were carried out to identify phytochemicals lethal to this economically important cyst nematode. in vitro investigation of a polar extract and fractions showing activity led to the isolation of phenolic compounds (flavonoids and phenolic acids). in the non-polar extract, few fatty acids, their methyl esters and thiophenes (including a-terthienyl) were detected. in studies of compo ...201121780738
reproduction of heterodera zeae and its suppression of corn plant growth as affected by temperature.reproduction of the corn cyst nematode (heterodera zeae) and its effect on growth of corn (zea mays) was studied in plant growth chambers at 24, 27, 30, 33, and 36 c. reproduction of h. zeae increased directly with increase in temperature from 24 to 36 c. fifteen-cm-d pots of corn seedlings inoculated with a mixture of 5,000 eggs + j2 and maintained for 8 weeks in growth chambers contained an average of 7,042 cysts + females at 36 c, but only 350 cysts + females at 24 c. fresh weights of plants ...199319279742
investigations of the host range of the corn cyst nematode, heterodera zeae, from maryland.the host range of the corn cyst nematode, heterodera zeae, recently detected in maryland, was investigated. a total of 269 plant entries, representing 68 families, 172 genera, and 204 species, was inoculated with cysts or a mixture of eggs and second-stage juveniles of h. zeae. the host range of the maryland population of h. zeae was limited to plants of the gramineae and included 11 tribes, 33 genera, 42 species, and 77 entries. all 22 corn (zea mays) cultivars tested were hosts. other economic ...198719290286
resistance in zea mays to heterodera zeae.twenty-three precommercial field corn lines (zea mays) were screened in the greenhouse and in vitro for the ability to support reproduction of heterodera zeae. although h. zeae reproduced on all corn lines, reproduction was only 0.4 to 4.5% on the five least suitable corn lines in greenhouse tests compared with the susceptible check line pioneer brand 3184. the least suitable experimental line supported an average of 30 cysts plus females after 8 weeks growth, whereas the susceptible check, pion ...199319279847
sterol composition of the corn cyst nematode, heterodera zeae, and corn roots.sterols from free sterol and steryl ester fractions from heterodera zeae and from total lipids of zea mays roots were analyzed by gas-liquid chromatography (glc) and by glc-mass spectrometry. the major free sterols of h. zeae were 24-ethylcholesterol (54.4% of total free sterol), 24-ethylcholesta-5,22-dien-3beta-ol (13.3%), 24-methylcholesterol (12.5%), and cholesterol (7.2%). the same four sterols comprised 34.6%, 7.2%, 30.3%, and 18.6%, respectively, of the esterified sterols of h. zeae. corn ...198519294060
identification of cyst nematodes of agronomic and regulatory concern with pcr-rflp of its1.the first internally transcribed spacer region (its1) from cyst nematode species (heteroderidae) was compared by nucleotide sequencing and pcr-rflp. european, asian, and north american isolates of five heterodefid species were examined to assess intraspecific variation. pcr-rflp patterns of amplified its1 dna from pea cyst nematode, heterodera goettingiana, from northern ireland were identical with patterns from washington state. sequencing demonstrated that its1 heterogeneity existed within ind ...199719274157
characterization of heterodera zeae populations from portugal.three populations of the corn cyst nematode heterodera zeae, one found in the rhizosphere of a fig tree and two infecting corn, were studied using the morphology and morphometry of cysts and second-stage juveniles, and compared with other populations. the intrapopulation and intraspecific variability are discussed. a simple and improved technique to prepare vulval cones for sem is described. the non-specific esterase patterns of females, isolated from infected corn, were analyzed by electrophore ...200519262881
metabolism of plant sterols by nematodes.parasitic nematodes do not biosynthesize sterols de novo and therefore possess a nutritional requirement for sterol, which must be obtained from their hosts. consequently, the metabolism of phytosterols by plant-parasitic nematodes is an important process with potential for selective exploitation. the sterol compositions of several species of plant-parasitic nematodes were determined by capillary gas chromatography-mass spectrometry and compared with the sterol compositions of their hosts. satur ...19911779708
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