| carbohydrate-recognition domains on the surface of phytophagous nematodes. | human red blood cells (hrbc) adhered to preparasitic second-stage juveniles (j2) of heterodera avenae, heterodera schachtii, meloidogyne javanica, pratylenchus mediterraneus, rotylenchulus reniformis, and tylenchulus semipenetrans over the entire nematode body. binding was conspicuously confined to the head and tail of longidorus cohni, xiphinema brevicolle, and xiphinema index. binding was ca2+ and mg2+ dependent. in contrast, hrbc did not adhere to anguina tritici, aphelenchoides subtenius, di ... | 1995 | 7895833 |
| the potential efficiency of irrigation management and propargyl bromide in controlling three soil pests: tylenchulus semipenetrans, fusarium oxysporum and echinochloa crus-galli. | propargyl bromide (3-bromopropyne, 3bp) is a potential alternative for methyl bromide. little information is available about its efficiency in controlling pests. the purpose of this paper is to estimate the 3bp dose required for killing three pests and to compare the efficiency of water management approaches to that of fumigation. the pests, fusarium oxysporum schlecht (fungus), echinochloa crus-galli (l) beauv (grass) and tylenchulus semipenetrans cobb (nematode) were exposed to different 3bp c ... | 2005 | 15912563 |
| survival of plant pathogens in static piles of ground green waste. | ground green waste is used as mulch in ornamental landscapes and for tree crops such as avocados. survival of armillaria mellea, phytophthora cinnamomi, sclerotinia sclerotiorum, and tylenchulus semipenetrans was assessed for 8 weeks within unturned piles of either recently ground or partially composted green waste. s. sclerotiorum survived at the pile surface and at 10, 30, and 100 cm within the pile for the entire 8 weeks in both fresh green waste (fgw) and aged green waste (agw). a. mellea an ... | 2008 | 18943222 |
| nematode and grape rootstock interactions including an improved understanding of tolerance. | sixteen cultivars of grape were screened over a two-year period in the presence or absence of 10 different nematode populations. populations of meloidogyne spp., xiphinema index, and mesocriconema xenoplax developed more rapidly and caused greater damage than populations of x. americanum and tylenchulus semipenetrans. populations of mixed meloidogyne spp. having a history of feeding on grape were among the fastest developing populations. tolerance to nematode parasitism appeared to be based on d ... | 2006 | 19259534 |
| eggs of tylenchulus semipenetrans inhibit growth of phytophthora nicotianae and fusarium solani in vitro. | in previous greenhouse and laboratory studies, citrus seedlings infested with the citrus nematode tylenchulus semipenetrans and later inoculated with the fungus phylophthora nicotianae grew larger and contained less fungal protein in root tissues than plants infected by only the fungus, demonstrating antagonism of the nematode to the fungus. in this study, we determined whether eggs of the citrus nematode t. semipenetrans and root-knot nematode meloidogyne arenaria affected mycelial growth of p. ... | 2002 | 19265943 |
| infection of citrus roots by tylenchulus semipenetrans reduces root infection by phytophthora nicotianae. | bioassays and whole-plant experiments were conducted to investigate the interaction between tylenchulus semipenetrans and phytophthora nicotianae. both organisms are parasites of the citrus fibrous root cortex. nematode-infected and non-infected root segments were excised from naturally infected field roots and placed on water agar in close proximity to agar plugs of p. nicotianae and then transferred to a phytophthora-selective medium. at 10 and 12 days, 50% fewer nematode-infected segments wer ... | 2002 | 19265961 |
| tylenchulus semipenetrans alters the microbial community in the citrus rhizosphere. | infection of citrus seedlings by tylenchulus semipenetrans was shown to reduce subsequent infection of roots by phytophthora nicotianae and to increase plant growth compared to plants infected by only the fungus. hypothetical mechanisms by which the nematode suppresses fungal development include nutrient competition, direct antibiosis, or alteration of the microbial community in the rhizosphere to favor microorganisms antagonistic to p. nicotianae. a test of the last hypothesis was conducted via ... | 2003 | 19265991 |
| 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 ... | 1999 | 19270925 |
| seasonality of tylenchulus semipenetrans cobb and pasteuria sp. in citrus orchards in spain. | population densities of the mediterranean biotype of tylenchulus semipenetrans were monitored in soil and citrus roots at 3-month intervals for 3 consecutive years in four citrus orchards in the provinces of tarragona (amposta and xalamera) and valencia (moncada and ca rcer). nematode population densities in soil peaked once a year in april or july depending on the orchard and year. numbers of females per gram of root increased once or twice each year. the maximum density of eggs per gram of roo ... | 2000 | 19271018 |
| pasteuria sp. parasitizing trophonema okamotoi in florida. | two populations of trophonema okamotoi parasitized by pasteuria sp. were found on liquidambar styraciflua (sweetgum) and on an unidentified tropical grass in north-central florida. endospores of this pasteuria sp. attached to motile vermiform second-stage juveniles (j2) and males of t. okamotoi, but not to other developmental stages. sporangia and new endospores were produced only inside the bodies of swollen and sedentary third- and fourth-stage juveniles and females that developed in the host ... | 1992 | 19283199 |
| leaching soluble salts increases population densities of tylenchulus semipenetrans. | the effect of salinity on population densities of tylenchulus semipenetrans was measured on 3-month-old salt-tolerant rangpur lime growing on either loamy sand, sand, or organic mix and on 4-month-old salt-sensitive sweet lime in organic mix. salinity treatments were initiated by watering daily with 25 mol/m(3) nacl + 3.3 mol/m(3) cacl for 3 days and every other day with 50 mol/m(3) nac1 + 6.6 mol/m(3) cac1 for one week, with no salt (ns) treatments as controls. salinity was discontinued in one ... | 1992 | 19283210 |
| influence of four nematodes on root and shoot growth parameters in grape. | two grape cultivars, susceptible french colombard and tolerant rubired, and four nematodes, meloidogyne incognita, pratylenchus vulnus, tylenchulus semipenetrans, and xiphinema index, were used to quantify the equilibrium between root (r) and shoot (s) growth. root and shoot growth of french colombard was retarded by m. incognita, p. vulnus, and x. index but not by t. semipenetrans. although the root growth of rubired was limited by all the nematodes, the shoot growth was limited only by x. inde ... | 1989 | 19287609 |
| accelerated movement of nematodes from soil in baermann funnels with temperature gradients. | baermann funnels were modified to eliminate or reverse the small temperature gradient (1-2 c/cm) across the soil layer that normally results from water evaporation. effects of modifications on extraction efficiency were examined at various ambient temperatures and after overnight adaptation of three nematode species at 20 and 30 c. extraction of meloidogyne incognita from sandy loam, tylenchulus semipenetrans from sandy clay loam, and rotylenchulus reniformis from silt was greatly accelerated si ... | 1989 | 19287622 |
| parasitism of the citrus nematode, tylenchulus semipenetrans, by pasteuria penetrans in iraq. | | 1989 | 19287633 |
| antagonists of plant-parasitic nematodes in florida citrus. | in a survey of antagonists of nematodes in 27 citrus groves, each with a history of tylenchulus semipenetrans infestation, and 17 noncitrus habitats in florida, approximately 24 species of microbial antagonists capable of attacking vermiform stages of radopholus citrophilus were recovered. eleven of these microbes and a species of pasteuria also were observed attacking vermiform stages of t. semipenetrans. verticillium chlamydosporium, paecilomyces lilacinus, p. marquandii, streptomyces sp., art ... | 1990 | 19287759 |
| distribution, hosts, and morphological characteristics of tylenchulus palustris in florida and bermuda. | studies on the geographical distribution and hosts of tylenchulus palustris were conducted over a 3-year period in florida and bermuda. tylenchulus palustris was found on aster elliottii and liquidambar styraciflua roots in swamps of northern and central florida. it was detected also on borrichia arborescens and b. frutescens roots in tidal marshes of northern florida and coastal rocklands of southern florida and bermuda. posterior bodies of t. palustris swollen females from bermuda did not diff ... | 1990 | 19287787 |
| plant-parasitic nematode problems in the pacific islands. | the pacific islands have a diverse range of food and cash crops with indigenous and introduced nematode problems. the staple food crops have serious nematode pests, such as meloidogyne spp. on sweet potato, hirschmanniella miticausa causing corm rot of taro, and pratylenchus coffeae and radopholus sp. producing tuber dry rot of yams. bananas are infested with p. coffeae or r. similis, citrus with tylenchulus semipenetrans, rice with aphelenchoides besseyi, and ginger with meloidogyne spp. and r. ... | 1988 | 19290200 |
| nematode problems affecting agriculture in the philippines. | nematodes are considered major pests on most economic crops in the philippines, particularly on banana, pineapple, citrus, tomato, ramie, and sugarcane. radopholus similis is the most destructive nematode on banana, while meloidogyne spp. are more serious on various vegetable crops such as tomato, okra, and celery and on fiber crops such as ramie. tylenchulus semipenetrans is a problem on citrus and rotylenchulus reniformis on pineapple and some legume crops. hirschmanniella oryzae and aphelench ... | 1988 | 19290204 |
| geographical distributions of rotylenchulus reniformis, meloidogyne incognita, and tylenchulus semipenetrans in the lower rio grande valley as related to soil texture and land use. | a survey was conducted over a 22-year period to evaluate the influence of soil texture and land use on the geographical distributions of rotylenchulus reniformis, meloidogyne incognita, and tylenchulus semipenetrans in the lower rio grande valley. the distributions of r. reniformis and m. incognita were related to soil texture, whereas t. semipenetrans occurred wherever host plants were present regardless of soil texture. the incidence of m. incognita was greatest in elevated sandy loams and mod ... | 1987 | 19290268 |
| characterization of sialyl and galactosyl residues on the body wall of different plant parasitic nematodes. | the plant parasitic nematodes helicotylenchus multicinctus, meloidogyne javanica, tylenchulus semipenetrans, and xiphinema index, differing in their host specificity and parasitic habits, were analyzed as to their cuticle surface sialyl, galaclosyl, and/or n-acetylgalactosaminyl residues. the procedure involved the selective oxidation of sialic acid and galactose/n-acetylgal-actosamine residues using periodate and galactose oxidase, respectively, to form reactive aldehyde groups. these functiona ... | 1982 | 19295671 |
| effects of pratylenchus coffeae-tylenchulus semipenetrans interactions on nematode population dynamics in citrus. | the distributions of pratylenchus coffeae and tylenchulus semipenetrans in a central florida citrus grove were mutually exclusive. in a challenge experiment conducted in the grove, indigenous populations of either species did not prevlude infection by the other species. inoculation with either t. semipenetrans or p. coffeae tended to reduce the population size of the other nematode species. in greenhouse tests, individual feeder roots were parasitized predominantly by one or the other of the two ... | 1982 | 19295723 |
| influence of metalaxyl on three nematodes of citrus. | metalaxyl significantly reduced population of pratylenchus coffeae, radopholus similis, and tylenchulus semipenetrans in roots of citrus limon (rough lemon) under greenhouse conditions. postinoculation treatment of rough lemon seedlings was not as effective i n reducing nematode populations as was treatment before inoculation. fewer nematodes infected metalaxyl-treated roots than nontreated roots. however, incubation of nematodes in metalaxyl did not inhibit nematode motility or their ability to ... | 1983 | 19295833 |
| parasitic habits of trophotylenchulus floridensis (tylenchulidae) and its taxonomic relationship to tylenchulus semipenetrans and allied species. | parasitism by trophotylenchulus floridensis raski, 1957 was studied on roots of sand pine (pinus clausa [chapm.] vasey). different life stages of the nematode were observed to be covered by dark, spherical, brittle, capsule-like structures which protruded from the root surface. the mature capsule enveloped a single sedentary female with a gelatinous matrix containing an average of 76 (44-117) eggs. the capsule was composed of a single layer of cells which appeared to be of plant origin. the ante ... | 1983 | 19295840 |
| response of pinus ponderosa seedlings to stylet-bearing nematodes. | of 12 stylet-bearing nematodes used for inoculations, pratylenchus penetrans, p. brachyurus, p. vulnus, ditylenchus destructor, meloidogyne incognita, m. javanica, and m. hapla reproduced on pinus ponderosa, while xiphinema index, aphelenchus avenae, paratylenehus neoamblycephalus, tylenchulus semipenetrans, and macroposthonia xenoplax did not. p. vulnus, p. brachyurus, p. penetrans, a. avenae, d. destructor, t. semipenetrans, and p. neoamblycephalus significantly suppressed both the shoot and r ... | 1979 | 19300659 |
| population fluctuation of three parasitic nematodes in florida citrus. | in florida, tylenchulus semipenetrans on citrus has two high and two low population levels each year. high levels occur in april-may and november-december, and low levels, in february-march and august-september. population increases occur about 4-5 weeks after the spring and fall flush of root growth. populations of pratylenchus coffeae on citrus varied widely, and were not related to season. populations of p. brachyurus showed seasonal variation with a high in june-july and a low in march-may. ... | 1972 | 19319266 |
| transport and fate of methyl iodide and its pest control in soils. | for fumigants, information on transport and fate as well as pest control is needed to develop management practices with the fewest negative environmental effects while offering sufficient pest control efficacy. for this purpose, a 2-d soil chamber with a surface-mounted flux chamber was designed to determine volatilization, real-time soil gas-phase concentration, degradation, and organism survivability after methyl iodide (mei) fumigation. three types of pests were used to give a broad spectrum ... | 2010 | 20704226 |
| predicting methyl iodide emission, soil concentration, and pest control in a two-dimensional chamber system. | due to ever-increasing state and federal regulations, the future use of fumigants is predicted on reducing negative environmental impacts while offering sufficient pestcontrol efficacy. to foster the development of a best management practice, an integrated tool is needed to simultaneously predict fumigant movement and pest control without having to conduct elaborate and costly experiments. the objective of this study was (i) to present a two-dimensional (2-d) mathematical model to describe both ... | 2011 | 21488499 |
| resistance of grape rootstocks to plant-parasitic nematodes. | candidate grape rootstocks were selected through a rigorous screening program initiated with important sources of resistance to meloidogyne pathotypes and to xiphinema index in muscadinia rotundifolia and vitis species native to north america. based on their rooting capability and horticultural characteristics, 200 candidates were selected from 5,000 progeny of multiple crosses between commercial grape rootstocks and wild grape species that exhibited resistance to nematodes. after a 15-year scre ... | 2012 | 23482972 |
| effect of the nematode biocide dbx-1003 in controlling citrus nematode infecting mandarin, and interrelationship with the co-inhabitant fungi. | in a field experiment, the nematode-biocide, dbx-1003, was evaluated against the citrus nematode, tylenchulus semipenetrans infecting mandarin, citrus reticulata, dbx-1003 20% g., was applied in october 2008 at the rate 1/2 kg/tree, and root and soil samples were collected monthly until the next october, 2009. successive treatment of the same biocide was added in may 2009. for the comparison, vydate 24% l, was applied as well as non-treated check trees were left. data revealed that the biocide t ... | 2013 | 25151818 |
| spot drip application of dimethyl disulfide as a post-plant treatment for the control of plant parasitic nematodes and soilborne pathogens in grape production. | plant parasitic nematodes and soilborne pathogens can reduce the overall productivity in grape production. not all grape growers apply soil fumigants before planting, and there is no single rootstock resistant to all nematode species. the aim of this investigation was to evaluate the effect of dimethyl disulfide (dmds) applied at 112, 224, 448 and 897 kg ha(-1) as a post-plant treatment against soilborne plant parasitic nematodes and pathogens on the grape yield in established grapevines. | 2014 | 24307137 |
| use of chitin for controlling heterodera avenae and tylenchulus semipenetrans. | the nematicidal effect of chitin, relative to other pesticides, was evaluated against two plant-parasitic nematodes, heterodera avenae and tylenchulus semipenetrans. wheat seedlings, grown in soils artificially or naturally infested with h. avenae, were treated with 0.4% (w/w) clandosan (cla) prepared from crustacean chitin, aldicarb (temik 15g), or ethylene dibromide (edb 90ec). the cla treatment significantly increased wheat straw, ear, and average grain dry weights of nematode-infected plants ... | 1989 | 19287630 |
| mode of parasitism of meloidogyne and other nemaiode eggs by dactylella oviparasitica. | hyphae of dactylella oviparasitica proliferated rapidly through meioidogyne egg masses, and appressoria formed when they contacted eggs. the fungus probably penetrated egg shells mechanically, although chitinase production detected in culture suggested that enzymatic penetration was also possible. in soil, d. oviparasitica invaded egg masses soon after they were deposited on the root surface and eventually parasitized most of the first eggs laid. occasionally the fungus grew into meloidogyne fem ... | 1979 | 19300648 |
| colonization of greenhouse nematode cultures by nematophagous mites and fungi. | unproductive > 7-year-old greenhouse cultures of citrus nematode (tylenchulus semipenetrans) had a well-developed soil invertebrate fauna that included nematophagous mite species characteristic of florida citrus groves. nematophagous mite densities in box cultures were 285 +/- 42 mites/liter, 2.5 to 25 times higher than densities in citrus nematode-infested groves. vigorous root-knot nematode (meloidogyne incognita) cultures grown in steam-pasteurized soil had few nematophagous mites until more ... | 1993 | 19279841 |
| establishment of orchards with black polyethylene film mulching: effect on nematode and fungal pathogens, water conservation, and tree growth. | placement of a 3-m-wide, black, polyethylene film mulch down rows of peach (prunus persica 'red haven' on 'lovell' rootstock) and almond (prunus dulcis 'nonpareil' on 'lovell') trees in the san joaquin valley of california resulted in irrigation water conservation of 75%, higher soil temperature in the surface 30 cm, a tendency toward greater root mass, elimination of weeds, and a greater abundance of meloidogyne incognita second-stage juveniles in soil but reduced root galling when compared to ... | 1992 | 19283045 |
| screening of a granular chelate of metham-zinc for nematicidal activity using citrus and root-knot nematodes. | a granular formulation of a chelate of metham-zinc (cmz) which liberates the biocidal methyl isothiocyanate was tested for nematicidal activity on tylenchulus semipenetrans in a jar soil screening and on meloidogyne javanica (greenhouse test) and m. incognita (field test) infecting tomato. comparisons were made with 1,3-d in the jar and pot experiments. the cmz caused only 3.9% mortality of citrus nematode juveniles at 1.0 mug a.i./g soil, but 95.4% mortality at 10.0 mug a.i./g and 100.0% at 100 ... | 1988 | 19290294 |
| effect of films on 1,3-dichloropropene and chloropicrin emission, soil concentration, and root-knot nematode control in a raised bed. | soil fumigation is an important component of u.s. agriculture, but excessive emissions can be problematic. the objective of this study was to determine the effects of agricultural films (e.g., tarps) on soil fumigant atmospheric emissions and spatiotemporal distributions in soil, soil temperature, and plant pathogen control in the field using plastic films with various permeabilities and thermal properties. a reduced rate of 70% inline (60.8% 1,3-dichloropropene (1,3-d) and 33.3% chloropicrin (c ... | 2013 | 23343207 |
| sensitivity of meloidogyne javanica and tylenchulus semipenetrans to isothiocyanates in laboratory assays. | abstract isothiocyanates are released through enzymatic degradation of glucosinolates produced by plants in the family brassicaceae. glucosinolate profiles differ among plant species and the isothiocyanate derivatives differ in their toxicity to nematodes. control of plant-parasitic nematodes in soil by isothiocyanates released from incorporated brassicaceous plant material has been inconsistent. success might be improved with knowledge of the relative toxicities of various isothiocyanates again ... | 2003 | 18943062 |
| influence of urea, hydroxyurea, and thiourea on meloidogyne javanica and infected excised tomato roots in culture. | urea (u), hydroxyurea (hu), and thiourea (tu), in various concentrations, were added to chemically defined plant tissue culture medium on which meloidogyne javanica was reared on excised tomato roots. concentrations as low as 3 ppm hu or 12 ppm tu inhibited nematode maturation by 70-90% 4 weeks after inoculation, and the coenocytes in the parasitized tissue were poorly developed. gall weight was also inhibited by 50% in cultures treated with 3 and 6 ppm hu. however, exposing juveniles of m. java ... | 1984 | 19295888 |
| development and evaluation of loop-mediated isothermal amplification assay for rapid detection of tylenchulus semipenetrans using dna extracted from soil. | tylenchulus semipenetrans is an important and widespread plant-parasitic nematode of citrus worldwide and can cause citrus slow decline disease leading to significant reduction in tree growth and yield. rapid and accurate detection of t. semipenetrans in soil is important for the disease forecasting and management. in this study, a loop-mediated isothermal amplification (lamp) assay was developed to detect t. semipenetrans using dna extracted from soil. a set of five primers was designed from th ... | 2017 | 28381965 |
| management of the citrus nematode, tylenchulus semipenetrans. | of the many nematode species that parasitize citrus, tylenchulus semipenetrans is the most important on a worldwide basis. management of the citrus nematode remains problematic as no one tactic gives adequate control of the nematode. an overall management strategy must include such components as site selection, use of non-infected nursery stock, use of at lease one post-plant nematode control tactic, and careful management of other elements of the environment that may stress the trees. nematicid ... | 2004 | 19262822 |
| concentration-time exposure index for modeling soil fumigation under various management scenarios. | best management decisions in soil fumigation require informed management selections of soil type, field geometry, application dosage, and depth to maximize fumigant distribution for efficacy and minimize off-site transport for environmental safety. an efficacy- or exposure-based concentration-time exposure index (ctei) was used to serve as a continuous quantitative efficacy assessment for soil fumigation by subsurface drip irrigation using numerical model simulations. the ctei was defined as the ... | 2006 | 15074821 |
| osmolyte allocation in response to tylenchulus semipenetrans infection, stem girdling, and root pruning in citrus. | previous studies indicated that tylenchulus semipenetrans infection reduced concentrations of inorganic osmolytes, (na, cl, k), in roots, along with leaf k in citrus. however, infection increased leaf na and cl, along with carbohydrates in roots. pruning of roots also increased carbohydrates in intact roots, whereas shoot pruning increased carbohydrates in shoots. carbohydrates are translocated as reducing sugars, which collectively form organic osmolytes. because changes in concentrations of os ... | 2002 | 19265944 |
| changes in arginine, pal activity, and nematode behavior in salinity-stressed citrus. | de novo arginine biosynthesis has been described as a response of citrus to a range of stresses. it is often noted that stress in plants enhances susceptibility to herbivory and pathogenic attack. using a citrus and nematode (tylenchulus semipenetrans) system, the effects of salinity stress on nematode behavior, amino acids (particularly arginine), and phenylalanine ammonia lyase (pal) activity was investigated. the hypothesis was tested that under salinity stress, citrus grows more slowly and p ... | 1998 | 9747539 |
| control of citrus nematode, tylenchulus seimipenetrans, with cadusafos. | granular (rugby 10g) and liquid (rugby 100 me) formulations of cadusafos were evaluated for the control of tylenchulus semipenetrans on mature lemon trees in a commercial citrus orchard at yuma, arizona. three applications of cadusafos, with 2 months between applications, at the rate of 2 g a.i./m(2) reduced nematode populations to undetectable levels and increased the yield and rate of fruit maturity of 'rosenberger' lemons. yields were increased 12,587 kg/ha with rugby 100me and 8,392 kg/ha wi ... | 1996 | 19277185 |
| population changes of tylenchulus semipenetrans under localized versus uniform drought in the citrus root zone. | population development of tylenchulus semipenetrans in dry soil was investigated in a greenhouse study. citrus seedlings were grown in sandy soil in vertical tubes with upper and lower sections. nematode population densities in the upper tubes were measured at 16, 23, and 37 days, post-treatment. three treatments consisted of i) irrigating both tubes when soil water potential reached -1 5 kpa (non-drought), ii) irrigating only the bottom tube (local drought), and iii) no irrigation (uniform drou ... | 1996 | 19277154 |
| sampling citrus fibrous roots and tylenchulus semipenetrans. | sampling precision was investigated for tylenchulus semipenetrans juveniles and males in soil and females from roots and for citrus fibrous root mass density. for the case of two composite samples of 15 cores each, counts of juvenile and male nematodes were estimated to be within 40% of mu, at p < 0.06 (alpha) in orchards where x > 1,500 nematodes/100 cm(3) soil. a similar level of alpha was estimated for measurements of fibrous root mass density, but at a precision level of 25% of mu. densities ... | 1994 | 19279914 |
| influence of aldicarb and fenamiphos on tylenchulus semipenetrans population densities and orange yield. | the effect of aldicarb and fenamiphos on tylenchulus semipenetrans population densities and on orange yield was investigated during a 3-year (1986-88) field trial in italy. rates were 10 and 20 kg a.i./ha as an early spring single application, 5 kg a.i./ha in spring and 5 kg after flowering, and 5 kg a.i. in spring followed by 2.5 kg/ha after flowering and 2.5 kg/ha in early autumn. rates and times of application of the two nematicides did not affect numbers of females of t. semipenetrans on the ... | 1993 | 19279837 |
| responses of tylenchulus semipenetrans to citrus fruit removal: implications for carbohydrate competition. | sixteen mature valencia orange trees on rough lemon rootstock were selected on the basis of approximately equal, naturally occurring populations of tylenchulus semipenetrans in soil. in march, fruit 1 cm in diameter or less were removed from eight of the trees, which were kept free of fruit for 15 months. in july, 4 months after fruit removal, fibrous root (<2 mm d) mass density of defruited trees was 51% greater and insoluble starch in fibrous roots was 24% less than on control trees with fruit ... | 1993 | 19279735 |
| efficient procedure for extracting tylenchulus semipenetrans from citrus roots. | investigations were undertaken to determine the suitability of sucrose and magnesium sulphate solutions and a silica colloidal suspension with centrifugation for extracting tylenchulus semipenetrans from citrus roots. the efficiency of incubation, sodium hypochlorite, centrifugation, and maceration methods was also compared. numbers of females recovered by centrifugation with colloidal silica were greater than those from sucrose or magnesium sulphate. incubation, sodium hypochlorite, and centrif ... | 1990 | 19287763 |
| tylenchulus palustris parasitizing peach trees in the of nited states. | most morphological characteristics of three populations of a tylenchulus sp. from peach roots in alabama, arkansas, and georgia did not differ from those of t. palustris paratypes. however, some mature females differed slightly from those of t. palustris paratypes from florida. these mature females were more swollen in the posterior portion of their bodies, and they possessed digitate postvulval body sections with round rather than conoid termini. these morphological variants had a wide postvulv ... | 1990 | 19287688 |
| application of taylor's power law to sample statistics of tylenchulus semipenetrans in florida citrus. | taylor's power law was fit to tylenchulus semipenetrans population data obtained from individual trees in a survey of 50 florida citrus orchards (geographic survey) and to data from individual trees within a single orchard collected at regular intervals for 2 years (temporal survey). no significant differences were detected between slope or intercept values when log variance was regressed against log mean for the geographic and temporal data sets. the geographic survey was divided into two subse ... | 1989 | 19287677 |
| effect of fenamiphos placement on tylenchulus semipenetrans and yield in a florida citrus orchard. | grapefruit trees on sour orange rootstock on the east coast of florida were treated with 22.3 kg a.i./ha fenamiphos (broadcast equivalent) in 1.52-m bands extending from the dripline to beneath the canopy, in 1.52-m bands extending from the dripline toward the row middle, or left as untreated controls. during the course of the experiment, mean density of feeder roots and tylenchulus semipenetrans in control plots was 3.8 and 5.8 times greater, respectively, in samples from beneath tree canopies ... | 1989 | 19287676 |
| host status of citrus and citrus relatives to tylenchulus graminis. | studies were conducted on the host suitability of four citrus rootstocks--rough lemon (citrus limon), sour orange (c. aurantium), trifoliate orange (poncirus trifoliata cv. argentina), and swingle citrumelo (c. paradisi x p. trifoliata)--to tylenchulus graminis which was previously considered a "grass" race of t. semipenetrans. in an uncultivated field, sour orange seedlings grown with t. graminis-infected broomsedge (andropogon virginicus) were not infected with this nematode after 18-month's e ... | 1989 | 19287668 |
| tylenchulus graminis n. sp. and t. palustris n. sp. (tylenchulidae), from native flora of florida, with notes on t. semipenetrans and t. furcus. | tylenchulus graminis n. sp. and t. palustris n. sp. are described and illustrated from broomsedge (andropogon virginicus l.) and pop ash (fraxinus caroliniana mill.), respectively. t. graminis resembles t. furcus in having a distinct anus, but t. graminis second-stage juveniles (j2) do not have a bifid tail. t. semipenetrans does not have a perceptible anus. the mature female of t. graminis has a mucronate pointed terminus while t. semipenetrans has a smooth and round terminus. t. graminis males ... | 1988 | 19290211 |
| first report of a tylenchulus sp. on peach in alabama, arkansas, georgia, and south carolina. | a tylenchulus sp. found in a georgia peach orchard parasitized peach roots in the greenhouse. citrus roots were not parasitized, indicating that the nematode was not the citrus nematode. morphologically similar populations were found in one peach orchard in alabama, two orchards in arkansas, and one in south carolina. males were present in the alabama populations and one of the arkansas populations. a population was also found in an area of mixed hardwood and pine in arkansas. the populations ar ... | 1987 | 19290292 |
| distribution of tylenchulus semipenetrans in a texas grapefruit orchard. | distribution of the citrus nematode (tylenchulus semipenetrans) was studied over 18 months in a 6-year-old orchard of grapefruit (citrus paradisi cv. ruby red) on sour orange (c. aurantium) rootstock. the 1.8-ha orchard was under chemical weed control, no tillage, and flood irrigation. highest numbers of nematodes were found in the top 15 cm of the soil profile. the nematode population peaked in april and declined to lowest levels in august and september. numbers of nematodes were negatively cor ... | 1984 | 19294028 |
| estimate of yield loss from the citrus nematode in texas grapefruit. | chemical control of the citrus nematode, tylenchulus semipenetrans cobb, has consistently increased yield of grapefruit on sour orange rootstock in texas. in this study, data from chemical control tests conducted from 1973 to 1980 were analyzed to determine the relationship between nematode counts and grapefruit yield and fruit size. the correlation between yield and nematode counts was negative (r = -0.47) and highly significant (p < 0.01). the data best fit the exponential decay curve: y = 160 ... | 1982 | 19295756 |
| characterization of citrus rootstock responses to tylenchulus semipenetrans (cobb). | citrus rootstocks which significantly limited the reproduction of tylenchulus semipenetrans (cobb) "citrus" and "poncirus" biotypes responded to infection by producing a hypersensitive-type response in the root hypodermis, wound periderm and/or cavities in the root cortex, and/or abnormal vacuoles in nurse cell cytoplasm. rootstocks which limited nematode reproduction also had significantly fewer nematodes in the rhizoplane within 8 d of inoculation than did rootstocks which did not limit reprod ... | 1981 | 19300795 |
| a classification of tylenchulus semipenetrans biotypes. | the presence of two biotypes of the citrus nematode (tylenchulus semipenetrans) in italian citrus and olive orchards has been confirmed by comparing host specificity. host reaction to california biotypes c1 and c3 and to three populations from arizona, texas, and florida indicates that of these five united states biotypes, all except c3 consistently fit biotype c1. these findings, and the results of host-range studies in other countries, show that four biotypes of t. semipenetrans are distribute ... | 1980 | 19300704 |
| control of tylenchulus semipenetrans on citrus with aldicarb, oxamyl, and dbcp. | soil application of dbcp (l,2-dibromo-3-chloropropane) and foliar applications of oxamyl (methyl n',n'-dimethyl-n-[(methylcarbamoyl)oxy]-l-thiooxamimidate) were compared for control of tylenchulus semipenetrans in a grapefruit (citrus paradisi) orchard, dbcp reduced nematode populations and increased fruit growth rate, fruit size at harvest, and yield compared to the untreated controls in the 2 years following treatments. foliar applications of oxamyl reduced nematode populations and increased f ... | 1979 | 19300660 |
| the influence of glomus mosseae on tylenchulus semipenetrans-infected and uninfected citrus limon seedlings. | greenhouse studies have shown that when rough lemon (citrus limon) seedlings infected with tyienchulus semipenetrans were transplanted into soil infested with glomus mosseae, the mycorrhizal fungus infection increased seedling growth compared to nonntycorrhizal seedlings. tylenchulus semipenetrans significantly suppressed seedling growth below that of mycorrhizal seedlings. histological observations of nematode-free mycorrhizal roots showed that hyphae penetrated the epidermis and invaded the co ... | 1979 | 19300642 |
| effects of aldicarb and its sulfoxide and sulfone on the biology of tylenchulus semipenetrans. | in laboratory testing, egg hatch of tylenchulus semipenetrans was stimulated at concentrations of 1 and 10 microg/ml aldicarb solution and inhibited at 50 and 100 microg/ml. aldicarb was more inhibitory to egg hatch than the aldicarb sulfoxide and the aldicarb sulfone. inhibition of hatch at the high concentration was associated with delays in the molting processes, lack of larval movement within the egg, and delays in embryonic development. nematode motility was reduced at 10, 50, and 100 micro ... | 1978 | 19305820 |
| comparison of five populations of tylenchulus semipenetrans to citrus, poncirus, and their hybrids. | the infectivity of five populations of tylenchulus semipenetrans were compared and differentiated on 10 hosts (5 citrus spp., 1 poncirus trifoliata, and 4 hybrids of citrus spp. x p. trifoliata). differences in levels of infection and development (p = 0.01) occurred between citrus spp. and p. trifoliata cv. 'pomeroy' and their three hybrids, c. paradisi x p. trifoliata cv. 'swingle' citruntelo and c. sinensis, cv. 'ruby' orange x p. trifoliata cv. 'webber fawcett 14-7', and '15-7'. poncirus trif ... | 1977 | 19305585 |
| control of citrus nematode tylenchulus semipenetrans on fine-textured soil with dbcp and oxamyl. | three grapefruit orchards on sour orange rootstock were treated by metering dbcp (l,2-dibromo-3-chloropropane) at 56 kg(a.i.)/ha into 15 cm of water in a flood irrigation system. in orchards with 43-49% clay in the surface foot, dbcp reduced numbers of tylenchulus semipenetrans below control levels for 1.5-2.0 years. in the 3 orchards, dbcp treatment resulted in increases in yield or fruit size in the 2 seasons following treatment. no increases in yield, fruit size, or fruit numbers were observe ... | 1977 | 19305570 |
| effects of oxamyl on the citrus nematode, tylenchulus semipenetrans, and on infection of sweet orange. | foliar sprays of 4 microg/ml oxamyl on sweet orange trees in a greenhouse slightly depressed the number of tylenchulus semipenetrans larvae obtained from roots and soil, but similar treatments were not effective in two orchards. soil drench treatments decreased the number of citrus nematode larvae obtained from roots or soil of citrus plants grown itt a greenhouse and in orchards. exposure to 5-10 microg/ml of oxamyl in water was lethal to only a few second-stage larvae treated 10 days, and many ... | 1976 | 19308209 |
| the effects of dbcp on citrus root nematode and citrus growth and yield in iraq. | in lraq, treatment of producing citrus trees with a 75% emulsifiable formulation of 1,2-dibromo-3-chloropropane (dbcp), applied in irrigation water at rates of 66-88 kg (a.i.)/hectare, gave excellent control of the citrus nematode (tylenchulus semipenetrans) greatly improved tree vigor, and increased the fruit yield for at least 3 years after treatment. applications made during the spring gave much better results than those made in the fall. | 1975 | 19308170 |
| four biotypes of tylenchulus semipenetrans in california identified, and their importance in the development of resistant citrus rootstocks. | four biotypes (pathotypes) of the citrus nematode, tylenchulus semipenetrans, occurring in california, u.s.a. were differentiated on the basis of differences of infectivity on 'homosassa' sweet orange, 'troyer' citrange, 'pomeroy' and 'rubidoux' poncirus trifoliata, 'thompson seedless' grape, and 'manzanillo' olive. a method for differentiating biotypes of t. semipenetrans is described. field observations indicate that biotypes of this nematode are very stable. the importance of using highly inf ... | 1974 | 19319369 |
| the effect of soil type on movement and infection rate of larvae of tylenchulus semipenetrans. | most of the tylenchulus semipenetrans larvae applied on the surface of four soils in pots 14.5-cm deep moved no further downward than 6.5 crn, and remained in the upper half of the pot. the percentage of second-stage larvae that developed into adult females on 'homosassa' sweet orange in the soils were: sandy loam, 6.8% in the same soil with inoculation holes, 8.6%; loamy sand, 5.4%; coarse sand, 0.2%; and in sand-peat (2:1, v/v)mixture 0.04%. low percentage infection in coarse sand and sand-pea ... | 1974 | 19319368 |
| postplant fumigation with dbcp for citrus nematode control in florida. | eleven citrus groves of diverse varieties and ages infected with tylenchulus semipenetrans growing in differing soils in florida were treated with three rates of 1,2-dibromo-3-chloropropane (dbcp) applied by various means. yield, fruit size, and t. semipenetrans populations in the roots were compared between dbcp-treated and untreated trees over a period of i-3 yr. maximum fruit size and yield were obtained by applying dbcp at 38-58 kg/hectare (ha) (34-52 lb/acre); whereas best nematode control ... | 1974 | 19319363 |
| preplant fumigation for citrus nematode control in florida. | preplant soil fumigation experiments were conducted to control the citrus nematode, tylenchulus semipenetrans. generally, d-d (1,3-dichloropropene, 1,2-dichloroptopane and related chlorinated c(3)-hydrocarbons), telone (1,3-dichloropropene and related chlorinated c(3)-hydrocarbons), telone pbc (80% 1,3-dichloropropene, 15% chloropicrin, 5% propargyl bromide), and edb (ethylene dibromide) controlled t. semipenetrans effectively for 4 years. the trials involved four scion varieties, two rootstock ... | 1973 | 19319312 |
| infectivity of two biotypes of the citrus nematode on citrus and on some other hosts. | the infectivity and development of two biotypes of citrus nematode (tylenchulus semipenetrans) were compared on highly resistant poncirus trifoliata selection 'pomeroy,' moderately susceptible 'troyer' citrange, and highly susceptible sweet orange selection 'homosassa' small seedlings in a glasshouse. biotype-1 was more infective on the above hosts and developed faster on sweet orange and on 'troyer' citrange than biotype-2. the differences in infectivity were interpreted to reflect differences ... | 1969 | 19325669 |