bluuebunny/crossref_metadata_2025_split huggingface dataset:
The distribution of immature thrips among flowers of faba beans in commercial crops and experimental plots
Authors: STODDARD F. L. 
Published: February 2008

SUMMARYNumbers of eggs and larvae of thrips {Kakothrips pisivorus (Westw.)) infesting pistils of various stocks of faba beans (Viciafaba L.) were recorded in different environments. By the end of flowering in spring beans, 25 times as many flowers were infested with, on average, twice as many thrips, as at the onset of flowering in winter beans. Within each of two seasons, levels of infestation varied up to 30‐fold with location. At a single location, some bean stocks were much more heavily infested (greater proportions of flowers contained thrips and/or greater numbers of thrips per infested pistil) than others. Levels of infestation were not clearly associated with the closed‐flower character (cf). Stocks with lush growth were more heavily infested than those with either generally restricted growth or with terminal inflorescences (ti). Those with white flowers, long pods or cytoplasmic male‐sterility were more infested than those which contrasted for these three characters. The path of the pollen tubes was blocked by eggs of thrips in less than 0–5% of flowers. Infestation had no apparent effect on the fertilisation of flowers.
Studies of the infection of the winged bean by Synchytrium psophocarpi in Papua New Guinea
Authors: DRINKALL M. J. , PRICE T. V. 
Published: February 2008

SUMMARYInfection of leaves and stems of Psophocarpus tetragonolobus by Synchytrium psophocarpi only occurred following spray inoculation of motile zoospore suspensions and incubation for a minimum of 12 h in polyethylene bags or a mist chamber. The incubation period was 7 days and generation time 22 days at temperatures of 31 oC max, 24 oC min and r.h. of 90% max, 70% min. Young, 1–2 day‐old leaves were most susceptible; there was no infection on 10 day‐old leaves and susceptibility was not increased by the removal of leaf waxes.No infection occurred when plants were grown from seed from infected pods, seed inoculated with zoospores or sporangia and seed sown in soil containing infected leaf debris. Resting spores were not found in infected tissues stored for 12 wk or in plant debris. S. psophocarpi did not infect Arachis hypogaea, Glycine max, Phaseolus aureus, P. coccineus, P. vulgaris, Pisum sativum, Psophocarpus scandens, Vicia faba, Vigna sesquipedalis and V. unguiculata. S. minutum did not infect winged bean.Inoculation confirmed the susceptibility of the winged bean lines UPS 62, UPS 122, UPS 126 and resistance of two Thai winged bean lines 1602/1 and 1611/2.
A comparison of the level of resistance in diploid Triticum monococcum and hexaploid Triticum aestivum wheat seedlings to the aphids Metopolophium dirhodum and Rhopalosiphum padi
Authors: SPILLER N. J. , LLEWELLYN M. 
Published: February 2008

SUMMARYResistance to the aphids Metopolophium dirhodum and Rhopalosiphum padi was assessed by measuring adult weight, development time and fecundity on seedlings of three ‘ancient’ diploid wheat lines (Triticum monococcum) and four ‘modern’ hexaploid wheat cultivars (T. aestivum). Adult weight and fecundity were consistently greater on the hexaploid cvs but development time and the intrinsic rate of increase were less affected. Unvernalised seedlings formed the basis of a screening method, the results of which showed the same pattern as already published studies using older plants.
Inheritance of adult plant resistance to mildew in oats
Authors: JONES I. T. 
Published: February 2008

SUMMARYAdult plant resistance of a durable nature in oat cv. Maldwyn was studied in a cross with the very susceptible cv. Selma, using a replicated F3 population grown under field conditions. Segregation was found to be continuous, with no discrete classes, and a preponderance of segregants showing intermediate values between the two parents indicating additive genetic control. The number of effective genetic factors segregating in this cross was estimated to be four when material was at the ‘boot stage’ (G.S. 45) and eight or nine at the stage when flowering was complete (G.S. 69). At this latter stage Maldwyn was estimated to be contributing about seven factors for resistance, and the susceptible Selma one or possibly two.Further improvement, through accumulation of factors from both parents, could be expected and this has subsequently been achieved.The possible effects, on the durability of resistance in highly resistant transgressive segregants, from increased selection pressure on the pathogen are discussed.
Comparison of sampling methods for alate aphids and observations on epidemiology of soybean mosaic virus in Nanjing, China
Authors: HALBERT SUSAN E. , ZHANG GUANG‐XUE , PU ZU‐QIN 
Published: February 2008

SUMMARYUsing standard diversity indices, samples of aphids collected on a vertical net were found to be more diverse than collections from green pan traps in experiments conducted in Nanjing, China in 1981. Some species, notably Myzuspersicae, Aphis citricola, and Eriosoma (Schizoneura) japonicum, were collected in greater relative numbers in the pan traps. Several species, including the Macrosiphoniella spp., were under‐represented in the green pan traps presumably because they were not attracted to the green colour of the traps. Yellow pan traps, used concurrently to monitor landing rates of economic species, caught relatively more Aphis craccivora and M. persicae and relatively fewer Aphis gossypii than green ones.In the Nanjing area soybean mosaic virus (SMV) usually spreads in spring planted soybeans during the latter half of May, causing damage. The predominant aphid species trapped at that time were M. persicae, Lipaphis erysimi, A. gossypii, A. craccivora and E. japonicum, of which the first four are known vectors. Summer planted soybeans are usually affected during a second period of virus spread occurring in mid‐August when various Aphis spp. are abundant. The predominant vector of SMV at that time was thought to be Aphis glycines which colonises the crop; in 1981, however, A. citricola and A. gossypii, which do not colonise soybean and A. craccivora. which rarely colonises soybean, were much more abundant in mid‐August than A. glycines. A. citricola, A. gossypii and A. craccivora are all able to transmit SMV, and thus should be considered as potentially important vectors. In infectivity assays, only four of 1040 aphids transmitted SMV. These included an A. craccivora, two Toxoptera citricidus and one Aphis sp.
The quantitative assessment of arthropod predation rates by electrophoresis
Authors: FITZGERALD JEAN D. , SOLOMON M. G. , MURRAY R. A. 
Published: February 2008

SUMMARYThe development of an electrophoretic technique for the quantitative assessment of specific prey material in the gut of a predator is described. Panonychus ulmi and Tetranychus urticae were used as test prey species. Samples prepared from these mites were electrophoresed on polyacrylamide concentration gradient slab gels, which were then treated to reveal esterase activity. The relationship of intensity of a stained band with sample concentration and staining time was not linear for some esterases. Possible causes of this non‐linearity were identified but could not readily be eliminated. However, quantitative assessment of prey material is possible after the preparation of a calibration curve.
Epidemics of Phymatotrichum root rot (Phymatotrichum omnivorum) in cotton: environmental correlates of final incidence and forecasting criteria
Authors: JEGER M. J. , LYDA S. D. 
Published: February 2008

SUMMARYEpidemics of Phymatotrichum root rot (PRR), caused by Phymatotrichum omnivorum, in cotton were monitored in field plots at the Blackland Research Center, Temple, Texas during the years 1969–1982. In most years disease incidence, assessed at periodic intervals during the growing season, increased smoothly and levelled off at values in the range 0–04‐0‐99 (proportion of plants killed). During two years there were marked increases in PRR late in the growing season. Increments in PRR were associated with preceding increments in precipitation but only when the latter were large. The final incidence of PRR late in August was directly related (in all but one of the 14 years) to cumulative precipitation in the range 36–100 cm, and inversely related (in all 14 years) to air temperatures greater than 34 oC. Regression was used to relate final PRR incidence to derived weather variates but the equations obtained did not provide a realistic basis for forecasting: the best predictive variates included cumulative precipitation up to mid‐August. A threshold criterion given by P/T > 1·45, where P was cumulative precipitation (cm) from 1 January and T was the mean maximum temperature (°C) during the preceding 10 days, was derived. This criterion satisfactorily grouped years with high (>0·;50) and low (<0–50) incidences of PRR. In those years where a forecast of high incidence was made, the criterion was satisfied prior to the first appearance of PRR (mid‐June); where a forecast of low incidence was made, the criterion was not satisfied until late August. The forecasting criterion was evaluated at three sites in the Blacklands region in 1983, at two in 1984, and at Temple only in 1985. In 1983 and 1984, final PRR incidences of less than 0–50 were forecast and observed; in 1985, cumulative annual precipitation exceeded 50 cm by early June, the threshold criterion was satisfied prior to the first observation of symptoms, and PRR incidence was 0–80 late in August.
Restricted distribution of potato leafroll virus antigen in resistant potato genotypes and its effect on transmission of the virus by aphids
Authors: BARKER H. , HARRISON B. D. 
Published: February 2008

SUMMARYEnzyme‐linked immunosorbent assay was used to measure the concentration of potato leafroll virus (PLRV) antigen in different parts of field‐grown secondarily infected plants of three potato genotypes known to differ in resistance to infection. The antigen concentration in leaves of cv. Maris Piper (susceptible) was 10–30 times greater than that in cv. Pentland Crown or G 7445(1), a breeder's line (both resistant). Differences between genotypes in antigen concentration were smaller in petioles and tubers (5–10‐fold) and in above‐ground stems (about 4‐fold), and were least in below‐ground stems, stolons and roots (about 2‐fold). PLRV antigen, detected by fluorescent antibody staining of tissue sections, was confined to phloem companion cells. In Pentland Crown, the decrease in PLRV antigen concentration in leaf mid‐veins and petioles, relative to that in Maris Piper, was proportional to the decrease in number of PLRV‐containing companion cells; this decrease was greater in the external phloem than in the internal phloem. The spread of PLRV infection within the phloem system seems to be impaired in the resistant genotypes.Green peach aphids (Myzuspersicae) acquired < 2800 pg PLRV/aphid when fed for 4 days on infected field‐grown Maris Piper plants and < 58% of such aphids transmitted the virus to Physalis floridana test plants. In contrast, aphids fed on infected Pentland Crown plants acquired <120 pg PLRV/aphid and <3% transmitted the virus to P. floridana. The ease with which M. persicae acquired and transmitted PLRV from field‐grown Maris Piper plants decreased greatly after the end of June without a proportionate drop in PLRV concentration. Spread of PLRV in potato crops should be substantially decreased by growing cultivars in which the virus multiplies to only a limited extent.
An alternative method of flax retting during dry weather
Authors: SHARMA H. S. S. 
Published: February 2008

SUMMARYDuring exceptionally dry and hot weather undesiccated flax (Linum usitatissi‐murri) and flax desiccated with glyphosate that was pulled and laid on the ground to dew‐ret, retted 1–2 wk before flax that was desiccated and left as a standing crop. This was because dew‐retted flax was colonised by fungi faster than that left standing. Cladosporium herbarum, Epicocum nigrum and yeast, including Aureoba‐sidium pullulans, appeared first; they were followed by Alternaria alternata, Fusarium culmorum and Phoma, Mucor and Rhizopus species. The standing crop retted more slowly despite the presence of greater concentrations of cell‐wall degrading enzymes. However, the fibres of flax retted as a standing crop retained more of their strength than those of flax retted on the ground. Thus dew‐retting provides means of retting when the weather is dry and hot.
Radiation absorption and growth of Viciafaba under shade at two densities
Authors: KASIM K. , DENNETT M. D. 
Published: February 2008

SUMMARYFaba beans were grown under various shading treatments at densities of 20 and 60 plants m‐2. The amount of PAR absorbed by each treatment was estimated from measured leaf area index. The conversion factor (E, g MJ‐1) relating dry matter production to absorbed PAR increased as shading increased. Application or removal of shade changed E rapidly, though there was some evidence for an increased value of ɛ persisting after removal of shade. Differences in dry matter production between the two years were due to as much to differences in ɛ as to changes in the amount of light absorbed. Increased plant density increased PAR absorbed but hardly affected e.
Changes in peel pigmentation during ripening of mango fruit (Mangifera indica var. Tommy Atkins)
Authors: MEDLICOTT A. P. , BHOGAL MOHINDER , REYNOLDS S. B. 
Published: February 2008

SUMMARYThe pigments in the peel of Tommy Atkins mango were analysed at six stages during ripening at 22 oC. The loss of green colour and the development of yellow colouration was associated with an almost complete loss of chlorophyll and an increase in carotenoids. Anthocyanin content showed a slight decrease during ripening. An ultrastructural study showed plastids in green fruit with a well developed grana network system. On ripening the chloroplasts underwent extensive disorganisation which was associated with the development of large osmiophilic globules.
A rain tower and wind tunnel for studying the dispersal of plant pathogens by rain and wind
Authors: FITT B. D. L. , WALKLATE P. J. , MCCARTNEY H. A. , BAINBRIDGE A. , CREIGHTON N. F. , HIRST J. M. , LACEY M. E. , LEGG B. J. 
Published: February 2008

SUMMARYThe rain tower/wind tunnel complex at Rothamsted consists of a rain tower (height 11 m, cross‐section 1 m2) linked to the upwind end of a wind tunnel (length 12 m, cross‐section 1 m2), which may be operated in either an open or a closed configuration. At the top of the rain tower, water drops with diameters of 2.5 to 5 mm are produced by a drop generator, which can be fitted with different nozzles. Simulated rain with a drop diameter of 1 to 3 mm is produced at a rate of 8 to 12 mm h‐1 by a rain generator with an area of 52 × 67 cm. The rain tower may be operated in conjunction with the wind tunnel in an open configuration. The windspeed can be decreased from a maximum of 8 m s‐1 by decreasing the speed of the fan. The wind tunnel has its own internal lighting. When the wind tunnel is in a closed configuration, temperature and humidity can be controlled in the range 12 oC (62–80% r.h.) to 35 oC (22–50% r.h.). Data presented illustrate the use of this rain tower/wind tunnel complex to study dispersal of plant pathogen spores by rain‐splash or wind.
A comparison of methods of seed tuber inoculation for assessing the susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica) in the field
Authors: LAPWOOD D. H. , READ P. J. 
Published: February 2008

SUMMARYExperiments were done with the aim of developing a reliable method for assessing the susceptibility of potato cultivars to blackleg caused by Erwinia carotovora subsp. atroseptica, in the field. Over four years seed tubers were either stab‐inoculated at the heel‐end prior to planting, vacuum infiltrated with bacteria just after harvest or vacuum infiltrated prior to sprouting and after ‘cutting’ or ‘pricking’.Stab inoculation produced fewer diseased plants but generally a greater range of symptoms than vacuum infiltration. Vacuum infiltrated ‘cut’ seed gave most disease whereas infiltration at harvest and infiltration of ‘pricked’ seed gave similar disease incidence. The cultivar Maris Piper was more resistant than Desiree in 1981 and 1982, and Pentland Javelin than Ulster Sceptre in 1983 and 1984, largely irrespective of the inoculation treatment. Irrigation improved yields but did not affect disease symptoms.In further field experiments over three years, each with a minimum of 20 cultivars, seed tubers were sliced just before planting at a standard distance from the apex and inoculated by applying a pad impregnated with inoculum. Differences were shown between cultivars and it is suggested that the method could be adapted for testing for blackleg susceptibility under controlled environment conditions.
Purification and properties of lucerne Australian symptomless virus, a new virus infecting lucerne in Australia
Authors: REMAH A. , JONES A. T. , MITCHELL M. J. 
Published: February 2008

SUMMARYA virus with isometric particles c. 26–28 nm in diameter isolated from naturally infected lucerne (Medicago sativa) in Australia and reported there to be a strain of lucerne Australian latent virus (LALV), is shown to be a distinct virus. The virus, called lucerne Australian symptomless (LASV), was mechanically transmitted to 10 of 22 plant species inoculated, but only induced symptoms in three Chenopodium species and Gomphrena globosa. Virus particles occurred in relatively low concentrations in plant sap, and the virus could not be reliably maintained in culture by serial transmission to plants during winter (October‐April). During the summer, sap of infected C. quinoa remained infective after diluting 10‐2 but not 10‐3, after heating for 10 min at 50 but not 55 oC and after storage for 24 days (the longest period tested) at 20, 4 and ‐15 oC. LASV was seed‐borne to 6% of C. quinoa seedlings. Partially purified preparations of virus particles contained one nucleoprotein component with a sedimentation coefficient of c. BOS. Particles contained two polypeptide species of estimated mol. wts 26 000 and 40 000, and two ssRNA species which, when denatured in glyoxal, had apparent mol. wts of 2–5 times 106 and 1–4 times 106. The infectivity of virus RNA was abolished by incubation with proteinase K. Purified particles of LASV reacted with homologous antiserum (gel diffusion titre 1:256) but not with antiserum to LALV or to 13 other plant viruses with isometric particles including arracacha B (AVB), broad bean wilt, rubus Chinese seed‐borne (RCSV) and strawberry latent ringspot (SLRV) viruses, and five comoviruses.These properties distinguish LASV from LALV and from all recognised nepoviruses and comoviruses. Its closest affinities are with SLRV, RCSV and possibly AVB; these viruses may comprise a distinct virus group or nepovirus subgroup.
Inheritance of resistance to yellow rust (Phragmidium rubi‐idaei) in red raspberry
Authors: ANTHONY VIVIENNE M. , WILLIAMSON: B. , JENNINGS D. L. , SHATTOCK R. C. 
Published: February 2008

SUMMARYThe inheritance of resistance in red raspberry (Rubus idaeus) to yellow rust (Phragmidium rubi‐idaei) was studied in a diallel cross among the cultivars Boyne, Meeker, Mailing Jewel, Glen Prosen and Glen Clova. The progenies and clonally propagated parents were exposed initially in a rust‐infected plantation where the incidence and severity of infection was assessed at the telial stage. The following spring leaves on new canes of the same plants were inoculated with urediniospores in a glasshouse at 18 ± 2 °C. The latent period and number of uredinia per cm2 of abaxial leaf surface were determined 13 and 18 days after inoculation. Cv. Boyne developed only chlorotic flecking on inoculated leaves in the glasshouse and no sporulation was observed. It is postulated that this reaction was determined by a major gene which is designated Yr. Some of the other parents showed incomplete resistance of the slow rusting type, and segregants of Boyne selfed that were susceptible also showed low levels of rust, which suggests that Boyne carries both major‐ and minor‐gene resistance. Diallel analyses of both the field and glasshouse data from the susceptible segregates indicated that the degree of incomplete resistance present was determined predominantly by additive gene action, though small but significant non‐additive effects also occurred: cv. Meeker was the most resistant parent and contributed the most resistance to the progenies.The Meeker progenies also segregated for gene H, which determines cane hairiness and is known to be associated with resistance to other diseases. Segregants without hairs (genotypes hh) were found to be the more resistant to rust.
The capture efficiency of the Dietrick vacuum insect net for aphids on grasses and cereals
Authors: HAND S. C. 
Published: February 2008

SUMMARYThe capture efficiency of the Dietrick vacuum insect net (D‐vac) for cereal aphids on grasses and cereals was investigated in the field and laboratory. Capture efficiency varied between different aphid species and instars and different plant species, age and density. Numerous other factors probably also affect its capture efficiency. Despite this variability, the D‐vac is suitable for determining population structure of aphids and for detecting alatae. It may also remain the only method to obtain some quantitative measurements of populations of insects at low densities.
Epidemics of take‐all during 16 years of continuous spring barley
Authors: HORNBY D. , HENDEN D. R. 
Published: February 2008

SUMMARYIn 1969 spring barley was the third consecutive cereal crop following a mixed rotation, which included cereals, on a sandy‐loam at Woburn, Beds. The incidence (42%) of roots with take‐all was approximately eight times greater than in any of the next 11 crops of an ensuing spring barley monoculture. Until 1981 it was assumed that the peak of take‐all in 1969 represented the terminal phase of the epidemic that preceded take‐all decline and that the subsequent low level of take‐all was a consequence of take‐all decline. In 1981 a secondary outbreak of take‐all infected 12% of roots and in the next two years 16% and 27.5% of roots were infected, but in 1984 the disease resumed a very low incidence (0.6% of roots infected) which characterised most of the 1970s.The most probable number of infectious fragments per 150 cm3 of soil was determined by bioassay on 115 occasions. The maximum recorded was 36.5 in June 1969 and the most recorded in the secondary outbreak was 29.7 in July 1983. From early 1971 to mid‐1981 the numbers were always under five and mostly less than one per 150 cm3. Soil collected in mid‐August 1969 after harvest was most infectious (50 roots infected per 190 cm3 of soil) in bioassays and thereafter until mid‐1981 there were never more than 6.5 infected roots per 190 cm3 of bioassay soil. Soil infectivity in the second epidemic never matched that of the first, peaking at 23 roots infected in 190 cm3 of soil in early July, 1983.Take‐all on a silty clay loam, 13 km to the east at Silsoe, was prevalent in a third spring barley in 1973. Its decline to very little in a seventh crop in 1977, was interrupted in 1975 by a slight, temporary recovery also recorded at Woburn. Although changes in cultivars, nitrogen rates and sowing dates may have accounted for some of the changes in disease it is suggested that the polyetic epidemic that began in spring barley monoculture at Woburn in the late 1970s and entered its terminal phase in 1983 was weather‐determined and reflected a general, long‐term, trend in the UK and Ireland.