bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and some properties of strawberry mottle virus
Authors: YOSHIKAWA N. , CONVERSE R. H. 
Published: February 2008

SUMMARYStrawberry mottle virus (SMoV) (three isolates: HJ, 3E and N) were transmitted to Chenopodium quinoa plants by sap inoculation. All three isolates induced very similar symptoms consisting of chlorotic spots and ringspots in inoculated leaves, and vein chlorosis, mottling, and dwarfing of the upper leaves. SMoV isolate HJ was purified from infected C. quinoa by homogenisation with 10 mM phosphate buffer, pH 7.2 containing 5% Triton X‐100, followed by differential, sucrose density‐gradient and CsCl equilibrium density‐gradient centrifugations. A fraction with a buoyant density of 1.42g‐ cm‐3 after CsCl density‐gradient centrifugation was highly infectious to C. quinoa and contained many isometric virus‐like particles c. 37 nm in diameter. These virus‐like particles were never found in fractions from uninfected preparations. Electrophoretic analysis of a fraction containing virus‐like particles revealed that these particles might have a single coat protein subunit with the apparent molecular mass of 26 K daltons and one nucleic acid of 6.6 kilobases. Double‐stranded RNA analysis of isolate HJ‐infected or uninfected C. quinoa and Fragaria vesca var. semperflorens seedling line ‘Alpine’ plants showed that both infected plants had two infection‐specific dsRNA bands of mol. wts 4.5 and 3.9 × 106.
Transmission of prunus necrotic ringspot virus using plum pollen and thrips
Authors: GREBER R. S. , KLOSE M. J. , MILNE J. R. , TEAKLE D. S. 
Published: February 2008

SUMMARYPrunus necrotic ringspot virus (PNRSV) was transmitted to cucumber but not to peach seedlings after they were dusted with infective plum pollen and caged with 8–10 thrips per seedling for 24 h. When the pollen was taken from three plum trees shown by mechanical inoculation tests to have highly infective flower buds and pollen, the transmission rates to cucumber seedlings were 56% with Thrips tabaci and 66% with a mixture of five thrips species collected from Ageratum houstonianum flowers. However, the transmission rate averaged only 7% when pollen was taken from five other plum trees which had flowers with less infectivity in sap transmission tests. In 1990 T. imaginis, T. tabaci and T. australis, which were present in the mixture of thrips from A. houstonianum, also formed the major part of the thrips population in flowers of the plum trees used as the pollen source.
Comparison of eight isolates of beet yellows virus by filter hybridisation and enzyme‐linked immunosorbent assay
Authors: MOSELEY J. , HULL R. 
Published: February 2008

SUMMARYAn improved method of virus purification was developed for beet yellows virus (BYV), which resulted in higher virus yields and fewer broken particles than from other methods.Double antibody sandwich enzyme‐linked immunosorbent assay (ELISA) was not able to differentiate eight isolates of BYV, but filter hybridisation analyses, using cloned cDNA from one of the isolates as the probe was successful in distinguishing some of these isolates.The degree of hybridisation did not correlate with the severity of the symptoms associated with infection by isolates. Therefore, hybridisation cannot be used as a means of predicting symptom severity. The hybridisation data also indicated that the isolates consisted of stable mixtures of strains.Cross‐hybridisation of clones derived from one isolate indicated that certain areas of the BYV genome cloned preferentially to other areas.
Control of potato pale cyst‐nematode, Globodera pallida, with a granular nematicide and partially resistant potatoes
Authors: WHITEHEAD A. G. , NICHOLS A. J. F. , SENIOR J. C. 
Published: February 2008

SUMMARYThe effects of oxamyl applied to the seedbed and growing partially resistant potatoes in controlling potato pale cyst‐nematode, Globodera pallida, were assessed in eleven field experiments on sandy, peaty and silty loam soils in England from 1986 to 1988. Standardised procedures allowed valid comparisons to be made between data from the three experiments in 1987 and from the seven experiments in 1988.In soil moderately or heavily infested with G. pallida, oxamyl frequently increased tuber yields of susceptible cv. Désirée and of partially resistant potatoes and lessened crude nematode increase (Pf/Pi) significantly at some sites but not at others. Although 2.8 kg oxamyl ha“1 often increased tuber yields significantly, it was significantly less effective than 5.6 kg in controlling G. pallida at one site and at another site G. pallida increased more than in untreated plots.Potatoes partially resistant to G. pallida were more effective that oxamyl in controlling nematode increase at some sites but not at others. Combined use of oxamyl and partially resistant potatoes was generally more effective in controlling G. pallida than either measure alone. As measured by a ‘control coefficient’ (weight of tubers over 40mm diameter (t ha“1) 4‐crude nematode increase (Pf/Pi)), the most effective integrated control of G. pallida was obtained by growing cvs Glenna, Morag or Santé in soil treated with 5.6 kg oxamyl ha‐1.
Agro‐ecology of onion couch (Arrhenathemm elatius var. bulbosum).
Authors: KHAN AMIN U. 
Published: February 2008

SUMMARYThe agro‐ecology of onion couch (Arrhenatherum elatius var. bulbosum), a well known weed of arable land is studied. Contribution of seeds from onion couch and a more widespread variety of Arrhenatherum elatius: tall oat‐grass, towards future ingress of onion couch in arable fields has indicated that the tall oat‐grass variety is not a potential weed of arable land. It appears that vegetative propagules rather than the seeds are the effective means of propagation of the onion couch variety in arable fields. An experiment performed to test any modifying effect of the soil texture indicated that onion couch is restricted to loamy soils and there is a complete absence from heavy clays and sandy soils. This could be due to the moist and protective micro‐environment provided by the texture of the soils to partially buried vegetative propagules of onion couch, which are susceptible to drought.
Agro‐ecology of onion couch (Arrhenathemm elatius var. bulbosum (Willd.)).
Authors: KHAN AMIN U. , MORTON ALAN J. 
Published: February 2008

SUMMARYThis study investigates the performance of vegetative propagules of onion couch (Arrhenatherum elatius var. bulbosum) of varying sizes during the crop growth cycle; especially trends in tiller and bulb production and crop yield loss. The results suggest that the earlier the crop canopy closes the more suppression it will exert on the bulb formation stage of onion couch and hence its future reproductive potential. The closed canopy provided by a dense crop cut short the bulb formation phase and forced onion couch to invest more in aerial tillers in order to compete and coexist with the taller tillers of the crop. An additive experimental design used here to predict the crop losses indicated that natural infestation of onion couch caused greater crop yield loss compared to artificially planted plots. It was found that, although the regrowth from large aggregates with densely packed bulb chains is reduced by correlative dominance and density dependent mortality, presence of such large aggregates can affect crop yield by interfering with the establishment of crop. The competitiveness and development pattern of onion couch suggests that the recent spread of the weed and the reported variable results of control measures is due to the recent shift in agricultural practices.
Optimum plant densities for three semi‐leafless combining pea (Pisum sativum) cultivars under contrasting field conditions
Authors: HEATH M. C. , KNOTT C. M. , DYER C. J. , ROGERS‐LEWIS D. 
Published: February 2008

SUMMARYYield and yield components of three semi‐leafless pea (Pisum sativum) cultivars, of contrasting seed type/growth habit, were assessed at target planting densities of 40–140 plants/m2 on nine sites over three years. Flat‐topped parabolic/asymptotic yield/density relationships were obtained. The plant density required to maximise (p max) and optimise (p opt) yield differed between cultivars: Helka, small blue, p max 126 plants/m2, p opt 101 plants/m2; Solara, large blue, p max 124 plants/m2, p opt 94 plants/m2; and Countess, white‐seeded, p max 104 plants/m2, p opt 71 plants/m2. Near‐maximum yields were maintained between 70 and 140 plants/m2 due to the ability of the pea crop to make compensatory increases in the number of pods per plant as density declined. Yield/density responses were influenced by site (e.g. soil type) more than by seasonal factors. The risk of yield reductions occurring at densities below 70 plants/m2 was greater on a mineral soil than on a fertile organic soil. On the basis of agronomic and economic considerations, there was no evidence that target plant densities required to optimise yield should necessarily be higher for semi‐leafless cultivars studied than for conventional leafed peas.
A cotyledon double inoculation technique for evaluating resistance to anthracnose (Colletotrichum orbiculare) and scab (Cladosporium cucumerinum) in cucumber
Authors: VAKALOUNAKIS D. J. , WILLIAMS P. H. 
Published: February 2008

SUMMARYA technique for simultaneous inoculation of cucumber cotyledons with Colletotrichum orbiculare race 1 and Cladosporium cucumerinum has been developed. The procedure permitted both resistant and susceptible plants to be recovered. Seedlings were grown at 20°C and inoculated 24 h after emergence with Colletotrichum orbiculare (200 spores in 2 μ1 of water) and Cladosporium cucumerinum (1000 spores in 5 μ1 of water) followed by 48 h of incubation in the dark at 20°C and 100% r.h., and 48 h in a 20°C lighted growth chamber. Seedlings were then moved to a growth chamber at 21°C at night and at 26°C during the day for 4 days and plants were rated as resistant or susceptible 8 days after inoculation. No interference in the expression of resistance or susceptibility of cultivars to either pathogen was detected in simultaneous inoculations.
Pathogenicity and identification of the lilac pathogen, Pseudomonas syringae pv. syringae van Hall 1902
Authors: YOUNG J. M. 
Published: February 2008

SUMMARYComparative in planta studies with Pseudomonas syringae pv. syringae have established optimum conditions for disease expression in lilac in terms of inoculum concentration, host age and post‐inoculation conditions (temperature and day‐length). Reproducible disease reactions required an inoculum concentration exceeding the ED50, 5 × 106 cfu/ml, and a temperature for post‐inoculation incubation not exceeding 19°C. A revised host range of P. syringae pv. syringae, proposed on the basis of confirmation of pathogenicity of strains to lilac, comprises 44 species from monocotyledonous and dicotyledonous plants. Nine new hosts Abelmoschus esculentus, Bromus willdenowii, Camellia sinensis, Centrosema pubescens, Citrullus lanatus, Cotoneaster sp., Cucumis melo, Populus×euramericana and Triticum aestivum, are recorded.A comparative laboratory study was made of strains of P. syringae pv. syringae using more than 30 selected biochemical and nutritional tests. The pathovar could be characterised on the basis of 11 of these which may prove to be useful determinative tests.
Recognition and differentiation of seven whitefly‐transmitted geminiviruses from India, and their relationships to African cassava mosaic and Thailand mung bean yellow mosaic viruses
Authors: HARRISON B. D. , MUNIYAPPA V. , SWANSON M. M. , ROBERTS I. M. , ROBINSON D. J. 
Published: February 2008

SUMMARYParticles resembling those of geminiviruses were found by immunosorbent electron microscopy in extracts of plants infected in India with bhendi yellow vein mosaic, croton yellow vein mosaic, dolichos yellow mosaic, horsegram yellow mosaic, Indian cassava mosaic and tomato leaf curl viruses. All these viruses were transmitted by Bemisia tabaci whiteflies, all reacted with at least one out of ten monoclonal antibodies to African cassava mosaic virus (ACMV), and all reacted with a probe for ACMV DNA‐1, but scarcely or not at all with a full‐length probe for ACMV DNA‐2. Most of the viruses were distinguished by their host ranges when transmitted by whiteflies, and the rest could be distinguished by their pattern of reactions with the panel of monoclonal antibodies. Horsegram yellow mosaic virus was distinguished from Thailand mung bean yellow mosaic virus by its lack of sap transmissibility, ability to infect Arachis hypogaea, failure to react strongly with the probe for ACMV DNA‐2 and its pattern of reactions with the monoclonal antibodies.Structures resembling a ‘string of pearls’, but not geminate particles, were found in leaf extracts containing malvastrum yellow vein mosaic virus. Such extracts reacted with two of the monoclonal antibodies, suggesting that this whitefly‐transmitted virus too is a geminivirus. All seven viruses from India can therefore be considered whitefly‐transmitted geminiviruses.
Further studies on cucumber mosaic virus infection of narrow‐leafed lupin (Lupinus angustifolius): seed‐borne infection, aphid transmission, spread and effects on grain yield
Authors: JONES R. A. C. , PROUDLOVE W. 
Published: February 2008

SUMMARYFour field trials were done with narrow‐leafed lupins (Lupinus angustifolius) in 1988 ‐ 1989, to examine the effect of sowing seed with 5% and 0.5% cucumber mosaic virus (CMV) infection on subsequent virus spread, grain yield and percentage of infection in harvested seed. A proportion of the CM V‐infected seed failed to produce established plants and thus, plots sown with 5% and 0.5% infected seed contained 1.5‐2.9% and 0.2‐0.3% of seed‐infected plants respectively. The rate of virus spread by aphids was faster and resulted in more extensive infection at maturity in plots sown with 5% infected seed than with 0.5% infected seed. In three trials, sowing 5% infected seed resulted in yield losses of 34 ‐ 53% and CMV infection in the seed harvested of 6 ‐ 13%. The spread of CMV infection resulting from sowing 0.5% infected seed did not significantly decrease yield. However, late CMV spread in these plots caused > 1% seed infection. In the fourth trial, which was badly affected by drought, CMV spread only slowly, there was no significant effect of CMV on grain yield and the percentage of infected seed harvested was 3–5 times less than that in the seed sown.When CMV‐infected seed was sown at different depths, target depths of 8 and 11 cm decreased the incidence of seed‐infected plants by c. 15% and c. 50% respectively compared with sowing at 5 cm. However, in glasshouse tests, treatment with the pre‐emergence herbicide simazine failed to selectively cull out seed‐infected plants.The field trials were colonised by green peach (Myzus persicae), blue‐green (Acyrthosiphon kondoi) and cowpea (Aphis craccivora) aphids. When the abilities of these aphid species and of the turnip aphid (Lipaphis erysimi) in transmitting CMV from lupins to lupins were examined in glasshouse tests, short acquisition access times favoured transmission. With 5–10 min acquisition access times, overall transmission efficiencies were 10.8%, 9.4%, 6.1% and 3.9% for the green peach, cowpea, blue‐green and turnip aphids respectively.
A greenhouse technique to screen pigeonpea for resistance to Heterodera cajani*
Authors: SHARMA S. B. , ASHOKKUMAR P. , McDONALD D. 
Published: February 2008

SUMMARY Heterodera cajani is an important nematode pest of pigeonpea in India and a simple and reliable greenhouse procedure has been developed to screen pigeonpea genotypes for resistance to it. In pot experiments, white cysts of H. cajani were counted on the roots of the susceptible genotype ICPL 87 at 15, 30 and 45 days after seedling emergence in soils infested with different levels of H. cajani. The seedlings were rated for the number of white cysts per root system on a one (highly resistant, no cysts) to nine (highly susceptible, more than 30 cysts) scale. White cysts were not easy to see on wet roots but were clearly visible on slightly dried roots. Cyst counts and ratings were more uniform when roots of 30 day old seedlings were evaluated than when 15 or 45 day old seedlings were examined. Effects of different H. cajani infestation levels on the ratings were not significant although the use of higher inoculum densities (16 to 27 eggs and juveniles/cm3 soil) was effective in reducing variability. This procedure was used to screen 60 pigeonpea genotypes and all of them were rated seven or nine. Ten accessions of Atylosia spp. and Rhynchosia spp. were rated three.
The resistance of six potato cultivars to English populations of potato cyst‐nematodes, Globodera pallida and G. rostochiensis
Authors: WHITEHEAD A. G. 
Published: February 2008

SUMMARYSix cultivars of potato (Santé, Morag, Paladin, Glenna and Fingal bred for resistance to both potato cyst‐nematodes (Globodera rostochiensis and G. pallida) and Valiant bred for resistance to G. pallida alone) were exposed to 28 English populations of G. pallida and eight English populations of G. rostochiensis in pots. Susceptible cv. Désirée potatoes served as controls for all 36 populations. Inoculum (Pi) was 12000 eggs in cysts per 400ml pot of soil.Average increase of G. rostochiensis (Pf/Pi) on cv. Désirée was 23.5 but on cvs Sante, Glenna and Fingal it was < 1.0 and on cv. Morag it was 2.2. In contrast, cvs Paladin and Valiant were susceptible (average Pf/Pi = 17.4 and 26.5, respectively).Against G. pallida populations, average Pf/Pi for cv. Désirée was 21.7; on cvs Paladin, Santé and Glenna it was 2.9, 2.6 and 2.4, respectively; cvs Morag and Fingal were less resistant (7.4 and 5.6, respectively) and cv. Valiant was quite susceptible (11.0).Resistance to the different populations of G. pallida and G. rostochiensis varied but for the most resistant cultivars (Santé, Glenna and Paladin) the variation was usually small. The value of the six resistant cultivars studied to the integrated control of potato cyst‐nematodes in England and the genetic diversity of the nematode populations to which they were exposed are discussed.
Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on yield and quality of the cultivated mushroom Agaricus bisporus
Authors: GREWAL P. S. , RICHARDSON P. N. 
Published: February 2008

SUMMARYThirteen species of saprobic rhabditid nematodes (11 genera) were identified from samples of compost and casing material collected from mushroom farms in the British Isles. Caenorhabditis elegans, the most frequently found saprobe, was mass‐produced monoxenically and its effects on the cultivated mushroom, Agaricus bisporus (strain U3) were studied. C. elegans did not multiply in well‐prepared, pasteurised, spawned compost, whereas casing material proved to be a highly suitable environment for its reproduction. An initial casing inoculum of 106 nematodes/crate of compost (7.5 kg), caused a significant reduction in mushroom yield. Losses in total mushroom yields of 11%, 20% and 26% were caused by initial inoculum rates of 106, 107and 2 × 107 nematodes/crate, respectively. Yields were negatively correlated with the initial nematode inoculation level and regression equations were derived. The nematode treatments caused fewer mushrooms to be produced and an absence of the usual distinctive flushing patterns. C. elegans caused considerable deterioration in mushroom quality and characteristic distortion of mushrooms. Individual sporophores were mis‐shapen, notched and had brown or violet coloured grills. Up to 3.8%, 6.7% and 10.8% of total weight and 3.5%, 5.4% and 8% of total numbers of mushrooms were distorted at the three highest nematode inoculum rates tested. Weights and numbers of distorted mushrooms were positively correlated with the initial nematode population. C. elegans commonly colonised sporophores.
The effects of a paclobutrazol‐based growth regulator on the yield, quality and ease of management of oilseed rape
Authors: BAYLIS A. D. , HUTLEY‐BULL P. D. 
Published: February 2008

SUMMARYA mixture of paclobutrazol and chlormequat chloride plant growth regulators (JF10405, Parlay C) was tested on field crops of two ‘double zero’ oilseed rape cultivars in two seasons. Application rate and timing of JF10405 were varied. Very large plots enabled the use of commercial farm equipment to treat and harvest the experiments.Untreated plots showed considerable lodging at harvest in all experiments. Treatment with JF10405 had only small effects on the height of mature plants but, generally, reduced lodging substantially even at the lowest rate tested. All JF10405 treatments increased seed yields, several significantly so, particularly a 2.50 litre/ha rate, although the optimum timing varied between experiments. Seed oil contents were little affected, but levels of glucosinolates were significantly decreased in some instances. Treatments giving good control of lodging also took less time to harvest, especially when cutting against the direction of the lodging. The results‐are discussed in relation to the means by which these improvements in seed yield and quality were achieved, and crop management facilitated.
Variation in the glucosinolate content of oilseed rape (Brassica napus L.) leaves
Authors: DOUGHTY K. J. , PORTER A. J. R. , MORTON A. M. , KIDDLE G. , BOCK C. H. , WALLSGROVE R. 
Published: February 2008

SUMMARYThe glucosinolates are thought to contribute to resistance to pests and diseases in members of the Cruciferae, including oilseed rape (Brassica napus) and they are known to accumulate in Brassica tissues after infestation by various pests. The present study investigated the changes in glucosinolate concentration in leaves of oilseed rape following inoculation with the dark leaf spot pathogen (Alternaria brassicae). Fourth and sixth leaves of the single‐low cultivar Bienvenu (low in erucic acid) and the double‐low cultivar Cobra (low in erucic acid and glucosinolate) were removed at intervals up to twenty days after inoculation and analysed for glucosinolate content using HPLC. Glucosinolates accumulated in inoculated leaves of both cultivars but the accumulation was greater for cv. Bienvenu, especially in sixth leaves. Among the glucosinolates, aliphatic compounds accumulated rapidly in cv. Bienvenu, but later declined. Indolyl and aromatic glucosinolates accumulated in both cultivars, but at a slower rate than the aliphatic glucosinolates. There were differences in the extent to which individual glucosinolates accumulated after inoculation. Disease symptoms were initially more extensive on cv. Cobra than on cv. Bienvenu but were similar on corresponding leaves of the two cultivars by the end of the experiment. However, sixth leaves had significantly less lesioning than fourth leaves. Glucosinolate accumulation in infected oilseed rape may restrict the spread of existing fungal infection or inhibit subsequent attempted infections, especially in younger leaves.