bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and properties of cassava green mottle, a previously undescribed virus from the Solomon Islands
Authors: LENNON ANGELA M. , AITON MAUD M. , HARRISON B. D. 
Published: February 2008

SUMMARYA sap‐transmissible virus obtained from cassava with a green mottle disease occurring at Choiseul, Solomon Islands, was transmitted to 30 species in 12 plant families and was readily seed‐borne in Nicotiana clevelandii. In cassava plants infected by inoculation with sap, the first leaves to be infected systemically developed a mottle with some necrosis whereas leaves produced subsequently were symptomless but contained the virus. Most other species developed chlorotic or necrotic local lesions and systemic mottle or necrosis. This was followed, in several species, by production of small symptomless virus‐containing leaves. The virus was cultured in N. clevelandii; Chenopodium quinoa was used for local‐lesion assays. Leaf extracts from infected N. clevelandii were infective after dilution to 10–5 but usually not at 10–6, after heating for 10 min at 60°C but not at 65°C, and after storage at 20°C for at least 12 days. The virus has isometric particles of 26 nm diameter which sediment as three components, all containing a protein of mol. wt c. 53000. The two fastest sedimenting components respectively contain single‐stranded RNA of mol. wt, estimated after glyoxylation, c. 2.9 × 106 and 2.3 × 106. Both RNA species are needed for infection of plants. In tests with antiserum prepared to purified virus particles, the virus was detected in cassava and N. clevelandii by gel‐diffusion precipitin tests, by immunosorbent electron microscopy and by ELISA. Despite its similarity to nepoviruses, the virus did not react with antisera to 18 members of the group. It was named cassava green mottle virus and is considered to be a previously undescribed nepovirus.
Components of partial resistance as criteria for identifying resistance
Authors: GRIFFITHS HELEN M. , JONES D. GARETH 
Published: February 2008

SUMMARYThe components of partial resistance, incubation period, lesion area, latent period and sporulation were recorded on plants of six winter and two spring wheat cultivars which had been artificially inoculated with Septoria nodorum spores. Incubation period gave a guide as to how the cultivars would respond in the field to Septoria nodorum but statistical analysis showed that it could not be used alone to predict accurately the resistance of each cultivar to the pathogen. Average sporulation, however, could be used with more confidence for predicting the field resistance of the cultivars. From a regression analysis of NIAB rating versus incubation period, lesion area, latent period and sporulation, an equation was devised to obtain resistance indices for each cultivar. These resistance indices clearly reflected the NIAB ratings for the cultivars. It would therefore appear that resistance indices could be used as a pre‐field evaluation method for identifying resistance to Septoria nodorum and thus be a valuable technique in breeding programmes.
Propagation of lettuce (Lactuca sativa) breeding material by tissue culture
Authors: PINK D. A. C. , CARTER PHILIPPA J. 
Published: February 2008

SUMMARYA tissue culture method using Murashige and Skoog's (MS) medium was devised to propagate healthy plants from field grown lettuce plants selected for seed production. Explants (2–3 mm long) from axillary buds were successfully grown on MS + 1.0 or 2.0 mg litre‐1 kinetin and 6.4 mg litre‐1 IAA to promote shoot growth. Concentrations of 0.5 and 4.0 mg litre‐1 kinetin gave poor shoot growth. The cultures were successfully rooted after 3–4 wk on MS + 6.4 mg litres‐1 IAA after transfer from MS + 1.0 mg litre‐1 kinetin and on MS + 4.8 mg litre‐1 IAA after transfer from MS + 2.0 mg litre‐1 kinetin. Concentrations of 3.2 and 8.0 mg litre‐1 IAA gave poor root initiation. Root initiation was more successful when cultures were grown at 40 Wm‐2 than in cultures grown at 5 Wm‐2. Rooted cultures were established in compost with a 90–95% success rate and the regenerated plants flowered c. 18 wk after the cultures were initiated.
Tiller development and flowering in swards of Bmchiaria decumbens
Authors: STUR W. W. , HUMPHREYS L. R. 
Published: February 2008

SUMMARYSwards of Brachiaria decumbens were burnt and the development of tillers emerging 5 (T5) or 10 (T10) days later was studied. The stages of raceme initiation, spikelet initiation, spikelet differentiation and inflorescence exsertion occurred in 50% of tillers c. 14.5, 21, 26.5 and 59 days after tiller emergence respectively. Growth of T5 tillers was faster than that of T10 tillers, and raceme initiation occurred when T5 tillers were slightly longer and heavier than T10 tillers, making the external identification of early development events unreliable. Attention is directed to the large variability in the development of tillers emerging on the same day and to the need for better synchrony of raceme initiation as a basis for increased uniformity of inflorescence exsertion.
Migration of alate morphs of the bird cherry aphid (Rhopalosiphum padi) and implications for the epidemiology of barley yellow dwarf virus
Authors: TATCHELL G. M. , PLUMB R. T. , CARTER N. 
Published: February 2008

SUMMARYSuction trapping data indicate three periods of migration of Rhopalosiphum padi in spring, summer and autumn. Four alate morphs are present at different times during the year. A comparison of data from suction traps operating at 12·2 and 1·5 m suggests a different behaviour of females in autumn with more being recorded at 12·2 than 1·5 m. Males, which are only present in autumn, were also more numerous at 12·2 m. During tests to measure barley yellow dwarf virus (BYDV) infectivity, only 9% of female R. padi reproduced on oat seedlings in autumn compared with 74% in summer. Tests on alate female R. padi trapped alive showed that in summer all were exules, but during the first half of September these were largely replaced by gynoparae so that in autumn only 5% of all R. padi trapped at 12·2 m were alate exules. The aerial densities of gynoparae and males were 10 times greater at 12·2 than 1·5 m while densities of alate exules were similar at both heights. It is suggested that gynoparae and males fly higher to increase the chance of finding a taller dispersed host plant.The implications for BYDV epidemiology of the behaviour and presence of the various R. padi alate morphs indicate that autumn‐sown cereals emerging before mid‐September are particularly at risk from colonisation by alate exules before the transition to a mainly sexual migrant population is complete. Alate exules introduce BYDV from comparatively local sources. The ratio of total R. padi to Sitobion avenae in suction trap samples in autumn usually exceeds 100: 1, but on crops it was only 10: 1. The ratio of alate exule R. padi to S. avenae in suction traps in autumn was only 12: 1, similar to that observed on crops.
Factors affecting the efficacy of methyl bromide fumigation to control Liriomyza trifolii in imported chrysanthemum cuttings
Authors: MORTIMER E. A. , POWELL D. F. 
Published: February 2008

SUMMARYLaboratory investigations were made into the effect of cultivar type, prior cold storage, fumigation temperature and methyl bromide concentration, on the efficacy of a fumigation treatment to control Liriomyza trifolii in chrysanthemum cuttings. The tests related to the standard quarantine treatment used in the UK to control Spodoptera littoralis on imported chrysanthemum cuttings: cold storage for 2 days at 1 – 2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3. L. trifolii larvae, within detached leaves, and 1 – 2 and 2 – 3 day old pupae, were treated. Methyl bromide concentrations of 6·75 or 13·5 g/m3 were used to achieve a range of CTPs and thus obtain accurate dose‐response lines and estimates of the LD99 and LD99·9 for each insect stage. Fumigation temperatures were 8, 11 or 15°C.Efficacy of the standard treatments differed between the three cultivars tested, but the LD99 for larvae remained below 54 g h/m3. Decreasing fumigation temperature to 11°C or less increased LD99 values for larvae and pupae and substantially increased variability. There is therefore little scope for using fumigation temperatures of less than 15°C for quarantine purposes. Omitting the cold storage treatment prior to fumigation did not significantly affect efficacy of fumigation. Reducing the methyl bromide concentration from 13·5 to 6·75 g/m3 did not significantly affect the LD99 for larvae but significantly reduced LD99s for pupae.
The short‐term effects on birds and mammals of the use of chlorpyrifos to control leatherjackets in grassland
Authors: CLEMENTS R. O. , BALE J. S. 
Published: February 2008

SUMMARYThe impact on birds and mammals of treating two grass fields in Devon and Yorkshire with chlorpyrifos (Dursban 4*) to control leatherjackets was assessed. Both fields had leatherjacket populations in excess of 3 million/ha.Samples of leatherjackets and earthworms were collected for chlorpyrifos residue analysis at intervals before and after spraying. Samples of leatherjackets and earthworms, were also obtained for residue analysis from a nearby unsprayed field, 7 and 10 days after the day on which the treated field was sprayed.Observations of birds and mammals were made for 2 h at dawn and dusk, on two days before spraying and on six occasions afterwards. Several species of birds, many of which appeared to feed on leatherjackets brought to the surface by chlorpyrifos treatment, and three species of mammals were observed in the treated fields. Some of the bird species, e.g. magpie and carrion crow, together with hares were present frequently and it is probable that the fields were part of their feeding territories and that the same individuals were returning to feed at frequent intervals. At least some of the birds, e.g. starlings and carrion crows appeared to feed on leatherjackets. None showed any immediate sign of abnormal behaviour and the consistent reappearance of the territorial species during the study period suggests there were no longer‐term effects.Thorough searches were made of the field, its hedgerows and ditches for dead birds and animals on seven occasions. None was found.
Dispersal of Rhynchosporium secalis conidia from infected barley leaves or straw by simulated rain
Authors: FITT B. D. L. , McCARTNEY H. A. , CREIGHTON N. F. , WALKLATE M. E. LACEYP. J. 
Published: February 2008

SUMMARYSimulated rain (mean drop diameter c. 1 or 3 mm) was allowed to fall for 10 – 15 min on to barley leaves or straw infected by Rhynchosporium secalis (leaf blotch). The leaves were supported on a mesh through which run‐off water drained and the straw was supported on a rigid surface on which run‐off water collected. The numbers of R. secalis conidia and spore‐carrying splash droplets collected by horizontal samplers (microscope slides and pieces of photographic film) decreased rapidly with increasing distance from and increasing height above the sources, with half‐distances of 2 – 10 cm. Less than 10% of the spores or droplets reached heights of more than 30 cm. Incident drops 3 mm in diameter produced more spore‐carrying droplets and dispersed more conidia than did 1 mm drops. The size category of splash droplets with the greatest proportion of the spore‐carrying droplets dispersed by 3 mm drops was 200 – 400 μm, whether the source was infected barley leaves or barley straw. For leaves or straw the greatest proportions of spores were carried in droplets > 1000 μm in diameter. The mean diameter of spore‐carrying droplets (478 μm) dispersed from free‐draining leaves was less than that of droplets from straw plus run‐off water (563 μm). However, the leaf source had more spores cm‐2 and the mean number of spores per droplet was greater (113 as opposed to 6·8) than for the straw source.
Confirmation of the transmission of barley yellow mosaic virus (BaYMV) by the fungus Polymyxa graminis
Authors: ADAMS M. J. , SWABY A. G. , JONES P. 
Published: February 2008

SUMMARYResting spores (cystosori) of Polymyxa graminis, selected from roots of barley plants infected with barley yellow mosaic virus (BaYMV), were used to start mono‐fungal sand cultures. Out of 20 attempts using over 800 cystosori, P. graminis became established in 12, and in two of these BaYMV symptoms also occurred.BaYMV was detected by ELISA in extracts of dried roots heavily infected with cystosori and in zoospores of P. graminis. Calculations suggested that, on average, each zoospore carried less than 100 virus particles.In two virus acquisition experiments, non‐viruliferous isolates of P. graminis failed to acquire BaYMV from roots of mechanically‐inoculated plants. In two further experiments, non‐viruliferous isolates were grown on rooted tillers produced from healthy plants and those infected with BaYMV by either vector or mechanical inoculation. Zoospores and cystosori of P. graminis subsequently transmitted the virus, but only from plants where it had been introduced by the vector. Repeated mechanical transmission appeared to have selected a strain of virus that could not be acquired and/or transmitted by the vector.The results provide convincing evidence that P. graminis is a vector of BaYMV but suggest that, in natural populations, only a small proportion of spores may be viruliferous.
Quantitative methods for detecting invertebrate predation occurring in the field
Authors: SUNDERLAND K. D. 
Published: February 2008

SUMMARY

Brief descriptions are given of methods that can be used either to determine the mortality caused by a complex of predators to a single target prey species or to quantify the diet of a single target predator species.
The following methods can be used quantitatively; direct observation, field caging, recovery of labelled prey, electrophoresis, single radial immunodiffusion, rocket immunoelectrophoresis, enzyme‐linked immunosorbent assay.
The following methods have potential for quantitative use; faecal analysis, gut dissection, tube precipitin test, ring test, Oakley‐Fulthorpe test, crossed immunoelectrophoresis, crossover immunoelectrophoresis, fluorescence immunoassays.
The following tests are likely to remain qualitative; chromatography, double‐diffusion, immunofixation, standard immunoelectrophoresis, latex agglutination, passive haemagglutination inhibition assay, complement fixation test.
Examples are given of the use of these tests in predation studies.
Precautions associated with the use of these methods are described.
Various equations are reviewed for estimating predation rates using data on predator density, proportion positive and detection period in post‐mortem tests.
There are limitations to the use of all current methods. Direct observation and field caging are of restricted application and often involve disturbance to the system being studied. Faecal analysis and post‐mortem methods can confuse scavenging and secondary consumption with predation and they measure biomass ingested rather than number of prey killed or injured. Recovery of labelled prey has the faults of all these methods.
Potential new techniques are described for determining, from an examination of its gut contents, what a predator has eaten, when it ate it and in what quantity.
The relationship between the Andean strain of potato virus S and pepino latent virus
Authors: DOLBY CHRISTINE A. , JONES R. A. C. 
Published: February 2008

SUMMARYThe titres obtained in microprecipitin tests with purified preparations of pepino latent virus (PepLV) and the Andean strain of potato virus S (PVSA) using PepLV antiserum and two antisera to the ordinary strain of PVS (PVS°) indicated a close serological relationship between PepLV and PVSA. Using antiserum to PVS°, both viruses were detected by ELISA when infective Chenopodium quinoa sap was diluted to 10‐5but not to 10‐6. Particles of both viruses were decorated equally well by antibodies to PVSo, PVSAand PepLV in all virus‐antiserum combinations. When PepLV was inoculated to C. quinoa, C. amaranticolor and potato plants, the symptoms induced closely resembled those of PVSAin these hosts. It is concluded that PepLV is an isolate of PVSAfrom pepino.
Concentration of virus and ultrastructural changes in oats at various stages of barley yellow dwarf virus infection
Authors: EWEIDA M. , OXELFELT P. , TOMENIUS K. 
Published: February 2008

SUMMARYEnzyme‐linked immunosorbent assay was used to monitor the concentration of barley yellow dwarf virus (BYDV) in roots and leaves of oats inoculated at the 1 ‐ 2 leaf stage and at the 4 ‐ 5 leaf stage, respectively. Virus was detectable 20 h after inoculation in the roots and after 48 h in the leaves of plants inoculated at the 1 ‐ 2 leaf stage. The virus concentration reached a plateau in the roots after 7–8 days, and was 3–4 times higher than in the leaves. In plants inoculated at the 4 ‐ 5 leaf stage virus was detectable in roots and leaves after 3 and 5 days, respectively. The concentration reached a maximum after 10 days in the roots and after 18 days in the leaves; the concentration in the leaves was 2–3 times higher than in the roots.Virus was readily detectable in seeds from infected plants, both fresh and old dried seeds. However, seed transmission could not be demonstrated.Virus‐like particles were first observed in phloem cells of roots 4 days after inoculation, but no ultrastructural changes were detected at this stage. After 5–6 days, disintegrated nuclei and virus‐induced vesicles were observed in many cells and abnormal production of callose was found after 10 days. Necrotic phloem cells were observed from day 13, shortly after the appearance of external symptoms.
Methods and strategies for detecting Solanum tuberosum dihaploids in interspecific crosses with S. phureja
Authors: CALIGARI P. D. S. , POWELL W. , LIDDELL K. , MAINE M. J. DE , SWAN G. E. L. 
Published: February 2008

SUMMARYThe frequency of dihaploid production following the interspecific pollination of Solanum tuberosum clones with Solanum phureja has been investigated. Seventeen hybrid combinations were tested and the crosses differed significantly in the number of seed produced, the proportions that were viable and the proportions that were dihaploid. The overall frequency of dihaploid production was 62%. The dominant embryo spot marker of the pollinator (IVP 48) in conjunction with seed diameter was used to classify the seed samples. Number of days taken to germinate was also recorded. It was therefore possible to examine retrospectively the effect of selecting sub‐sets of the seed based on the presence or absence of the embryo spot, seed size and germination time. A seed selection system based on the absence of the embryo spot in conjunction with seed greater than 1.25 mm in diameter resulted in 93.6% of the potential dihaploids being identified.
The fate of Datura ferox seeds in the soil as affected by cultivation, depth of burial and degree of maturity
Authors: BALLARÉ C. L. , SCOPEL L. , GHERSA C. M. , SÁNCHEZ R. A. 
Published: February 2008

SUMMARYSeeds of Datura ferox were collected in soybean fields, grouped into four categories according to the degree of fruit maturity and placed just level with the soil surface or buried to a depth of 7 or 15 cm. Seed survival after 8 months was c. 30% when the seeds were left on the soil surface, but between 40 and 90% when the seeds were buried. The riper seeds were the more persistent. A similar pattern was observed after 20 months. Seedling emergence was negatively related with the degree of seed maturity and depth of burial, but it was never great enough to explain seed losses.In another experiment seeds from ripe capsules were superficially sown and the soil was: (0) left undisturbed, (1) cultivated in late winter or (2) cultivated in late winter and late spring. In all cases there was a small flush of seedlings at the beginning of the first spring; other flushes occurred only after soil cultivation and were larger during the second spring than during the first. In the plots cultivated twice a year (2) the seedlings that emerged in the first spring represented c. 4% of the initial seed bank. Survival after 20 months was about 25% in all treatments. In an arable field under soybean cropping the seedling flushes during the spring months were related to the pattern of soil cultivation. The seedlings that emerged after crop drilling represented c. 18% of the seed bank (estimated before drilling). Implications for weed management are discussed.
The effects of soil conditions, soil sterilisation and seed treatmen on the emergence of cabbage in controlled temperature cabinets and the field
Authors: WHITE J. G. 
Published: February 2008

SUMMARYPrevious cropping history of the soil and the changes that occurred in soil moisture content and temperature were the major factors determining the emergence of cabbage seedlings from pathogen‐free seeds. Seedling losses caused by soil‐borne pathogens could be high but these losses were prevented by seed treatment with metalaxyl or soil sterilisation with methyl bromide prior to sowing. The beneficial effects of metalaxyl and methyl bromide treatments were confirmed in field experiments involving repeated sowings of cabbage seeds.In experiments with sterilised soil and cabbage seed infected with Alternaria brassicicola emergence at – 0·2 bars soil moisture potential was reduced by 7·8–23.5% at 5, 10, 20, and 25°C. In the field, losses due to A. brassicicola were greatest when the soil became capped after sowing.The results show that recently developed fungicides may facilitate emergence under conditions extremely favourable for seed‐ and soil‐borne pathogens. For maximum benefit, selection of seed treatments should be based on knowledge of the range of pathogens likely to reduce emergence.
Time of sowing and temperature effects on the flowering of Stylosanthes guianensis
Authors: TRONGKONGSIN K. , HUMPHREYS L. R. 
Published: February 2008

SUMMARYSeedlings of Stylosanthes guianensis var. guianensis cv. Cook and of two selections of S. guianensis var. pauciflora (CIAT 1280 and CIAT 1062) were grown at day/night temperatures of 20°/25°, 30°/25°, and 35°/30°C in a naturally‐lit glasshouse at latitude 27°30'S. Sowings were made in decreasing daylength at 30‐day intervals from 22 January to 21 May.Cv. Cook and the CIAT 1280 selection did not flower fully if sown after 22 January and the CIAT 1062 selection did not flower if sown after 22 March. This is interpreted as a long‐short day flowering response. Usually, flowers were initiated earlier and at a lower node at 25†/20°C than at the warmer temperatures. At 25†/20°C the first flowers to appear were produced predominantly at the terminal apex of the main stem in cv. Cook and the CIAT 1062 selection, but not in the CIAT 1280 selection. At the two warmer temperatures first flowers were more commonly produced at the terminal apex of primary, secondary and tertiary branches. There were more inflorescences per plant on earlier than later sown plants when measured 21 days from appearance of the first flower and the most inflorescences were produced by cv. Cook at 25†/20°C, by selection CIAT 1062 at 30°/25°C, and by CIAT 1280 at 35°/30°C.