bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host range, purification and properties of potato virus T
Authors: SALAZAR L. F. , HARRISON B. D. 
Published: February 2008

SUMMARYPotato virus T (PVT) infected nine species of tuber‐bearing Solanum, most of them symptomlessly, and as a rule was transmitted through the tubers to progeny plants: two genotypes of S. tuberosum ssp. andigena were not infected. The virus was also transmitted by inoculation with sap to 37 other species in eight plant families. Chenopodium amaranticolor is useful as an indicator host, C quinoa as a source of virus for purification, and Phaseolus vulgaris as a local‐lesion assay host; the systemic symptoms in Datura stramonium, Nicotiana debneyi and in these three species are useful for diagnosis. Attempts to transmit PVT by aphids failed, but the virus was transmitted through seed to progeny seedlings of four solanaceous species, and from pollen to seed of S. demissum.PVT was purified by clarifying sap with n‐butanol or bentonite, followed by precipitation with polyethylene glycol, differential centrifugation and sedimentation in a sucrose density gradient. Purified preparations had an E260/E280 ratio of 1.18 and contained a single infective component with a sedimentation coefficient of 99 S. This component consisted of flexuous filamentous particles of about 640 times 12 nm that showed a characteristic substructure when stained with uranyl acetate. The virus particles contained a single species of infective single‐stranded RNA, of molecular weight 2–2 times 106 daltons, and a single species of polypeptide of molecular weight about 27 000 daltons.PVT is serologically related to apple stem grooving virus but not to four other common potato viruses with flexuous filamentous particles. Apple stem grooving virus and PVT cause similar symptoms in several hosts, but also differ somewhat in host range and symptomatology. Apple stem grooving virus did not infect potato, caused additional symptoms in C. quinoa also infected with PVT, and its particles did not show the structural features specific to PVT. The two viruses are considered to be distinct. The cryptogram of PVT is R/1:2–2/(5): E/E: S/C.
The virulence characteristics of Bremia lactucae populations present in Sweden from 1971 to 1976
Authors: WELLVING A. , CRUTE I. R. 
Published: February 2008

SUMMARYOne hundred and four Swedish isolates of Bremia lactucae were tested between 1971 and 1976 for their virulence phenotypes. Eighty of these isolates showed patterns of virulence previously recorded in other countries while the remainder conformed to seven previously unreported virulence factor combinations. The simplest resistance factor combination that could give resistance to all isolates collected was R2 plus Rl 1.This combination now exists in some recently bred lettuce cultivars. Most of the possible virulence factor combinations occurred in the population at the expected frequency. However, several combinations, which had not been directly selected (by the growing of cultivars carrying the comparable resistance factor combinations) were present at higher or lower than expected frequencies.
Studies on plant growth‐regulating substances
Authors: WILKINS SHEENA M. , WILKINS HENRY , WAIN R. L. 
Published: February 2008

SUMMARYRoots of Pisum seedlings grown in a compact silt loam soil (bulk density 1–5 g/cm3) were shorter than those of seedlings grown in loose soil (bulk density 1 ? 1 g/cm3). Incorporating 3,5‐dibromo‐4‐hydroxybenzoic acid (DBHB)or 3,5‐dichloro‐4‐hydroxybenzoic acid (DCHB) into the compact soil enhanced root elongation and decreased root bending. DBHB was more effective than DCHB in promoting pea root growth but a much higher concentration was required for optimal activity. Shoot height was increased by DCHB treatment of the compact soil but DBHB had little effect. In loose soil, significant effects were detected only at high concentrations, when DBHB promoted and DCHB inhibited the root growth of pea seedlings.Although development of barley seedlings in compact soil was enhanced by DCHB, that of wheat seedlings was inhibited by this treatment.
Extent of disease in populations of Heterodera, with especial reference to H. schachtii
Authors: TRIBE H. T. 
Published: February 2008

SUMMARYAnalysis was made of the extent of disease in 112 populations of Heterodera schachtii, comprising 88 populations of cysts obtained from soil samples and 24 populations of females and cysts taken from host roots. Overall, some 14% of full cysts taken from soil were diseased, although much variation was found. About half of the cysts were substantially and half partially diseased. Where beet monoculture had long been practised, overall disease was approximately doubled. Less than 50% of diseased cysts were parasitised by recognised egg pathogens and nearly the same proportion showed symptoms of lysis, coagulation or decay, the causes of which could not be ascertained. The remainder contained unexamined or miscellaneous fungi and a few showed oily degeneration. Disease in 10 populations of cysts from roots was higher than in cysts from soil. In females from roots it was especially variable, for most diseased females were invaded by one or two specific fungal pathogens in whose absence all were healthy. Examination of six populations of Heterodera avenae indicated the extent and nature of disease was not dissimilar from that in H. schachtii.The pathogens, which were all fungi, and the disease symptoms of uncertain origin found in cysts and females of H. schachtii are briefly summarised.
Preliminary observations on variation in susceptibility to clubroot among collections of some wild crucifers
Authors: BUCZACKI S. T. , OCKENDON J. G. 
Published: February 2008

SUMMARYCollections of Capsella bursa‐pastoris and other common cruciferous weeds showed significant differences in susceptibility to populations of Plasmodiophora brassicae as defined on the European Clubroot Differential (ECD) set. Some evidence was obtained that selection for tolerance may occur within natural populations of C. bursa‐pastoris. Overall virulence of P. brassicae collections on the ECD set was not correlated with virulence to the weeds tested. The significance of wild hosts in studies of resistance to P. brassicae is discussed.
Feral pigeon damage to field beans
Authors: LAWSON H. M. 
Published: February 2008

SUMMARYFeral pigeon (Columba livia) feeding behaviour and its effect on crop growth and yield of field bean (Viciafaba) sown at three depths is described. By digging up seeds and destroying seedlings, pigeons reduced plant populations by over 95% on plots sown at 1–6 cm depth and by over 50% on plots with seeds at 2–2 cm in comparison with plant populations on plots sown at 2–9 cm. The pigeons returned at harvest time and caused varying levels of crop loss depending on plant density and especially on the degree of lodging of the crop. The results are used to illustrate the need to consider potential bird damage as a factor when changes in husbandry systems are being developed.
Studies on the tolerance of Erysiphe graminis f. sp. hordei to systemic fungicides
Authors: WALMSLEY‐WOODWARD DIANNE J. , LAWS F. A. , WHITTINGTON W. J. 
Published: February 2008

SUMMARYSuccessive sowings of glasshouse‐grown barley plants were treated with either tridemorph, ethirimol or both fungicides, and inoculated with an initially fungicide‐sensitive isolate of Erysiphe graminis f. sp. hordei. The time taken for symptoms to appear, compared with that for untreated plants, decreased with successive sowings. This was interpreted as evidence for the increase in the frequency of fungicide‐tolerant propagules in the pathogen population.Effective mildew control was obtained by the use of either or both fungicides in trial plot and field crops. Seedling assays for tolerance to tridemorph and ethirimol showed that tolerance was more evident in treated than in untreated crops in June. Some mildew populations partially tolerant to one fungicide also showed reduced sensitivity to the other. By July a response intermediate between tolerant and sensitive was recorded on all the plots, probably indicating the mixing of fungal populations from adjacent plots. Larger numbers of tolerant isolates were found in random samples from treated than from untreated crops.
Effect of temperature on competition amongst strains of Rhizobium trifolii for nodulation of two white clover varieties
Authors: HARDARSON G. , JONES D. GARETH 
Published: February 2008

SUMMARYThe effect of temperature and soil type on the relative success in nodulating cultivars of white clover (Trifolium repens) by mixtures of antibiotic‐resistant mutants of Rhizobium trifolii was studied.Under aseptic test‐tube culture, 75 str nodulated the plants 5 days earlier than 33 spc at the lowest temperature, but the temperature ×Rhizobium strain interaction was not significant. 33 spc was more effective than 75 str at 25°C and, although no significant difference was found between the two mutant strains at the lower temperatures, die temperature ×Rhizobium strain interaction was highly significant.In soil, when inoculated with mixed inoculum, cv. S100 was more uniformly nodulated by 75 str (81%) than S184 (49%). Success in nodulation could be altered by temperature and the temperature × bacterial strain interaction was significant. In the mixed inoculum treatments, 75 str was most compatible with S100 at 12°C, whereas 33 spc was most compatible with SI84 at 25°C; the bacterial strain × variety × temperature interaction was highly significant.The results are discussed from the point of view of improving symbiotic nitrogen fixation by selecting effective strains of Rhizobium which are compatible with the particular host cultivar, which are competitive with the indigenous population and whose optimum temperatures for nodulation and competitiveness are similar to the soil temperature at the times of inoculation.
The dispersal of Ditylenchus dipsaci with vegetable seeds
Authors: GREEN C. D. , SIME S. 
Published: February 2008

SUMMARY Ditylenchus dipsaci was found in 36–45% of seed stocks of broad beans, red beet and carrots examined, in 14–17% of those of shallots and runner beans, and in less than 3% of those of peas, onions and leeks. None was found in any samples of chive and dwarf (French) bean seed. There was a tendency for seed stocks to be very lightly or very heavily infested so that small samples would be adequate to identify the stocks most likely to introduce stem eelworm. Seed from all sources whether merchant or farmer was equally likely to be infested and a difference in infestation between varieties was found only for broad bean. Judging by samples tested for export the risk of distributing D. dipsaci with onion seed seems to have decreased since 1968 so that there is more risk of introducing it with other crops grown before onions.
Aggregated distribution of Ditylenchus dipsaci on broad bean seeds
Authors: GREEN C. D. 
Published: February 2008

SUMMARYThe distribution of Ditylenchus dipsaci (Kühn) Filipjev between seeds in infested samples of broad bean seed was skewed so that the nematodes were concentrated on a few seeds. Such aggregation increases the likelihood of reproduction by the nematodes in infested plants and the consequent establishment of foci of infestation in the soil. These foci will be small and scattered giving the nematode the best chance of a finding a favourable environment in the field. The numbers of foci of infestation introduced by seed tend to be nearly constant, independent of the numbers of nematodes on the seed and therefore provide a stable unit of population.
The origins of weed beet
Authors: HORNSEY K. G. , ARNOLD M. H. 
Published: February 2008

SUMMARYSamples of weed beet were collected from two fields in Norfolk, one in which they had been present for several years and could have evolved from normal sugar beet varieties, and another in which the weed beet were thought to have arisen more recently, through contamination of a monogerm variety. The samples were grown to maturity and used as mother plants in test crosses with monogerm O‐type (non‐restorer lines. Observations on the mother plants and on the progenies of the test crosses, with respect to the occurrence of the monogerm gene and of cytoplasmic male sterility, were consistent with the hypothesis that weed beet can arise by evolution from bolting plants in uncontaminated seet lots, as well as from seed lots that have been contaminated with annual forms of Beta vulgaris. This conclusion is important in relation to the need for implementing agronomic control measures for weed beet, as well as for eliminating the risk of releasing contaminated seed lots.
Efficacy of carboxin and heat treatment for controlling the growth of Sclerotium rolfsii during culture of the mushroom Pleurotus flabellatus
Authors: RAJARATHNAM S. , SINGH N. S. , BANO ZAKIA 
Published: February 2008

SUMMARYSoaking paddy straw for 18 h in a carboxin suspension in water (5 mg a.i./l) effectively controlled the growth of Sclerotium rolfsii occurring as a natural contaminant in paddy straw, during culture of the mushroom Pleurotus flabellatus. Carboxin at this concentration delayed sporophore formation by 2–3 days, but did not affect total yield. No detectable carboxin residues were found in the mushrooms grown on the treated paddy straw. Treatment of the paddy straw with hot water at 60°C for 10 min completely controlled the contaminant without affecting mushroom growth and yield; but 20 mm treatments with hot air at 60°C or heating with the steam to 75–80°C did not control S. rolfsii.
The inheritance of preference for strains of Rhizobium trifolii by white clover (Trifolium repents)
Authors: HARDARSON G. , JONES D. GARETH 
Published: February 2008

SUMMARYThe preference or selection of Rhizobium strains by both parental and F1 white clover plants was studied using antibiotic resistant mutants of Rhizobium trifolii.Highly significant differences were found between crosses in their preference for 75 str. Progenies from crosses between plants in which the preference for 75 str was 90–100% had 85% of the nodules inhabited by that strain. Progenies of crosses between plants in which the preference for 75 str was less than 50% had only 13% of their nodules inhabited by 75 str. Intermediate values were found for progenies from other crosses. The inheritance for this particular character was clearly additive and without any dominance or maternal effect.The results are discussed from the point of view of improving symbiotic nitrogen fixation by breeding white clover for uniform preference for effective strains of R. trifolii.
Vigour control, an integrated approach to cane, pest and disease management in red raspberry (Rubus idaeus)
Authors: WILLIAMSON B. , LAWSON H. M. , WOODFORD J. A. T. , HARGREAVES A. J. , WISEMAN J. S. , GORDON S. C. 
Published: February 2008

SUMMARYThe first flush of young canes of red raspberry (Rubus idaeus) was removed at different dates in spring, using the contact herbicide dinoseb. In comparison with untreated plots, cane removal increased fruit yield, controlled excessive cane vigour, and improved the health status of vegetative canes in a plantation infested by raspberry cane midge (Resseliella theobaldi). At the end of the growing season vegetative canes on treated plots were shorter and thinner, and sustained less physical injury than those on untreated plots. Access to the fruit at harvest was also improved. Reduced competition between fruiting and vegetative canes increased yield in the year of treatment by an average of 35%. Yield was not affected by date of cane removal, but growth of replacement cane was reduced below optimum when first flush cane was removed after mid‐May.The later the canes were removed, the less was the incidence of pest and diseases. Cankers and lobate vascular lesions (‘patches’) resulting, respectively, from the feeding of first and second generation midge larvae (with associated fungi) affected fewer canes in treated than in untreated plots. Significantly fewer live larvae of R. theobaldi were recovered in the following winter from soil in plots treated on or after 11 May than from untreated plots. The main effect of vigour control on R. theobaldi and midge blight was that replacement canes provided fewer egg‐laying sites (natural splits) than did the first flush canes on untreated plots. The incidence of spreading vascular lesions (‘stripes’) attributed to Leptosphaeria coniothyrium infecting either physical wounds (cane blight) or midge feeding wounds (midge blight) was substantially less in treated than untreated plots. Cane botrytis (Botrytis cinerea) and spur blight (Didymella applanata) were also less common in treated plots.Interactions between vigour control and pest and disease incidence are discussed in relation to the efficient management of cv. Glen Clova in eastern Scotland.
Effects of fungicides and surfactants on the zoospores of Olpidium brassicae
Authors: TOMLINSON J. A. , FAITHFULL ELIZABETH M. 
Published: February 2008

SUMMARYLettuce big‐vein disease is transmitted from diseased to healthy plants by zoospores of the lettuce root‐infecting fungus Olpidium brassicae. A laboratory technique based on microscopical examination of Olpidium Zoospores is described for assaying the toxicity of chemicals to zoospores.Chemcials found to kill zoospores in <1 h included copper (4 μ/ml), zinc (10μ/ml), diluted preparations of carbendazim (methyl‐2‐yl‐benzimidazole carbamate) as Bavistinand a formulation of Bavisitin containing no carbendazim. Bavistn controlled the disease when introduced at a concentration of 0.6 g/litre into a lettuce crop grown in a re‐circulated film of nutrient.Various surfactants inlcuding Agral, Cetrimide, Deciquam, Ethylan CPX, Hyamine 1622, Manoxol/OT and sodium lauryl sulphate were toxic to zoospores at concentrations of 1–10 μ/ml.
Application of iprodione by thermal fogging for the control of grey mould of tomato
Authors: MORGAN W. M. 
Published: February 2008

SUMMARYA ready‐to‐fog' formulation of iprodione applied with themal foging equipment was a satisfactory alternative to high‐volume (HV) sparys of iprodione for the control ofnatural infecton with grey mould (Botrytis cinerea) in an unheated tomato crop. There were no significant differences in numbers of droped fruit nor in the control of naturally‐occurring lesions in stems or leaves, nor of ghost‐spotting on fruit, between the HV sprays and fogs applied every fortnight. Except for ghost‐spotting, control by fogs applied weekly was better than by eihter for nightly treatment. In contrast, the control of infection from B.cinerea inoculations on peitoles was significantly better by the fortnightly HV treatment than by either frequency of foging. Control of infection imporved with increase in the number of fungicide applications to the peitole before inoculation; two HV sprays gave complete control but six fog applications did not. The variation in the conrrol of infection by fogs and presumbly therefore in the distribution of fungicide within the 61 m2 glasshouse compartments was small. Application of the iprodione fogging formulation significantly reduced the number of fruits see by about 5% compared with the HV treatment.
A strain of guniea grass mosaic virus naturally occurring on maize in the Ivory Coast
Authors: LAMY D. , THOUVENEL J.C. , FAUQUET C. 
Published: February 2008

SUMMARYDuring a survey of cereal crops in Ivory Coast, a virus wiht flexuous filamentaous paricles c. 825 nm long was isolated from diseased maize. Its host range, biological properties, morphology and aphid transmission place it in the potyvirus group. Antigenically it is closely related to guinea grass mosaci virus, from which it differs in hos range, aphid transmissibility and behaviouir on isoelectric focusing. It is named guinea grass mosaic virus strain B.
The control of voulunteer potatoes in the autumn in cereal stubbles.
Authors: LUTMAN P. J. W. 
Published: February 2008

SUMMARYThe emergence of volunteer potatoes and their regrowth after the cereal harvest were studied in four barley crops. Cutting the shoots of the potato plants before or during cereal harvest did not prevent regrowtth of many of them afer harevet. There was more regrowth (i) after winter barley, (ii) after barley grown at above normal seed rates and (iii) when the early growth of the potatoes in May an June ws suppesed by dry conditions. In one experiment the number of emerged plants on 12 May was negatively correlated with the number of emerged plants on 12 May was negatiely correlated with the number regrowing in September. These studies suggest that control of volunteer potatoes may be possible with foliar applied herbicides after cereal harvest.
The Control of volunteer potatoes in the autumn in cereal stubbles.
Authors: LUTMAN P. J. W. 
Published: February 2008

SUMMARYMany of the volunteer potato plants present in two winter barley crops continued to grow after the cereal harvest. Aminotriazole applied to this regrowth resulted in 50–69% fewer potato plants emerging in the year following treatment. Glyphosate gave better control, averaging 72% in one experiment and 88% in the other. Few of the potato plants regrew after harvest of two spring barley crops and with the same two herbicides over 70% of the tubers survived. Herbicide response was not affected by dose (glyphosate 0.5‐3.0 kg/ha and aminotriazole 1.5‐4.0 kg/ha). With adequate time for the potatoes to start regrowing after harvest (3–4 wk), there was no improvement in performance from further delay. The potential use of these two herbicides in cereal stubbles for groundkeeper potato control is discussed
Acetylene reduction assay on white clover genotypes and on grass/clover swards
Authors: CONNOLLY V. , O'KEEFFE M. 
Published: February 2008

SUMMARYAcetylene reduction assay was used to measure the nitrogenase activity of white clover genotypes in pots and of grass/clover swards in situ. Much of the variation in nitrogenase activity of single genotypes and hybrid populations was associated with plant dry weight. After adjustment for plant dry weight it was concluded that there was limited scope for selection for increased nitrogenase activity. In plant breeding this technique would seem to have greatest application in the selection for continued nitrogen fixation activity in the presence of inhibitory factors such as high levels of mineral nitrogen.The in situ studies revealed differences in nitrogenase activity of grass/clover swards based on contrasting cultivars of white clover. These differences were due to variation in clover density and also to variation in activity per unit clover dry weight. It was concluded that the variation in nitrogenase activity per unit dry weight reflected differences in growth pattern of the cultivars in the autumn when these assays were made.The in situ studies offer a means whereby the nitrogenase activity of cultivars and selected families can be monitored under varying levels of mineral nitrogen and other husbandry treatments without disruption of the sward.
Doubling of onion bulbs as affected by size and planting date of sets
Authors: RABINOWITCH H. D. 
Published: February 2008

SUMMARYThe effect of size of sets and planting dates on the frequency of double bulbs was investigated with two early onion cultivars. The two cultivars varied significantly in their performance, with the cv. Beit‐Alfa being more prone to doubling than the cv. Ori. Bulbs developing from large sets produced more shoots per bulb and showed a higher percentage of doubling in the field. Environmental conditions changing with planting dates significantly affected the tendency for axillary shoot development. The effect of genotype and environmental conditions on doubling is discussed.