bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of darkness on the uptake and movement of diquat and paraquat in tomatoes, sugar beet and potatoes
Authors: BRIAN R. C. 
Published: February 2008

SUMMARYUptake of diquat and paraquat was doubled and occasionally quadrupled when tomatoes were darkened after treatment. The increase was not directly related to the duration of darkness because, after a time, uptake decreased. Three possible explanations for this decrease are considered, namely: diquat exudation from the leaves, downward movement into the roots and the complexing of diquat in plant tissue. Evidence was against exudation from leaves and downward movement into the roots.Diquat activity also depends on its degree of movement in the plant but the possible influence of other factors is discussed when treatments are made in the afternoon or in the morning after a period of reduced light intensity.In a CO2‐free atmosphere, uptake and activity increased in light and were comparable to those in darkness. Uptake is therefore not impeded by phyto‐toxic effects of diquat but possibly by the presence of a high concentration of solutes or by photosynthetic intermediates.
Sampling for aphids by traps and by crop inspection
Authors: HEATHCOTE G. D. , PALMER J. M. P. , TAYLOR L. R. 
Published: February 2008

SUMMARYThe catches of thirty aphid genera and species during 3 years in a suction trap at 40 ft and on a yellow cylindrical sticky trap at 5 ft at Rothamsted and Broom's Barn are tabulated. Suction‐trap catches were the more consistent but both were more effective at recording the first seasonal immigration of Myzuspersicae (Sulz.) and Aphis fabae Scop, than the British Sugar Corporation crop‐inspection scheme.The catches show the differential attraction to yellow by different species, the effects of local vegetation, and the seasonal distribution of aphids that are crop pests or potential vectors of viruses.
Purification, serological relationships and some characteristics of plum line‐pattern virus
Authors: PAULSEN AVELINA Q. , FULTON R. W. 
Published: February 2008

SUMMARYPlum line‐pattern virus (PLV) was purified by homogenizing inoculated leaves of Nicotiana megalosiphon in 0·02 M phosphate buffer, pH 8·0 (1·5 ml/g leaf), containing 0·02 M 2‐mercaptoethanol. The homogenate was centrifuged at low speed and the supernatant liquid was clarified by adjusting the pH to 4·8 with 0·1 M citric acid. The green coagulum was removed by centri‐fugation and the extract adjusted to pH 6·5. After concentrating the virus by high‐speed centrifugation, remaining host protein was precipitated with the gamma‐globulin fraction of antiserum to N. megalosiphon protein. Purification was completed with two cycles of high‐ and low‐speed centrifugation.Purified PLV had an A260/A280 ratio of c. 1·7 and formed two zones when centrifuged in density gradients at pH 6·0–7·0. The virus was about 30 mμ in diameter in negatively stained preparations. The particles were easily disrupted. PLV was closely serologically related to cultures of plum line‐pattern virus from other areas, but no relationship was found to apple mosaic, Prunus necrotic ringspot or prune dwarf viruses, or to a plum line‐pattern virus from Denmark.
Effects of infection by Phytophthora injestans (Mont.) de Bary on the stomata of potato leaves
Authors: FARRELL G. M. , PREECE T. F. , WREN M. J. 
Published: February 2008

SUMMARY Phytophthora injestans infection of potato leaves causes abnormal opening of the stomata in the tissue colonized by the fungus before sporangiophores emerge through them. The affected area, which may be up to 7 mm wide, extends from the necrotic tissue to within 1–2 mm of the advancing edge of the colonizing mycelium. These stomata open wider than those in uninfected parts of the leaf, and do not close in the dark, but closure can be induced experimentally by a high water deficit. Affected guard cells have an increased osmotic value, reduced starch content, and show degradation of the chloro‐plasts. No direct infection of the guard cells has been observed. Autoradiography of infected leaflets which had been exposed to 14CO2 in the light, showed that a zone of increased photosynthesis occurs in the region of wide‐open stomata.
Survival of the causal agents of ‘early‐dying disease’ (Verticillium wilt) of potatoes
Authors: HARRISON J. A. C. , ISAAC IVOR 
Published: February 2008

SUMMARYAlthough the isolation of Verticillium albo‐atrum and V. dahliae from soil and dried moribund stems following infection of a potato crop proved extremely difficult, both fungi were equally capable of overwintering in these substrates and of inducing disease in a subsequently planted susceptible crop. In the absence of a susceptible crop some weed species became colonized.The two species, however, appeared to differ in their capacity for survival both beneath a monocotyledonous crop and within the potato tubers. Colonization of the roots of wheat, barley, oats, rye and maize was observed with V. dahliae but not with V. albo‐atrum. The latter appeared to be capable of prolonged survival in the tubers, whereas V. dahliae did not remain viable in storage over winter. Consequently only tubers infected with V. albo‐atrum produced infected plants.The presence of the fungi within the tubers affected neither dormancy nor the initial development of the sprouts. Some correlation was noted between tuber size, the percentage of tubers infected, the distribution of V. albo‐atrum within the tubers and the development of disease in plants subsequently grown from these tubers.
Inherited resistance of sugar beet to aphid colonization
Authors: Lowe H. J. B. , Russell G. E. 
Published: February 2008

SUMMARYResults of glasshouse experiments have confirmed that inbred lines of sugar beet differ in each of three types of resistance to Myzus persicae Sulz. and Aphis fabae Scop., namely: resistance to settling, resistance to multiplication, and tolerance. Resistance to multiplication was not invariably associated with resistance to settling, although plants of some lines showed both forms of resistance. Plants that were resistant to settling of alatae were not always resistant to apterae of the same species, and there was not a close relationship between resistance to M. persicae and to A. fabae. The mechanisms involved in resistance to aphids in sugar beet are not understood.Progenies of plants, selected for resistance to aphids from inbred lines, were often more resistant than progenies of unselected plants. Inheritance of each type of resistance is probably polygenic. The potential value of the different kinds of resistance, in reducing direct feeding damage and controlling the spread of virus yellows in the field, is discussed. The ultimate breeding objective is to produce commercial varieties in which appropriate kinds of resistance to aphids are combined with resistance to virus yellows. The use of such varieties would reduce the need to control aphids in the field by applications of chemicals.
The distribution of bait pellets for slug control
Authors: HUNTER P. J. , SYMONDS B. V. 
Published: February 2008

SUMMARYObservations were made on the movement and mortality of Agriolimax reticulatus (Müller) on plots with various densities of metaldehyde and methiocarb pellets. The optimum density of pellets was found to lie between 25 and 100/m2 (pellets 20 and 10 cm apart). This confirmed an estimate derived from a theoretical model.
Influence of soil moisture on the performance of granular systemic insecticides applied to soil
Authors: ETHERIDGE P. , GRAHAM‐BRYCE I. J. 
Published: February 2008

SUMMARYControl of aphids by the four systemic insecticides, dimethoate, disulfoton, menazon and phorate, applied as granules below seed potatoes at planting, was investigated under different soil moisture conditions. Results confirmed previous conclusions that dimethoate and menazon are more effective in wet than in dry soils, whereas disulfoton and phorate are equally effective in both. However, even with dimethoate and menazon effects of moisture were small and were probably the result of several different interacting factors.
Species and age specificity of malathion towards the locusts Schistocerca gregaria and Locusta migratoria
Authors: AHMED HAFIZ 
Published: February 2008

SUMMARYThe toxicity of malathion (2.5 % solution in kerosene) was determined by topical application to the hindwing base of mature adults of Schistocerca gregaria and Locusta migratoria migratorioides and of immature adults of S. gregaria. Mature adults of L. m. migrator ioides were slightly more resistant to malathion than those of S. gregaria. Immature adults of S. gregaria were approximately as susceptible as mature ones (at LD89 level) when the criterion for toxicity was taken as the ultimate death of the dosed insects, but the symptoms of poisoning developed earlier and more strongly in the immature insects.Penetration of malathion was least in the mature L. m. migratorioides and highest in the immature S. gregaria. The higher rate of activation of malathion in the immature S. gregaria was, however, counterbalanced by a higher rate of hydrolysis.The toxicity reflected the rate of accumulation of malathion and/or mala‐oxon inside the insect body.
The seasonal carry‐over of Botrytis tulipae (Lib.) Lind., the cause of tulip fire
Authors: PRICE D. 
Published: February 2008

SUMMARYDamage done by Botrytis tulipae developed in a variety of ways after planting naturally and artificially inoculated bulbs, the fungus sometimes rapidly invading developing shoots, preventing their emergence. In other instances (a) leaves emerged above ground, but not before being severely infected (the traditional ‘primaries’), (b) leaves emerged uninfected but the flower stalks were attacked at a later stage causing mechanical weakness (and hence frequent snapping), or (c) leaves and flower stalks remained uninfected, with the development of B. tulipae being restricted to its spread from mother to daughter bulbs, which also occurred in (a) and (b).More emerging shoots were infected when inoculated bulbs were grown at 10° and 15.5° than at 4 °C—an effect suggesting that greater numbers of foliar primaries would develop in mild winters.The underground transmission of B. tulipae indicates the need for eradicating infections in the bulb, the primary sources of this pathogen.
Testing the viability of fungal sclerotia
Authors: COLEY‐SMITH J. R. , JAVED Z. U. R. 
Published: February 2008

SUMMARYSimple methods for producing, handling and testing the viability of sclerotia were used on five fungi, three of which produced sclerotia freely in sand‐maizemeal cultures; the other two did not, and were grown on agar. After air drying, which did not affect viability, sclerotia were buried in the field in bags of nylon fabric. After recovery from soil they were surface‐sterilized with calcium hypochlorite and plated on a medium containing chloramphenicol and streptomycin sulphate. Some fungi, particularly those having basidiomycete affinities, are sensitive to high concentrations of chloramphenicol.
Alterations in peroxidase activity and peroxidase isozymes in virus‐infected plants
Authors: BATES D. C. , CHANT S. R. 
Published: February 2008

SUMMARYPeroxidase activity and isozyme patterns were investigated in two leguminous species infected with viruses which produced either local necrotic or systemic chlorotic symptoms. Highest peroxidase activity was recorded when the hosts reacted to infection with necrotic local lesions. No new virus‐specific isozymes were found as a result of infection, but some isozymes, apparently associated with senescence, appeared earlier in extracts from leaves showing necrosis than in extracts from healthy leaves, or from infected leaves showing only very mild chlorosis. Increase in peroxidase activity was accompanied by alteration in isozyme pattern.
The relationship between growth rate and the expression of tolerance to barley yellow dwarf virus in barley
Authors: JONES A. T. , CATHERALL P. L. 
Published: February 2008

SUMMARYBarley varieties were most tolerant to infection with barley yellow dwarf virus (BYDV) when they grew rapidly, whether the rate of growth was determined by manipulation of the environment or by the innate genetic constitution of the host. A specific, incompletely dominant gene conditioning a high level of tolerance to the virus in certain rapidly growing genotypes in which it occurred naturally, failed to do so when transferred to slower growing genotypes. However, reintroduction into genotypes capable of rapid growth led to full restoration of the gene's effectiveness. Virus‐free aphids recovered BYDV less readily from quick‐ than from slow‐growing genotypes, all homozygous for the tolerance gene.
Host status of some plants for Xiphinema diversicaudatum (Micol.) and their susceptibility to viruses transmitted by this species
Authors: THOMAS P. R. 
Published: February 2008

SUMMARYForty plant species were grown in pots containing viruliferous Xiphinema diversicaudatum (Micol.) for 15 wk to assess the host range of the nematode in relation to infection with arabis mosaic (AMV) and strawberry latent ring‐spot (SLRV) viruses. Host status for the nematode was determined mainly from changes in total populations, but the presence of eggs in the uteri of females and changes in the numbers of adults provided additional criteria. The nematode multiplied on relatively more woody perennials than on herbaceous crop plants or weeds. Chrysanthemum coronarium was the only plant on which numbers declined significantly below those on the controls.Most plant species became infected with either AMV or SLRV. Neither virus was detected in eight out of thirteen species of trees and shrubs although four were good hosts for the nematode.Galling or distortion of the terminal region of fine feeder roots, associated with X. diversicaudatum feeding, was seen on many of the experimental plants.
Effects of population density on alienicolae of Aphis fabae Scop.
Authors: SHAW M. J. P. 
Published: February 2008

SUMMARYApterae reared at different population densities produced alatae among their progeny, but not all these alatae behaved in the same way. Some flew before depositing nymphs (here called migrants), others flew after parturition (flyers) and some never flew (non‐flyers). The proportions of alatae, among the progeny from both uncrowded (‘U’) and crowded (‘C’) parents, that flew before depositing nymphs increased as the population density in which they were reared increased. Both crowded and uncrowded apterous parents produced similar numbers of larvae but, on average, ‘C’ apterae produced 17% more migrants. The proportions of migrants among alate progenies were closely correlated with the proportions of alatae among progenies.
Patterns of distribution of insects near a windbreak of tall trees
Authors: LEWIS T. 
Published: February 2008

SUMMARYThe distribution of shelter to leeward of a windbreak of tall trees was compared with the pattern of distribution of insects above and within a wheat crop.The pattern for flying insects blown from elsewhere resembled the shelter profile, in contrast to insects originating in the windbreak, which accumulated immediately behind the trees, and those originating a few metres to windward, which accumulated in a zone between 1/2 and 1 H (10–20 m) to leeward. These patterns were more distinct in direct than in oblique incident winds.The pattern of infestation of a breeding population of cereal thrips in the wheat resembled the distribution of airborne primary migrants 1–2 months earlier; the pattern of scatophagid flies on the crop also resembled that of airborne populations of other dung feeders originating slightly to windward of the trees.
Development of coffee berry disease in relation to the stage of berry growth*
Authors: MULINGE S. K. 
Published: February 2008

SUMMARYThe susceptibility of coffee berries to coffee berry disease (CBD) varies with the stage of berry development. It is well known that mature green berries are relatively resistant, while ripening berries are highly susceptible; however, differences in susceptibility of berries during early stages of development have not hitherto been examined in any detail.Experiments were carried out at a medium‐altitude site (5200 ft) to examine the effect of inoculation, in the field, 4, 6, 10 and 14 weeks after flowering. The highest infection rates occurred when berries were inoculated 6 and 10 weeks after flowering when the berries were expanding rapidly. At 4 weeks, when berries were at the ‘pinhead’ stage, and at 14 weeks, when they were attaining full size, much lower rates were recorded. Comparable results have also been obtained at a high altitude (6000 ft) site.In an experiment carried out on a long‐rains crop, flowering on 1 March, lesions regularly developed 2–4 weeks after inoculation, whereas in an experiment on a short rains crop, flowering at the end of October, symptom expression was apparently delayed. Possible reasons for this difference are discussed.
Ecology of fungi associated with moist stored barley grain
Authors: MULINGE S. K. , CHESTERS C. G. C. 
Published: February 2008

SUMMARYA study of the ecology of fungi associated with moist stored barley grain was carried out on samples from a partially sealed silo in Cumberland. Samples were collected during harvest and after storage at high moisture content in a partially sealed silo. At harvest, the field fungi Alternaria, Fusarium, Cladosporium and Mucor spp. were dominant both in the husks and in the dehusked, surface‐sterilized grain but they were rapidly succeeded by the storage fungi: Aspergillus, Penicillium and Absidia spp. then constituted about 80 % of the initial invasion. At this stage internal grain infection rarely exceeded 5 % compared to 65–80 % infection in the husks. In subsequent months, there was a remarkable increase in invasion, mainly by Penicillium, Aspergillus and Absidia spp. and by yeasts, which appeared both in the husks and in dehusked grain. In the third month of storage, Penicillium cyclopium, P. roqueforti, Absidia corymbifera, Aspergillus candidus, A. terreus and yeasts became dominant. The thermophilous species Aspergillus fumigatus, A. terreus, Absidia corymbifera, Mucorpusillus and Dactylomyces crustaceus were isolated from husks and in dehusked grain incubated at 37 and 45 °C. Most grains were infected significantly by single genera.
The establishment of a new strain of tobacco mosaic virus resulting from the use of resistant varieties of tomato
Authors: PELHAM J. , FLETCHER J. T. , HAWKINS J. H. 
Published: February 2008

SUMMARYTomato varieties with monogenic resistance (tolerance) to tobacco mosaic virus (TMV) were used by British growers for the first time in 1966. Samples of TMV collected before 1966, and in 1967 and 1968, were tested for their ability to produce virus symptoms on a series of isogenic tomato differential hosts differing in three factors for TMV resistance. Samples collected before 1966 yielded only strain o of TMV, which was unable to overcome any of the three factors. Strain 1, able to infect the newly‐introduced resistant varieties, was found with increased frequency after 1966. It was found less frequently on nurseries which had resumed growing susceptible varieties, suggesting that in these it may be unable to compete successfully with strain o. The dangers of indiscriminate release of varieties protected from disease by only one gene are discussed.
Some effects of barley yellow dwarf virus on spring and winter cereals in glasshouse trials
Authors: DOODSON J. K. , SAUNDERS P. J. W. 
Published: February 2008

SUMMARYThe tolerance of spring and winter varieties of wheat, oats and barley to infection by barley yellow dwarf virus (BYDV) was examined in glasshouse tests. Severely affected plants were stunted and grain yields were considerably decreased because of decreases in both ear number and numbers and sizes of grains. Winter barley varieties were very susceptible and many were killed by BYDV infection. The winter wheat varieties were more widely tolerant than those of oats and barley.Individual seedling symptoms, although correlated with reductions in yield, could not be relied upon for accurate classification of all varieties in order of their susceptibility to infection. Symptoms of seedling infection incorporated into an index of infection permit estimates to be made o eventual decreases in yield by applying the formulaDY = 1.4 × (SH+LA+LL)+18.Thus decrease in grain yield (DY) can be related to decreases in height (SH) and leaf length (LL) and increases in leaf area discoloured (LA) in seedling plants infected with BYDV.
Plant and soil nematode population changes in wheat grown continuously in ploughed and in unploughed soil
Authors: CORBETT D. C. M. , WEBB R. M. 
Published: February 2008

SUMMARYIn general, more migratory plant‐parasitic nematodes are found in soil under cereals drilled after ploughing than in unploughed land drilled after being sprayed with weed‐killer; but some non‐parasitic nematodes are more numerous in the unploughed, herbicide‐sprayed soil.Spraying a mixture of DDT, diazinon, chlordane and thionazin on the soil before drilling did not affect populations of soil nematodes.
Decline viruses of pawpaw (Carica papaya L.) in East Africa
Authors: KULKARNI H. Y. 
Published: February 2008

SUMMARYThree viruses or virus strains were isolated from pawpaw showing field decline symptoms in Tanzania and Kenya, where they are of wide occurrence. Each virus caused a distinct type of local lesion in Chenopodium quinoa; a fourth type of local lesion was induced when transmission was from a source containing two of the three viruses. When re‐inoculated to pawpaw, alone or in combination, they caused stunting and decline symptoms similar to those observed in the field.Two were recovered from pawpaw pollen; none was transmitted through seed or from fruit to fruit, nor was any vector found.Purified preparations of the three viruses contained stiff rod‐shaped particles 750 times 12 nm.Latex from pawpaw petiole and fruit totally inhibited sap transmission.
Weed plants as sources of cucumber mosaic virus
Authors: TOMLINSON J. A. , CARTER ANNE L. , DALE W. T. , SIMPSON CAROL J. 
Published: February 2008

SUMMARYSevere yellowing and stunting was widespread in lettuce crops in Britain in 1968. Cucumber mosaic virus was consistently obtained from affected plants and from weeds which were prevalent in lettuce fields. Infection was most frequent in Stellaria media but also occurred, more or less commonly, in Senecio vulgaris, Urtica urens, Tripleurospermum maritimum ssp. inodorum, Capsella bursa‐pastoris, Lamium purpureum and Sonchus oleraceus. Most infected weeds were symptomless. Infected weeds were still common in January‐April 1969 and are considered to be a major overwintering source of the virus for aphid transmission to lettuce.
The quantitative estimation of the infection of bean seed with Pseudomonas phaseolicola (Burkh.) Dowson
Authors: TAYLOR J. D. 
Published: February 2008

SUMMARYA routine laboratory method for the detection of Pseudomonas phaseolicola in bean seed is described. The method will detect low levels of seed‐borne infection and has been used in a statistical procedure (the most probable number method) to give an estimate of percentage infection. Infection in seeds harvested from heavily infected crops varied from 10 to 1%, compared with from 1% to less than 0.1% in commercial seed stocks. A high proportion of infected seeds failed to produce infected plants and this may account for the very low levels of primary infection reported in the field. Removal of seeds showing possible ‘symptoms’ of disease reduced, but did not eliminate, infection from seed stocks.