bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on the biology of chrysanthemum eelworm Aphelenchoides ritzema‐bosi (Schwartz) Steiner in florists' chrysanthemum
Authors: HESLING J. J. , WALLACE H. R. 
Published: February 2008

SUMMARYThe chrysanthemum eelworm moved in sand and in a clay soil at much the same rate as other eelworm species so far studied. Leaf washing and soil examination in infested chrysanthemum plots showed that the eelworm never spread laterally through the soil or from leaf to leaf more than to the second row of plants from the source of infestation, a maximum distance of about 30 in. At Rothamsted and in the National Chrysanthemum Society's variety trial the number of infested varieties increased greatly in September, during periods of heavy mists. Experiments with isolated leaves, artificially infested and kept under either dry or humid conditions suggested that eelworms were more active in humid conditions. They invaded isolated leaves within 15–30 min. In pot experiments, eelworms added to soil invaded chrysanthemum plants inducing symptoms in 18 days: 26 days after such inoculations no eelworms could be detected in the soil. Few eelworms persisted in fallow soil in pots after 32 days. No eelworms were found after the end of November in soil taken from an infested field plot at intervals between August 1959 to January 1960. Attempts to infest plants with eelworms from stored soil taken from highly infested plots failed. Examination of stools during the winter showed that many eelworms were present in the green tissues. It is concluded that infestation from eelworms which persist over the winter in soil is slight and that the main source of the pest is the chrysanthemum stool.
Observations on the biology of chrysanthemum eelworm Aphelenchoides ritzema‐bosi (Schwartz) Steiner in florists' chrysanthemum
Authors: HESLING J. J. , WALLACE H. R. 
Published: February 2008

SUMMARYIn stained sections of eelworm‐infested chrysanthemum leaves the earliest effect of the attack is the appearance of a brown substance inside the leaf cells; this browning extends and ultimately reaches the leaf epidermis. The number of chloroplasts dwindles, the cell walls break down and large spaces appear in the leaf. Finally the leaf shrinks, the epidermis disintegrates and the brown substance is found on all the cell walls. The collenchyma around the main veins, where it reaches the upper and lower epidermis, does not break down until the final stage of attack.Cuttings of thirteen chrysanthemum varieties, each artificially infested with about 110 eelworms, showed leaf blotches, stunting, blindness, browning of the stem and leaf petiole, leaf distortion, leaf scars or feeding areas and puffy, blistered and puckered leaves. Infested cuttings with severe symptoms may produce side‐shoots or breaks which seem healthy but become badly infested later in the season when the plants are wetted by rain or prolonged mists. The eelworms often failed to penetrate further than the substomatal space in the youngest leaves. All the symptoms listed above, except leaf blotches, probably result from ectoparasitic feeding by the eelworm.
The epidemiology of apple scab (Venturia inaequalis (Cke.) Wint.)
Authors: HIRST J. M. , STEDMAN O. J. 
Published: February 2008

SUMMARYThe number of ascospores caught by automatic volumetric spore traps differed widely in six orchards where the air was sampled in some or all of the years 1955 to 1959. To compare amounts of inoculum in different orchards the total catch in each was expressed as the ‘relative ascospore dose’. The reason for the much smaller doses in the later years is uncertain. The results confirmed earlier work on the phenology of ascospore liberation and stressed the practical need to decrease their number as much as possible.Because conidia have previously been trapped almost only on wet and windy days, they have been considered to be rarely air‐dispersed. Our apparatus, which efficiently traps dry conidia but catches water‐borne ones only when in very small droplets, caught airborne conidia in all orchards when they operated during summer. Traps among heavily infected, unsprayed trees caught most conidia around noon on warm dry days and the highest concentration measured exceeded 1300 per m.3of air.
The influence of sunshine and rain on tea blister blight, Exobasidium vexans Massee, in Ceylon
Authors: VISSER T. , SHANMUGANATHAN N. , SABANAYAGAM J. V. 
Published: February 2008

SUMMARYThe germination of spores of blister blight of tea (Exobasidium vexans Massee) requires moisture, but 0.1 in. of rain in a day provides sufficient for a high percentage of germination to occur; more rain does not materially increase germination. Spores are killed by sunshine of a few hours' duration, even if there is adequate rain on the same day. An average of about 3 3/4 hr. of sunshine per day over 5 days is enough to reduce the blister‐blight disease to subeconomic levels. Ten‐day spraying rounds with copper fungicide usually give adequate control of the disease but add to the cost of production. A method is put forward of using recorded sunshine hours as the criterion in deciding on the frequency of spraying; spraying is postponed, by successive 5‐day periods, until the average sunshine for the previous 5 days has dropped below 3 3/4 hr. A reduction approaching one‐half of the number of spray applications can be made in this way.
Infection of bean plants (Vicia faba L.) with Botrytis cinerea and B. fabae
Authors: DEVERALL B. J. , WOOD R. K. S. 
Published: February 2008

SUMMARYThe infection of bean plants (Vicia faba L.) by Botrytis fabae has been studied by inoculating detached leaves with standard volumes of spore suspensions of known concentrations, or with single spores.Increasing the number of spores in the inoculation drops increased the number of lesions, and lesions were more readily produced on older than on younger leaves.The addition of glucose, a number of other carbohydrates, and also sodium polypectate and pectin, increased the number and rate of the spread of lesions. Xylose caused a decrease, and a number of nitrogen compounds had little effect.The number and rate of spread of lesions was increased if the surface of leaves were gently rubbed with a mild abrasive before inoculation. Calcium‐deficient plants were more susceptible than plants which had received normal nutrition. Deficiencies of other major elements had much less effect.A larger proportion of the spores in inoculation drops germinated when these drops were on older leaves, when the drops contained glucose, and on leaf surfaces that had been gently abraded. Addition of xylose reduced the amount of germination and the fungus grew very poorly in liquid culture when this was the only carbon source. The addition of small quantities of glucose allowed the fungus to use xylose as efficiently as glucose.When single spores were used to inoculate leaves, very different results were obtained with leaves taken from different plants, but under some conditions single spores often induced lesion formation. B. fabae caused lesions more readily than did B. cinerea, in spite of the fact that a greater proportion of B. cinerea spores in inoculation drops germinated.
Further observations on the reaction of wheat varieties to physiologic races of loose smut
Authors: MANTLE P. G. 
Published: February 2008

SUMMARYThe reaction of forty‐one wheat varieties to the three Cambridge physiologic races of Ustilago tritici has been determined by a combination of the embryo test and growth in the field. Wide variations in susceptibility were observed and there was no consistent relationship between the extent of mycelial distribution in the scutellum and subsequent field reaction to infection. Immunity is rare. The best differential varieties for identifying the three races are suggested.
Observations on the use of predacious fungi for the control of Heterodera spp
Authors: HAMS A. F. , WILKIN G. D. 
Published: February 2008

SUMMARYLaboratory and pot experiments by various workers up to 1956 suggested that the effects of eelworm attack on certain crops could be partly overcome by inoculating eelworm‐infested soil with the mycelium of predacious fungi.The present paper demonstrates some of the factors operative in soil which affect the ‘predacity’ of some of these fungi.The results obtained strongly suggest that under laboratory conditions and in pot cultures congenial conditions for growth in soil of the predacious fungi can be produced but that, in the field, only sparse growth of these fungi can be obtained, insufficient to affect eelworm attacks.The use of farmyard or green manure has consistently given better crops in eelworm‐infested soils irrespective of whether predacious fungi were naturally present 01 added.
Cherry leaf‐roll virus
Authors: CROPLEY R. 
Published: February 2008

SUMMARYA virus was transmitted consistently by sap inoculation from cherry trees with leaf‐roll disease to herbaceous indicator plants, from tobacco to Prunus avium and from P. avium to P. pennsylvanica.Herbaceous host reactions, physical properties and particle size and shape of the virus were similar to those of arabis mosaic, raspberry ringspot and tomato black‐ring viruses. Plant protection and gel‐diffusion serological tests indicated that cherry leaf‐roll virus is distinct from arabis mosaic, raspberry ringspot, tomato black‐ring, tobacco ringspot and tomato ringspot viruses.
Viruses causing rasp‐leaf and similar diseases of sweet cherry
Authors: CROPLEY R. 
Published: February 2008

SUMMARYTrees with rasp‐leaf symptoms have been found in seventeen orchards in England. In some orchards only a few trees are infected, while in others the disease is prevalent.Transmission tests from diseased trees indicate that raspberry ringspot virus is the cause of cherry rasp‐leaf disease in most English orchards, but arabis mosaic virus can cause similar symptoms.
The toxicity of mixtures of zinc and copper sulphates to rainbow trout (Salmo gairdnerii Richardson)
Authors: LLOYD R. 
Published: February 2008

SUMMARYThe toxicity to rainbow trout of a mixture of zinc and copper sulphates in relatively low concentrations can be calculated from the toxicities of the individual metals by assuming that they exert a similar joint action. Higher concentrations of the mixture in soft water exhibit a synergistic action.
Changes in the free amino acids and amides in tomato plants inoculated with tomato spotted wilt virus
Authors: SELMAN I. W. , BRIERLEY M. R. , PEGG G. F. , HILL T. A. 
Published: February 2008

SUMMARYLeaves of tomato plants grown in water culture in growth rooms were inoculated with sap from healthy tomato leaves or with sap containing tomato spotted wilt virus (t.s.w.v.). Changes in the free amino acids and amides of stems and of inoculated leaves, stem growth and infectivity were determined. Samples were analysed 5, 9, 13 and 17 days after inoculation using two‐dimensional paper chromatography.Inoculation with sap from healthy leaves, mixed with celite and sodium sulphite, caused small increases in glutamic acid, asparagine, glycine and serine in the inoculated leaves, and in glutamic and aspartic acids in the stems.In leaves inoculated with t.s.w.v., glutamine and asparagine increased greatly, reaching maxima at day 13. Both infectivity and amide levels were greater with more concentrated inoculum. The total free amino acids increased in leaves inoculated with t.s.w.v. by 150–180%. Increases were found in α‐alanine (day 9, 13 and 17) and in aspartic acid, valine, glycine and the leucines (day 13).Systemic infection of stems increased total free amino acids by 200–300% and amides by more than 400%. Serine, threonine, phenyl‐alanine, proline and the leucines increased at day 9 and reached maxima at day 13. Glutamine, asparagine, glutamic acid, aspartic acid, valine, tyrosine, α‐alanine, glycine and γ‐amino‐butyric acid increased at days 13 and 17.Changes in total free amino acids in stems and leaves were closely correlated with changes in infectivity.Five days after inoculation and 3 days before symptoms appeared, the levels of serine and threonine in the stems of plants receiving a dilute inoculum were less than those in controls.It is suggested that accumulation of NH2 compounds in an infected plant may interfere with virus synthesis; this may explain the observed cyclical changes in infectivity.Free tyrosine and hydroxylysine were recorded for the first time in leaves and stems of healthy tomato plants and tyrosine and methionine in healthy roots.
Laboratory and field studies on the relation of arabis mosaic virus to its nematode vector Xiphinema diversicaudatum (Micoletzky)
Authors: HARRISON B. D. , WINSLOW R. D. 
Published: February 2008

SUMMARY Xiphinema diversicaudatum is widely distributed in southern Britain, mainly in heavy soils, but also in the peat soil of the Fens and in medium textured soils in the south‐west. Patches of plants infected with arabis mosaic virus (AMV) in a range of crops including some, like celery and marrow, not before known to be hosts, coincide with patches of soil infested with X. diversicaudatum. Roots of some plants infested with the nematode carried small galls; not all such plants were infected with, or even susceptible to, AMV. Adult X. diversicaudatum transmitted AMV more readily than larvae, but none of 103 nematodes, transferred when moulting, infected healthy plants. X. diversicaudatum were still infective after 24 days in moist peat, free from plants. X. diversicaudatum is common in several districts in soil from old hedgerows but not in the adjacent fields. Hedgerow trees seem to be hosts of the nematode and at least one, elder, is also a host of AMV. In other districts, plants with AMV occur in crops near to infested hedges or isolated trees, and on land taken into cultivation after being derelict. In the Tamar Valley, Devon, X. diversicaudatum is common in pastures; white clover in these often contains AMV. Planting such fields with strawberry leads to disease outbreaks.A few X. diversicaudatum occur down to 3 ft. in soil, but most are at 3–9 in. At a site where arable land has reverted to woodland, the nematodes apparently have spread from a hedge into the woodland at an average rate of 1 ft. per year over a period of 75 years. It is suggested that both X. diversicaudatum and AMV are common constituents of natural woodland in Britain and that their incidence has decreased since the advent of agriculture.
The development of filter‐passing organisms in Corynebacterium fascians cultures
Authors: LACEY MARGARET S. 
Published: February 2008

SUMMARYViable filter‐passing particles have been obtained from gall‐tissue cultures of Corynebacterium fascians. On gelatine media filtrates of the cultures first produced a faint clouding of the liquefied gelatine; this was due to masses of granules of very variable size. In some cultures further development took place, the next phase being the appearance of diplococci. Sometimes the coccal stage persisted but occasionally complete regeneration of the normal C. fascians type rod finally ensued. This sequence of growth follows the pattern designated as the ‘L phase’, occurring in the life‐history of certain bacteria. Growth of L forms probably occurs in Agrobacterium tumefaciens also.
Dispersion and deposition of airborne Lycopodium and Ganoderma spores
Authors: GREGORY P. H. , LONGHURST T. J. , SREERAMULU T. 
Published: February 2008

SUMMARYSpores were liberated at 0.25 and 1.0m. above grass. Airborne concentrations at twenty or more points in the spore cloud were measured with specially designed and calibrated miniature suction traps, operated off a portable vacuum system. Deposition in the downwind direction was measured on artificial surfaces on the ground. Measurements were made up to 10 m. from the source.The observed increase in horizontal cross‐wind standard deviation of the Lycopodium cloud agreed well with O. G. Sutton's theory, but was incompatible with that of W. Schmidt.The coefficient of deposition, p, calculated from mean cloud concentration per c.c. and deposition to ground per cm.2, as well as the velocity of deposition, vg, varied with distance from source. Both p and vg were larger for Lycopodium than for Ganoderma, and at the greater distances tested, vg approximated to the expected terminal velocities of the particles in still air.The total number (Q0) of Lycopodium spores liberated in each experiment was known, and tentative estimates of the proportion deposited within the sampling area indicated that, under day‐time winter conditions in England, the cloud lost not less than 13 to 24% of its load within 10 m. of the source.
Black‐pod disease of cocoa
Authors: SPENCE J. A. 
Published: February 2008

SUMMARYIsolates of Phytophthora palmivora from various countries were compared for compatibility in oospore production with standard isolates of the ‘rubber’ and ‘cocoa’ groups. It was found that most of the isolates belonged to the ‘cocoa’ group, one to the ‘rubber’ group, and three did not form oospores under any circumstances.The isolates showed different growth rates in wound‐inoculated pod tissue. Individual isolates showed different growth rates on pods of two varieties of cocoa.
Black‐pod disease of cocoa
Authors: SPENCE J. A. 
Published: February 2008

SUMMARYActive pectolytic enzyme could not be recovered from cocoa‐pod shell tissue parasitized by Phytophthora palmivora, but was recovered from autoclaved potato blocks invaded by this parasite. Browned extracts of cocoa bean and pod tissue inactivated pectolytic enzymes of P. palmivora obtained from invaded potato blocks. When allowed to brown before exposure to enzyme, discs of cocoa‐pod tissue showed increased resistance to maceration by pectolytic enzymes of P. palmivora.Attack of cocoa pods by a weakly virulent isolate was promoted by low oxygen tension and low temperature. Attack by a virulent strain was accelerated at low oxygen tension and retarded at high oxygen tension.The results suggest that a balance exists during parasitism of cocoa pods by P. palmivora between the pectolytic enzyme system of the fungus and the polyphenol oxidase system of the host and that the activity of the polyphenol oxidase system acts as a host resistance mechanism.
Studies on the chemical control of Phytophthora palmivora (Butl.) Butl. on Theobroma cacao L. in Nigeria
Authors: Hislop E.C. , Park P.O. 
Published: February 2008

SUMMARYThe tenacity of a number of fungicide formulations when sprayed on to cocoa pods has been tested by applying artificial rain produced in an experimental rain tower. A general relationship between leaching of deposits and rainfall has been obtained. The effect of incomplete drying on the tenacity has been correlated with observations in the field. The effect of pod growth on the attenuation of fungicide deposits was demonstrated and possible improvements to formulations and spraying techniques are discussed.
A study of the heating of stored grain caused by insects
Authors: HOWE R.W. 
Published: February 2008

SUMMARYThe rates of increase of temperature and of population density are calculated for an insulated culture of granary weevils, assuming a Malthusian rate of increase, and basing heat production on respiration rates. This is done first by a step method, but it is shown that the increase in population density can be related to rise in temperature, irrespective of the original density, which makes a short‐cut method possible.The calculations are then modified for the situation in which the culture is embedded in and loses heat by conduction to a bulk of uninfested grain. The spread of heat by conduction is slow; spread by convection is not considered. At I m. from a hot pocket with a steady heat output, the rise of temperature at equilibrium will be less than half the rise at the margin of the hot pocket and only 15% of this rise will be achieved in 4 weeks. The numbers of insects needed to raise the temperature of an infested pocket in a grain bulk are much larger than those required for an insulated culture. The extra time required to reach a temperature is that needed to build up a sufficient population in the original environmental conditions.It is argued that hot pockets increase in size because of the movement of insects induced by high temperatures and by overcrowding, rather than because of spread of heat by conduction. Convection currents cause upward, but not lateral, extension of hot pockets. If sufficient insects are to develop to produce enough heat to cause high temperatures the expansion of a hot spot is necessary, so that small cages of insects cannot be used to induce heating experimentally.Warehouse observations are described to support these predictions. Heating of home‐produced grain in Britain is caused chiefly through storing either grain which is damp and therefore heats, or dried grain which has been insufficiently cooled. Either produces an ideal environment for any stored‐grain insect species.Stored grain should be inspected both to find insects and to measure its temperature and moisture content. Any warehouse containing grain at temperatures above 22° C. and insects should be examined monthly.
A virus causing axillary bud sprouting of tobacco in Rhodesia and Nyasaland*
Authors: GATES L.F. 
Published: February 2008

SUMMARYA virus first found in tobacco in Rhodesia in 1958 was widespread in 1959, usually together with other viruses. It is readily transmitted by mechanical inoculation. Myzus persicae transmitted it from plants that were also infected with another virus, probably tobacco vein‐distorting virus, but not from plants infected with it alone. The aphids became increasingly likely to transmit as their feeding time on infected plants increased up to 24 hr.; after virus‐acquisition feeding times of 24–48 hr. they remained infectious for several days. The virus, named tobacco bushy‐top because of the characteristic way it stimulates the growth of axillary shoots, resembles tobacco mottle virus in many respects, and as tobacco mottle virus partially protects plants against bushy‐top virus they may be related strains.
Studies on strawberry mildew, caused by Sphaerotheca macularis (Wallr. ex Fries) Jaczewski*
Authors: PERIES O. S. 
Published: February 2008

SUMMARYCross‐inoculation trials have shown that Sphaerotheca macularis on strawberries is a specialized form of this fungus.Conidia germinated consistently well on dry healthy leaf surfaces. Cardinal temperatures for germination of conidia were 2°, 20° and 35° C., while infection and sporulation were not recorded below 5° and 13° C, respectively. Conidia retained their viability for periods up to 5 weeks at 0° C. in a saturated atmosphere, and for short periods under more exacting environmental conditions. Low humidities, although injurious to conidia, especially at high temperatures, had no effect on growth and sporulation of the fungus. Light too had no effect on conidial germination and development of the fungus. Free water had a lethal effect on conidia and no germination was recorded on wet leaf surfaces.A diurnal periodicity of spore liberation, with a maximum in the afternoon, has been observed. Rain has a drastic effect on spore dispersal, reducing the numbers trapped to very low levels. There was a steep falling gradient in the number of spores trapped both with increasing distance and height from the source.Heavy shade, high humidities and temperatures between 60 and 80° F. were conducive to the production of perithecia. There was no evidence to show that strawberry mildew is heterothallic. Inoculation experiments have shown that the perithecia do not play any essential part in the life history of the fungus.