bluuebunny/crossref_metadata_2025_split huggingface dataset:
The control of damping‐off in Pisum sativum L. by cycioheximide
Authors: AKINREFON O. A. 
Published: February 2008

SUMMARYExperiments on the effect of cycioheximide (Acti‐dione) in controlling damping‐off disease of peas confirmed that phytotoxicity would preclude its use despite its high toxicity to Pythium spp.The antibiotic did not inhibit germination of peas, but retarded growth of the shoot; the tap root was apparently unaffected, but the lateral roots were stunted.
Orientation of male Heterodera rostochiensis Woll. and H. schachtii Schm. to their females
Authors: GREEN C. D. 
Published: February 2008

SUMMARYA chemical attractive to their males is emitted by females of Heterodera rostochiensis and H. schachtii. The attraction is evident in agar plates when the females have been killed or removed from the agar, and on 3 mm. thick agar it takes more than 15 min. at 20° C. to diffuse sufficiently to be perceptible to males 5 mm. from the females. The perception is gustatory and seems to elicit klinokinetic aggregation behaviour and klinotaxic orientation. The males respond to a decrease in stimulation by stopping, followed by either a reversal and turn, or a swing and turn. Fatigue of the receptors, leading to loss of acuity of perception, occurs at greater concentrations of the attractant and decreases the frequency of turning. Then the intensity of turning increases and the approach to the female is less well orientated. Females of H. schachtii secreted a less labile or more concentrated attractant; thus their males were more frequently less well orientated and removal of the females caused more direct attraction. Male behaviour was efficient enough to ensure mating even of isolated females.
The permeability of artificial windbreaks and the distribution of flying insects in the leeward sheltered zone
Authors: LEWIS T. , STEPHENSON J. W. 
Published: February 2008

SUMMARYThe number of flying insects in the sheltered zone to leeward of artificial windbreaks of 0, 25, 45 and 70% permeability was greater than in unsheltered areas. Insects accumulated in the air nearer to dense windbreaks than to more permeable ones, and the position of maximum aerial density of insects coincided with that of maximum shelter. The more dense the windbreak the greater the numbers in the air to leeward. Absolute wind speed slightly affected the position of maximum aerial density behind a 45% permeable fence.
Artificial windbreaks and the distribution of turnip mild yellows virus and Scaptomyza apicalis (Diptera) in a turnip crop
Authors: LEWIS T. 
Published: February 2008

SUMMARYIn a turnip crop natural infection with turnip mild yellows virus was greatest in two narrow zones, one to leeward of an artificial windbreak, the other in a long shallow depression in the earth. Both zones were approximately across wind when Myzus persicae flew in early summer. Later in the summer, similar windbreaks facing different prevailing winds increased the number of larvae of Scaptomyza apicalis on the plants immediately to leeward and windward of the windbreaks, probably because shelter affected adults that were flying and laying eggs in the crop.
Host range and some properties of groundnut rosette virus
Authors: OKUSANYA BOLAJOKO A. M. , WATSON MARION A. 
Published: February 2008

SUMMARYTwo isolates of groundnut rosette virus from East Africa (GRVE1 and GRVE2) and from West Africa (GRVW1 and GRVW2) were transmitted by Aphis craccivora obtained from West Africa. A third isolate from West Africa (GRVW3) was not transmitted by A. craccivora from three widely separated sources. GRVW1, GRVW2 and GRVW3 caused leaf‐symptoms in groundnut of a mosaic pattern in light and dark green. GRVE1 and GRVE2 caused chlorosis or chlorosis and leaf distortion as well as mosaic symptoms. Groundnut plants with GRVW1 could not be infected by means of aphids with GRVE1, and GRVE1 gave similar protection against GRVW1, which suggests that they are strains of the same virus.All isolates were transmissible manually from groundnut to groundnut (Arachis hypogea), Trifolium incarnatum and T. repens, and caused systemic infection. Inoculated Nicotiana clevelandii and N. rustica developed symptoms but virus could not be recovered from them. Chenopodium amaranticolor, C. hybridum and C. quinoa showed local lesions on inoculated leaves. Virus could be acquired by aphids from groundnut or Trifolium repens infected by means of aphids, but not from those infected by manual inoculation. Virus could not be recovered from T. incarnatum manually or by aphids, but was transmitted by cleft‐grafting from clover to groundnut.Saps extracted in borax buffer plus zinc sulphate at pH 9 from plants infected with GRVW1 and GRVE1 remained infective at 18° C. for 1 week, and at — 20° C. for up to 4 weeks. Virus could be recovered from frozen leaves. Buffered saps lost infectivity when heated above 50° C. for 10 min.; most were still infective when diluted 1/10 and some at 1/100.Electron micrographs of partially purified preparations contained spherical particles 25–28 mμ in diameter. There were usually only about five per microscope field and they resembled those of some other viruses.
The influence of germinating seeds and developing roots on re‐establishment of micro‐organisms in fumigated soil
Authors: VAUGHAN E. K. , NEWHOOK J. F. , ROBERTSON G. I. 
Published: February 2008

SUMMARYA laboratory study was made of re‐invasion of soils fumigated in closed containers at rates of 3 ml./sq.ft. 10 in. deep with chloropicrin, methyl bromide and a 67:33 mixture of the two materials (MBC–33), using the dilution plate method of determination. Counts after aeration, 3 weeks later, showed that all three fumigants eliminated practically all fungi. Chloropicrin and MBC–33 also killed almost all bacteria and actinomycetes, whereas fumigation with methyl bromide markedly increased numbers of bacteria without materially altering numbers of actinomycetes.Subsequently, in soils fumigated with chloropicrin or MBC–33, fungi recolonized rapidly, but up to 93 % of the colonies isolated were Trichoderma viride. Increase of fungi in soils fumigated with methyl bromide was slower and Penicillium spp. predominated. Bacteria at first declined in numbers, then increased rapidly in soils fumigated with all three materials. In soils fumigated with methyl bromide, actinomycetes, usually considered to include good antagonists, increased but did not exploit their initial advantage over fungi. In soils fumigated with chloropicrin and MBC–33 actinomycetes did not recolonize in appreciable numbers.The greatest variety of fungous genera occurred in isolates from rhizo‐spheres of red beet, but the greatest numbers of colonies of both fungi and bacteria were isolated from rhizospheres of pea and pumpkin. None of the crops tested greatly stimulated recolonization by actinomycetes. Compared with the drastic changes brought about by fumigants the influence of seed and root exudates on either the magnitude or the composition of re‐invading micro‐organisms was slight.
Uptake and binding of dodine acetate by fungal spores
Authors: SOMERS E. , PRING R. J. 
Published: February 2008

SUMMARYUptake of the dodine cation from acetate solutions by conidia of Alternaria tenuis and Neurospora crassa was characterized by a rapid rate of sorption, a ‘Langmuir type’ adsorption isotherm, and independence of temperature: all of which suggests an ionic bonding mechanism. Metal cations competed with dodine for the anionic binding sites of the cell—regarded as carboxyl and phosphate groups—and dodine uptake also decreased as ionization of the carboxyl group was suppressed.Cell walls of A. tenuis had a greater capacity to bind dodine than did those of N. crassa. Binding at the cell wall may detoxify some of the large amount of dodine that must be accumulated by the spores to achieve toxicity. The dodine retained by N. crassa cell walls could not be exchanged or desorbed by washing and is probably bound covalently rather than by weaker ionic bonds. At sub‐lethal concentrations there was no evidence that dodine disorganized cell wall structure.Disruption of spores which had been incubated with 14C‐labelled dodine showed the fungicide to be associated with intra‐cytoplasmic organelles. It is suggested that dodine reacts with the protoplast membrane so as to alter its permeability and allow more dodine to penetrate into the cytoplasm where it may destroy intracellular membrane structure.
The effect of some microphagous saprobic nematodes on mushroom culture
Authors: HESLING J. J. 
Published: February 2008

SUMMARYWhen added to spawned mushroom compost the microphagous saprobic nematodes Pelodera cylindrica, Mesorhabditis spiculigera and Acrobeloides bütschlii did not affect mycelial growth or compost pH. The eelworms multiplied at first but their numbers declined as the mycelium colonized the compost. In contrast, the fungal‐feeding Aphelenchoides composticola increased rapidly and destroyed the mycelium. Excess water, and the presence of the fungal competitor of mushroom, Chaetomium olivaceum, allowed some increase of the microphagous forms. Different numbers of Mesorhabditis spiculigera added to the ‘casing’ had no effect on mushroom yield but the mushroom ‘flushes’ seemed less pronounced. Reasons for the failure of the saprobic eelworms to affect mushroom, and the possibility of synergistic pathogenicity by these eelworms and bacteria, are discussed.
The effects on a population of potato‐root eelworm (Heterodera rostochiensis) of growing potatoes resistant to pathotype B
Authors: COLE C. S. , HOWARD H. W. 
Published: February 2008

SUMMARYThe effects on a potato‐root eelworm (Heterodera rostochiensis Woll.) population of growing potatoes resistant to pathotype B of the eelworm were investigated. The eelworm population, which was originally nearly entirely pathotype A, had been changed into a mixture of pathotypes A, B and C before 1961, when the experiments described in this paper began, by growing potatoes resistant only to pathotype A.The resistant potatoes grown in the years 1961 and 1962 were certain clones of the hybrid triploid species Solarium xjuzepczukii Buk., clones bred from S. multidissectum Hawkes with the gene H2 and clones bred from S. vernei Bitt. et Wittm. In the years 1963‐65 the clone used was D 40 which has both the gene H2 from Andigena and the gene H2 from 5. multidissectum and is resistant to both pathotypes A and B of the eelworm. The only potatoes which caused a reduction in the egg population were those bred from S. vernei. The clone D 40, although it had little effect on the egg population, appeared to have more resistance than could be accounted for from possessing genes H1 and H2.
Effects of infection with narcissus mosaic, narcissus yellow stripe and tobacco rattle viruses on the growth and flowering of narcissus cv. ‘Minister Talma’
Authors: REES A. R. 
Published: February 2008

SUMMARYThree plots were planted with similar‐sized narcissus bulbs: healthy; infected with narcissus mosaic virus (NMV); and infected with narcissus yellow stripe + tobacco rattle virus (NYSV+TRV). No effects of infection were observed on flower number, diameter, paracorolla length or flower dry weight, but the flower stalks were shorter in the infected plants. NMV‐infected plants produced slightly blemished flowers, and 74% of the NYSV + TRV‐infected flowers were of poor quality. Virus infection delayed leaf growth and loss of bulb dry weight early in the season and senescence in July. NYSV+TRV‐infected plants were more affected than NMV‐infected plants. However, maximum leaf area was similar for all plants. The maximum plant dry weight and the final weight of the bulb were not significantly affected by infection, but small differences, which could be cumulative in successive years would not have been detected. Differences in net assimilation rate, if any, were small.
Bacterial canker of stone‐fruits: Infection experiments with Pseudomonas mors‐prunorum and P. syringae
Authors: CROSSE J. E. , GARRETT CONSTANCE M. E. 
Published: February 2008

SUMMARYThe effect was compared of inoculating Pseudomonas mors‐prunorum and P. syringae at high inoculum concentration through wounds in plum stems and cherry branches, and through cherry‐leaf scars. In the wound inoculations a North American cherry strain of P. syringae was considerably more virulent than any of three indigenous cherry strains of P. mors‐prunorum, but two pear strains of P. syringae were less virulent. P. mors‐prunorum showed a much greater capacity to invade through leaf scars, particularly towards the end of the leaf‐fall period, when all three P. syringae strains were largely ineffective. Evidence is discussed which suggests that the greater infectivity of the P. mors‐prunorum strains through leaf scars was related to their capacity to colonize the host tissues from small inocula. The P. syringae strains died out in cherry cankers earlier than P. mors‐prunorum strains and they were less stable during host passage. The results of the experiments indicate that virulence in these organisms is a complex phenomenon and determined by several factors.
Studies on the nutrition of Arthrobotrys oligospora Fres. and A. robusta Dudd: The predaceous phase
Authors: HAYES W. A. , BLACKBURN F. 
Published: February 2008

SUMMARYThe effects of substrate on the predaceous activity in sand cultures of two isolates of the genus Arthrobotrys were measured by expressing the number of non‐survivors of a free‐living nematode population exposed to the fungi for 4 days as a percentage of a comparable population of nematodes not exposed to predation. This percentage is designated the predacity number.By varying the energy source it was shown that nutrient requirements for the extension of mycelium may differ from those for the expression of predacity. There is a greater reduction in the activity of A. oligospora when nitrogen is supplied as ammonium than when it is presented as nitrate or nitrite. The predacity of A. robusta is greatest on media deficient in biotin and with nitrite as nitrogen source.The relationship of results derived from artificial cultures to results from more direct examination of soils is discussed.
Powdery mildew of tobacco (Erysiphe cichoracearum DC.): Susceptibility of proximal and distal parts of leaves from different stalk positions on intact and topped field plants in relation to free amino nitrogen and carbohydrate content*
Authors: COLE J. S. 
Published: February 2008

SUMMARYThe area covered by visible mycelium of E. cichoracearum on the upper surface of leaves 4, 8, 12 and 16 of tobacco plants in field plots in Rhodesia was expressed as percentages of the proximal and distal halves at weekly intervals. Free amino nitrogen and carbohydrate in discs from proximal and distal halves of the same leaves were analysed when each leaf was expanding rapidly and was not infected, and several weeks later, when the rate of expansion had slowed down and there was slight infection. On two other occasions, similar leaf discs were inoculated with conidia, to measure the percentage germination and hyphal length from individual conidia after incubation for 2–3 days at constant temperature and humidity; duplicate discs were chemically analysed.Leaves were not susceptible until at least 6 weeks after they had emerged from the bud. Soluble carbohydrate increased and free amino nitrogen decreased during the change from resistance to susceptibility.Proximal parts of leaves were usually infected first; they initially contained less amino nitrogen and soluble carbohydrate than distal parts. All parts of the leaf seemed to be equally susceptible later, when there were no differences in their amino nitrogen or soluble carbohydrate.Upper leaves of intact plants had more natural infection than those from corresponding leaves from topped plants. More conidia germinated on discs from them and produced longer hyphae. The discs from intact plants contained less free amino nitrogen and more soluble carbohydrate than those from topped plants.The accuracy of visual assessments of susceptibility was, generally, confirmed by measurements of percentage germination and length of hyphae from individual conidia on leaf discs.Regressions of hyphal length on leaf composition showed that susceptibility was apparently related inversely to free amino nitrogen and water content and directly to insoluble carbohydrate per unit dry matter.
Properties of wilt‐toxins produced by Verticillium albo‐atrum Reinke & Berth.
Authors: STODDART J. L. , CARR A. J. H. 
Published: February 2008

SUMMARYCultures of Verticillium albo‐atrum grown in a liquid, mineral salts/sucrose medium, were harvested at daily intervals and subjected to gel‐filtration on Sephadex G‐25 columns eluted with demineralized water. Ultraviolet scanning of the eluate indicated a broad division into high and low molecular weight fractions (HMW and LMW). The HMW material was found to be a variable mixture of a protein component (M.W. c. 100,000) possessing mild cellulase activity, and fructosan (M.W. 5,000–10,000). Both components produced wilting in a lucerne detached‐leaf bioassay. Heat denaturation resulted only in the loss of the protein component with a corresponding reduction in wilt‐toxicity. A number of LMW components were found to produce leaf necrosis, but only in high concentrations and long‐duration assays. These were considered to be of doubtful significance in the wilt syndrome. The possible action mechanisms and the basis of resistance are discussed.
Cellulase activity of Polyporus betulinus
Authors: BELL M. K. , BURNETT J. H. 
Published: February 2008

SUMMARYMethods are described for isolating and crossing monocaryons of P. betulinus and of determining their cellulase activity by observing changes in viscosity of a carboxy‐methyl cellulose preparation.Cellulase activity, so measured, is not correlated with growth rate in the presence or absence of cellulose.Cellulase activity is almost certainly controlled polygenically and is inherited independently of mating type.
Some observations on size and biological activity of spray deposits produced by various formulations of copper oxychloride
Authors: EVANS E. , COX J. R. , TAYLOR J. W. H. , RUNHAM R. L. 
Published: February 2008

SUMMARYChemical estimations and biological assays, using Botrytis fabae, of spray deposits on beans (Vicia faba) in the laboratory have shown that the amount of an initial spray deposit of copper oxychloride is dependent on the volume of application used per unit area and the concentration of copper in the spray liquid. The addition of 0.1 % of an anionic surfactant (dioctyl sodium sulpho‐succinate) greatly reduced the amount of these initial deposits although another anionic surfactant did not. In the laboratory trials the fungitoxicity of the spray deposit was related to the actual copper levels initially present. In general, the addition of surfactants improved the fungitoxicity of the initial deposit.The addition of surface‐active agents did not materially affect the rain‐resistance of the spray deposits, while their presence in emulsions of PVA, PVC and PVB gave an improved biological performance. All three polymeric materials greatly improved the tenacity of copper oxychloride spray deposits without reducing their fungitoxicity in laboratory tests.When examined in field experiments against potato blight (Phytophthora infestans) these apparent biological advantages due to the tenacity and good distribution of the polymeric emulsion formulations did not materialize. An explanation for this apparent contradiction between laboratory and field data has been given based on certain features of the epidemiology of the pathogen.
The relative toxicity and persistence of insecticides applied as water‐dispersible powders against stored‐product beetles
Authors: PARKIN E. A. 
Published: February 2008

SUMMARYTwelve insecticides, formulated as water‐dispersible powders, were applied to strips of filter paper and their toxicities to eight species of stored‐product beetles were determined. The insecticides were DDT, methoxychlor, lindane, aldrin, dieldrin, synergized pyrethrins, malathion, fenthion, Chlorthion, diazinon, trichlorphon and carbaryl. The insects were adults of Sitophilus granarius (L.), S. zeamais Mots., Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.), Stegobium paniceum (L.), Lasioderma serricorne (F.), and Ptinus tectus Boield. Tables of LD 50 values are presented in terms of deposits of active ingredient between the limits investigated, namely 0.625 and 80 mg./sq.ft., for 2‐day and 3‐day periods of continuous exposure at 25d̀ C. and 70% R.H. The data give a broad view of the susceptibility of each insect species to the different insecticides, the effectiveness of each insecticide against the range of insect species, and the speed of action of the insecticides. Trichlorphon had a very low toxicity to all species except O. surinamensis and was omitted from further testing.Deposits of the remaining eleven water‐dispersible powders on filter paper were stored and tested at intervals up to 16 months. This yielded information on the persistence of the formulations after application to a chemically inert substrate. Five of the insecticides‐malathion, fenthion, Chlorthion, diazinon and carbaryl were then investigated for their persistence on cement, tile, whitewash on tile, wood, and sacking. This test revealed loss of effectiveness of some of the organophosphorus insecticides because of volatility or of alkalinity of the substrate, although some of the results obtained with tiles were difficult to explain. Factors such as surface activity, porosity and real surface area may have played a role, as well as the physical state of the insecticide in the formulation.
Measurement of narcotic potency using houseflies
Authors: BRADBURY F. R. , O'CARROLL F. M. 
Published: February 2008

SUMMARYA method is described for the measurement of narcotic potencies of chemical compounds, using houseflies. Narcotic potency measurements give rise to statistical problems which differ from those encountered in toxicity determinations in so far as the narcotic process is reversible, and successive values of the number of affected insects in a group subjected to the test do not normally increase monotonically and in some case considerable oscillation occurs. An earlier method (Bradbury & Armstrong, 1954) used probit analysis, but it is now shown that this treatment and also regression analysis both fail to provide a valid method of dealing with variability in this type of test. A test based on the response of two flies, one male and one female per flask, is now described. The test, based on sixteen flies per compound, gave figures for:α0, the partial saturation of the test compound giving the same average knock‐down time as chloroform at a partial saturation of 0.005; α1, the partial saturation of the test compound giving knock‐down in I hr.; b, the slope of the straight line relating log. knock‐down time to log. partial saturation; s, the residual standard deviation of log. knock‐down time about its regression line on log. partial saturation.From these values the 95% confidence limits for the slope and for the values of α0 were calculated. The test also provided information on the convulsive action of compounds and a modification of it was used to determine knock‐down times of very potent narcotics at high dosages. Results are presented for fifty‐seven halogenated hydrocarbons and the hypothesis that variations in potency between narcotics are determined mainly by rates of diffusion is examined. The results do not support this hypothesis. Narcotic and convulsant potencies measured by the method described are a useful guide to the behaviour of compounds in mouse tests.