bluuebunny/crossref_metadata_2025_split huggingface dataset:
A preliminary study of the effect of physical activity on the resistance of rainbow trout (Salmo gairdnerii Richardson) to two poisons
Authors: HERBERT D. W. M. , SHURBEN D. S. 
Published: February 2008

SUMMARYThe toxicity of zinc sulphate and ammonium chloride to rainbow trout forced to swim continuously against water currents of three known velocities has been compared with their toxicity to similar fish tested simultaneously in still water. For fish swimming at 85% of the maximum sustainable velocity the concentration of ammonium chloride killing 50% at 24 hr. was 0·81 times that for still water, and the corresponding factor for 48 hr. exposure to zinc sulphate was 0·70. Current speeds up to 55% of the maximum sustainable velocity produced no detectable increase in susceptibility to either poison. The increase in metabolic rate with current velocity was measured, and its relation to the increase in susceptibility to poisons is discussed.
The influence of temperature on the emergence of the cabbage root fly (Erioischia brassicae (Bouché)) from overwintering pupae
Authors: COAKER T. H. , WRIGHT D. W. 
Published: February 2008

SUMMARYThe pupae of Erioischia brassicae (Bouché) overwinter in diapause, which extends for 105–126 days at a constant temperature of 41° F. (5° C.) and terminates, in the field, between the end of January and the beginning of February. Morphogenesis is completed at constant temperature after an accumulation of about 368 day degrees above 42° F., and in the field at Wellesbourne the first flies usually emerge during April.Phenological relationships of emergence and beginning of oviposition with accumulated day degrees and the flowering of Anthriscus sylvestris appear to provide reliable methods for the prediction of the emergence of the first flies and for the determination of the appearance of the first eggs in the field.
The systemic action of benzene hexachloride seed dressings
Authors: BRADBURY F. R. 
Published: February 2008

SUMMARYWheat seedlings absorb γ‐BHC freely when grown with their roots in a saturated water solution of the insecticide but less than 10 % of the γ‐BHC applied as a seed dressing finds its way into the plants from treated seed grown in compost. About the same proportion of the dressing is absorbed by cabbage seedlings grown from treated seeds, although the usual rate of application is higher in this case. The brassica seems better able than wheat to absorb the insecticide, with the result that concentration of γ‐BHC expressed as μg./g. fresh weight is greater and it is maintained for longer in cabbage than in wheat.The rate of loss of γ‐BHC from soil is shown to be slow compared with the expected life of a seed dressing.Phytotoxic damage to wheat seedlings grown from seed dressed at 1000 p.p.m. γ‐BHC was evident when they were planted in sand but not in compost. Particle size of γ‐BHC in the dressing appeared to be without effect on phytotoxicity.
The relationship of insects, fungi and nematodes to the deterioration of roots of Trifolium hybridum L.*
Authors: LEACH C. M. , DICKASON E. A. , GROSS A. E. 
Published: February 2008

SUMMARYTo evaluate the relative importance and possible interrelationships of insect, fungus, and nematode injury to the deterioration of roots of alsike clover plants, Trifolium hybridum L., heptachlor, chloropicrin, and ethylene dibromide were applied singly and in combinations to the soil prior to seeding. The most effective treatment was an insecticide plus a soil fumigant (heptachlor plus chloropicrin or ethylene dibromide), which improved the uniformity of stand, plant height and flowering, and reduced the density of weeds. In the second year this treatment greatly increased plant survival and yields of forage. All the plants died in the untreated control plots during the third year of the experiment.There was a significant relationship between the occurrence of vascular decay and the incidence of injury by the clover root curculio, Sitona hispidula (Fabr.). There was a less marked relationship between insect injury and cortical decay; but no apparent relationship between insect injury and rootlet rot. Although root lesion nematode, Pratylenchus sp., was present, no direct relationship between nematode injury and root rots was established.The fungi most frequently isolated from alsike clover roots were Fusarium oxysporum Schl. sensu Snyd. and Han., a species of Pyrenochaeta and an unidentified fungus. Verticillium dahliae Kleb. was also present. Tests with F. oxysporum, the Pyrenochaeta sp., and V. dahliae confirmed their pathogenicity on alsike clover roots. In laboratory tests, plants with severe rootlet rot rapidly regenerated feeder rootlets in the presence of adequate soil moisture.
Pyricularia grisea(Cooke) Sacc. causing pitting disease of bananas in Central America
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYDark‐coloured, depressed spots (‘pits’), up to 10 mm. in diameter, are recorded on Giant Cavendish banana fruits in Costa Rica. Pits first appear in the field, usually on almost mature bunches, and increase in numbers during cold storage and ripening. Symptoms are identical with those of ‘Johnston fruit‐spot’ and ‘pitting disease’ described by earlier workers. Disease is maximal during and for a short time after heavy rainfall.Pyricularia griseawas consistently isolated from typical pits, and disease was reproduced by inoculating fruit in the field with conidia of P.griseafrom pure culture. Conidia germinate after 1–2 hr. in a film of water on the peel of immature fruits. An appressorium is formed and there is some evidence that this produces an infection hypha which, in the first instance, penetrates the cuticle but not the epidermis cell wall. In most cases, there is no evidence of further penetration until the fruit is ready for harvest, or until after harvest. The fungus then resumes activity and invades the epidermis and underlying tissues to cause a pit. Latency in P.griseais compared with that inGloeosporium musarum.
Effects of mineral nutrition on the production of tulip bulbs
Authors: CHEAL W. F. , HEWITT E. J. 
Published: February 2008

SUMMARYTwo varieties of tulip, Golden Harvest and Elmus, of selected bulb weight ranges, were grown in sand culture with different levels of nitrogen, phosphorus and potassium in factorial combination, and at different levels of magnesium.The effects of nitrogen were dominant, but the levels giving optimal bulb yields differed for the two varieties. Potassium and magnesium had smaller, but significant, effects and there were significant interactions between nitrogen and potassium.The weight distribution for all daughter bulbs produced from a single planting bulb was discontinuous in certain ranges. Nitrogen had an outstanding influence on the pattern of bulb multiplication, which also reflected a nitrogen/potassium interaction. Responses in weight distribution, as in total bulb production, showed both varietal and seasonal differences.
Studies on the lettuce big‐vein virus and its vector Olpidium brassicae (Wor.) Dang
Authors: TOMLINSON J. A. , GARRETT R. G. 
Published: February 2008

SUMMARYIt was demonstrated by serial graft transmission experiments that the big‐vein disease of lettuce was caused by lettuce big‐vein virus (LBVV).An Olpidium sp., always found in the roots of naturally affected plants, induced the disease when its zoospores were transferred to healthy plants. The fungus was identified as O. brassicae (Wor.) Dang.The same fungus was found in the roots of healthy lettuce, but zoospores from this source would not induce big‐vein when transferred to healthy plants.When a non‐viruliferous isolate of O. brassicae was grown in the roots of lettuce affected by big‐vein the fungus acquired LBVV and was able to transmit the disease. Conversely, the viruliferous Olpidium was converted to a non‐viruliferous form by culture in the roots of Plantago major or Veronica persica. These results were not caused by the selection of non‐vector strains of the fungus during its culture in these species, as the fungus reacquired and transmitted LBVV when again cultured in big‐vein affected lettuce roots. The results suggested that LBVV did not multiply in P. major or V. persica, or in the fungus during its growth in them.Attempts to transmit LBVV with Cuscuta campestris, C. gronovii, C. reflexa and C. subinclusa and by sap inoculation were unsuccessful.No causal relationship between tobacco necrosis virus (TNV) and big‐vein was found: the reasons for the frequent association of TNV with the disease are discussed.
A quantitative laboratory method for inoculating cabbage seedlings with Plasmodiophora brassicae Woron
Authors: CHANNON A. G. , FLINT ANNE E. , HINTON R. A. L. 
Published: February 2008

SUMMARYIn studies on root‐hair and rhizodermal cell infection of cabbage seedlings by Plasmodiophora brassicae Woron. seeds were germinated in an incubator at 25°C. on nylon mesh circles placed on glass dishes containing nutrient solution. After 3 days the original nutrient solution was replaced by a similar one containing a known quantity of resting spores of the fungus. After a further 5–7 days in the incubator the roots were removed and stained. The infected plants were counted and the extent of infection on each plant was assessed in grades 0–4.Optimal infection was obtained by using spores from decomposing clubbed roots, by thoroughly washing the resting spores, and by using thirty plants per dish grown from seed of 1·5‐2·0 mm. diam. There was a rapid increase in infection from the 3rd to the 6th day after introduction of the spores.Infection of large numbers of seedlings was easily obtained by this technique, which is now being used for assessing the effects of chemicals in controlling clubroot.
Studies on sharp eyespot disease of cereals
Authors: PITT D. 
Published: February 2008

SUMMARYSeveral isolates of Rhizoctonia solani Kühn were obtained from wheat stems bearing lesions of sharp eyespot in the summers of 1960 and 1962. Differences in virulence of these isolates, assessed by severity of attack on seedlings, were demonstrated. Isolates taken from different plants in the same crop were shown to differ in virulence. All isolates obtained from wheat‐stem lesions attacked both winter and spring varieties of wheat, barley, oats and rye. Several varieties of spring and winter wheats showed no differences in susceptibility to disease.Infection of the wheat host took place at any time during the growing period, but was most severe in the earlier stages of growth.Sharp eyespot occurs over a wide range of soil types, but the most severe attacks all occurred on lighter soils with neutral to slightly acid pH. Sand‐culture experiments showed no effect of pH on disease development over the range 5·9‐8·1. Disease development in seedling wheat plants was favoured by cool (9·3°C.) dry (ca. 20% of the water‐holding capacity) conditions in the greenhouse. Disease incidence in the field over the period 1959‐63 could be correlated with the weather conditions prevailing over this time.
The effects of black‐currant yellows virus and a strain of reversion virus on yield
Authors: CROPLEY R. , POSNETTE A. F. , THRESH J. M. 
Published: February 2008

SUMMARYBlack‐currant yellows virus restricted the growth of bushes var. Baldwin and Wellington XXX and decreased the total weight of fruit harvested in six seasons by 70%. The size and number of fruits were decreased and in one season ripening was retarded. Virus spread naturally to only four of 250 other bushes in the trial.A strain of reversion virus which caused transitory vein‐pattern symptoms did not restrict vegetative growth, yet decreased the number and size of fruits. In contrast to the more severe effects of prevalent virulent strains, the total crops from the Wellington XXX and Baldwin bushes were decreased by 50 and 33% respectively. The virus spread to fifteen of the 136 healthy bushes and to at least six of the 108 bushes previously infected with yellows virus.The black‐currant gall mite (Phytoptus ribis Nal.) increased more rapidly on the Wellington XXX bushes than on those of Baldwin. In each variety the infestation was much greater on reverted than on other bushes, apparently because infection with reversion virus decreased natural resistance to mites.
The epidemiology of tomato mosaic
Authors: BROADBENT L. 
Published: February 2008

SUMMARYFour experiments were done under glass in which tomato plants were inoculated with TMV (tomato strains of tobacco mosaic virus) at different times during their growth, and most of the healthy control plants were kept uninfected throughout the season. Leaf symptoms were visible 2–3 weeks after inoculation, and infected plants were checked and grew more slowly than healthy ones. Leaves of infected plants were sometimes scorched by overhead damping with water, and lower leaves died earlier than those of healthy plants.In the 1960 experiment, with a winter‐sown crop, plants inoculated on 3 March, when the first trusses began to flower, suffered a 15% loss in weight of fruit; those inoculated on 14 April, when the fifth trusses began to flower, an 18% loss, and those inoculated on 31 May, when most of the fruits had set, a 14% loss. The two early infections caused 13% fewer fruits to set, but the last one only 3% fewer; however, with successively later infection dates, mean fruit size progressively decreased. Fruit quality was severely affected by later infection, 10% of the fruits from plants infected in April showing necrotic pitting, bronzing or severe mottle, but 31% of those infected on 31 May.Three experiments with spring‐sown plants gave similar results. In the 1961 experiment, plants inoculated on 3 May, when the first trusses began to flower, yielded 21% less weight of fruit than the controls, and those inoculated on 8 June, when the fifth trusses began to flower, 14% less. A tobacco strain of TMV that caused no symptoms in tomato failed to protect plants from later infection with a tomato strain. In the 1962 experiment, seedlings inoculated on 13 March, just after pricking out, yielded 10% less weight of fruit; plants inoculated on 4 April, just after planting out, 3% less; those inoculated on 3 May, when the first trusses began to flower, 11% less; and those inoculated on 7 June, when the fifth trusses began to flower, 16% less. In the 1963 experiment, plants inoculated on 21 May, when the first trusses began to flower, yielded 17% less weight of fruit than the controls, and those inoculated on 20 June, when the fifth trusses began to flower, yielded 23% less; many of the control plants became infected during August in this last experiment. As in the first experiment, losses were largely due to poor setting of fruits at the time the plants became systemically infected with virus, and necrotic pitting and severe bronzing again mainly affected fruits from the late‐infected plants. The plants grew vigorously and were ‘soft’ or lush in all the four experiments.
Powdery mildew of tobacco (Erysiphe cichoracearum DC.)
Authors: COLE J. S. 
Published: February 2008

In water culture experiments, tobacco plants of Hicks variety were supplied with factorial combinations of high and low concentrations of nitrogen, phosphorus and potassium. Incidence of powdery mildew and growth and chemical composition of infected and healthy plants were compared.There was more disease when all elements were supplied at the higher of two concentrations, but the increase in infection was less than the increase in growth. Plants grown in media containing a low ratio of potassium to nitrogen produced the least susceptible leaves; their disease indices were up to 30 times less than those of plants that received the full nutrient treatment. Potassium‐deficient leaves had thinner cell walls, larger water content, smaller sugar and potassium contents, and greater amino nitrogen and magnesium contents, compared with those of plants grown in any of the other media. The possible relation between these characteristics and susceptibility to Erysiphe cichoracearum DC. are discussed.
The effect of high temperatures on aqueous suspensions of stem eelworm, Ditylenchus dipsaci (Kühn) Filipjev
Authors: GREEN C. D. 
Published: February 2008

SUMMARYThe relationship between the time and temperature necessary for killing Ditylenchus dipsaci in hot water suggests that the cause of death at 48° is different from that below 46° C. The ability of nematodes, which survived one hot‐water treatment, to recover their resistance so as to survive a second hot‐water treatment and yet to show a susceptibility to storage temperatures which are not lethal to untreated nematodes, supports the view that there are at least two causes of death after heat treatment.Acclimatization increases the heat resistance of the nematodes and would cause failure of hot‐water treatment as a control measure against bulb eelworm. Storage at temperatures of 25–30° C. after hot‐water treatment increases the proportion of dead nematodes and, if applied to bulbs, might improve control. The effects of such temperatures before and after hot‐water treatment are not due to heat shock following the sudden rise or drop in temperature.
Growth of Picea sitchensis in old forest nurseries
Authors: REDDY M. A. RAM , SALT G. A. , LAST F. T. 
Published: February 2008

SUMMARYThe poor yield of Sitka spruce (Picea sitchensis Carr.) seedlings in old forest nurseries at Kennington and Ringwood results from losses of seedlings during germination, and stunted growth of those that survive.Losses, which are attributed mainly to invasion by Pythium spp. and secondarily by Cylindrocarpon radicicola Wr. and Fusarium spp., were decreased by (a) partially sterilizing soil with formalin, dazomet or metham‐sodium, (b) applying the fungicides maneb and quintozene to soil, and (c) dressing the seed with fungicides. In contrast, only partial sterilization increased growth of the survivors.Fungicidal seed‐dressings, which did not affect growth, increased numbers of survivors most in partially sterilized soils, suggesting that soil microfloras developing after partial sterilization controlled seed‐borne pathogens no more effectively than do the microfloras of unsterilized soils.Experiments with transplants indicated that the growth stimulus from partial sterilization operated equally at all stages of seedling development, and was independent of root damage done by parasites.
The toxicity of some insecticides to first‐instar nymphs of the desert locust, Schistocerca gregaria (Forsk.)
Authors: MacCUAIG R. D. , YEATES MAUREEN N. D. B. 
Published: February 2008

SUMMARYThe toxicities of γ‐BHC, diazinon, dieldrin, DNOC, heptachlor and parathion to first‐instar hoppers of the desert locust were determined. Parathion was the most toxic followed in descending order of toxicity by dieldrin, γ‐BHC, heptachlor, diazinon and DNOC. Results with diazinon showed a non‐linearity of the probit/log. dose regression line. Changing the post‐treatment temperature from 26 to 31° C. had no effect on the final toxicity of the insecticides, excepting that of dieldrin which was 1·48 times as toxic at the higher temperature.
The toxicity to fish of mixtures of poisons
Authors: HERBERT D. W. M. , SHURBEN D. S. 
Published: February 2008

SUMMARYExperiments have been made with rainbow trout in solutions of ammonium chloride and zinc sulphate to examine the empirical rule that a mixture of two poisons, P and Q, should be at the threshold concentration for acute toxicity when PS/PT + QS/QT= I, where the suffix S stands for the concentration in solution and T for the threshold concentration of a poison when tested by itself. The most detailed experiment, with a hard dilution water in which the dissolved‐oxygen concentration was at the air‐saturation value, gave results within 4% of those expected from the hypothesis. Agreement was not so close in a soft dilution water, nor in a hard dilution water containing a reduced concentration of dissolved oxygen, but in these two cases the threshold concentrations for the mixtures were within 26 and 17% of the expected value of unity. In every case the rule under examination provided a better description of the data than models based on the hypothesis of independent joint action.
Investigation of carnation viruses
Authors: HOLLINGS M. , STONE OLWEN M. 
Published: February 2008

SUMMARYCarnation mottle virus (CarMV) was present in every plant tested of over forty‐four varieties from commercial carnation stocks. Inhibitors of infection in carnation sap prevent transmission to many species, but not to Chenopodium amaranticolor, which proved the best indicator and assay host. CarMV infected thirty‐three of 113 plant species inoculated, but only Dianthus spp. are likely to be affected in practice. Healthy carnations were infected when handled after diseased ones. CarMV was not transmitted by Myzus persicae, through carnation seed, or through dodder (Cuscuta campestris).The type strain occurred in all ‘Sim’ carnations tested; another strain, designated ‘PSR’, occurred in vars. Pink Shibiuya and Orchid Beauty. The two strains were distinguished by the symptoms caused in Chenopodium amaranticolor and other plants. The type strain protected against the PSR strain in Atriplex hortensis. An ‘attenuated’ form of the virus, which multiplied much more slowly than the typical form, withstood adverse conditions better.Although the virus concentration decreased in the terminal 1–2 mm. of the carnation shoot apex, CarMV was always detected in the meristem dome. Nevertheless, some virus‐free clones were obtained by aseptic culture of excised tips. CarMV was not eliminated by growing plants at 38°C., although its concentration in the apical tissues was diminished.Sap was infective after dilution to I/200,000, heating (10 min.) to 85°C. (but not 90°C.), storage for up to 81 days at 18°C., or over 3 years at o°C. Purified and concentrated preparations of CarMV were readily obtained from carnation by several methods: they contained ‘spherical’ particles about 28 mμ diameter, were antigenic, and produced a specific light‐scattering virus zone in density‐gradient centrifugation. The S20,w at infinite dilution was 122.Although CarMV shares many in vitro properties with eleven other viruses having similar particle shape, it is not serologically related to any of them and differs in other respects.Control of the virus depends on the production and distribution of virus‐free clones of carnation.
Some effects of other viruses and of temperature on the multiplication of potato virus X
Authors: CLOSE R. 
Published: February 2008

SUMMARYThe severity of symptoms shown by tobacco plants infected with potato virus X (PVX) was correlated with virus concentration. The virus multiplied optimally between 20 and 24deg;C. and increasing temperature above 25°C. decreased symptoms and virus concentration. PVX did not multiply detectably in plants at 34°C.Tobacco leaves systemically infected with both PVX and potato virus Y (PVY) contained more PVX than leaves infected with PVX alone. The greatest relative increase was at 31°C. because at this temperature PVX alone barely multiplied and failed to move out of the inoculated leaf. The concentration of PW was not altered by the presence of PVX and the optimum temperature for its multiplication appeared to be 28°C. Three other viruses (namely tobacco mosaic virus, cucumber mosaic virus (yellow strain), and henbane mosaic virus) that multiply at 31°C. also assisted the systemic spread of PVX at this temperature, possibly by aiding its movement between mesophyll cells and into the phloem. PVY may also aid PVX at lower temperatures mainly by increasing the number of cells it infects.