bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiologic races of Phytophthora fragariae
Authors: HICKMAN C.J. 
Published: February 2008

SUMMARYPathogenicity tests with forty‐nine isolates of Phytophthora fragariae, cause of red core disease of strawberry, using the strawberry varieties Huxley, Perle de Prague, Climax, Talisman, Aberdeen and Cambridge Vigour, revealed the existence of twelve physiological races of the fungus on the basis of a pathogenic or non‐pathogenic reaction. Further differentiation, on the basis of degree of pathogenicity to Perle de Prague and to Climax, allowed the recognition of nineteen races.Varying the concentration of zoospores used as inoculum, and the length of inoculation period, which did not affect the relative pathogenicities of two isolates tested, had greater effects on the level of invasion with a highly pathogenic isolate than with a slightly pathogenic one.Amongst the isolates differences uncorrelated with other characters such as pathogenicity were demonstrated in growth characters in agar culture and in abundance of zoospore production.
Biological activity of bulbiformin in soil
Authors: VASUDEVA R.S. , SINGH G.P. , IYENGAR M.R.S. 
Published: February 2008

SUMMARY Bacillus subtilis is capable of producing the antibiotic bulbiformin in soil. Antibiotic production is considerably enhanced when the soil is sterile and enriched with nutrients such as aspartic acid or asparagin, and dextrose or certain root residues. In the presence of the root supplements the antibiotic persists in soil over several weeks in fairly high concentrations.Under favourable conditions for antibiotic production such as the presence of root residues, inoculation of B. subtilis into soil results in a marked lowering of the incidence of pigeon‐pea wilt due to Fusarium udum.
The effect of growing resistant potatoes on a potato‐root eelworm population—a microplot experiment
Authors: COLE C.S. , HOWARD H.W. 
Published: February 2008

SUMMARYThe effect of growing resistant potatoes bred from Solanum tuberosum subsp. andigena and of non‐host crops on a potato‐root eelworm, Heterodera rostochiensis, population was studied for 4 years in microplots of a sandy loam. The reduction in the egg population from growing resistant potatoes was about 80% per year, a higher value than had been obtained previously for a black fen soil but agreeing with Dutch and German results. After 4 years of resistant potatoes the egg population was only about 1% of the initial value, and no increase in the frequency of ‘resistance‐breaking’ (biotype B) eelworms was detectable. Reductions in the egg populations from growing non‐host crops were about 60% in the first year but very much smaller in the second to fourth years. After 4 years of non‐host crops the egg population was still about 25% of the initial value.
Further studies on the host range and properties of Trinidad cowpea mosaic virus
Authors: CHANT S.R. 
Published: February 2008

SUMMARYAdditional to previously recorded host reactions, Trinidad cowpea mosaic caused local lesions in French bean (Phaseolus vulgaris L.), Bengal bean (Mucuna aterrima, Holland), Petunia hybrida Vilm. and Chenopodium amaranticolor Coste & Reyn; the last two are the only known non‐leguminous hosts. C. amaranticolor and French bean were used to study some properties of the virus. Infectivity was not affected by exposure to pH values between 5 and 9.1, to a 50% saturated solution of ammonium sulphate or a 50% solution of acetone or ethyl alcohol. The virus has polyhedral particles with a mean diameter of 25 mμ (approx.).
Alternate hosts of cucumber powdery mildew
Authors: STONE OLWEN M. 
Published: February 2008

SUMMARYCucumber powdery mildew is a common obligate parasite of glasshouse cucurbit crops in Britain. In the Cucurbitaceae only the genus Luffa was immune to infection. The fungus cannot survive the winter on cucurbits, but may persist on alternate hosts. Several common weeds were susceptible to experimental infection by the fungus and Sonchus asper is a very probable source of re‐infection for cucurbits. Chrysanthemum powdery mildew would not infect cucurbits, nor would the cucurbit mildew infect chrysanthemums.
Studies on strawberry mildew, caused by Sphaerotheca macularis (Wallr. ex Fries) Jaczewski*
Authors: PERIES O.S. 
Published: February 2008

SUMMARYThe development of S. macularis from spore germination to sporulation is described.Two Fragaria species and thirty‐six varieties of cultivated strawberries were tested for foliar reaction to mildew infection. Both F. chiloensis (originally from Ecuador) and F. ovalis were extremely susceptible. In the cultivated varieties tested, leaves of Cambridge Favourite, Huxley and Late Pine were found to be the most resistant. There were no immune varieties.Tests with isolates of the fungus from different parts of the country gave no evidence for the existence of physiologic races.The effects of certain leaf‐surface fractions on conidial germination have been demonstrated and their significance discussed.Histological studies have shown that leaf resistance is correlated with the relative difficulty of penetration of the cuticle and epidermal wall by the fungus. Necrotic symptoms appearing in leaves of certain varieties of strawberries on infection had no bearing on host resistance.
Overwintering of hop downy mildew Pseudoperonospora humuli (Miy. and Tak.) Wilson
Authors: COLEY‐SMITH J.R. 
Published: February 2008

SUMMARYThe experiments described in this paper show that Pseudoperonospora humuli can overwinter in infected hop rootstocks in the form of mycelium and that primary infected shoots (basal spikes) are produced from dormant buds infected by such mycelium. Crop yield from plants with infected rootstocks averaged 27.7% less than that from healthy plants.
Root exudates from banana and their relationship to strains of the Fusarium causing Panama wilt
Authors: BUXTON E.W. 
Published: February 2008

SUMMARYA method is described for obtaining sterile exudates from banana roots still attached to the parent plant. Root exudates from the varieties Gros Michel (susceptible to Panama wilt) and Lacatan (resistant) were tested for their effects on spore germination of three strains of the pathogen, Fusarium oxysporum f. cubense.In a medium otherwise optimal for spore germination, root exudates from 3–6‐month‐old Lacatan plants inhibited spore germination whereas root exudates from Gros Michel did not. The extent of the inhibition depended on the strain of the Fusarium tested and it decreased with ageing of the plants from which the root exudates came. In weak sucrose or soil‐extract media, root exudates from Gros Michel promoted spore germination of each strain. Exudates from young Lacatan plants did not promote germination in these two media, but exudates from 7–9‐month‐old did, although less than Gros Michel exudates.Chromatograms showed eighteen amino acids in the root exudates, thirteen common to both banana varieties. Gros Michel root exudates contained no detectable cystine or threonine, and Lacatan no leucine, serine or tyrosine. Root exudates from young Lacatan contained more aspartic acid, glutamine and proline than those from young Gros Michel, but the differences decreased as the plants aged.Total carbohydrates were maximal in root exudates from 6‐month‐old plants of both varieties. Gros Michel had 1.5 times more carbohydrate than Lacatan when young, but plants 3 and 9 months old contained almost equal amounts. Chromatograms showed that eight sugars were present and Gros Michel exudates had more of each sugar than did Lacatan at all stages of sampling.Materials that inhibited spore germination on Dox‐agar media were demonstrated at RF 0.7 on chromatograms of Lacatan exudates. Neither ninhydrin‐reactive spots nor spots that fluoresced under ultra‐violet light occurred at RF 0.7 with Gros Michel exudates; nor did any materials at that RF inhibit spore germination.The relationships between materials in the root exudates from the wilt‐susceptible and wilt‐resistant plants and differences in spore germination responses are considered as part of a wilt‐resistance mechanism in the rhizosphere of banana.
The effects of temperature and relative humidity on mortality in Limothrips cerealium Haliday (Thysanoptera) overwintering in bark
Authors: LEWIS T. 
Published: February 2008

SUMMARYThe temperature, relative humidity and pressure changes in the bark of Austrian pine during the winter 1960/61 are described. The lowest temperatures occurred in December and January, and the highest mostly in March and April. There was a large diurnal temperature range of up to 34° C. on sunny days, which was usually greatest on the eastern side of the trunk. The relative humidity of air in bark crevices on the sunny side of the tree often fell below 30%: it increased to over 80% at night and in wet weather. In dull weather the temperature and relative humidity fluctuations were less. Changes of temperature and humidity produced contractions and expansions of up to 0.006 in. in the radial thickness of the bark.The susceptibility of L. cerealium to low temperatures was not affected by the acclimatization temperature within the range tested. Thrips were tolerant of continuous chilling and rapid fluctuations in temperature far more severe than conditions experienced in the field, providing that humidity was high. Prolonged artificial chilling caused muscular incoordination and eventually death. Activity ceased between 0° and 5° C. There was a suggestion, which was not satisfactorily proved, that cold hardiness increased slightly from October to March, but frost is unlikely to cause much mortality during the winter.Thrips died quickly in warm, dry air and such conditions in the bark in spring, when emergence is starting, are probably the most important cause of the small amount of mortality which occurs. In these conditions the bark contracts and thrips may be crushed or perhaps trapped and subsequently desiccated by the sun.
Studies of earthworm populations in orchards
Authors: RAW F. 
Published: February 2008

SUMMARYThe amount of leaf litter buried by worms between leaf fall and spring was measured in two stages in five grass and two arable orchards near Wisbech, Cambs. A known number of weighed leaves was placed on the ground beneath wire cages at leaf fall and again several weeks later and those remaining at the end of each stage were counted and weighed. Unburied leaves lost about one‐quarter of their dry weight during each stage. Buried leaves were pulled into burrows by Lumbricus terrestris (Linn.), apparently the only species present that did so. Populations of L. terrestris beneath the cages were estimated from the number brought to the surface by dilute formalin.In grass orchards, the number and weight of leaves buried was closely correlated with the estimated fresh weight of L. terrestris. Some orchards had 3/4 to 1 ton of L. terrestris per acre and in these over 90% of the normal leaf fall (1/2 ton dry weight) was buried during winter. Earthworm activity could account for the observed amounts of leaf litter removed in winter and observed differences between orchards could be attributed to differences in their L. terrestris population.Apple leaves were buried more rapidly in arable than in grassed orchards, probably because they were the only ones and were easier to find and bury when there was no grass. Evidence to support this came from one grass orchard where the number of leaves buried from each cage was inversely proportional to the amount of surface vegetation. Twice as many leaves were buried in cages initially containing 200 leaves as in cages containing 100 leaves.The rate at which L. terrestris buried leaves depended on soil temperature, and burial probably stops at 2° C, which is about 1.6° C. below the lowest weekly average temperature reached in Wisbech soils in winter.The long‐term effect of leaf burial was shown by the contrasting soil profiles of a typical grass orchard and one where L. terrestris is rare, where the crumb structure is poor and where the accumulated remains of up to 15 years leaf fall now form a surface mat 1/2 ‐1 1/2 in. thick.
The epidemiology of tomato mosaic
Authors: BROADBENT L. 
Published: February 2008

SUMMARYA type of ‘White Burley’ tobacco distinguished between the strains of tobacco mosaic virus (TMV) present in sixty out of sixty‐four smoking tobaccos and in 187 out of 203 British tomato crops and tests with it suggest that smoking tobacco is seldom a source of virus for tomato crops. A tobacco strain was found on one nursery only, in some grafted plants. Cucumber mosaic virus occurred in one and potato virus X in thirteen crops. Tomato plants were not readily infected when handled after handling infected dry tobacco, though they were usually infected when rubbed with water extracts. Infection with tomato strains of TMV usually, but not always, protected tomatoes against infection with the tobacco strain.
Some effects of far‐red irradiation and gibberellic acid on the growth of tomato plants
Authors: SELMAN I.W. , AHMED E.O.S. 
Published: February 2008

SUMMARYThe effects of supplementary irradiation with a far‐red (FR)‐rich source on tomato plants raised in a growth room with warm‐white fluorescent tubes as the FR‐deficient, primary light source have been studied with and without the application of gibberellic acid (GA).Stem elongation in response to FR was independent of the amount of GA applied. Small but significant increases in fresh weight of leaflet laminae were sometimes obtained with GA. The optimal dose was about one‐eighth of the saturation dose for stem height. By combining the optimal daily GA dose for fresh weight laminae with FR, significant increases were obtained for fresh and dry weights of laminae and for stems plus petioles. The increase in lamina dry weight and leaf area amounted to 55 and 54%, respectively, with 15 days of treatment.It was concluded that GA and FR affect growth in distinct ways. FR may release a growth factor in both leaves and stems and GA probably substitutes for native gibberellins in stems.
The effects of cathode ray irradiation of wheat on surface moulds, respiration, flour flavour and odour, and germination
Authors: CROPSEY M.G. , LEACH C.M. , CHING TE MAY , SATHER LOIS A. , WIANT D.E. 
Published: February 2008

SUMMARYThe effects of cathode ray radiation on the respiration, germination, flavour and odour, and microflora of stored wheat were determined by irradiating kernels at different moisture levels, under different combinations of dosage (10,600‐2,000,000 rep) and of voltage (600,000–1,000,000 V.) and on one side or two sides.The lethal effects of irradiation on the natural microflora of kernels, and on the spores of Penicillium corymbiferum artificially inoculated onto kernels, were determined in preliminary experiments. Extensive studies with kernels artificially inoculated with Aspergillus repens, a proven storage mould, showed that as dosage was increased there was a corresponding reduction of viable spore load, with some reduction even at the lowest dosage of 10,600 rep. Irradiation of kernels at the highest applied voltage of 1,000,000 was more effective in killing spores than at 600,000; also a dosage applied on two sides was more effective than an equal dosage applied on one side. Spores were more readily killed when kernels were irradiated at a higher moisture level.Dosages above 42,400 rep (total dosage at 600,000 V.) significantly reduced the total number of normal plants germinating from irradiated kernels whether radiation was applied on one or both sides, or at high or low moisture levels. At 23,000 rep (total dosage at 1,000,000 V.) the number of normal plants produced from germinated kernels was significantly reduced, whether radiation was applied on one or both sides, or to kernels held at high or low moisture levels.The thresholds for irradiated flavour and odour for flour milled from irradiated kernels were about 169,600 rep (total dosage at 600,000 V.) and about 46,000 rep (total dosage at 1,000,000 V.), regardless of the moisture content or whether the dosage was applied on one or both sides. There was a significant reduction of the respiration of high moisture wheat inoculated with Aspergillus repens, when irradiated at dosages greater than 11,500 rep (total dosage at 1,000,000 V.), whether radiation was applied on one or both sides. Likewise, there was a significant reduction in respiration of kernels irradiated at dosages of 19,500 rep (total dosage at 600,000 V.), whether this was applied to one or both sides. The respiration of high moisture kernels was not reduced to that of the low moisture kernels until the 500,000 rep dosage.
The ecology of nematode‐trapping fungi in the soil
Authors: COOKE RODERIC C. 
Published: February 2008

SUMMARYThe decomposition of sucrose in non‐sterile soil stimulates an increase in both the population of free‐living nematodes and the activity of indigenous nematode‐trapping fungi. After sucrose decomposition reaches a certain stage the fungi cease to trap the nematodes still present in the soil. Increasing the amount of sucrose added to the soil stimulates greater increases in nematode population but results in a decrease in predacious activity of the fungi. Experiments using nematode‐free soil suggest that the presence of nematodes is necessary to initiate the formation of trapping organs, but that the fungi are incapable of remaining in a predaciously active state in the absence of an organic energy source other than the nematodes. The significance of this is discussed.
An approach to the chemotherapy of silver leaf disease (Stereum purpureum (Fr.) Fr.) of plum trees*
Authors: BENNETT MARGERY 
Published: February 2008

SUMMARYThree‐ or 4‐year‐old plum trees of the varieties Victoria and Purple Pershore, infected in the trunk with spore suspensions during the autumn, proved suitable for testing the effects of chemicals injected in the attempt to cure silver leaf disease (Stereum purpureum) and provided material for the assessment of the effects over more than one season.Indications were found that the amount of silvered foliage was related to the amount of mycelium present in the wood. Injection of 0.5% 8‐hydroxyquinoline potassium sulphate (Oxine KS) at different times in the season increased the volume of diseased wood, but there was evidence that it reduced the density of active fungal mycelium in the wood. No permanent reduction in disease symptoms was found to result from the injection of either Oxine KS or griseofulvin.
The epidemiology of apple scab (Venturia inaequalis (Cke.) Wint.)
Authors: HIRST J.M. , STEDMAN O.J. 
Published: February 2008

SUMMARYThe liberation of Venturia inaequalis ascospores in orchards is subject to many variables, some of which were studied in the laboratory either in a wind tunnel of approximately 1 ft. square cross‐section or in four smaller tunnels where the annual ascospore production from replicated, small, uniform area samples of dead apple leaf could be compared.Dew releases some ascospores, but very few compared to rain. The equivalent of 0.2 mm. of rain applied evenly with an atomizer released very many. Some small daytime releases occurred in dry weather but followed wetting at night, either by rain or dew. In orchards 75% of the spores released by brief rains were liberated within 3 hr.; for rains of all durations the comparable figure was 6 hr. Despite the part rain plays in release, there were more ascospores on average in the air at the middle of the day than at any other time, a distribution not shared by rain. This discrepancy could not be explained by the individual effects of light, the time elapsed between wettings, or by temperature (except when very close to freezing point). Observations of the release when atmospheric turbulence was constant or slight suggested that the smaller liberation at night could result from the interaction between temperature and the time for maturation since the previous wetting.When wetted at weekly intervals, the maturation of ascospores followed an approximately normal distribution, although the peak was often narrow. The distribution could be modified by changing environmental factors, such as temperature and moisture, or the date when the leaves were collected. Tests of these factors were used to formulate a routine laboratory method for comparing the annual ascospore productivity of a standard area of dead leaf. It can be used to assess the ascospore potential of variously treated small plots, or of leaf samples from different varieties and localities. It allows new methods to be introduced for studying ascospore discharge by Venturia and other fungi. Although current experimental designs and the high variability of samples restricted its usefulness to distinguishing large differences, such differences are common, and their existence suggests that the control of apple scab could be improved by attacking the overwintering ascospores.
Some observations on the joint action of insecticides upon adult mosquitoes
Authors: HADAWAY A.B. , BARLOW F. , TURNER C.R. 
Published: February 2008

SUMMARYThe joint action of insecticides on adult female mosquitoes, Aedes aegypti and Anopheles stephensi, has been studied by topical applications of known dosages separately and in mixtures. Results indicated that the two organophosphorus compounds, malathion and diazinon, have a similar action on the mosquitoes. Responses to mixtures of an organophosphate (malathion) and a carbamate (Sevin), an organo‐phosphate (malathion) or a carbamate (Sevin) and a chlorinated hydrocarbon (DDT or dieldrin), and of two chlorinated hydrocarbons (DDT and dieldrin) were less than expected for similar action.In other experiments in which two insecticides were applied separately with an interval of 48 hr. between treatments, the order of application was of importance. Mosquitoes receiving a sublethal dose of malathion were more susceptible to Sevin, DDT and dieldrin than untreated mosquitoes from the same population, whereas pre‐treatment with Sevin did not influence susceptibility to malathion, DDT and dieldrin.
The effect of temperature and relative humidity on the rate of development and the mortality of Tribolium madens (Charp.) (Coleoptera, Tenebrionidae)
Authors: HOWE R.W. 
Published: February 2008

SUMMARYUsing wheatfeed as food the rate of development and the developmental mortality of Tribolium madens were studied at 50 and 70%r.h. over a series of constant temperatures between 17.5 and 37.5°C. and additionally at 10, 30 and 90%r.h. at 22.5, 25 and 30°C.About 80% of eggs hatched at all temperatures except 37.5°C. where only 59% hatched. The egg period was shortest at 35°C; humidity did not affect the duration of this stage.Larvae failed to reach the pupal stage at 17.5 and 37.5°C. In all other conditions except 25°C. and 10%r.h. larval mortality was below 10%. The rate of larval development increased consistently with rise in temperature at 70%r.h., but at 50%r.h. there was an optimum between 30 and 32.5°C. Larval development was fastest at the higher humidities, except at 22.5°C. where the results were irregular. The populations used at this temperature were heterogeneous and one larva needed over 200 days to pupate. At 20°C. many larvae entered a resting stage when fully grown and some failed to pupate after 350 days, but did so when placed at 25°C. It is suggested that this resting stage might be a diapause.The duration of the pupal period was not affected by humidity but it decreased at higher temperatures. The sex ratio was significantly different from unity, with a predominance of females.The lengths of the various stages, that of the total developmental period and the weight of pupae are compared with corresponding data for T. confusum and T. castaneum. In all conditions, these smaller, more important species develop at least as quickly as T. madens. Also the temperature range over which they can breed is wider.