bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenotype‐phenotype analysis: field application of the gene‐for‐gene hypothesis in host‐pathogen relations
Authors: WOLFE M. S. , BARRETT J. A. , SHATTOCK R. C. , SHAW D. S. , WHITBREAD R. 
Published: February 2008

SUMMARYThe frequency of occurrence of a virulence phenotype in a pathogen population is equivalent to its probability of occurrence in that population. From the compound probability law it can thus be shown that the expected frequency of occurrence of phenotypes with combined virulences is a product of the observed frequencies of the individual virulences. In many host‐pathogen interactions, observed and expected frequencies of combined virulences are closely similar. Deviations from expectation, in both directions, do occur however, and these may be of crucial importance in disease control.
The use of high‐pressure sodium discharge lamps as an aid to obtaining clubroot infection
Authors: BUCZACKI S. T. 
Published: February 2008

SUMMARYA high‐pressure sodium discharge lamp was more effective than a high‐pressure mercury discharge lamp of identical wattage in stimulating the production of clubroot symptoms on cabbage seedlings growing in infested soil in a glasshouse. Although the maximum total radiation from the sodium lamp was 3*2 times that from the mercury lamp, the differential effects were also observed on plants subjected to identical radiation from either lamp. It was considered that high‐pressure sodium discharge lamps could be a valuable aid to clubroot experiments made in glasshouses during the winter months or under conditions with restricted global radiation such as controlled‐environ‐ment cabinets.
Use of the plant growth regulator chlormequat chloride to control the aphid Hyperomyzus lactucae on black currants
Authors: SINGER M. C. , SMITH B. D. 
Published: February 2008

SUMMARYA single application of chlormequat chloride at 2500 ppm reduced the density of Hyperomyzus lactucae on black currants below that at which damage was caused. This treatment had no short‐term effects on the aphid predators present, but did affect interactions between the aphids, their host and the predators. There were no effects on yield in the year of the experiment, but in the following year bushes which had been treated gave considerably higher yields. This increase was attributed both to direct action of the chlormequat chloride and to indirect effects through the reduction of aphid density. Prospects for the use of plant growth regulators as dual‐function compounds in integrated control programmes are discussed.
Stemphylium botryosum f. lactucae‐ its developmentjn vifro and its pathogenicity to lettuce leaves
Authors: SIVAN J. , BARKAI‐GOLAN R. 
Published: February 2008

SUMMARY Stemphylium botryosum f. lactucae, incitant of a leaf‐spot disease of stored lettuce, was found to be relatively restricted in its host range. Cross‐inoculations with spore suspension of this fungus failed to induce symptoms in any of the host plants tested, except carrot. Among isolates of S. botryosum from various hosts, only the isolate from carrot induced slight symptoms on lettuce.While mycelial growth of the lettuce isolate was confined to the range 13–37 oC spores germinated at more extreme temperatures. The optimum temperature for germination and for radial growth on PDA was found to be between 25 and 30 oC. Wet spores were quickly inactivated at 50 oC, whereas more than 40 % of dry spores withstood a 24 h exposure to that temperature.Only the outer leaves of lettuce responded readily to inoculation with a spore suspension, the required incubation period being 3 days at 25 oC. Symptoms developed less readily on bruised leaves. Relative humidity approaching saturation was necessary for prompt and typical infection, notably during the 24 h following inoculation. Short dry periods (60 % r.h.) interposed at a later stage, while somewhat inhibitory, did not prevent infection.
The behaviour of Bretnia lactucae on cultivars of Lactuca sativa and on other composites
Authors: CRUTE I. R. , DICKINSON C. H. 
Published: February 2008

SUMMARYThe spores of an isolate of Bremia lactucae obtained from lettuce germinated equally well on Cellophane and on the surfaces of all plant species inoculated. The fungus penetrated the epidermal cells of both host and non‐host plants but extensively invaded only certain lettuce cultivars. Many of the species and cultivars inoculated showed no macroscopic symptoms but exhibited a hypersensitive response to invasion that was limited to a few cells and only visible microscopically. However, the hypersensitive response was not always so limited and in some species, fungal development and associated host cell necrosis was more extensive and visible macroscopically. In such instances, limited sporulation occasionally occurred. On some lettuce cultivars symptoms developed more slowly than on fully susceptible ones and less seedlings became diseased. This was due to the heterogeneity of the inoculum with respect to its ability to overcome certain race specific resistance genes. Such cultivars reacted hypersensitively to the majority, but not all, of the fungal propagules applied and the observed effect was thus due to a lower effective inoculum concentration. Without due care, both these types of ‘intermediate’ reaction could easily be misinterpreted as race non‐specific resistance particularly under field conditions. These observations emphasized the problems of categorizing cultivars and species rigidly as resistant or susceptible when inoculum could be heterogenous or when resistance reactions allowed some macroscopic symptom development.
Development of powdery mildew on leaves of several barley varieties at different growth stages
Authors: RUSSELL G. E. , ANDREWS CHRISTINE R. , BISHOP C. D. 
Published: February 2008

SUMMARYOn detached leaves and intact plants of several barley varieties at different growth stages, lower percentages of germinated conidia of Erysiphe graminis f.sp. hordei penetrated the host and initiated infection on the abaxial than adaxial surface. More and larger E. graminis colonies developed on the adaxial surface and these comprised more densely packed hyphae and produced more conidiophores than did colonies on the abaxial surface. These results are consistent with the observation that there is usually more powdery mildew on the adaxial than abaxial surface of barley leaves in the field.Smaller proportions of germinated E. graminis conidia penetrated and infected the host on leaves of adult or near‐adult plants than on those of seedlings or juvenile plants. Older plants also supported fewer, smaller and less dense colonies with less sporulation than young plants. The effects of growth stage of the host plant on development of powdery mildew were much greater in some barley varieties, and with some E. graminis isolates, than others.
Effects of mildew (Erysiphe graminis) on green leaf area of Zephyr spring barley, 1973
Authors: JENKYN J. F. 
Published: February 2008

SUMMARYA single spray of tridemorph on 1 June almost doubled leaf area index of Zephyr barley during much of the second half of June. Increases in leaf area duration before ear emergence seemed important in these plots, because they yielded much better than plots sprayed on 11 June although differing little from them in leaf area duration after ear emergence.
The incidence of rosette disease in groundnut in relation to plant density and its effect on yield
Authors: DAVIES J. C. 
Published: February 2008

SUMMARYTrials are described in which the relationships between plant density, rosette disease incidence and the yield and quality of groundnuts were investigated on sprayed and unsprayed groundnut plants.During growth, the number and percentage of sprayed and unsprayed plants showing symptoms of rosette disease was significantly greater at low plant populations than at high. At harvest, in general on unsprayed plots the numbers attacked were also greater at low plant populations, but on the sprayed plots the results were inconsistent. The percentage attack at harvest was much lower on sprayed plots at all plant populations.Menazon used as a seed dressing did not affect the incidence of the disease but used as a spray it significantly reduced the amount of disease found. The spray was applied at a rate of 294 g a.i./ha, four times at 10‐day intervals, the first spray being applied 10 days from germination. Spraying controlled secondary spread of the virus within the crop and appeared to reduce the severity of early attack. There was a marked improvement of yields and quality of nuts from sprayed plots. Plant density did not affect quality of the groundnuts obtained, but yields per ha were highest on both sprayed and unsprayed plots at the highest plant densities (seed rate up to 134 kg/ha).
Purification and properties of sweet potato mild mottle, a white‐fly borne virus from sweet potato(Ipomoea batatas) in East Africa
Authors: HOLLINGS M. , STONE OLWEN M. , BOCK K. R. 
Published: February 2008

SUMMARYA virus obtained from sweet potatoes in Kenya, Uganda and Tanzania was transmitted by inoculation of sap and by whiteflies (Bemisia tabaci). It infected forty‐five of 119 plant species in fourteen of thirty‐six plant families. It was propagated in Nicotiana glutinosa and N. tabacum, in which diagnostic symptoms of vein clearing, leaf curling and distortion developed. Cheno‐podium quinoa was a good local lesion host.Different seedling lines of sweet potato differed greatly in their susceptibility to infection and in symptoms produced; some developed leaf mottling and were stunted, some were symptomless, and some appeared immune.The virus was transmitted by dodder (Cuscuta campestris) but not by aphids, or through seed of Ipomoea nil or N. clevelandii. Sweet potato sap contained strong inhibitors of infection, and a low concentration of virus.Virus‐free cuttings of sweet potato were obtained by thermotherapy (4–5 wk at 35 °C), or by meristem‐tip culture.The virus remained infective in sap of N. tabacum after dilution to 10‐3, or after 10 min at 55 °C (but not 60 °C), 3 but not 7 days at 18 °C, or 42 but not 49 days at 2 °C. Infectivity was abolished by sonication or u.v. irradiation, by 2% formaldehyde or 2% tri‐sodium orthophosphate, and was greatly decreased by 20 % CHC13 or 20 % ether.Purified virus preparations were obtained from N. tabacum by clarifying phosphate buffer extracts with n‐butanol, virus precipitation with polyethylene glycol, and differential centrifugation. The virus sedimented as one band in density gradients, and produced a single sedimenting boundary in analytical centrifugation (s°20, w = 1555)‐ It contained one polypeptide species of mol wt 37700, and preliminary digestion experiments suggested a single‐stranded RNA.Antisera prepared against the virus reacted specifically in precipitin tube tests with titres of 1/16384, but no serological relationships could be found between the virus and fourteen viruses of the potato virus Y group.Electron micrographs showed straight, filamentous particles c. 950 nm long when mounted in MgCla, but 800–900 nra long in EDTA. The present cryptogram is: (R/i):*/*:E/E:S/Al. This virus is probably the same as Sheffield's virus B.
Eradication of apple powdery mildew (Podosphaera leucotricha) with dormant season sprays of surface‐active agents
Authors: HISLOP E. C. , CLIFFORD D. R. 
Published: February 2008

SUMMARYselection of surfactants (5%, w/v, a.i.) representative of the three main ionic types eradicated Podosphaera leucotricha from buds on dormant apple trees, cvs Cox's Orange Pippin, Jonathan and Michelin.The pathogen was apparently killed without undue damage to buds, although a phytotoxic response in the form of staining of vascular tissue and some crop reductions were observed. Treatments applied with hand lances were equally effective at reducing infections of vegetative buds on terminals, on non‐flowering spurs and flower buds. Indication of a positive correlation between the eradication of mildew from Cox's Orange Pippin trees and an increase in the incidence of apple canker (Nectria galligena) was found at Long Ashton, but this effect was negligible at sites in the West Midlands region.Efficacy of active formulations was reduced by rain soon after application or by a reduction in the concentration of applied material. Applications with a mist‐blower were effective on the cv. Cox's Orange Pippin, but less so on the cv. Jonathan, while on both cultivars efficacy of a spray containing 5 % a.i. decreased in the order 2240:1120:560 1/ha.Anti‐mildew activity was not associated with any particular chemical or ionic type of surfactant, and there was an indication that eradicant activity of alkyl phenol ethoxylates was related to their HLB value.The ecological and economic implications of the use of surfactants as fungicides are discussed.
Studies on plant growth‐regulating substances. XL. 2‐Chloro‐3‐phenylpropionitriles
Authors: KEMP M. S. , WAIN R. L. 
Published: February 2008

SUMMARYThe complete series of chloro‐, dichloro‐, methyl‐, dimethyl‐ and chloro‐methyl‐ring substituted 2‐chloro‐3‐phenylpropionitriles and several related compounds have been prepared. Their auxin activities have been assessed in the wheat coleoptile, pea segment and pea curvature tests, and the results, which are discussed in relation to molecular structure, support the suggestion by other workers that the observed activity is due to rapid uptake of the nitriles by the plant tissues, followed by metabolism to the corresponding phenylacetic acid.The high growth promoting activity of 2‐chloro‐3‐(3‐chloro‐2‐methyl‐phenyl)propionitrile (orthonil) is confirmed but 2‐chloro‐3‐(2,3‐dichloro‐phenyl)propionitrile and 2‐chloro‐3‐(2,3‐dichlorophenyl)butyronitrile are shown to be the most active members of the series.
The effect of plant density on populations of the cabbage root fly on four cruciferous crops
Authors: FINCH S. , SKINNER G. , FREEMAN G. H. 
Published: February 2008

SUMMARYTo study the effects of plant density on populations of the cabbage root fly (Erioischia brassicae), cabbage, cauliflower, Brussels sprout and swede were each planted in plots with twenty‐four concentric circles of plants at spacings ranging from 10 to 90 cm between the individual plants. Plants treated with a root drench of chlorfenvinphos and untreated plants were each sampled at ten plant densities which ranged from 1–5 to 68‐3 plants/m2.In the absence of insecticide, the numbers of overwintering cabbage root fly pupae produced ranged from c. four per m2 at the lowest plant density to 200 per m2 at the highest. The number of pupae per m2 was proportional to plant density to the powers 0–98,0‐77,0–69 and o‐6i for the swede, cauliflower, cabbage and Brussels sprout crops, respectively. The magnitude of each cabbage root fly population was determined mainly by plant density but also by the cultivar used as host plant.The results suggested that, in a given locality, when changing from low to high plant density crops during a growing season it should be unnecessary to apply insecticide to control cabbage root fly; conversely, a change from high to low plant densities would necessitate an extremely efficient application of insecticide.
A seedling method for measuring the susceptibility of wheat cultivars to Pucdnia striiformis
Authors: PRIESTLEY R. H. , DOLING D. A. 
Published: February 2008

SUMMARYThe Wycombe seedling method for measuring the susceptibility of wheat cultivars to physiologic races of Puccinia striiformis involves determining the percentage of seedlings bearing uredosori at a fixed time after inoculation under controlled environment conditions. Each cultivar is classified statistically as either vertically or horizontally susceptible and this classification is utilized in expressing the susceptibility of each to a number of races as a single value.The method has been used for three years to evaluate wheat cultivars and examples of significant differences in susceptibility between cultivars are given.A highly significant correlation has been established between data collected using the Wycombe seedling method and field data from physiologic race test beds.
Properties and relationships of broad bean stain virus and Echtes Ackerbohnenmosaik‐Virus
Authors: JONES A. T. , BARKER H. 
Published: February 2008

SUMMARYThe sedimentation coefficients (s020, w) of the two sedimenting nucleoprotein components of broad bean stain virus (BBSV) were 92 S and 113 S, and of Echtes Ackerbohnenmosaik‐Virus (EAMV) were 93 S and 114 S. Particles from each of these sedimenting components contained a single RNA species and two polypeptides. Estimates of the molecular weights of these constituents obtained by electrophoresis in polyacrylamide gels were: 42000 and 22200 (BBSV) and 41400 and 21800 (EAMV) for the polypeptides; and 2–64 and 1·62 × 106 (BBSV) and 271 and 175 × 106 (EAMV) for the RNAs. In mixtures, the protein and RNA components of BBSV and EAMV were indistinguishable from those obtained from particles of the yellow strain of cowpea mosaic virus.In freshly made virus preparations each of the sedimenting components of BBSV contained two, and those of EAMV contained three electrophoretic components. After storage for 7–10 days, BBSV preparations contained only the component migrating fastest towards the anode.Both BBSV and EAMV are distantly related serologically to cowpea mosaic but, whereas BBSV reacted only with antiserum to the severe strain, EAMV reacted only with antiserum to the yellow strain.
Effects of daylength and day/night temperatures on growth and seed yield of cowpea cv. K 2809 grown in controlled environments
Authors: HUXLEY P. A. , SUMMERFIELD R. J. 
Published: February 2008

SUMMARYThe effects of climatic factors on the growth, reproductive development and seed yield of cowpea (cv. K 2809) were investigated in controlled environment cabinets. Plants were grown to maturity in eight environments comprising all combinations of two day lengths (11 h 40 min and 13 h 20 min), two day (27 and 33 oC) and two night (19 and 24 oC) temperatures. The plants were nodulated (Rhizobium strain CB 756) and received 197 ppm N throughout growth.Treatments changed the time to the appearance of first flowers by a maximum of 6 days but the later‐flowering plants more than doubled their dry weight during this period, so that effects on plant form and, ultimately, seed production were considerable. Warm nights (24 oC) not only hastened the onset of flowering but also enhanced dry matter production during the pre‐flowering period; they did not extend the total growing period. Warm days (33 oC) did not enhance dry matter production but shortened the duration of the growing period by an average of 21 days (20%).Variation in final seed yield was mainly due to differences in the number of pods borne on branches. Warm days markedly decreased the number of pods per plant (an overall average reduction of 49%) as did warm nights in conjunction with the long (13 h 20) daylength.The number of seeds per pod was effected only by daylength (8.3 and 7.6 seeds in the long and short daylengths, respectively). Mean seed weight was decreased by 19% in warm as compared to cool nights but was increased by 18% in warm as compared to cool days.These responses are compared with those obtained with soyabean cv. TK5 in a previous experiment and are shown, in general, to be similar.
Studies on nodulated and mycorrhizal peanuts
Authors: DAFT M. J. , EL‐GIAHMI A. A. 
Published: February 2008

SUMMARYYields of fruits, plant size and chemical content of shoots, roots and seeds were higher in peanuts infected with Glomus mosseae. Infection with Glomus and Rhizobium stimulated nodulation and acetylene reduction rates. Dually infected plants given various phosphorus treatments, produced more fruits, dry matter, and nodules and contained more phosphorus and nitrogen compared with nodulated‐only plants. Mycorrhizal infections were high in all treatments. Together these two endophytes contributed greatly to the vigour of the host.
Effect of different soil and nitrogen fertilizer conditions on 32P‐labelled phosphate uptake by two grass species
Authors: HUGHES D. M. , GOODMAN P. J. 
Published: February 2008

SUMMARYIn two years of trials, roots of ryegrass took up more 32P‐labelled phosphate than roots of fescue. Application of 672 kg N ha‐1 increased phosphate absorption compared with application of 112 kg N ha‐1. Roots in mineral soil absorbed more phosphate than those in peat soil. In both soils uptake decreased as depth of phosphate injection increased from 5 to 30 cm. An interaction occurred whereby roots in the intermediate depth (10–22‐5 cm) in peat absorbed less phosphate than in mineral soil and this was apparently unrelated to the exchange or sorption properties of the soil.
The translocation of 14C photosynthate from leaves and pods in Phaseolus vulgaris
Authors: LUCAS E. O. , MILBOURN G. M. , WHITFORD P. N. 
Published: February 2008

SUMMARYField experiments were undertaken to study the pattern of distribution of photosynthate produced by the leaves and the pods of Phaseolus vulgaris (cv. Purley King) by means of the 14C technique. It was found that the UC photosynthate produced by a trifoliate leaf (38 days after anthesis) was shared almost equally between the leaf and the pod at its axil with 33–50% of the fixed 14C finding its way to the seeds in that pod. However, during the early stages of pod development (10 days after anthesis) some 13–14% of the fixed 14C was detected in the stem, indicating the inadequacy of the pod as a sink at that stage. When the pod was treated, virtually no 14C was detected in other parts of the plant. Of the 14C fixed by pod photosynthesis in the later stages (38 days after anthesis), 55–60% was translocated to the seeds within the same pod. These results indicate the importance of current photosynthesis during the pod fill stage in P. vulgaris as has been suggested in other grain legume crops.
Temperature control in the rooting medium during propagation
Authors: WHALLEY D. N. , RANDALL R. E. 
Published: February 2008

SUMMARYControl of rooting medium temperature by using electronic controllers with thermistor or semiconductor sensors is described and compared with electromechanical sensors. Electronic controllers are advantageous in that they are versatile, and can more accurately sense and control temperature in the rooting zone itself. Such improved control may often result in higher percentage of rooted cuttings and in better root systems.
The susceptibility of the elm bark beetle Scolytus scolytus to the DD‐136 strain of Neoaplectana sp.
Authors: FINNEY J. R. , MORDUE W. 
Published: February 2008

SUMMARYAdults and larve of Scolytus scolytus were highly susceptible to the DD‐136 strain of Neoaplectana sp. in the laboratory.
The influence of the parasitic Striga species on the host crops sorghum and maize
Authors: Parker C. 
Published: February 2008

ABSTRACTThe biology of the Striga species will be briefly described. Pot experiments indicate that damage to the host plant is very much greater than is explained by removal of photosynthates. A phytotoxin is almost certainly involved, which causes decreased shoot growth of the host plant but which also directly or indirectly encourages increased root growth. The significance of this change in root/shoot ratio will be discussed in relation to host resistance and various control measures.