bluuebunny/crossref_metadata_2025_split huggingface dataset:
The overwintering and abundance of cereal aphids
Authors: DEAN G. J. 
Published: February 2008

SUMMARYThe longevity of Sitobion avenae varied inversely with temperature from 25 to over 100 days when reared outdoors on barley under lantern jars, being longest between December and April–May. This was due mainly to changes in the length of the pre‐ and post‐reproductive periods rather than the length of the period of reproduction. Fecundity varied directly with temperature, from eight to sixty‐seven nymphs per female. When reared on winter wheat and sheltered from wind, rain and snow, S. avenae survived best, Metopolophium dirhodum survived less well and Rhopalosiphum padi worst; when exposed in the open none of the three species survived.Close relationships were not demonstrable between the numbers of alate M. dirhodum, S. avenae and Rhopalosiphum spp. trapped in any year, between the abundance of these aphids and weather conditions between January and April, or between the numbers of these alatae and the size of crop infestations. This was probably because insufficient information was available about their biology, both inside and outside the crop.
Study on inheritance of resistance to root aphid, Pemphigus bursarius, in lettuce
Authors: DUNN J. A. 
Published: February 2008

SUMMARYThe inheritance of resistance to lettuce root aphid, Pemphigus bursarius, was studied in lettuce using the Wellesbourne cultivars Avondefiance and Avoncrisp as resistant parents and Borough Wonder and Webb's Wonderful as aphid‐susceptible parents. All four cultivars were crossed in all possible combinations including reciprocals and the response to root aphid of plants in the P1F1F2 and BC generations was assessed using apterae of P. bursarius from the lettuce cv. Iceberg. Resistance to attack was clearly inherited and the parents appeared to be homozygous for their resistance or susceptibility. In the F1 generation, however, in all crosses between resistant and susceptible parents, segregation into susceptible, resistant and some slightly less resistant plants occurred. This and the highly significant differences in segregation between pairs of reciprocal crosses in the F1 and other generations indicate that the inheritance of resistance to root aphid is controlled by extra‐nuclear factors. Modifying genes might also be involved but there appears to be no linkage of root aphid resistance with resistance to downy mildew, for which the Wellesbourne lettuces were bred.
The induction of top‐roll symptoms on potato plants by the aphid Macrosiphum euphorbiae
Authors: GIBSON R. W. 
Published: February 2008

SUMMARYIn the field, caged potato plants of King Edward and Majestic cultivars infested with the potato aphid Macrosiphum euphorbiae developed top‐roll symptoms, the proportion of affected plants increasing with the size and persistence of the aphid population. Yield of tubers from plots in which 90% of the plants had top‐roll symptoms was 40% less than that from control plots; yield of saleable ware was even less. Foliage produced after the aphids had been killed was symptomless even when it arose from the axil of an affected leaf. Caged field plants treated with phorate granules to prevent aphid attack did not develop top‐roll.Prolonged infestation of Pentland Crown, Majestic and King Edward plants by M. euphorbiae in a glasshouse induced rolling of upper leaves similar to top‐roll of field plants. Experimental results suggest that rolling was directly attributable to heavy attack by M. euphorbiae, not to an aphid‐transmitted pathogen.
The rates of fungal development and lesion formation in leaves of Vicia faba during infection by Botrytis cinerea and Botrytis fabae
Authors: MANSFIELD J. W. , DEVERALL B. J. 
Published: February 2008

SUMMARYLoss of the water droplet above inoculation sites during the first day after inoculation inhibited lesion formation by Botrytis cinerea and prevented the development of spreading lesions of B. fabae. With droplets present two general patterns of infection by B. cinerea were determined; in one, few or no symptoms were produced and in the other, limited lesions developed with marked browning of the inoculation site. Where few or no symptoms were produced, germination and germ‐tube growth were inhibited on the leaf surface. B. cinerea was inhibited within the leaf at sites bearing limited lesions; invading hyphae were restricted to brown epidermal cells. Fungal growth on the leaf surface was greatest at sites with most browning beneath the droplet area. Variation in lesion development by B. cinerea could not be related to droplet position or leaf damage during normal preparation for inoculation. Plants differed in their susceptibility to lesion formation by B. cinerea. B. fabae, with droplet present, was not inhibited on the leaf surface and spread inter‐ and intra‐cellularly beneath the inoculum drop and then into surrounding tissues. Delay in spread until the inoculation site was completely necrotic and colonized suggested that B. fabae is partially inhibited during the initial phase of infection. The rate of lesion spread varied in different plants and was most rapid in the youngest leaves.
Transmission of the hop strain of arabis mosaic virus by Xiphinema diversicaudatum*
Authors: VALDEZ R. B. , McNAMARA D. G. , ORMEROD P. J. , PITCHER R. S. , THRESH J. M. 
Published: February 2008

SUMMARYHop plants became infected with the hop strain of arabis mosaic virus (AMV(H)) when grown in hopfield and woodland soil in which infected plants had been growing. Infection occurred in soil infested with the dagger nematode Xiphinema diversicaudatum, but neither in uninfested soil nor in soil previously heated to kill nematodes. X. diversicaudatum transferred direct from hop soils transmitted AMV(H) to young herbaceous plants and to hop seedlings; some of the hop seedlings developed nettlehead disease. A larger proportion of plants was infected using X. diversicaudatum obtained from a woodland soil and then given access to the roots of hop or herbaceous plants infected with AMV(H). AMV(H) was transmitted by adults and by larvae, in which the virus persisted for at least 36 and 29 wk, respectively.Difficulties were encountered in detecting AMV(H) in infected hop plants, due partly to the delay in virus movement from roots to shoots. Infection of hop shoots was seldom detected until the year after the roots were infested and sometimes nettlehead symptoms did not appear until the third year. Isolates of arabis mosiac virus from strawberry did not infect hop. The results are discussed in relation to the etiology and control of nettlehead and related diseases of hop.
Transference of resistance to black‐currant gall mite, Cecidophyopsis ribis, from gooseberry to black currant
Authors: KNIGHT R. L. , KEEP ELIZABETH , BRIGGS J. B. , PARKER JILL H. 
Published: February 2008

SUMMARYField and insectary tests confirmed that the black‐currant gall mite (Cecidophyopsis ribis) is unable to survive on gooseberry and red currant.A dominant gene Ce, controlling resistance to the gall mite, has been transferred from gooseberry to black currant. Resistant, large‐fruited, self‐fertile black currants of commercial potential have been obtained in the third backcross.One accession of Ribes bracteosum and three of R. americanum proved field susceptible to the gall mite, but twenty‐four accessions of other Ribes species remained free from galled buds for at least 3 years in an infection plot.
Breeding for resistance to American gooseberry mildew, Sphaerotheca mors‐uvae, in the gooseberry (Ribes grossularia)
Authors: KEEP ELIZABETH 
Published: February 2008

SUMMARYStrong resistance to American gooseberry mildew (Sphaerotheca mors‐uvae) occurred in eight out of ten F1 progenies from crosses of resistant North American Eugrossularia species with European gooseberry cultivars or seedlings. Bimodal segregations in four of these F1's and in one F1 derived from the wild European Ribes grossularia uva‐crispa suggested that each donor carried a major dominant resistance gene. Such a gene, Sph1 was identified in a first backcross from R. oxyacanthoides.Accessions of R. oxyacanthoides, R. leptanthum and R. watsonianum proved the most promising donors of resistance to mildew and leaf spot (Pseudopeziza ribis).
A comparison of seasonal changes in deposition of spores of Erysiphe graminis on different trapping surfaces
Authors: JENKYN J. F. 
Published: February 2008

SUMMARYVertical sticky cylinder traps were as useful as a volumetric trap for detecting seasonal changes in numbers of Erysiphe spores from barley crops. Changes in spore catches by both traps also resembled changes in numbers of pustules developing on initially healthy barley seedlings exposed in the same crop. Seasonal changes in catches on cylinders exposed at some distance from any crop differed from those on cylinders just above barley crops.Cylinder traps are cheap, simple and quicker to scan than volumetric traps and seem likely to be acceptable alternatives to them for much work on cereal mildew and other air‐dispersed pathogens, particularly for rautine trapping at many sites.
Disease gradients and small plot experiments on barley mildew
Authors: JENKYN J. F. , BAINBRIDGE A. 
Published: February 2008

SUMMARYIn two experiments, on Julia and Zephyr spring barley, evidence was obtained that the development of powdery mildew in sprayed plots depended very much on their proximity to unsprayed crop. The effective period of control achieved with one spray was greater where plots were well separated from unsprayed crop than where they were surrounded by or very close to unsprayed crop. There is probably a risk that small plot experiments may not only underestimate the potential effectiveness of fungicides in agricultural practice, but also give misleading information on optimal spray timing.
Aphid‐transmitted viruses from lilies in Britain
Authors: MOWAT W. P. , ŠTEFANAC ZLATA 
Published: February 2008

SUMMARYThree aphid‐transmitted viruses, tulip breaking, lily symptomless and cucumber mosaic, were obtained from lilies in Britain. Tulip breaking virus was detected by the leaf mottle produced in Lilium formosanum, cucumber mosaic virus by inoculation of sap to Nicotiana clevelandii and Chenopodium quinoa, and lily symptomless virus by electron microscopy of crude leaf extracts from symptomless L. formosanum. Liiy symptomless virus was transmitted by Myzus persicae, Macrosiphum euphorbiae, Aulacorthum solani and Aphis fabae. M. persicae, which in a small experiment appeared a more efficient vector than A. fabae, transmitted the virus in a non‐persistent manner. This conflicts with the original report of transmission in a persistent manner by A. gossypii but no transmission by M. persicae. The possibility that there are two distinct viruses with similar pathological effects is discussed. Tulip breaking and lily symptomless viruses spread to bait plants of L. formosanum within a field planting of lilies in Scotland especially during July to September; lily symptomless virus was the more prevalent. No spread of cucumber mosaic virus was detected.
Effects of photoperiod, temperature and vernalization on the phenology and spikelet numbers of spring wheats
Authors: WALL P. C. , CARTWRIGHT P. M. 
Published: February 2008

SUMMARYFourteen cultivars of north temperate, Australian, Mexican and Rhodesian origins, were grown in eight treatments: 2‐day‐lengths (10 h and 14h) × two temperature regimes (18/13 °C and 25/20 °C) × two seed vernalization treatments (unvernalized and 28 days at 1–2 °C). Numbers of days to 50 % ear emergence, leaf numbers and spikelet numbers of the main shoots were recorded.The north temperate cultivars were the most sensitive to daylength: in long days their mean spikelet number was 15 and they headed in 40–50 days, while in short days they had a mean of 24 spikelets and failed to head in 100 days. The Rhodesian cultivars were the least sensitive, but nevertheless headed 20–30 days earlier and had three to five fewer spikelets per ear in long days.The effects of vernalization on the tropical cultivars were related to maturity class: they ranged from negligible in early cultivars such as Sonora 64 and Devuli to decreases of 20 days to heading and seven spikelets in late cultivars such as Mexico 120 and Cajeme 71 in long days.The effects of temperature varied with cultivar and with vernalization treatment. Early cultivars and vernalized late cultivars headed earlier and had fewer spikelets in the warmer regimes while unvernalized late cultivars tended to have more spikelets and headed later. It is suggested that some vernalization of these late cultivars took place in the cooler regime.The significance of the results for the understanding of the physiological basis of the adaptation of wheat cultivars to different climatic zones is discussed.
Bird damage to sugar beet
Authors: Dunning R. A. 
Published: February 2008

SUMMARYPest damage to sugar beet, including that by birds, has been recorded since 1957. During that time damage by rooks has decreased almost to nil, but some other bird damage has greatly increased, most probably as a result of changing agronomic practices, especially the extensive use of herbicides, the introduction of monogerm seed, and the increasing practice of ‘planting‐to‐a‐stand’. The most severe bird damage in the spring is grazing by several species, and in early summer localized felling of plants by pheasants. Observations in the mid–1960's of causes of seedling and plant losses suggested that birds were then of minor importance; the British Sugar Corporation currently consider that birds are the most serious pest of sugar beet. The distribution of the reported damage does not seem to follow any national pattern. In small‐plot field trials possible repellent materials such as anthraquinone, methiocarb or thiram, applied to seed or foliage, did not decrease the extent of grazing.
Pustules on wood as sources of inoculum in apple scab and their response to chemical treatments
Authors: COOK R. T. A. 
Published: February 2008

SUMMARYThe green stems and leaves of potted Cox's Orange Pippin trees were susceptible to infection by Venturia inaequalis from June to August. Some isolates of the fungus showed conspicuous ability to attack the wood.In the orchard, many conidia were released from pustules in early March (2—3 wk before bud‐burst) but in the 3 years examined (1967—9) most were liberated in April and May. In 1969 it was shown that a decline in numbers in June was accompanied by a decrease in viability of conidia.Infections near the tips of leading shoots were partially controlled by a single treatment with 5% urea (aqueous solution) in October 1966 or 2% urea or 0·01% phenylmercuric chloride (PMC) in March 1967. The subsequent reduction in inoculum was correlated with a reduction in the numbers of primary infections developing on leaves. Basal infections on leading shoots were not susceptible to treatment in October 1967 or March 1968, but in 1969 similar infections were controlled with PMC applied mid‐April when the pustules had burst and were actively sporulating.
Changes in wyerone acid concentrations in leaves of Vicia faba after infection by Botrytis cinerea or B.fabae
Authors: MANSFIELD J. W. , DEVERALL B. J. 
Published: February 2008

SUMMARYWyerone acid was produced by leaves of Vicia faba in response to infection by both Botrytis cinerea and B.fabae. Host cell death caused by either fungus appeared to be the trigger for rapid wyerone acid synthesis, although the phytoalexin was not confined to brown cells. At B. cinerea inoculation sites wyerone acid concentration increased rapidly, at the time of fungal invasion of the epidermis, to levels greater than that completely inhibitory to mycelial growth. Wyerone acid is therefore probably the primary cause of the inhibition of B. cinerea within infected tissue. The partial blackening of B.fabae inoculation sites and surrounding peripheral tissues was accompanied by an increase in wyerone acid. There followed a striking decrease as tissues became completely blackened and invaded by B.fabae. B.fabae appeared to metabolize wyerone acid and prevent its accumulation in invaded tissues. Mycelial growth of B. fabae was less sensitive to wyerone acid than was B. cinerea.The differing abilities of B.fabae and B. cinerea to spread from lesions after both have induced wyerone acid production probably depend on both their differing sensitivities to the phytoalexin and their abilities to metabolize it to less toxic products.
Spread of raspberry bushy dwarf virus by pollination, its association with crumbly fruit, and problems of control
Authors: MURANT A. F. , CHAMBERS J. , JONES A. T. 
Published: February 2008

SUMMARYRaspberry bushy dwarf virus (RBDV) was transmitted to raspberry seed both through the pollen and through the ovule and it infected plants pollinated with infected pollen. It did not infect plants prevented from flowering, and transmission through pollen seems to be the only method of spread in the field; in the proximity of infectors, most plants became infected during the first two or three flowering seasons. Plants containing RBDV showed no obvious symptoms, but healthy or infected flowers pollinated with infected pollen produced ‘crumbly’ fruit, containing a high proportion of aborted drupelets. RBDV was difficult to eliminate from infected raspberry by heat therapy. Raspberry cultivars that fail to become infected naturally were also immune to infection by grafting. Use of immune cultivars offers the only method of control and, because infected plants may produce crumbly fruit, future cultivars should if possible possess immunity to RBDV.
The time of determination of gynoparae and males in the bird cherry–oat aphid, Rhopalosiphum padi
Authors: DIXON A. F. G. , DEWAR A. M. 
Published: February 2008

SUMMARYApterous exules of Rhopalosiphum padi which experienced short photoperiods only during the first half of their nymphal life all produced gynoparae which made up 57% of the offspring produced in the first 7 days of the mother's reproductive life. Short photoperiods during the second half of a mother's nymphal life did not induce the production of gynoparae. However, when short photoperiods were experienced throughout a mother's nymphal life significantly more gynoparae (82%) were produced. Ten per cent of the offspring of mothers that experienced short photoperiods only during their adult life developed into gynoparae. Of the offspring reared in short photoperiods, but born to mothers reared and kept in long photoperiods, 30% developed into gynoparae. When mothers were exposed to short photoperiods in their adult life and their offspring so treated, then 90% of the offspring developed into gynoparae.Males only occurred amongst the last offspring of mothers that experienced short photoperiods in either the first or the second half of their nymphal life.
Supercooling and the low‐temperature survival of the green spruce aphid Elatobium abietinum
Authors: POWELL W. 
Published: February 2008

SUMMARYLaboratory investigations into the low‐temperature tolerance of the green spruce aphid, Elatobium abietinum, revealed that the insect was killed by freezing. Aphids and host Sitka spruce needles showed similar seasonal changes in supercooling ability. A noticeable increase in this ability occurred between June and October. Aphids were more susceptible to low temperatures when attached to the plant. It is suggested that mortality resulted from ice which formed in the sap of the host needles and spread into the feeding aphids via their mouthparts. Neither the chlorotic banding of needles, caused by aphid feeding, nor needle length affected needle supercooling. Increased duration of exposure increased the probability of freezing of supercooled needles at low temperatures.A small percentage of first‐instar nymphs supercooled to much lower temperatures than the remainder of the population. These were newly born nymphs whose high supercooling ability markedly decreased when they began to feed.
The effect of store conditions on the rotting of apples, cv. Bramley's Seedling, by Nectria galligena
Authors: SWINBURNE T. R. 
Published: February 2008

SUMMARYThe log of the time interval between inoculation with Nectria galligena in October and the onset of rotting in apples held in air was proportional to the deficit between the temperature of incubation and 25°C, but temperature did not affect the rate of subsequent rot expansion. Rots expanded equally fast whether apples were held in dry or moist air. The quantity of rotted tissue obtained after incubating inoculated apples in atmospheres containing up to 12.5% CO2 increased with increasing concentrations of CO2 greater than 2.5%. The quantity of rotted tissue obtained in apples incubated in 10% CO2 was three times as great as that obtained after incubation in air. The incidence of natural rots was lower in apples stored at 4% CO2 than in those stored in air and rotting increased with increasing concentrations of CO2 higher than 4%. Colonies of N. galligena grew faster on malt agar plates incubated in 5% CO2 than in air, but growth was slower in 10% CO2 than in air. The quantity of benzoic acid per mg hyphae accumulated in developing lesions was similarly related to the CO2 concentrations up to 2.5% but decreased at higher concentrations, and the quantities found in apples stored in CO2 concentrations >5.0% CO2 were less than in those stored in air.
Spiroplasmas are the causal agents of citrus little‐leaf disease
Authors: MARKHAM P. G. , TOWNSEND R. , BAR‐JOSEPH M. , DANIELS M. J. , PLASKITT AUDREY , MEDDINS BRENDA M. 
Published: February 2008

SUMMARYA spiroplasma isolated from citrus with little‐leaf disease was grown in a cell‐free medium and injected into leafhoppers (Euscelis plebejus) Injected leafhoppers, but not those fed on infected plants, transmitted the spiroplasma to white clover (Trifolium repens cv. S100) and sweet orange (Citrus sinensis cv. Valencia). Infected clover plants were severely stunted; infected sweet orange plants showed typical symptoms of citrus little‐leaf disease. The spiroplasma was detected in clover and sweet orange plants by electron microscopy; the helical morphology of the organisms was most easily recognizable in sections 150–200 nm thick. The organism was re‐isolated in cell‐free media both from infected plants and from injected E. plebejus. The original isolate and those re‐isolated from experimentally infected clover and sweet orange appeared by morphological, cultural, biochemical and serological criteria to be identical to each other and to the R8‐A2 (type) and C‐189 strains of Spiroplasma citri. Serological tests and electrophoretic analysis of protein preparations indicated no relationship to Acholeplasma laidlawii, although this organism survived for at least 10 wk after injection into E. plebejus. Our results show that the causal agent of little‐leaf disease is related to S. citri.
Resistance to organophosphates in red spider mite, Tetranychus urticae, from English hop gardens
Authors: CRANHAM J. E. 
Published: February 2008

SUMMARYTwo strains of Tetranychus urticae, collected in 1969 from hops in Kent (strain RK) and Wisbech, Cambridgeshire (RW), showed a similar pattern of resistance to organophosphates, high to parathion (> 100 ×), low to azinphos‐ethyl (7 ×) and intermediate to demeton‐S‐methyl (21–27 ×); they were both fully susceptible to tetradifon, dicofol and formetanate. RK showed greatei than 50 × resistance to fourteen other organophosphates; exceptions were azinphos‐methyl (11 ×), phosphamidon (21 ×) and methidathion (31 ×). Resistance in RK was shown to be controlled by a single major gene, incompletely dominant with parathion but nearer to intermediate in expression to demeton‐S‐methyl and azinphos‐ethyl. A test for allelism showed that the major genes for O.P. resistance in RK and the Dutch strain Baardse reside at the same locus or are closely linked. The results are compared with other work on T. urticae and on Panonychus ulmi.