bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the effectiveness of the four British virus vector species of Longidorus and Xiphinema
Authors: TRUDGILL D. L. , BROWN D. J. F. , ROBERTSON W. M.
Published: February 2008

The frequency with which the four virus‐vector species of longidoroid nematodes occurring in Britain transmitted their associated plant viruses were compared in a series of experiments using a standard procedure. In these tests Xiphinema diversicaudatum proved an effective vector of British isolates of arabis mosaic virus and strawberry latent ringspot virus and Longidorus attenuatus of an isolate of tomato black ring virus from England. In comparison, isolates of raspberry ringspot virus and tomato blackring virus from Scotland and of raspberry ringspot virus from England were transmitted much less readily by their respective vectors, L. elongatus and L. macrosoma. These differences in ability to transmit virus were not related to differences in feeding access on the virus source‐ or bait‐plants, in the extent to which virus was retained within the nematode feeding apparatus or in the frequency with which virus was recovered from Longidorus in concurrent slash tests. Three Scottish isolates of raspberry ringspot and tomato black ring viruses were transmitted equally infrequently by two populations of L. elongatus and the frequency with which virus was transmitted was not greatly increased when the species of source or bait plants was changed.
Growth, survival and reproduction of the bird‐cherry aphid, Rhopalosiphum padi, on its primary host
Authors: LEATHER S. R. , DIXON A. F. G.
Published: February 2008

Fundatrices died when caged on senescent leaves of bird cherry on which oviparae thrived. Fundatrigeniae had more ovarioles and a higher reproductive rate than fundatrices. Oviparae developed and matured eggs on unfurling leaves but they took longer to reach maturity and grew more slowly than when reared on senescent leaves. Fundatrices and oviparae in addition to having an intrinsic preference for bird cherry over other plants did better on particular growth stages of their primary host.
Control of subterranean clover red leaf virus in broad bean crops with aphicides
Authors: JOHNSTONE G. R. , RAPLEY P. E. L.
Published: February 2008

Trials at three sites in north‐western Tasmania monitored the spread of subterranean clover red leaf virus into and within broad bean crops with movement of its vector, Aulacorthum solani. Records indicated that almost all infections within the crops resulted from secondary spread by apterae following the establishment by migrant alatae of a very few foci of infestation and infection soon after crop emergence. Spread of the virus within the crops was reduced by sprays of demeton‐S‐methyl. Incidence of infection in sprayed plots at harvest was 23%, 13% and 23% at the three sites compared with 80%, 31% and 84% respectively, in unsprayed plots. Yield increases as a result of spraying were 980, 420 and 540 kg/ha.
A strain of cassava latent virus occurring in coastal districts of Kenya
Authors: BOCK K. R. , GUTHRIE E. J. , FIGUEIREDO GINA
Published: February 2008

A strain of cassava latent geminivirus (CLV) was isolated from mosaic‐affected cassava plants from coastal districts of Kenya. This virus (CLV‐C) did not infect Nicotiana clevelandii, a diagnostic host of the type strain (CLV‐T); experimental host range was very restricted and CLV‐C only infected N. benthamiana and N. rustica out of several solanaceous hosts readily infected by CLV‐T.

CLV‐C was also isolated from naturally infected Jatropha multifida (Euphorbiaceae) and Hewittia sublobata (Convolvulaceae).

CLV‐C was propagated in N. benthamiana with difficulty and only those isolates derived from cassava plants infected with severe mosaic symptoms were maintained more or less successfully; these sources usually contained a higher concentration of CLV than plants with mild symptoms. Symptom variants generally remained unchanged when grafted into a highly susceptible South American cassava variety.

CLV‐C and CLV‐T seemed to occur respectively only in coastal and western districts but their ranges overlapped in central Kenya where they could have been introduced in infected material.

CLV‐C could be purified satisfactorily with the method used for CLV‐T but only after modifying the procedure by substituting phosphate for borate in the extraction buffer, n‐butanol for n‐butanol/chloroform in clarification of extracts, and phosphate for borate buffer when resuspending concentrated virus.

A virus serologically indistinguishable from CLV‐T was isolated from mosaic‐ affected material obtained from Nigeria; East African and Nigerian isolates were essentially similar in host range and symptomatology. In gel‐diffusion serology tests, pronounced precipitation spurs developed between CLV‐T and CLV‐C indicating that the isolates were related but not identical serologically.

Symptoms typical of cassava mosaic disease appeared in only three of 105 plants in experiments on transmission of CLV‐C and CLV‐T by whiteflies, when attempted acquisition of either clarified CLV‐infective sap or purified CLV was made through ‘Parafilm’ membranes. Because it is possible that the three infections resulted from contamination, they cannot constitute proof of transmission. The presence of CLV in relation to the etiology of cassava mosaic thus remains unresolved.
The patterns of growth, assimilation of 14CO2 and distribution of 14C‐assimilate within vegetative plants of Loliumperenne at low and high density
Authors: COLVILL KAY E. , MARSHALL C.
Published: February 2008

The patterns of growth, assimilation of 14CO2 and distribution of 14C‐labelled assimilate were followed for 12 wk from sowing in individual plants of Lolium perenne grown in miniswards at either low (500 plants m‐2) or high (5000 plants m‐2) density. At the latter density, plants were characterised by a 50% reduction in RGR, by the production of fewer tillers, especially second‐ and third‐order tillers, and by a reduction in mean tiller weight. All the green and senescing leaves of each tiller assimilated 14CO2 and the overall assimilatory capacity of a tiller was directly related to its dry weight. At both densities the plant consisted of a main shoot and established tillers with comparable assimilatory activities and a range of developing tillers that assimilated relatively small amounts of 14CO2. As each successive primary tiller developed it was supplied with assimilate from the main shoot and the degree of support was inversely proportional to the dry weight of the tiller. At both densities it was concluded that the first primary tiller could be regarded as an independent assimilatory unit when it reached a dry weight of about 25 mg even though some import of main shoot assimilate continued until the tiller was double this weight. The supply of assimilate to the root system was greatly reduced at both densities compared with previous observations on plants grown singly.
Far‐ultraviolet sensitivity and photoreactivation of Hirsutella thompsonii
Authors: TUVESON R. W. , MCCOY C. W.
Published: February 2008

The far‐ultraviolet (FUV; 200–300 nm) sensitivity of four pathotypes of Hirsutella thompsonii, representative of three separate taxonomic varieties of the species, was investigated. The UV inactivation curves for the four strains were indistinguishable. A mutant exhibiting enhanced conidiation derived from the HTF‐72 strain was more FUV sensitive than the four wild type strains (fluence enhancement factor ≅ 1.5). All strains were capable of efficiently photoreactivating FUV damage by a process which appeared to enzymatic.
Serological studies on cassava latent virus
Authors: SEQUEIRA J. C. , HARRISON B. D.
Published: February 2008

Particles of cassava latent virus (CLV) were purified by a method that yielded up to 3 mg per 100 g of systemically infected Nicotiana benthamiana leaf. Specific antiserum was prepared and used for enzyme‐linked immunosorbent assay (ELISA), which detected purified virus at 5 ng/ml. As estimated by ELISA, CLV antigen reached a greater concentration in leaves of N. benthamiana plants kept at 20–25 °C than in those at 15 °C or 30 °C. CLV was also detected in leaf extracts of naturally infected cassava plants kept at 25 C but its concentration was only 1–7% of that in comparable extracts from N. benthamiana. Staining sections of N. benthamiana leaves with fluorescent antibody indicated that CLV particle antigen accumulates in the nuclei of many phloem cells and of some cells in other tissues.

In tests on mosaic‐affected cassava plants of Angolan origin, three plants were found in which CLV could not be detected by either ELISA or immunosorbent electron microscopy, or by transmission to indicator plants. This suggests that the mosaic symptoms were caused by a pathogen other than CLV, but no such agent was detected by electron microscopy of leaf extracts.

Three kinds of serological test indicated that CLV is related to bean golden mosaic virus. Evidence was also obtained of a distant relationship to beet curly top virus but none was detected to four other geminiviruses.
Selection for immunity in swede (Brassica napus) to infection by turnip mosaic virus
Authors: TOMLINSON J. A. , WARD C. M.
Published: February 2008

Fully heritable immunity to turnip mosaic virus (TuMV) was found in swede (Brassica napus) cvs Ruta Otofte and Bangholm. Attempts to ‘break’ this immunity were unsuccessful. The reactions of two immune lines of cv. Ruta Otofte to cauliflower mosaic virus, clubroot (Plasmodiophora brassicae) and powdery mildew (Erysiphe cruciferarum) were unchanged compared with the unselected parent line. A symptomless response to TuMV inoculation (possibly immunity) was also found in cv. Acme but not in the clubroot resistant cv. Marian. The percentage of plants which gave a symptomless response to TuMV inoculation differed greatly between cultivars and some seed stocks.
Pathology and properties of tulip virus X, a new potexvirus
Authors: MOWAT W. P.
Published: February 2008

Tulip virus X (TVX), a previously undescribed mechanically transmissible virus, causes chlorotic and necrotic lesions in leaves and streaks of intensified pigmentation in tepals of tulip plants. The virus infected 22 of 42 other plant species in 10 of 14 families, but most host species were infected only erratically. TVX is best propagated in Chenopodium quinoa and assayed in C. amaranticolor. Spindleshaped inclusions were observed in epidermal cells of C. amaranticolor leaves. Leaf extracts from C. quinoa contained flexuous filamentous particles measuring c. 495 ×13 nm. The extracts were infective after dilution to 10‐9, after heating for 10 min at 60 °C but not at 65 °C, and after storage at c. 20 °C for 30 days or at ‐20 °C for 6 months.

TVX particles were purified (500 μg/g C. quinoa leaf) from tissue extracts in 0.067 M phosphate buffer containing 10 mM EDTA at pH 7, by twice precipitating the virus with 8% polyethylene glycol in 0.2 M NaCl followed by differential centrifugation. The virus particles have a sedimentation coefficient (s20, w) of 102 S. They contain a protein of mol. wt c. 22 500 and a nucleic acid that, when glyoxalated, migrates in agarose gel like single‐stranded RNA of mol. wt 2.05 × 106. TVX particles tend to aggregate, and evidence was obtained that a 118 S component which was consistently observed in purified preparations and in infective sap is an end‐to‐end dimer. A distant serological relationship was found between particles of TVX and those of viola mottle and hydrangea ringspot viruses, but no serological relationship was detected to nine other potexviruses. TVX is considered to be a distinct and definitive member of the potexvirus group.
Ullucus virus C, a newly recognised comovirus infecting Ullucus tuberosus (Basellaceae)
Authors: BRUNT A. A. , BARTON R. J. , PHILLIPS SUE , JONES R. A. C.
Published: February 2008

Ullucus virus C (UVC) is a comovirus prevalent in Ullucus tuberosus grown at high altitudes in the Bolivian and Peruvian Andes. It was transmitted mechanically to U. tuberosus (Basellaceae) and to five of 26 species from three of eight other families, infecting U. tuberosus symptomlessly but inducing conspicuous systemic infection in Chenopodium amaranticolor and C. quinoa. Sap from infected C. quinoa was usually infective after 10 min at 70 but not 75 °C, after dilution to 10‐7 but not 10‐8, and after 8 but not 16 wk at 20 °C. UVC was not transmitted by either of two aphid species (Aphis gossypii and Myzus persicae) or through seed of C. quinoa, but it was transmitted by leaf contact between infected and healthy plants.

UVC has isometric particles which, in neutral phosphotungstate, are c. 28 nm in diameter. The particles sediment as three components (T, M and B) with sedimentation coefficients (s˚20, w) of 51 S (T), 95 S (M) and 116 S (B). M component particles have a buoyant density (g cm‐3) in caesium chloride of 1.404, and B component particles separated into minor and major sub‐components with densities of 1.409 and 1.463, respectively. T, M and B particles were serologically indistinguishable, and each contained similar relative amounts of two polypeptides of mol. wts 20 700 and 45 100. T particles contained only protein, but M particles also contained c. 30% ss‐RNA of mol. wt 1–45 ×106 and B particles c. 38% ss‐RNA of mol. wt 2·2 × 106.

The virus is serologically distantly related to cowpea mosaic virus but, as it showed no relationship to any of 11 other similar viruses, it is probably a distinct member of the comovirus group.
Effects of infection with a spiroplasma virus on the symptoms produced by Spiroplasma citri
Authors: ALIVIZATOS A. S. , TOWNSEND R. , MARKHAM P. G.
Published: February 2008

Multiplication of a virus resembling spiroplasma‐virus citri type 3 was observed in Spiroplasma citri cells within an infected Madagascar periwinkle plant showing unusually mild symptoms. Sap filtrates from this plant contained virus particles which gave rise to plaques on lawns of the lethal SP‐A strain of S. citri. Transmission of spiroplasmas containing virus to plants already infected with strain SP‐A resulted in suppression of symptoms and a reduction in the number of viable spiroplasmas.
The ATP method for rapid assessment of the efficacy of a single application of a fumigant against Globodera spp. in field soils
Authors: STOREY R. M. J.
Published: February 2008

Population estimates were carried out for Globodera pallida by both visual egg counts and measurement of the adenosine triphosphate (ATP) content of cysts from 26 fields in Northern England. The two methods agreed for seven non‐fumigated fields but covariance analysis suggested that the visual assessment underestimated mortality for all 19 fields shortly after a single treatment with a fumigant nematicide. Both methods indicated that three fields were safe for cropping for potatoes but the ATP method suggested that cropping was possible on a further eight fields considered unsuitable by visual assessments.

The results indicated that a high peat content contributed to the low efficacy of the fumigants in three fields. Comparison with previous results for the ATP method using cysts from 40 Dutch fields suggested that fumigation in early autumn was required for a satisfactory single treatment. The results show that the ATP method can assess the efficacy of a single application of a fumigant for economic control in time to allow retreatment when necessary or a change in the decision to plant potatoes the following season.
Laboratory assessments of resistance to the aphids Sitobion avenae and Metopolophium dirhodum in three Triticum species and two modern wheat cultivars
Authors: SOTHERTON N. W. , EMDEN H. F. VAN
Published: February 2008

Three ancient varieties of wheat and two spring‐sown modern varieties were screened in the laboratory to assess their resistance to the cereal aphids Sitobion avenae and Metopolophium dirhodum. Resistance was measured in terms of non‐preference and antibiosis on plants at three growth stages. The ancient variety Einkorn was the most resistant in terms of both non‐preference and antibiosis to both species of aphids at all growth stages examined. The ancient variety Emmer and the modern Sicco exhibited some resistant properties, whereas the ancient Spelt and modern Timmo were relatively susceptible to aphid attack.
The possible role of two species of Orthoptera in the dissemination of a plant pathogenic fungus
Authors: HASAN S.
Published: February 2008

The ability of the locusts, Locusta migratoria and Schistocerca gregaria, to disseminate Colletotrichum graminicola, the fungal pathogen of maize anthracnose, were studied. The insects were fed with the diseased plants and spores were recovered in viable condition from the faeces. The spores recovered were able to grow on artificial media and were still infectious to the host plant.
The effect of host plant on the control of Pratylenchus penetrans by aldicarb
Authors: ALPHEY T. J. W.
Published: February 2008

Replicated pot tests were made to study the effect of a host plant, red raspberry (Rubus idaeus), on the control of Pratylenchus penetrans by aldicarb.

Preliminary work indicated that nematodes from planted and fallowed soils could be distinguished by significantly different levels of lipid reserves in their bodies; and that the populations differed in their susceptibility to aldicarb.

In pot tests aldicarb (6 mg. a. i. or 12 mg a. i. per 15‐cm pot) was added to P. penetrans infested soil which was either left fallow or planted with a single raspberry host plant before, at the time of, or after treatment. The results indicated that nematodes in the presence of a plant were more susceptible to aldicarb treatment than those in fallow soil. The results showed that the closer treatment‐time was to planting‐time the greater the nematicidal effect.

It is suggested that P. penetrans may exist in different physiological states, active and quiescent, influenced by the presence of a host plant and that these two states differ in their susceptibility to the effects of aldicarb.
The effect of pesticides on establishment of grass swards in England and Wales
Authors: CLEMENTS R. O. , FRENCH N. , GUILE C. T. , GOLIGHTLY W. H. , LEWIS SERFIAH , SAVAGE AND M. J.
Published: February 2008

Pesticide applications made at the time of sowing significantly improved seedling stand and/or herbage dry matter yield at 20 of 45 sites studied during 1977‐79 in England and Wales. More autumn‐sown swards responded to pesticide treatment than spring‐sown ones and re‐seeded grass was attacked more often than grass sown after arable crops.

Pest damage was seldom obvious although some noticeable attacks by frit fly occurred. Slugs and leatherjackets appeared to be unimportant. The effect of nematodes was unresolved.
Resistance to Didymella applanata in red raspberry and some related species
Authors: JENNINGS D. L.
Published: February 2008

When raspberry canes were inoculated in summer with a mycelial inoculum of Didymella applanata resistant genotypes developed relatively small lesions which produced few fruiting bodies in the following spring. Scores of the frequency of these fruiting bodies provided the best discrimination between genotypes. Very strong resistance was found in R. pileatus, R. occidentalis and R. coreanus and in hybrids of these species with red raspberry. Hybrids with R. crataegifolius were less resistant. Resistance was also found in Malling 1473/35, a derivative of red raspberry cv. Chief, and in red raspberry segregates with gene H which determines cane pubescence. Both the expression of resistance and the ranking of resistance sources for their resistance was similar for D. applanata to that reported for Botrytis cinerea.
Specificity and mode of action of BTS 44584 and chlormequat chloride on wheat and soybeans
Authors: SMITH AILEEN R. , THOMAS T. H. , GARROD J. F.
Published: February 2008

The selective action of the growth retardants chlormequat chloride and BTS 44584 on the growth of wheat and soybean was investigated. Chlormequat chloride retarded the growth of wheat whether applied as a seed soak, foliar spray or soil drench, at concentrations from 10‐2 M to 10‐4 M, although effectiveness depended on the age of the plant at application. BTS 44584 retarded the growth of wheat only when applied to the seeds. In soybeans, chlormequat chloride did not retard elongation growth when applied as a seed soak but showed some effects when applied as a foliar spray and more especially as a soil drench. Irrespective of the type of application, treatment with BTS 44584 retarded growth of soybeans. Thus, the selective action of the two compounds was not solely related to different species but also to timing and mode of application.
Specificity and mode of action of BTS 44584 and chlormequat chloride on wheat and soybeans
Authors: SMITH AILEEN R. , THOMAS T. H. , GARROD J. F.
Published: February 2008

Increased gibberellin activity was detected in wheat and soybean plants following seed soaks with either BTS 44584 or chlormequat chloride. Foliar sprays with either compound did not affect the gibberellin levels in wheat plants but soybeans sprayed with BTS 44584 did not contain as much extractable gibberellin in the shoots as did control plants. It is concluded that there was little correlation between gibberellin content and the effect of the chemicals on growth of wheat and soybeans.
The effect of water potential on soil‐borne diseases of wheat seedlings
Authors: CASSELL DIANE , HERING T. F.
Published: February 2008

Under glasshouse conditions, Fusarium culmorum caused more injury to wheat seedlings in soil at 33% saturation (approximately – 1 bar) than at 66% (–0·1 bar). The same effect occurred with inoculated seeds raised on soil moisture tension tables at –0·1 and –0·5 bar, at 20° and at 15°C. In controls, spontaneous infection by soil‐borne F. culmorum was unaffected by soil water potential. Inoculated F. nivale, at 127deg; and at 15°C, showed a similar, but smaller, effect to that with inoculated F. culmorum. Water potential in this range did not affect disease incidence with inoculated Gaeumannomyces graminis, but disease was more severe in the drier soil. On tension tables, seedlings did not consistently develop faster under wetter conditions, and factors other than host growth rate probably played a part in limiting fungal attack.
Spacing and sucker management in the commercial plantain production in the rainforest belt of Nigeria
Authors: OBIEFUNA J. C. , MAJUMDER P. K. , UCHEAGWU A. C.
Published: February 2008

Maintaining one, two or three suckers per rootstock in plantain (Musa spp.) populations of 2000, 1600 and 1333 per hectare were evaluated for sustained yield in the orchard for three harvest cycles. The yield per plantain for the plant crop was not significantly affected by either population density or the number of suckers maintained. However, the total yield significantly increased with the increased plantain population per hectare.

The yield per plantain decreased in the first and subsequent ratoon crop harvests as the original plantain population per hectare doubled or tripled when two or three suckers were maintained respectively per rootstock. Although the total yield per hectare was significantly higher when two or three suckers were maintained per rootstock, the individual bunch weight and the fingers significantly decreased to an unacceptable size to the consumers. Establishment of orchards at 1600 plantains per hectare with two suckers maintained per rootstock in subsequent cycles produced consistently good quality marketable fingers and sustained high yield.
The effects of ripening and drying of carrot seed (Daucus carota) crops on germination
Authors: GRAY D. , STECKEL JOYCE R. A.
Published: February 2008

Carrot seeds taken from the parent plant were capable of germinating before the stage when maximum seed dry weight was reached but even after this stage, when the seed moisture content had fallen below 20%, improvement in seed germination characteristics continued. In the latter stages of seed growth losses by shedding were 12–20 kg/ha/day. For low density crops (10 plants/m2) the yield of viable seed was at a maximum in crops whose seed was harvested with a moisture content of between 20 and 40% but no consistent relationship could be established for high density crops (80 plants/m2).

There were no effects of umbel order or plant density on mean germination time or spread of germination. At any early harvest, percentage germination was highest for primary‐umbel‐seeds and seeds from low density crops but the differences between the seed origins diminished with later harvests.

Drying the seeds on the umbels improved the percentage germination, reduced the mean germination time and the spread of germination particularly at the early harvests compared with seeds removed from the umbels and germinated immediately without drying.
The development of a sampling method for the tick Ixodes ricinus and its use in a redwater fever area
Authors: GRAY J. S. , LOHAN G.
Published: February 2008

Tick sampling methods based on blanket dragging and flagging were assessed with a view to carrying out a tick survey in an area of endemic babesiosis. The strip‐flag method was finally selected for its efficiency, consistency, and practicality.

This method was used to sample larval tick populations on ten farms with endemic babesiosis and it was found that these farms harboured very low densities of ticks compared with a control site. Possible explanations for this finding are discussed.
Observations on the biology and ecology of Apion vorax (Coleoptera: Apionidae), a vector of broad bean stain and broad bean true mosaic viruses
Authors: COCKBAIN A. J. , BOWEN ROBERTA , BARTLETT PAUL W.
Published: February 2008

In spring 1974 and 1975 many adult Apion vorax were found at Rothamsted in woods bordering fields that had been cropped with field beans (Vicia faba) the previous season. The weevils were most common on bramble (Rubus spp.), dog's mercury (Mercurialis perennis) and nettle (Urtica dioica). A decrease in the woodland population in May coincided with the appearance of the weevil on field bean crops in neighbouring areas.

In laboratory feeding tests, adult weevils fed more on field bean leaves than on leaves of plants on which they were common in woodlands, and they fed more on field beans in May than at other times of the year. No difference was observed in the feeding of male and female weevils.

Many A. vorax were caught on sticky traps in woodlands at Rothamsted in 1975, particularly in April and May, but very few were caught on sticky traps in bean crops. The numbers of A. vorax recorded on the upper foliage of bean crops at Rothamsted in June each year from 1970 to 1980 ranged from 0 to 10 per 10‐m row.

Eggs, larvae and pupae of A. vorax were found in field bean flowers collected from field crops. The larvae were feeding on the tips of the pistils and stamens. Adult weevils that emerged in mid‐June from the flowers of autumn‐sown beans mated and produced a second generation when caged on glasshouse‐grown plants. Some Apion larvae, possibly A. vorax, were found inside flowers of common vetch (Vicia sativa).

The name ‘bean flower weevil’ is considered a suitable common name for A. vorax.
Studies of the incidence, severity and distribution of false rust (Synchytrium psophocarpi), leaf spot (Pseudocercospora psophocarpi) and powdery mildew (Oidium sp.) on winged bean (Psophocarpus tetragonolobus) in Papua New Guinea
Authors: PRICE T. V. , DRINKALL M. J. , MUNRO PATRICIA E.
Published: February 2008

The incidence, severity and distribution of false rust, (Synchytrium psophocarpi), leaf spot (Pseudocercospora psophocarpi) and powdery mildew (Oidium sp.) on winged beans (Psophocarpus tetragonolobus) were evaluated on pure lines and mixed stands grown in Papua New Guinea between 1976 and 1978. Almost all of the 148 pure lines were susceptible to false rust and leaf spot and the incidence of these diseases increased with plant age. Standard area diagrams were superior to disease keys in evaluating disease severity. Levels of false rust on 10 promising agronomic lines differed according to the locality where the lines were grown. Two Thai lines showed resistance to false rust but P. scandens was immune to false rust and leaf spot.

Surveys of 51 sites containing mixed stands of winged beans in the Eastern Highlands, Western Highlands, East New Britain, East Sepik, Madang and Morobe Provinces of Papua New Guinea indicated that leaf spot and false rust were present in both the wet and dry seasons and the apparent absence of disease was probably due to time and size of samples. The diseases appeared to be present in all the traditional winged bean growing areas of Papua New Guinea. It was difficult to obtain evidence of differences in palatability of tissues infected with false rust.

The value of surveys and disease assessment in relation to evaluation of crop losses of winged bean caused by these pathogens and selection for resistance is discussed.
Effects of barley mildew on green leaf area and grain yield in field and greenhouse experiments
Authors: CARVER T. L. W. , GRIFFITHS AND ELLIS
Published: February 2008

In 1980 the relationships between mildew severity, green leaf area (GLA) and grain yield of spring barley were examined using greenhouse‐grown plants and plants grown in micro‐plots in the field. Mildew, by causing premature senescence, reduced GLA and grain yield was strongly correlated with GLA integrated from growth stages 2–10.5 on the Feekes scale.

Early mildew attack reduced all yield components (including grain size) even when fungicidal control had eliminated mildew by anthesis. Analyses of culms at anthesis and harvest supported the view that the smaller grain size associated with early mildew attack resulted from a deficiency in carbohydrate stored in culms before anthesis and available for retranslocation to the developing grain. Amounts of total soluble carbohydrate at anthesis and the amounts lost beween anthesis and harvest were both strongly correlated with GLA up to anthesis.
Wetting and temperature requirements for infection of mature apples by Venturia inaequalis in South Africa*
Authors: SCHWABE W. F. S.
Published: February 2008

Conidia of Venturia inaequalis were used to inoculate mature (picking ripe stage) Granny Smith fruit in greenhouse inoculation chambers and in the orchard. Wetting periods necessary for fruit infection were longer than those previously reported for leaves, while continuous wetting was followed by heavier infection than intermittent wetting. Temperatures during storage affected symptom development and the degree of infection was greatly influenced by the inoculum potential (number of conidia). At high inoculum potentials and with infection indices [fruit wetting period (h) × mean temperature (°C)] of 440–600, 601–1000 and >1000 subsequent disease development was ‘light’, ‘moderate’ and ‘heavy’, respectively if fruit was unprotected by fungicides. It was concluded that after conditions favouring infection, fruit should not be stored for long periods, but should be marketed for consumption immediately after harvest.
Studies of the cereal cyst‐nematode, Heterodera avenae under continuous cereals, 1974–1978. I. Plant growth and nematode multiplication
Authors: KERRY B. R. , CRUMP D. H. , MULLEN L. A.
Published: February 2008

Population changes of Heterodera avenae and crop growth in a sandy loam soil were studied from 1974 until 1978; the nematode decreased plant growth but failed in two of the years to multiply on susceptible hosts. Spring oats were the most heavily invaded cereal and produced the smallest shoots. Second‐stage juveniles invaded cereal roots in decreasing numbers: spring oats > autumn oats > spring barley > spring wheat > autumn barley > autumn wheat. Numbers of females developing on the different cultivars were in a similar order. Most females developed on roots in 1976 despite poor crop growth in the severe drought.

Numbers of H. avenae in soil treated with oxamyl (Vydate) at 8.8 kg/ha a. i. were less in all years except 1975. In the dry winter and spring of 1975/76 nematode multiplication was prevented in soil treated with oxamyl before drilling in the autumn.

In all years large numbers of females were produced on the roots of all cultivars but in 1975 and 1978 nematode populations declined because few females survived to form cysts containing eggs and their fecundity was reduced. Numbers of cysts after harvest were not affected by formalin (38% formaldehyde) applied as a drench at 3000 litres/ha in 1977 but fecundity doubled in treated soil, and nematode multiplication increased from 3.8 × in untreated plots to 18.6 ×. When the plots were irrigated in 1978 numbers of cysts and fecundity increased in formalin treated soil resulting in an increase in multiplication from 0.3 × to 14.6 ×. Fungal parasites attacking H. avenae females and eggs are considered responsible for the poor multiplication of the nematode.
Helicotylenchus vulgaris and its association with damage to sugar beet
Authors: SPAULL ALISON M.
Published: February 2008

Severe and irregular stunting of sugar beet has been associated with Helicotylenchus vulgaris but little is known of the pathogenicity of this nematode. A survey was made at 10 sites in East Anglia on calcareous soils (Wantage series) on which the original damage was reported. Numbers were usually maintained under a variety of crops, despite fluctuations during the period. In field trials, aldicarb treatment did not improve the yield of either sugar beet or winter wheat on land infested with H. vulgaris. In pot tests growth of sugar beet was stimulated by low nematode inocula; this effect diminished as numbers inoculated increased. Sugar beet grown at 10 °C and 15 °C with H. vulgaris grew markedly better in sterilised soil than in untreated field soil, especially at the higher temperature early in the experiment.

It is concluded that though H. vulgaris may damage sugar beet it requires an atypical combination of external conditions to cause significant yield loss.
Effects of the nematicide oxamyl on life cycle stages of Globodera rostochiensis
Authors: EVANS SUSAN G. , WRIGHT DENIS J.
Published: February 2008

Hatched second stage juveniles of Globodera rostochiensis were found to be more sensitive than either unhatched juveniles or adult males to low concentrations of oxamyl (EC50 value for activity 0.5 μg oxamyl ml‐1). Development of juveniles in roots was significantly inhibited by 2.0 μg oxamyl ml‐1 probably due to impairment of normal feeding activity. The behavioural events necessary for orientation of juveniles towards roots for invasion and orientation of males towards females for fertilisation were found to be impaired by 0.5 and 1.0 μg oxamyl ml‐1 respectively. A comparison with previous work on Meloidogyne incognita showed G. rostochiensis juveniles to be more sensitive to oxamyl.
An investigation of difenacoum resistance in Norway rat populations in Hampshire
Authors: GREAVES J. H. , SHEPHERD D. S. , GILL J. E.
Published: February 2008

Observations are presented to show that resistance to difenacoum, a rodenticide commonly used for the control of warfarin‐resistant rodents, is widespread in populations of the Norway rat, Rattus norvegicus, in an area centred in north‐east Hampshire. Of 202 rats trapped on 42 farms in this district and tested in the laboratory, 85% were resistant to warfarin and 14% were resistant to difenacoum. Only rats that were resistant to warfarin showed difenacoum resistance, indicating it to be a form of cross resistance. The difenacoum‐resistant rats survived a dose of difenacoum that was lethal to more than 99% of susceptibles, but succumbed when this dose was increased fivefold. The results of four treatments carried out with difenacoum on farms illustrate that this level of resistance seriously reduces the effectiveness of difenacoum as a rodenticide in the field.
The effect of fungicides on field populations of Aphis fabae and on the infection of the aphids by Entomophthoraceae
Authors: WILDING N.
Published: February 2008

Numbers of Aphis fabae on spring‐sown field beans were little affected by weekly applications of the systemic fungicides benomyl or tridemorph or the non‐systemic captafol, manocozeb or maneb. Benomyl diminished the mortality of aphids caused by Erynia neoaphidis but not that caused by other species of entomophthoraceous fungi. The other fungicides failed to affect consistently the proportion of aphids infected by any fungus.
Effects of adding calcium and sodium salts to field soils on the incidence of clubroot
Authors: FLETCHER J. T. , HIMS M. J. , ARCHER F. C. , BROWN A.
Published: February 2008

The effect on clubroot of the addition to a mineral soil of calcium carbonate, calcium sulphate and sodium carbonate was studied in two field experiments during a 3‐yr period. Applications of calcium carbonate (ground limestone) at 10 or 20 t/ha increased the soil pH from 6×7 to 7×9; sodium carbonate at 7×5 t/ha to pH 8×3 and calcium sulphate (gypsum) at 20 t/ha caused a slight depression in pH to 6×6. 98% of cabbage plants showed clubroot symptoms in the untreated plots after 3 yr and the percentages were 0×7, 1×6 and 66×6 for the calcium carbonate, sodium carbonate and calcium sulphate treatments respectively. Yields were significantly increased by all three materials. There were no significant differences in disease incidence or in yield when calcium carbonate was used at 10 or 20 t/ha either applied as a single application or as two half‐rate applications. Soil from the calcium carbonate treated plots was used in a greenhouse experiment where the addition of inoculum of Plasmodiophora brassicae resulted in a large increase in clubroot incidence. There was no evidence that a biological suppressor was present in the high pH, low disease incidence soils.
Progress of infection by Erysiphe graminis on fungicide‐treated and untreated barley
Authors: LAWS F. A. , WALMSLEY‐WOODWARD DIANNE J. , WHITTINGTON W. J.
Published: February 2008

Tridemorph‐treated and untreated barley plants wre grown either in separate growth rooms or together. They were inoculated either with a sensitive or a tolerant isolate, and the progress of mildew was recorded. Comparisons were made between the rates of progress of sensitive and tolerant isolates on separated and unseparated fungicide treatments. Results suggested that interactions took place between pathogen populations on adjacent treated and untreated plants.

Barley cv. Golden Promise was sown in plots made up of two adjacent fungicide treatments. Triadimefon, triforine, tridemorph and ethirimol were paired with each other and with untreated crops in all combinations. The progress of mildew on each plot was recorded, and differences were found between similar fungicide treatments from different plot pairs. The likelihood of interactions between mildew populations exposed in the field to different fungicide treatments is discussed.
The effect of three herbicides on the number of spores of Rhynchosporium secalis on barley stubble and volunteer plants
Authors: STEDMAN O. J.
Published: February 2008

Single sprays of paraquat, glyphosate or dinoseb‐in‐oil, were applied to barley stubble or volunteer plants and their effects on the number of spores of Rhynchosporium secalis were studied weekly. Spore concentrations were measured by washing samples of stubble or volunteer plants and counting spores using a haemocytometer.

The number of spores recovered from stubbles was relatively small; both paraquat and glyphosate caused some reductions but the results were not consistent. Treatment with paraquat generally caused a transitory increase on volunteer plants; this effect was not found after glyphosate. Both herbicides caused persisting reductions from 4 wk after treatment. Volunteer plants treated with dinoseb‐in‐oil had fewer spores for 6 wk after treatment, but the plants were not killed and when new growth became infected, spore production recovered to equal that on untreated plants.

The fungicide captafol caused some reductions in spore number on stubble but results were not consistent, applied after paraquat it had no effect. It was generally ineffective when applied to volunteer plants; applied after paraquat it tended to increase spore number, but the differences were seldom significant.

Spores washed from volunteer plants treated with paraquat or glyphosate were inoculated to pot‐grown barley seedlings; neither herbicide had any effect on spore viability. Viable spores were recovered in February from stubble or volunteer plants treated the previous autumn with paraquat or glyphosate respectively.
Effects of fungicide timing on control of Rhynchosporium secalis in barley plants
Authors: JORDAN V. W. L. , TARR HILARY S. , MILES D. M.
Published: February 2008

Sprays of captafol, carbendazim, carbendazim + tridemorph + maneb, diclobutrazol, triadimefon or triadimefon + carbendazim all completely protected barley plants in a glasshouse against R. secalis for at least 30 days. However, their effectiveness in preventing disease development when applied after inoculation differed: triadimefon, traidimefon + carbendazim, or diclobutrazol were the most effective, completely preventing symptom development when applied up to 5 days after inoculation to plants grown above 16 °C, and up to 8 days below 8 °C. All the fungicides decreased the number of viable conidia produced by leaf blotch lesions, and when applied to infected plants at G. S. 30, greatly decreased the upward spread of the disease under simulated rain conditions; the most effective fungicides in these respects were triadimefon and triadimefon + carbendazim.

The above fungicides and fungicide mixtures, together with the recently introduced materials fenpropimorph and propiconazole were applied to diseased winter barley crops in winter or in spring. All treatments decreased leaf blotch development and increased yields. In most cases, a winter application was more effective than spring applications, particularly if applied in mid‐November. The most effective fungicides were triadimefon and propiconazole. The field trials data fitted well with the predictions of performance indicated by the glasshouse investigations.
Cowpea mottle virus: field resistance and seed transmission in virus‐tolerant cowpea*
Authors: ALLEN D. J. , THOTTAPPILLY G. , ROSSEL H. W.
Published: February 2008

Cultivars of cowpea (Vigna unguiculata) possessing tolerance to infection by cowpea mottle virus (CMeV) under screenhouse conditions exhibited both tolerance and resistance to infection by beetle vectors under field conditions. Resistance to infection was exemplified by delayed and reduced incidence of infection resulting from natural infection pressure, and appeared to be unrelated to vector feeding preference. This suggests that certain cowpea cultivars such as TVu 3901 possess more than one component of resistance (sensu Russell, 1978) to CMeV.

Despite some correspondence between results from artificial (mechanical) and natural (vector) inoculation, we suggest that field evaluation is often an important adjunct to greenhouse screening for virus disease resistance since resistance mechanisms operative under field conditions may be overlooked in artificial screening programmes.

In the susceptible cultivar TVu 612, when artificially inoculated, CMeV is transmissible through cowpea seed up to 0.4%. In only one instance was CMeV seed transmitted from natural infection. We suggest that apparent inefficiency in seed transmission may in part account for the restricted ecological and geographical distribution of CMeV.
Resistance to Botrytis cinerea in canes of Rubus idaeus and some related species
Authors: JENNINGS D. L. , WILLIAMSON B.
Published: February 2008

Mycelial inoculation of canes with Botrytis cinerea proved a useful method for assessing Rubus material for resistance. When canes were inoculated in summer resistant genotypes developed relatively small lesions which produced few small sclerotia in the following spring. The size of lesions in autumn generally provided the best discrimination between genotypes. Very strong resistance was found in several species, of which Rubus pileatus and R. occidentalis are the most useful for breeding; hybrids of raspberry with these species or with R. crataegifolius also had strong resistance. The resistance shown by a derivative of red raspberry cv. Chief was less strong, as was the resistance conferred by gene H, which determines cane pubescence.
Short and long term effects of simulated bullfinch damage on the cropping of Conference pear trees
Authors: SUMMERS D. D. B.
Published: February 2008

Trials in which Conference pear trees were disbudded by hand to simulate bullfinch damage were carried out over 5 years to ascertain the short and long term effects on yield. The first crop following damage was depressed in proportion to the severity of bud loss; the second crop following damage was enhanced in proportion to bud loss but cumulative yields for the 2 years were still depressed, though not significantly so.

Trees that were damaged annually for 5 years had yields depressed in every year, but crop loss was not consistently related to damage level after the first year. Trees that were damaged in alternate years had significantly depressed yields in the first year only. No difference could be detected between the yields of trees subjected to simulated bullfinch damage (clustered disbudding) and those of trees which had been evenly disbudded.
Resistance to organophosphates, and the genetic background, in fruit tree red spider mite, Panonychus ulmi, from English apple orchards
Authors: CRANHAM J. E.
Published: February 2008

Assays on adult females and eggs of Panonychus ulmi, on leaf discs of Myrobalan plum, were used to characterise and establish homogenous organophosphateresistant (OR) and susceptible strains. Reciprocal crosses of these strains, and assays on adult mites and eggs of the parent, F1 and F2 generations confirmed that resistance was controlled by a single major gene, the expression of which was dominant in the response to parathion, and incompletely dominant to vamidothion, dimethoate and demeton‐S‐methyl. Reproductive incompatibility, between strains, as in Tetranychus urticae, was not found.

Bioassays on larvae hatched from winter eggs, collected from several orchards in Kent, Essex and Somerset, were used to evaluate the spectrum of cross‐resistance to a range of 20 organophosphates (OPs). Together with assays on adult females, these tests showed 10‐ to 100‐fold resistance to most of the OPs used for several years including those noted above, but less than 10‐fold to azinphos compounds and to several recently‐introduced OPs, e. g. dialifos, triazophos, dioxathion. The resistance spectrum in strain OR and five field strains was similar, but some had higher levels to parathion and demeton‐S‐methyl, and others to dioxathion after 3–4 years' exposure. Resistance levels to individual OPs may be enhanced by specific selection. Strains resistant to OPs showed only 2‐ to 5‐fold resistance to two carbamates, and were fully susceptible to dicofol.
Epidemiology of ergot disease (Claviceps purpurea) in open‐flowering male‐sterile cereals
Authors: WOOD G. , COLEY‐SMITH J. R.
Published: February 2008

Ergot sclerotia collected from one source germinated over a period of about 6 wk, but those from many sources, over a period of about 5 months. The duration of ascospore discharge followed a similar pattern.

Individual ovaries of male‐sterile barley remained susceptible to infection for about 3 wk. After infection, 7 to 10 days elapsed before honeydew production started and this secondary source of inoculum (conidia) continued to be produced for about 2 wk in individual ovaries before ergot sclerotia started to develop.

A field trial demonstrated that the duration of ovary susceptibility is lengthened in practice because of unevenness in flowering and the production of successive flushes of tillers. The potential for increase of the disease from a small primary focus of infection was large with the majority of the infections occurring in the back‐ or late‐tillers.