bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipid metabolism of Pleurotus sajor caju
Authors: NAIR N. G. , HOLLEY M. P. , SONG C. H. , CHO K. Y.
Published: February 2008

The biosynthesis of lipids in the mycelium and sporophore of Pleurotus sajor caju was studied. Whereas in the mycelium the biosynthesis of lipids was directly primarily towards storage (e.g. tri‐acylglycerols), in the sporophore it was directed towards structural components (e.g. sterols). The incorporation of 14C precursors into non‐polar and polar lipid fractions was generally similar for 14C acetate, 14C palmitate, 14C oleate and 14C linoleate in the case of mycelium and sporophore. It appears that linoleic acid was utilised as a source of acetate for lipid biosynthesis in the sporophore. A significantly higher incorporation of label was seen in sporophore sterol than in mycelial sterol. Malate dehydrogenase activity increased in the mycelium grown in the presence of lipids. Lipase of P. sajor caju was inducive. The growth of P. sajor caju was enhanced by increased lipid utilisation. The implications of these results on commercial cultivation of this fungus are discussed.
Lettuce big‐vein virus: mechanical transmission and relationships to tobacco stunt virus
Authors: HUIJBERTS N. , BLYSTAD D. ‐R. , BOS L.
Published: February 2008

Big‐vein diseased lettuce plants contained an agent that could consistently be transmitted mechanically to Chenopodium quinoa, in which it caused characteristic local lesions. Mechanical transmission was also possible to five other plant species including Nicotiana benthamiana, N. clevelandii and N. occidentalis, but not to lettuce. Symptoms in N. occidentalis were reminiscent of those of tobacco stunt disease. With zoospores of originally virus‐free Olpidium brassicae, subcultured on the roots of N. occidentalis‐P1, sap‐inoculated either from lettuce or via C. quinoa, the agent could be transferred back to lettuce in which characteristic symptoms of big‐vein were reproduced.

Infectivity in sap at room temperature was reduced by half after 2 h, and was practically lost after one day. Thermal inactivation was considerable at 45°C and complete at 50°C. Most infectivity was lost at dilution 1:5, and the dilution end‐point was 1:10. The agent survived well in leaf material stored at ‐80°C, or in sap from leaves ground in buffer with DIECA and activated charcoal and freeze‐dried. Mechanical transmission required low dilution (1:2) in the buffer with charcoal, and chilling of materials and utensils.

In lettuce, N. occidentalis‐P1 and C. quinoa, with all isolates tested but one, infection was always associated with the presence of rod‐shaped particles which in the literature have been associated with lettuce big‐vein, and are similar to those described for tobacco stunt. Results obtained corroborate the assumption that these particles are the virions of lettuce big‐vein virus. The virus also resembles tobacco stunt virus in mechanical transmissibility, instability in sap and symptoms on N. occidentalis.
Transmission of potato leafroll virus in relation to the honeydew excretion of Myzus persicae
Authors: HEUVEL J. F. J. M. VAN DEN , PETERS D.
Published: February 2008

Honeydew excretion of single Myzus persicae nymphs on potato leafroll virus (PLVR)‐infected Physalis floridana was studied during the acquisition access period (AAP) in relation to the efficiency of virus transmission.

With increasing length of the AAP, the percentage of nymphs that transmitted the virus increased. These nymphs produced significantly more honeydew droplets during the AAP on PLRV‐infected P. floridana plants than nymphs which failed to transmit the virus. However, the number of honeydew droplets excreted during the AAP by transmitting nymphs did not affect the length of the latency period. Nymphs which infected the first test plant after a short latency period produced a similar amount of honeydew during the AAP to those with a longer latency period.

Honeydew excretion recorded on plants of varied age, showed that nymphs feeding on bottom leaves of infected plants produced more honeydew droplets than on comparable leaves of healthy plants. On infected plants, nymphs produced more honeydew droplets on bottom leaves with pronounced symptoms than on top leaves that hardly showed any symptom of PLRV infection.

The concentration of viral antigen measured by ELISA was lower in top leaves than in bottom leaves of infected plants. Nevertheless, nymphs feeding on top leaves transmitted the virus more efficiently than those which used bottom leaves as virus source. When bottom leaves were used as a virus source, the percentage of viruliferous nymphs decreased with plant age. These results indicate that the availability of virus for acquisition by aphids declines with increasing plant age and symptom severity.
Influence of Heterodera avenae on winter wheat in France: experiments with resistant and susceptible varieties
Authors: RIVOAL R. , DOUSSINAULT G. , HULLE M.
Published: February 2008

A succession of oat crops resistant or susceptible to Heterodera avenue produced plots lightly or moderately infested with the pest with little risk of interaction with other soil pathogens in succeeding cereal crops. Using these plots, the effects of the nematode on growth and yield of winter wheat were studied. The nematode affected the crop throughout its development, with a marked effect on yield. The effects of H. avenue are similar to those of water stress and are accentuated to a greater or lesser extent by climatic conditions. In the field the efficacy and durability of resistant genes incorporated in wheat and oats were checked. After four‐years' cultivation of oats (cv. Panema), no resistance‐breaking pathotypes were detected. Some advanced wheat lines with nematode resistance were also tolerant of nematode attack.
The response of spring barley and winter wheat to Avena fatua population density
Authors: WILSON B. J. , COUSENS R. , WRIGHT KATHRYN J.
Published: February 2008

Populations of Avena fatua were established in crops of spring barley and winter wheat, and relationships derived between yield and other crop parameters, and weed density. Competitive effects of A. fatua, which were similar to those found in other countries, were greatest at low crop densities. Crop head numbers were reduced proportionately less than crop yield, indicating that competition was affecting other yield components. Competition increased the proportion of thin grain of barley but not of wheat. Competition had little effect on the moisture content and the contamination of the harvested grain by A. fatua, suggesting that at threshold populations these factors are unlikely to be of economic significance. It was concluded that at average crop densities, low infestations of A. fatua are likely to result in cereal yield losses in the region of 1 % for each A. fatua plant m‐2.
Surveys of diseases of winter wheat in England and Wales, 1976–1988
Authors: POLLEY R. W. , THOMAS M. R.
Published: February 2008

Samples from 300 – 400 randomly selected winter wheat crops were taken annually at growth stage 73 – 75 from 1976 to 1988 with the exception of 1983 and 1984. The number of samples from each region was proportional to the area of wheat grown in each region. The percentage of the area of the top two leaves affected by diseases, the severity of ear and stem base diseases and, in 6 years, the severity of take‐all were recorded. Septoria tritici and Septoria nodorum were, on average, the most severe of the foliar diseases and eyespot (Pseudocercosporella herpotrichoides) was the most severe of the stem base diseases. Regional differences in levels of S. tritici, brown rust, sharp eyespot and nodal fusarium were significant. Cultivar resistance affected disease severity, and previous cropping patterns particularly affected take‐all and eyespot. Eyespot and sharp eyespot were less severe in late‐ than in early‐sown crops. The percentage of crops treated with a fungicidal spray increased from 14% in 1976 to over 90% between 1983 and 1985. Use of benzimidazole fungicides applied at growth stage 31 declined, while use of morpholines from flag leaf emergence onwards increased between 1985 and 1988.
Genotype by environment interaction in the assessment of tolerance of partially resistant potato clones to potato cyst nematodes
Authors: DALE M. F. B. , PHILLIPS M. S.
Published: February 2008

Genotype by environment interactions in a number of field trials in different years are examined in relation to tolerance of potato cyst nematodes and the subsequent yield losses. A biplot technique is used to display the interaction effects graphically and facilitate identification of any patterns in the data. The results are assessed and discussed in relation to breeding strategies and the variation found between different nematode populations.
The use of non‐destructive measurement and physiological models of yield determination to investigate factors determining differences in seed yield between genotypes of “desi” chickpeas (Cicer arietum)†
Authors: WILLIAMS J. H. , SAXENA N. P.
Published: February 2008

Mathematical models for yield determination are most commonly used to estimate the probable final crop yield in a given circumstance based on measured physiological parameters but the reverse may be done. Simple models of yield determination may be used to estimate the model parameters associated with a measured final product. One can then obtain a better understanding of the physiological attributes of large numbers of genotypes without the labour intensive destructive measurements usual to interpretive physiology. This approach has been demonstrated using 120 chickpea genotypes.

The total mass, seed yield, vegetative (Dv) and reproductive (Dr) durations were observed and the crop growth rates (C) and partitioning to seed (p) estimated. The contribution of variations in C., Dr, and p to the variations in seed yield were analysed by regression techniques. Contrary to expectations based on other crops, the variations in C were an important source of yield variation, rather than variations in p and Dr. Counteracting relationships existed between the parameters of the yield model; C was inversely related to Dr and p. The influence of these features of chickpea yield determination on genotype by environment interactions and maximising yield are discussed.
Some statistical considerations in the determination of thresholds in ELISA
Authors: FENLON J. S. , SOPP P. I.
Published: February 2008

The presentation of quantitative results from ELISAs is very variable, and, in particular, the positive‐negative threshold or critical value is poorly defined. A simple statistical model is presented which demonstrates how this value may be determined. Depending on what assumptions are made it is possible to estimate the necessary parameters in several different ways. These methods generally form a hierarchy, and greater precision can be achieved by combining variances from several plates. More problematical is the determination of the negative control, and indeed its definition. The results of a series of ELISAs taken from a study of polyphagous predators of the cereal aphid S. avenae are used to illustrate the methods. The ELISAs were done over a period of three months using 86 plates. Recommendations are made for the numbers and levels of controls to be used in future studies.
Analysing dose‐mortality data when doses are subject to error
Authors: RIDOUT M. S. , FENLON J. S.
Published: February 2008

In microbial control of insect pests, the dose of pathogen that a subject actually receives varies because of variation in individual intakes. Variation in intake of a given concentration is equivalent to varying the concentration for a given intake. The main effect of such variation is to flatten the dose‐response curve. If the dose‐variation is known, a correction for this effect can be made; new estimates for the slope and intercept of the probit line are given. However, the correction increases the variance of the estimates. The theory is illustrated with an example in which the diamond‐backed month, Plutella xylostella, was fed varying doses of the specific granulosis virus PxGV; intake assays using similar larvae showed the coefficient of variation of intake volume to be about 40%. Simulation studies showed that correction may be practically important only for the estimation of extreme percentiles, e.g. LD95s.
Effect of anaesthesia with carbon dioxide on vectoring ability and survival of the planthopper Laodelphax striatellus
Authors: CACIAGLI P.
Published: February 2008

This paper describes the effects of carbon dioxide anaesthesia on the ability of the planthopper Laodelphax striatellus to subsequently acquire and transmit maize rough dwarf reovirus (MRDV) and barley yellow striate mosaic rhabdovirus (BYSMV), both propagative in the vector.

Anaesthesia reduced the acquisition of MRDV by about 45%, but did not affect acquisition of BYSMV. In serial transfer transmission tests, anaesthesia caused interruption of transmission of both MRDV and BYSMV in about 11% of infectious insects; the effect may be due to impaired ability to find the phloem. The effect was stronger on third instar nymphs than on adults.

Transmission of MRDV was resumed 3 days after anaesthesia, but none of the insects that stopped transmitting BYSMV resumed it. The survival of insects which ceased to transmit BYSMV was significantly lower than that of hoppers that continued to transmit. No other effects on survival were detected. A possible interaction of carbon dioxide with BYSMV in L. striatellus is discussed, in the light of effects of carbon dioxide on Drosophila melanogaster infected by some rhabdoviruses.
Detection of bean yellow mosaic virus in gladioli corms by the polymerase chain reaction
Authors: VUNSH RON , ROSNER ARIE , STEIN ADINA
Published: February 2008

The polymerase chain reaction (PCR) method readily detected bean yellow mosaic virus (BYMV) in gladioli leaves, but in initial tests PCR did not detect virus in corm tissue. Extracts of RN A from corm tissue were shown to inhibit the amplification of viral sequences when added to a PCR reaction. An additional purification step for the RNA extracts using a Sephadex G‐50 column eliminated the inhibitory effect and enabled PCR to amplify and detect viral RNA in corm tissue preparations.
Cell membrane punctures during epidermal penetrations by aphids: consequences for the transmission of two potyviruses
Authors: POWELL GLEN
Published: February 2008

Electrical penetration graphs (EPGs) were used to investigate aphid stylet activities during brief penetrations and the importance of these events for the nonpersistent transmission of two potyviruses, beet mosaic virus (BMV) and potato virus Y (PVY). Stylet puncture of a cell membrane, recorded as a potential drop, was correlated with the acquisition and inoculation of PVY and acquisition of BMV by Myzus persicae.
The feasibility of producing inbred rather than F1 hybrid cultivars in Brussels sprouts (Brassica oleracea var. gemmifera): an assessment of recombinant inbred lines
Authors: WERNER C. P. , SMITH B. M. , GODWIN R. M. , KEARSEY M. J.
Published: February 2008

Results are presented for the performance of improved inbred lines of Brussels sprouts grown in replicated and fully guarded plots. Some lines were identified which out‐performed the reference F1 hybrid, Gower, for the yield of marketable sprouts and for sprout quality. No lines were found which were superior for both of these traits. These results support earlier contentions that inbred line performance in Brussels sprouts could be improved to levels comparable with those of commercial F1 hybrids. The genetic gains required to achieve commercial parity with hybrids for all agronomically important traits continue to be large. Therefore, the use of inbred lines as commercial cultivars can only be viewed as a long term objective. Previous studies have identified additive x additive epistasis and the segregation of many loci as important factors limiting the genetic gains to be expected from a single cycle of crossing and inbreeding. In addition to these factors the current study identifies areas of difficulty encountered when attempting to screen and select large numbers of inbred lines, produced either by single seed descent or by anther culture, in a single season. Evidence is presented which suggests that imperfect visual selection and/or genotype × seasonal interactions may substantially reduce the efficiency of selections based upon a single trial of very many unreplicated lines.
Indices of water deficit in susceptible and resistant cucumbers in response to infection by cucumber mosaic virus
Authors: LEVY D. , MARCO S.
Published: February 2008

Indices of water deficit were determined under conditions of non‐limited water supply in cucumber mosaic virus (CMV)‐infected seedlings of the susceptible cv. Bet Alpha. An increase in the concentration of soluble solids, decrease of water and osmotic potentials, and increase of proline concentration were found in the CMV‐infected cotyledons. In the cv. Shimshon, which is resistant to CMV, virus infection caused only a slight change in the concentration of the soluble solids and in the osmotic potential; water potential and proline content were not affected. Concomitantly, infectivity of cotyledons by CMV was much lower in the tolerant cv. Shimshon than in the susceptible cv. Bet Alpha. The possible association of water deficit with virus‐induced growth retardation is discussed.
Relative contribution of nematodes (Caenorhabditis elegans) and bacteria towards the disruption of flushing patterns and losses in yield and quality of mushrooms (Agaricus bisporus)
Authors: GREWAL P. S.
Published: February 2008

Laboratory tests of bacteria isolated from the body surface, or from the gut, of a saprophagous rhabditid nematode Caenorhabditis elegans infesting mushrooms (Agaricus bisporus) showed that some bacteria enhanced nematode reproduction and that others inhibited it. As some bacteria were shown to inhibit mycelial growth of the mushroom, the effects of Acinetobacter calcoaceticus var. anitratus, Enterobacter cloacae and Serratia liquefaciens, either alone or in combination with C. elegans, on the flushing patterns, quality and yield of A. bisporus (strain Horst U3) were studied.

Bacteria alone had little effect on flushing patterns whereas C. elegans delayed the onset of mushroom production and significantly disrupted the growth pattern of crops, with mushrooms appearing more regularly and not within obvious flushes. Inoculation with bacteria resulted in ‘browning’ of mushrooms that was even more pronounced in C. elegans treatments. Characteristic distortion of sporophores was observed only in the presence of C. elegans. Nematodes commonly colonised sporophores. Bacteria affected the size of nematode populations both on the sporophores and in the casing.

Significant yield loss occurred; up to 10% when bacteria were inoculated, up to 27.8% when C. elegans was inoculated, and up to 35% with both bacteria and nematodes. Synergism between C. elegans and A. calcoaceticus var. anitratus was observed; the combination resulted in significantly greater reduction in mushroom yield than any other treatment. It is concluded that bacteria contribute to yield loss and quality deterioration in A. bisporus but that the effects are far greater in the presence of C. elegans.
Effective pollination period in apricot (Prunus armeniaca L.) varieties
Authors: BURGOS L. , EGEA J. , DICENTA F.
Published: February 2008

A study of the effective pollination period (E.P.P.) of six varieties of apricot has shown that in the warm climate of the South Mediterranean this parameter is extremely short. The percentage of fruit set of emasculated flowers diminishes rapidly with time. Temperature plays an important role in this process and is responsible for the rapid degradation of the stigma, which hinders pollen germination.
Influence of boron on the reproductive growth of white clover (Trifolium repens L.) cultivars
Authors: MARSHALL A. H. , KHRBEET H. K. , HIDES D. H.
Published: February 2008

The effect of boron on the reproductive growth of four contrasting white clover cultivars was examined in a controlled environment and glasshouse experiment. Plants grown under a nutrient regime excluding boron and those receiving 0.5 mg/litre boron had fewer stolons, reproductive stolons and inflorescences than those receiving 1, 2 or 3 mg/litre. Inflorescences were also smaller and had fewer seeds per floret. A boron concentration of 1 mg/litre gave optimum reproductive growth, higher levels of boron giving no further increase. Peduncle length and nectar quantity, but not nectar quality, were also influenced by boron indicating a possible beneficial effect of this element on pollinator activity.

Cultivars differed in both vegetative and reproductive growth. Cv. Gwenda, a small leaved cultivar, had more stolons but fewer inflorescences than cv. Menna and smaller inflorescences than cv. Olwen, a large leaved cultivar. Generally, these cultivars responded similarly to boron.

The implications of these results for the reproductive growth of white clover are discussed.
The toxicity of aphicide residues to beneficial invertebrates in cereal crops
Authors: UNAL GULTEKIN , JEPSON PAUL C.
Published: February 2008

The toxicity of dimethoate, deltamethrin and pirimicarb residues to Bembidion lampros and Coccinella septempunctata was evaluated by confining groups of insects to winter wheat foliage and soil for 24 h at different times after treatment in the field. Flag leaf residues were found to be more toxic than first leaf residues: soil residues were the least toxic with pirimicarb showing virtually no soil toxicity. In general, dimethoate and deltamethrin showed similar levels of foliar toxicity with flag leaf toxicity on the first day after treatment being in the range 60–80% for B. lampros; deltamethrin was however, less toxic than dimethoate at ground level. Both of these products were more toxic than pirimicarb. The long‐term exposure of insects, surviving the 24 h bioassays, to treated soil at different times following application resulted in further mortality and provided estimates of the maximum levels of mortality that populations of predators might suffer migrating into the crop at different times following application. Dimethoate was shown to be particularly harmful at the current recommended field application rate and reduced doses were proposed to limit the severity of the initial effects.
Composition analysis of tropical white oyster mushroom (Pleurotus citrinopileatus)
Authors: GHOSH N. , MITRA D. K. , CHAKRAVARTY D. K.
Published: February 2008

The protein content of the mushroom (Pleurotus citrinopileatus) was determined at different stages of its growth cycle and compared with that of the tropical oyster mushroom Pleurotus sajor‐caju. In both species, maximum protein content was obtained at the bud stage but fell thereafter. All essential amino acids were present in adequate amounts, as were K, P, Fe, Ca, Na, Mg and Mn. The heavy metals, Cu and Zn, were present but in very low concentrations, much below the tolerance limit of human beings.
Biodegradation process and the nature of metabolism of metalaxyl in soil
Authors: DROBY S. , COFFEY M. D.
Published: February 2008

The enhanced biodegradation of metalaxyl was studied in tobacco, citrus, avocado and corn soils. The most rapid degradation of metalaxyl occurred in a tobacco soil in which the half‐life (50% degradation) of metalaxyl was 6 days. The main breakdown product of metalaxyl in all soils was the acid metabolite. Ring labelled [14C]metalaxyl incubated for 4 wk in 6 soils demonstrated a low rate of 14CO2 evolution ranging from 2.1% to 11.3% which was unrelated to the biodegradation properties of the soil. A relationship between the concentration of metalaxyl and the subsequent rate of biodegradation was found in the tobacco soils. Higher concentrations of metalaxyl resulted in faster biodegradation rates. A single exposure of tobacco and corn soils to metalaxyl (100 μg/ml or 200 μg/g dry weight of soil) significantly increased their subsequent capacity to degrade the fungicide. Addition of the fungicide thiram or the antibiotics streptomycin and chloramphenicol to an avocado soil resulted in 75% and 51% inhibition of metalaxyl degradation, respectively. A combination of the fungicide and antibiotics resulted in 89% inhibition. The results indicate that enhanced microbial degradation of metalaxyl can occur in a wide range of soils. Under experimental conditions using soil solutions or soil systems, a single application of the fungicide may trigger this event. A wide range of fungi and bacteria appear to take part in degrading metalaxyl.
A satellite RNA of arabis mosaic nepovirus and its pathological impact
Authors: LIU YUAN YI , COOPER J. IAN , EDWARDS MARY LOU , HELLEN CHRISTOPHER U. T.
Published: February 2008

Three RNA species were encapsidated in arabis mosaic nepovirus from lilac (ArMV‐L): the two genomic RNAs, RNA‐1 and ‐2, and an RNA‐3, Mr. 0.4 × 106. The genomic RNAs from ArMV‐L separated by gel electrophoresis from RNA‐3 were infectious and, during ten passages of this isolate (ArMV‐SF) RNA‐3 was not produced; only RNA‐1 and RNA‐2. When inoculated with the genomic species of ArMV‐L, or with those of other ArMV isolates, RNA‐3 replicated but did not do so in the absence of RNA‐1 and RNA‐2. The RNA‐3 did not share extensive regions of nucleotide sequences with the genomic RNAs but, like them, was polyadenylated and was linked to a protein (VPg) which did not seem essential for replication.

When the pathogenicity of ArMV‐L and ArMV‐SF was compared in 42 plant species/cultivars representing 36 genera and 14 families, the following differences were observed: in three species of legume, disease progressed more rapidly when RNA‐3 was present but in species from five families, the presence of RNA‐3 was correlated with symptom amelioration. When RNA‐3 was present, the amounts of ELISA detected antigen were not consistently different in tip leaves of Nicotiana megalosiphon, Chenopodium amaranticolor, C. quinoa or Pisum sativum from those in leaves where RNA‐3 was absent.
Particle purification, properties and epitope variability of Indian tomato leaf curl geminivirus
Authors: MUNIYAPPA V. , SWANSON M. M. , DUNCAN G. H. , HARRISON B. D.
Published: February 2008

A whitefly‐transmissible stock isolate of Indian tomato leaf curl geminivirus (ITmLCV) was cultured in graft‐inoculated tomato plants and its particles purified from chloroform‐clarified extracts in citrate buffer by precipitation with 70 g/litre polyethylene glycol, ultracentrifugation and sucrose density gradient centrifugation. Contaminating helical filaments were eliminated by banding in caesium sulphate gradients. ITmLCV particles had the shape typical for geminiviruses, measured c. 30 × 20 nm and contained a single major protein of estimated mol. wt c. 32 000. They reacted in immunosorbent electron microscopy with antisera to four other whitefly‐transmitted geminiviruses. ITmLCV reacted with one out of 17 monoclonal antibodies specific for different epitopes in the particle protein of African cassava mosaic geminivirus and five or six out of 10 monoclonal antibodies to the particle protein of Indian cassava mosaic geminivirus. Virus isolates from tomato at nine locations in Karnataka State showed only slight differences in epitope profile, and isolates from four weed species in tomato fields were similar or identical to those from tomato.
Barley mild mosaic virus inside its fungal vector, Polymyxa graminis
Authors: JIANPING CHEN , SWABY A. G. , ADAMS M. J. , YILI RUAN
Published: February 2008

In an electron microscope study to investigate the association of barley mild mosaic virus (BaMMV) with its fungal vector, Polymyxa graminis, thin sections were made of zoospores of the vector and of barley roots containing different stages in the life cycle of the fungus. Immunogold labelling was used to identify the virus in sections. Labelled bundles of presumed virus particles were seen in c. 1% of zoospores liberated from plant roots and in zoospores inside zoosporangia. A few zoosporangial plasmodia had localised labelling but no bundles were seen. No virus particles were seen in sections of resting spores.
The effect of sand particle size on Steinernema feltiae sensu Filipjev (1934) (=N. bibionis Bovien) activity against Galleria mellonella larvae
Authors: BLACKSHAW R. P. , SENTHAMIZHSELVAN M.
Published: February 2008

Activity of an isolate of Steinernema feltiae in different fractions of sand was measured by the mortality of host Galleria mellonella larvae. No deaths were recorded in particles less than 600 μ across. Maximum activity occurred with 700–800 μ size particles. Activity was also limited with a sand fraction containing particles of 1000–1100 μ. Host mortality in mixtures of two sand fractions varied. Generally, the addition of either small particles (500–700 μ) or large ones (1000–1100 μ) to fractions of the mid‐range (700–1000 μ) reduced the percentage kill of host larvae. Polynomial regression models fitted to data from single‐phase experiments could be used to predict accurately mortality of G. mellonella larvae in two‐phase mixtures of sand.
Seed quality effects in bulb onions (Allium cepa L.)
Authors: GIL M. OCANA , WERNER C. P. , CROWTHER T. C.
Published: February 2008

The nature and persistence of seed quality effects produced by a range of seed production treatments was investigated in the autumn‐sown onion crop. Genotypically equivalent seed lots raised in different glasshouses within the same year were found to germinate at significantly different rates. The seed lot which emerged earlier produced larger seedlings and this difference in size persisted throughout the growing period. In a comparison between the effects of hand crossing and self‐pollination techniques the hand crossing method produced a much lower total seed yield but heavier seeds and larger plants. The induced effects persisted throughout the year but were not significant in the mature bulb characters. The implications of these results upon the control of seed production for plant breeding and genetical experiments is discussed.
Mortality of the earthworm Eisenia fetida (Savigny) presented to the terrestrial planarian Ártioposthia triangulata (Dendy) (Tricladida: Terricola)
Authors: BLACKSHAW R. P.
Published: February 2008

Ártioposthia triangulata is a terrestrial planarian that feeds on earthworms. Up to 76% of field collected A. triangulata fed on Eisenia fetida earthworms at 10°C in the laboratory. In one experiment, the feeding rate declined from 63% of earthworms attacked to 36% and 34% in the first, second and third feeding opportunities over a week. The average number of E. fetida eaten was 1.4 per planarian per week. The gain in weight of individual A. triangulata was significantly related to the amount of earthworm tissue lost during the feeding process. Over a one week period, the amount of earthworm tissue lost was related to the total amount presented to the planarians but not to their size. Frequency of attack was, however, related to planarian size. The results are discussed in relation to an hypothetical population of earthworms in pasture. It is concluded that the results support the contention that A. triangulata could seriously deplete earthworm populations.
Bibionids (Diptera: Bibionidae) in agricultural land: a review of damage, benefits, natural enemies and control
Authors: D'ARCY‐BURT S. , BLACKSHAW R. P.
Published: February 2008

Records of crop damage caused by Bibionidae are reviewed together with evidence for their beneficial activities, natural enemies and control methods. Bibionids are sporadic and infrequent pests. Although grass and cereals are most vulnerable, a wide range of crops is attacked. Damage is most severe after grass or when plants are under stress. The presence of organic matter during oviposition increases the likelihood of damaging populations. Many natural enemies exist but their impact on adult or larval populations has not been quantified. Given the pattern of attacks and lack of approved insecticides, cultural control methods are more appropriate than chemical. The role of adult bibionids in pollination and of larvae involved in soil processes could be of greater importance than any damage caused by the group.
Possible impact of global warming on cabbage root fly (Delia radicum) activity in the UK
Authors: COLLIER R. H. , FINCH S. , PHELPS K. , THOMPSON A. R.
Published: February 2008

A program for simulating the patterns of egg‐laying by populations of the cabbage root fly was used to model the effects of global warming on future cabbage root fly attacks.

An increase of 3°C in mean daily temperature would cause the cabbage root fly to become active about a month earlier in the year than at present. Under such conditions, the emergence of flies from the overwintering population would be less synchronised, as the completion of diapause and post‐diapause development would occur at the same time in different individuals within the population. However, there would continue to be only three generations of fly each year, even in the south of England. With temperature increases of 5°C or 10°C, the fly would complete four generations each year and aestivation would seriously disrupt egg‐laying.

These rises in temperature would have a major impact on cabbage root fly activity and would require new strategies for controlling this pest.
Rubus host range of rubus yellow net virus and its involvement with other aphid‐borne latent viruses in inducing raspberry veinbanding mosaic disease
Authors: JONES A. T.
Published: February 2008

After graft inoculation with rubus yellow net virus (RYNV), 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cvs were graft‐inoculated with RYNV and three other aphid‐borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leaf spot, singly and in all combinations. In periods of up to 4 yr, classical veinbanding mosaic symptoms developed in sensitive cvs only when they contained both RYNV and RLMV. These symptoms were intensified in plants co‐infected with additional viruses. Veinbanding mosaic disease did not develop in any of 11 cvs infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.
Characterisation of datura yellow vein virus, a newly described rhabdovirus from Australia
Authors: THOMAS J. E. , DIETZGEN R. G.
Published: February 2008

A previously undescribed sub‐group 2 rhabdovirus was isolated in Queensland from Datura stramonium with symptoms of vein yellowing, leaf distortion and reduced leaf size. Particles accumulated in the perinuclear space of infected cells of D. stramonium and measured 77 × 166 nm in preparations from sap. The virus was named datura yellow vein virus (DYVV) and was graft‐transmitted to several hosts in the Solanaceae including Lycopersicon esculentum, Nicotiana tabacum and Solanum melongena, but not to Capsicum annuum or Solanum tuberosum. DYVV was not transmitted by mechanical inoculation and no insect vector was found. Purified particles of DYVV contained four structural proteins with molecular weights of about 78, 47, 41 and 36 kd. The 78 kd protein bound the lectin concanavalin A, thus identifying it as the viral glycoprotein. DYVV was serologically distinct from 11 other rhabdoviruses belonging to both subgroups, including potato chlorotic stunt, potato yellow dwarf (2 isolates) and tomato vein yellowing viruses. The glycoprotein only of DYVV cross‐reacted with a polyclonal antiserum to sonchus yellow net virus.
Effects of rotation length and oxamyl on potato yield and the potato cyst‐nematode, Globodera rostochiensis, in a sandy loam soil
Authors: WHITEHEAD A. G. , WEBB R. M. , BEANE J.
Published: February 2008

In sandy loam infested with golden potato cyst‐nematode, Globodera rostochiensis, oxamyl at 5.6 kg a.i. ha‐1 incorporated in the top 15 cm of the soil just before planting potatoes greatly reduced nematode population increase on susceptible cv. Désirée grown six, seven or eight years after the last susceptible potato crop, but did not significantly increase tuber yields. In four‐course and two‐course rotations, oxamyl also controlled increase of G. rostochiensis and greatly increased yields of both cv. Désirée and resistant cv. Maris Piper. Oxamyl maintained tuber yields in a four‐course rotation at the same level as in a six to eight‐course rotation. Decline of G. rostochiensis in the soil was much faster under barley in some two‐course rotations than under barley in four‐course rotations.
Selection for virulence in the potato cyst‐nematode, Globodera pallida
Authors: WHITEHEAD A. G.
Published: February 2008

The ability of six populations of Globodera pallida to multiply on Solanum vernei hybrids (Morag, 12380 2, Glenna and Santé) and S. tuberosum andigena hybrids (A 27/23, Paladin (ZB 35/29) and ZC 83/6) was studied in microplots and pots. Evidence was obtained of selection for virulence in one population after one year's cultivation of cvs Glenna or Morag. Similarly, after four years' continuous cultivation of cvs Morag or ZC 83/6 in microplots, three of five populations of G. pallida contained more virulent nematodes than the same populations maintained for the same period on cv. Pentland Crown (susceptible to G. pallida). These results are discussed in relation to earlier work and the use of partially resistant cultivars in the integrated control of G. pallida.
Turf strength and root characteristics of ten turfgrass cultivars
Authors: ROSS S. J. , ENNOS A. R. , FITTER A. H.
Published: February 2008

Ten turfgrass cultivars were grown, singly and in mixtures, in glasshouse culture, to create standard sods. The tearing strength of the sods was measured using an Instron Universal Testing Instrument. Two Poa cultivars were found to be the strongest, followed in order of decreasing strength by three Festuca cultivars, three Lolium cultivars and two Agrostis cultivars. The relationship between the values obtained and shear strength of the sod root mass was investigated with a view to using this latter measurement as an indicator of tearing strength. No correlation between the two was found. Various characteristics of the root mass of individual plants were examined in an attempt to account for differences in turf strength: root system architecture (magnitude, altitude, pathlength and link numbers and lengths), root numbers at different soil depths and root mass. Sod tearing strength was found to be very strongly inversely related to the interior link length and mass of roots. The use of these as indices of strength is discussed.
Variation in the glucosinolate content of oilseed rape (Brassica napus L.) leaves
Authors: PORTER A. J. R. , MORTON A. M. , KIDDLE G. , DOUGHTY K. J. , WALLSGROVE R. M.
Published: February 2008

The glucosinolate content of oilseed rape {Brassica napus) leaves was monitored over the growth period 30–70 days after planting, and a comparison made between a single‐low cultivar (low in erucic acid), Bienvenu, and a double‐low cultivar (low in erucic acid and glucosinolate), Cobra. In older, fully‐expanded leaves the glucosinolate concentration was very low (< 0.3 μmol/ml tissue water) and did not alter during the course of the experiment. In developing sixth leaves glucosinolate content increased rapidly and reached a maximum concentration (4–5 μmol/ml tissue water) 40 days after planting (6 days after leaf emergence). The concentration then declined, to about 1 μmol/ml after 60 days although the total glucosinolate content in leaves continued to increase until 50 days; much of the reduction in concentration was simply a result of leaf expansion. No major differences were seen between the two varieties in total glucosinolate content or in the individual compounds present. Cv. Cobra developed more quickly than cv. Bienvenu so direct comparison between leaves of the two cultivars was complex. When comparing the glucosinolate content of oilseed rape leaves, between cultivars or between treatments, it is vital to ensure that carefully matched leaves of comparable developmental age are selected.
The biology and host specificity of the onion weed rust, Puccinia barbeyi, a potentially useful agent for biological control in Australia
Authors: HASAN S.
Published: February 2008

Onion weed, Asphodelus fistulosus L., (Liliaceae) a weed of Mediterranean and Middle Eastern origin is widespread in southern Australia where it invades pastures making them unsuitable for grazing. A program of research is underway to discover natural enemies of this plant and to study their possible role in the biological control of onion weed. A rust fungus Puccinia barbeyi (Roum.) Magnus has been found to severely attack A. fistulosus. Observations on the biology of the rust confirmed that it is monoecious and microcyclic and multiplied essentially by aecial and telial stages, although occasionally urediniospores also appeared among teliospores. Several members of the Liliaceae exposed to the aeciospores of the rust remained unattacked indicating that it is most probably specific to Asphodelus spp. and thus its potential for the biological control of A. fistulosus in Australia should be studied further.
Contamination of seed potato tubers grown from stem cutting or microplant‐derived tubers by Phoma foveata and Polyscytalum pustulans in Scotland: the influence of site and fungicide treatment at harvest
Authors: CARNEGIE S. F. , CAMERON A. M.
Published: February 2008

A survey was made over 5 years of the incidence of contamination by Phoma foveata and Polyscytalum pustulans on 3‐year‐old virus‐tested stem cutting (VTSC) stocks assessed on three occasions during the storage season, and on their daughter tubers at five farms. The contamination occurring on plants grown in small plots from stem‐cutting/microplant tubers was also assessed at the farms.

Fungicide treatment soon after harvest reduced the incidence of both pathogens, especially P. pustulans. Tuber contamination was similar for samples collected after fungicide treatment and before planting. The incidence of contamination on daughter tubers, relative to that on the untreated mother tubers, was less with P. foveata but was similar or greater with P. pustulans. Contamination by both pathogens varied between farms and was reflected in the degree of contamination occurring on daughter tubers from stem‐cutting/microplant tubers.

The incidence of P. foveata on stems, soil and tubers of seed stocks classified at Foundation Stock grade from various regions of Scotland was assessed over 2 years. The incidence of tuber contamination was correlated (P < 0.05) with the amount of tuber‐borne soil contamination for all comparisons, but was correlated with stem inoculum in only 7 out of 13 comparisons. The largest amounts of stem inoculum of P. foveata were found in stocks in Aberdeenshire.

These results are discussed in relation to the spread of both pathogens to healthy VTSC stocks.
Enhancement of plant growth by Zygorrhynchus moelleri
Authors: BROWN AVERIL E. , SURGEONER R.
Published: February 2008

Cucumber, tomato, two flowering annuals and a flowering perennial produced plants of greater weight in soilless compost infested with Zygorrhynchus moelleri than in uninfested compost. In Z. moelleri‐infested compost the annuals commenced flowering 4 to 10 days earlier, cucumbers produced mature fruits more rapidly and a greater weight (20%) of fruit was harvested from 15‐wk‐old tomato plants. Leaves of 11 and 15‐wk‐old tomato plants grown in infested compost contained more chlorophyll than leaves from plants in uninfested compost. Z. moelleri was isolated from 99% of segments cut from roots of tomato plants grown in infested compost and it suppressed the growth of Trichoderma spp. at the root surface. Propagules of Z. moelleri remained viable in air‐dried compost for at least 12 months. In axenic culture, Z. moelleri enhanced lateral root development in tomato and cucumber seedlings.
Reflective mulch decreases the spread of two non‐persistently aphid transmitted viruses to narrow‐leafed lupin (Lupinus angustifolius)
Authors: JONES R. A. C.
Published: February 2008

Trials were done in 1987–1989, to investigate the effect of a reflective aluminium painted polythene mulch in protecting rows of narrow‐leafed lupin (Lupinus angustifolius) from infection with two non‐persistently aphid‐transmitted viruses, bean yellow mosaic (BYMV) and cucumber mosaic (CMV). The mulch greatly decreased the rate and extent of spread of BYMV from external sources into mulch‐protected rows in two trials, but was somewhat less effective in a third. The rate and extent of spread of CMV from an adjacent external source into reflective mulch‐protected rows was also greatly decreased in one trial in which the mulch also decreased spread within rows and was effective even when the primary infection source was only 2.5 m away. In a trial sown with CMV‐infected seed (c. 2% seed transmission), the mulch decreased CMV spread from primary foci within rows. Reflective mulch can be used to protect breeders' single row plots of lupins from infection with CMV and BYMV.
Improved purification procedure and some serological and physica properties of cassava common mosaic virus from South America
Authors: NOLT BARRY L. , VELASCO ANA CECILIA , PINEDA BENJAMIN
Published: February 2008

Large quantities of cassava common mosaic virus (CCMV) were purified from systemically infected Nicotiana benthamiana plants. A polyclonal antiserum, with a titre of 1/128 in the tube precipitin test, was produced by immunising rabbits with purified virus. Viral antigens were detected in cassava, using both the double‐antibody sandwich or plate‐trapped antigen forms of enzyme‐linked immunosorbent assay (ELISA). The virus reacted with antisera to the potexviruses potato virus X and tulip virus X in F(ab')2 ELISA. As determined by ELISA, isolates of CCMV from cassava and chaya are closely serologically related to each other. Leaf extracts from infected N. benthamiana plants were infective to a dilution of 10‐‐4 but not 10‐‐5; after heating for 10 min at 65 °C but not 70 °C; and after storage at room temperature for 14 days. The virus has a sedimentation coefficient of 126 S20,w, a single coat protein molecule of c. mol. wt 21 000, and a single‐stranded RNA genome of c. mol. wt 2.0 ± 106. Several dsRNA species, including the putative viral replicative form of c. mol. wt 4.1 ± 106, were isolated from virus‐infected cassava and N. benthamiana.
The Yd2 resistance to barley yellow dwarf virus is effective in barley plants but not in their leaf protoplasts
Authors: LARKIN P. J. , YOUNG M. J. , GERLACH W. L. , WATERHOUSE P. M.
Published: February 2008

The Yd2 gene for “resistance” to barley yellow dwarf virus (BYDV) has been widely used in barley (Hordeum vulgare). We have tested Australian isolates of BYDV of varying severity against barley genotypes with and without the Yd2 gene and report here a positive relationship between symptoms and virus levels determined by ELISA. Cultivar Shannon is the result of backcrossing the resistant line CI 3208 to cultivar Proctor, a susceptible line. It appears to be intermediate in reaction to BYDV between Proctor and CI 3208, although it carries the major gene, Yd2. Unlike the whole plant studies, no significant differences were observed with regard to the ability of protoplasts derived from these various genotypes to support BYDV replication. It is therefore demonstrated for the first time that the Yd2 gene is not among the small number of resistance genes which are effective against virus replication in isolated protoplasts.