bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of three whitefly‐transmitted geminiviruses occurring in Europe by tests with heterologous monoclonal antibodies
Authors: MACINTOSH S. , ROBINSON D. J. , HARRISON B. D.
Published: February 2008

Selected monoclonal antibodies (MAbs), prepared to particles of African cassava mosaic or Indian cassava mosaic geminiviruses, detected three geminiviruses that occur in Europe: abutilon mosaic virus in Abutilon pictum ‘Thompsonii’, tobacco leaf curl virus in Lonicera japonica var. aureo‐reticulata and tomato yellow leaf curl virus in Lycopersicon esculentum. All three viruses were detected in indirect ELISA by MAbs SCR 17 and SCR 20 but they were differentiated by their reactions with SCR 18 and SCR 23. Tobacco leaf curl virus was detected only when reducing agents were included in the leaf extraction medium. Inclusion of sodium sulphite slightly improved detection of tomato yellow leaf curl virus but reducing agents were not needed for detection of abutilon mosaic virus.
Transmission of sowbane mosaic virus by Thrips tabaci in the presence and absence of virus‐carrying pollen
Authors: HARDY V. G. , TEAKLE D. S.
Published: February 2008

When pollen of sowbane mosaic sobemovirus (SoMV)‐infected Chenopodium amaranticolor was dusted onto C. amaranticolor and C. quinoa test seedlings which were then infested with 5–10 adult Thrips tabaci, SoMV was transmitted to 25%C. amaranticolor and 88% of C. quinoa plants. Five hours access of T. tabaci to pollen‐contaminated C. quinoa seedlings was sufficient for SoMV transmission, but 1 h was not. SoMV was also transmitted when T. tabaci was mixed with pollen of C. amaranticolor and then placed on C. quinoa test seedlings. Further, plant‐to‐plant transmission of SoMV occurred in the absence of virus‐carrying pollen when T. tabaci was caged on infected non‐flowering C. amaranticolor or C. quinoa for 1–8 days and then adults transferred to C. quinoa test seedlings. This is the first time that thrips have been shown to be a vector of SoMV, and that a virus outside the ilarvirus group is reported to be transmitted using pollen and thrips.
Subterranean clover mottle sobemovirus: its host range, resistance in subterranean clover and transmission through seed and by grazing animals
Authors: WROTH J. M. , JONES R. A. C.
Published: February 2008

Subterranean clover mottle sobemovirus (SCMV) was transmitted by manual inoculation of sap to 27 cultivars belonging to three sub‐species of subterranean clover. The virus readily infected systemically all inoculated plants of five susceptible cultivars of ssp. subterraneum. Ten others showed partial resistance as not all infected plants developed systemic infection; cold winter conditions further delayed or prevented systemic movement in four of them. Two cultivars of spp. brachycalycinum and four of spp. yanninicum failed to develop systemic infection following inoculation and were considered highly resistant. Resistance to SCMV in three of the spp. yanninicum was further confirmed by the failure to establish detectable primary infections in most of the inoculated leaves. Moreover, when the four ssp. yanninicum cultivars were graft‐inoculated with SCMV, systemic infection eventually developed in them but the virus concentration was low. SCMV was also transmitted by manual inoculation of sap to a further 23 species of Trifolium, Medicago or Pisum. Three species were non‐hosts, five were infected only in inoculated leaves and 18 others developed systemic infection in some or all plants.

SCMV reached very high concentrations and was stable in subterranean clover sap. It was transmitted experimentally between subterranean clover plants by brushing infected leaves against healthy ones and in swards was readily transmitted by the trampling and grazing of sheep, but only poorly by mowing. Seed transmission of SCMV to seedlings of five cultivars of subterranean clover was low (0–0.12%). SCMV was not transmitted by Myzus persicae.
Antimicrobial and insecticidal activities of cashew tree gum exudate
Authors: MARQUES MARIA RITA , ALBUQUERQUE LAURENIA MARIA B. , XAVIER‐FILHO J.
Published: February 2008

The gum exudate of the cashew tree (Anacardium occidentale) was shown to inhibit growth of some fungi and bacteria. The gum also prevented oviposition and reduced the number of surviving adults of the Bruchid Callosobruchus maculatus. The feeding of larvae of the Chrysomelid Crimissa cruralis was also strongly affected by the gum. These results suggest an active role for the gum in the defence mechanisms of the plant.
Inheritance of the external mechanical damage resistance of potato cultivars
Authors: DE M. J. , BRADSHAW J. E. , CALIGARI P. D. S.
Published: February 2008

The examination of nine potato cultivars for external mechanical damage resistance found that tests involving the damage index of Robertson (1970) were reasonably consistent over five years. Progeny testing of eight cultivars in two years, by means of a half diallel with selfs, showed that all of the progeny variation was due to general combining ability and there was no evidence of significant specific combining ability. Ranking of cultivars by damage index was significantly correlated with their ranking by general combining ability from their progenies. The results indicate that the best parents for breeding to improve damage resistance can be predicted using their own damage index.
A review of the biology and control of the vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae)
Authors: MOORHOUSE E. R. , CHARNLEY A. K. , GILLESPIE A. T.
Published: February 2008

At the turn of the century, damage by Otiorhynchus sulcatus was sporadic and limited to small areas. Increasing horticultural intensification and the adoption of husbandry techniques favourable to the weevil, such as the use of polythene mulches, increased its pest status. The development of the early inorganic pesticides reduced the number of serious outbreaks of this pest and weevil control was further improved by the development of the persistent organochlorine insecticides in the 1940's. The banning of a number of the more persistent insecticides over recent years has now left the horticultural industry in a very vulnerable position.

O. sulcatus is now a pest on a range of horticultural crops throughout the temperate regions of the world. Infestations are most common in Europe (where it originated) and the USA, and nearly 150 plants species have been identified as potential hosts to O. sulcatus. Damage is most frequently caused by the root feeding larval stage. Populations as low as one larva plant can kill sensitive species such as Cyclamen. Severe damage by the leaf feeding adults is less common, although low levels of damage or contamination by adults may be unacceptable in certain situations. There is one generation a year. Oviposition by the flightless parthenogenetic females occurs over the summer months with oviposition rates of c. 500 and 1200 eggs adult‐1for outdoor and laboratory populations, respectively. O. sulcatus mainly overwinters as larvae, although significant numbers of adults may survive in areas where winter temperatures are not too severe.

A number of natural enemies, such as hedgehogs, frogs and predatory beetles, help to maintain O. sulcatus populations at a low level in natural environments, but they are less successful in intensive horticultural systems where persistent chemicals have been heavily relied on to maintain the population below the economic threshold level. Increasing environmental concern is now forcing growers to consider new pest control strategies. Controlled release formulations of non‐persistent products, such as fonofos and chlorpyrifos, have shown potential as control agents for O. sulcatus larvae. Biological control agents, such as insect parasitic nematodes, have been developed commercially and new microbial control agents are in the process of development. Most of the new control products are directed towards control of O. sulcatus larvae. Adult vine weevils are nocturnal and a much more difficult target for the new control agents. It is likely that an integrated approach to pest control will be required to maintain O. sulcatus populations below their economic threshold level.
Feeding behaviour of Aphis craccivora (Koch) on cowpea cultivars with different levels of aphid resistance
Authors: MESFIN T. , THOTTAPPILLY G. , SINGH S. R.
Published: February 2008

The feeding activity of Aphis craccivora (Koch) was monitored on cowpea plants of aphid‐susceptible (Vita 7) and aphid‐resistant (TVu 801) cultivars, using an AC electronic feeding monitoring system. Waveforms corresponding to salivation, phloem ingestion and non‐phloem ingestion were observed. Aphids probing on the resistant cultivar showed a significantly reduced ingestion of phloem sap compared with those aphids which fed on the susceptible cultivar. The insect also made more brief and repeated probes on TVu 801. In addition, the duration of non‐probing activities and non‐phloem ingestion was shorter on the susceptible than on the resistant cultivar.
The use of metabolic profiling in the identification of gall mite (Cecidophyopsis ribis Westw.)‐resistant blackcurrant (Ribes nigrum L.) genotypes
Authors: BRENNAN R. M. , ROBERTSON G. W. , McNICOL J. W. , FYFFE L. , HALL J. E.
Published: February 2008

The terpenoid fractions of bud extracts from blackcurrant genotypes showing resistance or susceptibility to gall mite (Cecidophyopsis ribis) infestation were examined and compared using gas chromatography. By the use of discriminant analysis, and the application of the derived discriminator to the data, resistance status was correctly predicted in 88% of the genotypes sampled. The use of metabolic profiling provides a useful alternative to lengthy field assessments.
Comparative effects of Steinernema feltiae (Nematoda: Steinernematidae) and insecticides on yield and cropping of the mushroom Agaricus bisporus
Authors: GREWAL P. S. , RICHARDSON P. N. , COLLINS G. , EDMONDSON R. N.
Published: February 2008

In a mushroom crop (Agaricus bisporus) affected by a very low level of sciarid fly (Lycoriella auripila) infestation, the effects of an indigenous isolate of insect‐parasitic nematode (Steinernema feltiae) and of two commonly used insecticides (diazinon and diflubenzuron) were studied. When compared with untreated plots, nematodes applied to the casing had no adverse effects on mushroom yields whereas insecticides decreased yields. At a rate of 3 × 106 infective juveniles per tray (surface area = 0.56 m2), S. feltiae elicited increases of 28.5% and 19% in the mean total numbers and weights of mushrooms respectively. Treatment only with diflubenzuron resulted in 14.6% and 6% reductions in mean total numbers and weights of mushrooms, respectively; treatment with both diazinon and diflubenzuron caused 18.5% and 9.4% losses.

Application of nematodes generally reduced the mean weight per mushroom whereas insecticides increased it; nematodes delayed the onset of mushroom production (first flush) whereas diflubenzuron delayed the third and fourth flushes. Nematode contamination of sporophores was minimal when S. feltiae was applied at casing. Although their numbers declined with time, the nematodes persisted, in the casing layer, throughout the cropping period of seven weeks. It is concluded that yield benefits associated with nematode application can result mainly from nematode effects on A. bisporus and not solely from suppression of a damaging pest population.
The role of refuge areas in the phenology of Rhopalosiphum padi in low rainfall cropping areas of South Australia
Authors: BARRO PAUL J. DE. , MAELZER DEREK A. , WALLWORK HUGH
Published: February 2008

Extensive surveys of possible aphid habitats in South Australia indicated that irrigated perennial grass pastures in the Mount Lofty Ranges and Lower Murray Valley were summer refuges for Rhopalosiphum padi (L.) (Hemiptera: Aphididae). Large numbers of aphids build up in these pastures each year during autumn (April and May) with numbers peaking in May. The size of the May peak was related to the number of aphids surviving the summer. The proportions of alates were highest in May and August/September. Both peaks coincided with a photoperiod of between 11.2 and 11.5 h, and partial correlations suggested that aphid density, photoperiod and temperature were all significant determinants of alate production.
Low‐temperature scanning electron microscopy of hyphal colonisation of Chenopodium quinoa during fermentation with Rhizopus oligosporus
Authors: PENALOZA W. , HEDGER J. N. , THOMAS B. J.
Published: February 2008

In a study of tempe made by fermenting quinoa (Chenopodium quinoa Willd.) with Rhizopus oligosporus Saito, the interaction between the substrate and the fungus varied according to the raw material used. Low‐temperature scanning electron microscopy confirmed that hyphal infiltration in quinoa was normally limited by the seed coat, but a massive penetration was found in fragments of quinoa where the testa was broken. This finding has implications for the texture and quality of tempe fermentation of grains and pulses.
Inheritance of antagonistic properties and lytic enzyme activities in sexual crosses of Talaromyces flavus
Authors: MADI LEA , KATAN TALMA , HENIS YIGAL
Published: February 2008

Two wild‐type strains and three benomyl‐resistant mutants of the antagonistic ascomycete Talaromyces flavus were crossed in six combinations, two of which yielded hybrid cleistothecia. Parental strains and their ascospore progenies varied in several traits considered to play an important role in the capacity to control soilborne fungal pathogens: extracellular activities of glucose oxidase and cell‐wall degrading enzymes, antibiosis towards Verticillium dahliae, and parasitism and biocontrol of Sclerotium rolfsii. A non‐Mendelian quantitative mode of inheritance was found for β‐1, 3‐glucanase and chitinase activities but only the latter exhibited a normal frequency distribution. Some of the progenies exhibited higher glucanase and chitinase activities than those found in the parental strains. Progeny analysis for chitinase, glucanase, cellulase, and glucose oxidase activities revealed no genetic association between any two of these enzymes. Antibiosis was correlated with glucose‐oxidase activity in one cross, but not in the other. The ability to reduce bean root rot caused by S. rolfsii was correlated with mycoparasitic activity against S. rolfsii sclerotia in one cross, but not in the other. One out of the 20 progenies tested was able to reduce bean root rot more effectively than its parent strains, thus demonstrating the feasibility of improving a biocontrol agent by conventional breeding.
The distribution and spread of hop latent viroid within two commercial plantings of hop (Humulus lupulus)
Authors: ADAMS A. N. , MORTON A. , BARBARA D. J. , RIDOUT M. S.
Published: February 2008

The distribution and spread of hop latent viroid (HLVd) in two adjacent plantings of the hop cultivars Omega and Wye Challenger have been studied for three seasons. The planting of cv. Omega was heavily infected at the start of the survey and spread was rapid; the density of infection was lower in the planting of cv. Wye Challenger and spread was much slower. It is not known whether the difference in rate of spread was a varietal effect or because of the higher density of infection in the Omega planting. The distribution of known infections in 1991 suggests that plant‐to‐adjacent‐plant spread, either by contact or on tools, does occur. However, the overall distribution of infection and the occurrence of new infections not adjacent to existing ones, suggests that this is not the only means of transmission; whether a vector is involved is not known.
The association between species of Trichodorus and Paratrichodorus vector nematodes and serotypes of tobacco rattle tobravirus
Authors: PLOEG ANTOON T. , BROWN DEREK J. F. , ROBINSON DAVID J.
Published: February 2008

Virus transmission bait tests with single trichodorid nematodes from England, the Netherlands, Scotland or Sweden showed that a substantial degree of specificity occurs between trichodorid vector species and tobravirus serotypes. This specificity was more apparent with associations between Paratrichodorus vector species and tobravirus serotypes than with those between Trichodorus species and tobravirus serotypes. P. pachydermus transmitted PRN‐serotype tobacco rattle virus (TRV) isolates, P. teres ORE‐serotype isolates and P. anemones TRV isolates which did not react with any of the antisera used, but which could be distinguished from all other isolates by their symptomatology in Chenopodium test plants. T. viruliferus, T. primitivus and T. cylindricus transmitted RQ‐serotype isolates and the latter species also transmitted TRV isolates reacting with TCB2 and pea early‐browning SP5‐antisera. Several TRV isolates transmitted by T. cylindricus failed to react with any of the antisera used.
Responses of some Asian and European barley cultivars to UK and Chinese isolates of soil‐borne barley mosaic viruses
Authors: JIANPING CHEN , ADAMS M. J. , FENGTAI ZHU , CEN SHI , HE CHEN
Published: February 2008

In field plots at Yancheng, Jiangsu, China, a range of European and Asian barley cultivars was grown in soil from three sites in China infested with barley yellow mosaic virus (BaYMV). Most of the cultivars resistant to the common European strain of BaYMV were susceptible to the Chinese isolates but cv. Energy remained disease‐free. Barley mild mosaic virus (BaMMV) was also detected in one of these soils but affected only one Chinese cultivar and not those susceptible to BaMMV in Europe. This is the first report of BaMMV in China.

Inoculation experiments confirmed the different cultivar response to UK and Chinese isolates of BaYMV and showed that resistance was to the virus and not to the vector. A range of Chinese cultivars selected for resistance to BaYMV were also resistant to a UK isolate of BaMMV.
Weeds as hosts of Mycocentrospora acerina
Authors: HERMANSEN ARNE
Published: February 2008

Weeds were collected from carrot fields and some other sites at 27 localities in seven counties in Norway during August and September of 1986 and 1987. Leaf and petiole lesions were microscopically examined for Mycocentrospora acerina. Viola arvensis and Viola tricolor were commonly observed with the pathogen. The fungus was also registered on Fumaria officinalis, Galium aparine, Matricaria inodora, Matricaria matricarioides, Ranunculus repens, Senecio vulgaris and Stachys palustris. In inoculation experiments in the greenhouse, M. acerina infected carrot leaves and 13 of 16 species of weeds. The symptoms on the various susceptible plants showed some variation, but were essentially of the same pattern. The investigation indicates that weeds are common hosts of M. acerina. A list of 23 host weed species is given.
The influence of pre‐floral growth and development on the pathway of floral development, dry matter distribution and seed yield in oilseed rape (Brassica napus L.)
Authors: TOMMEY ANDREW M. , EVANS ERIC J.
Published: February 2008

Patterns of floral development, dry matter distribution and seed yield were examined in winter oilseed rape plants subjected to different pre‐floral growth environments. The duration of pre‐floral growth and plant size at flower initiation, measured in terms of total mainstem leaf number, were manipulated by varying the temperature between seedling emergence and flower initiation.

Exposure of seedlings to low temperatures from cotyledon expansion onwards markedly reduced the duration of pre‐floral growth and the number of leaves on the mainstem. The subsequent development pattern of plants was largely dependent on the date of flower initiation and therefore vernalisation requirement. Indeed, the period of growth from flower initiation to maturity, considered on the basis of thermal time, was directly related to the duration of pre‐floral growth and mainstem leaf number. The thermal durations of the bud development phase and flowering period in plants exposed to different pre‐floral cold treatments but with a common date of flower initiation were similarly linked to these two parameters.

Plants exposed to prolonged periods of low temperature treatment from cotyledon expansion onwards initiated fewer mainstem leaves during a relatively short pre‐floral growth phase and their yield potential was limited by a reduction in branch and flower numbers. Plants maintained at higher temperatures produced more mainstem leaves during an extended period of pre‐floral growth and supported a greater number of branches and flowers. However, this additional yield potential was not realised due to a reduction in seed numbers and mean seed weight. It appeared that seed yield of these plants was limited by increased competition between an excessive number of lower branches and flowers, a problem apparently created by excessive pre‐floral growth. Minimal competition for available assimilates between the limited number of branches of plants with a shorter pre‐floral growth phase and fewer mainstem leaves, resulted in lower levels of pod abortion, greater seed production and ultimately increased seed yields.
Host‐specificity of Uromyces heliotropii, a fungal agent for the biological control of common heliotrope (Heliotropium europaeum) in Australia
Authors: HASAN S. , DELFOSSE E. S. , ARACIL E. , LEWIS R. C.
Published: February 2008

Common heliotrope, Heliotropium europaeum (Boraginaceae), a summer annual, is a serious weed of pastures in Australia causing poisoning in sheep and other grazing animals. The weed is native to Mediterranean and Middle Eastern regions of Eurasia where it is attacked by several arthropods and pathogens including the rust fungus Uromyces heliotropii. The host‐specificity of a virulent and effective strain of the rust from Turkey has been tested by inoculating 96 plants of importance to the Australasian region using both microscopic and macroscopic observations of the reaction of host and non‐host plants. The test plants included several members of the Boraginaceae and related families as well as species of Heliotropium native to Australia. The infection was mostly limited to European species of Heliotropium. U. heliotropii was thus found to represent a safe introduction and has recently been introduced to Australia for the biological control of common heliotrope.
A large improved rotary trap for sampling aerial invertebrates
Authors: TOPPING C. J. , SUNDERLAND K. D. , BEWSEY J.
Published: February 2008

A large rotary trap designed to measure aerial spider density is described. A comparison of the rotary trap catch and a suction trap catch of spiders and other invertebrate groups showed that the rotary trap was operating at a greater efficiency for most groups. For spiders and non‐staphylinid beetles the two traps caught equal numbers. There were no differences in the species composition of spiders between the rotary and suction trap catch.
A technique for assessing damage to roots of white clover caused by root feeding insects
Authors: MURRAY P. J. , CLEMENTS R. O.
Published: February 2008

A nutrient, slant‐board technique was developed in order to estimate the losses to roots of white clover (Trifolium repens L.), caused by the feeding of the larvae of Sitona weevils. In this preliminary experiment losses of up to 50% of root length were found. This simple technique was straightforward to use and has the potential for applications in a large range of root‐pest/feeding studies.
Effects of temperature, feeding position and crop growth stage on the population dynamics of the rose grain aphid, Metopolophium dirhodum (Hemiptera: Aphididae)
Authors: ZHOU X. , CARTER N.
Published: February 2008

The population dynamics of Metopolophium dirhodum were studied on winter wheat seedlings at constant (10°C, 15°C, 20°C, 25°C and 30°C) and fluctuating (12(night)‐22(day)°C) temperatures, and during booting to early inflorescence, and anthesis to early milky ripe stage, at 19°C. The pre‐reproductive development time was decreased by increasing the temperature from 10°C to 25°C. It was significantly shorter when the aphids were feeding during booting to early inflorescence than during anthesis to early milky ripe stage but was similar when the aphids were feeding on the flag, second or third leaves. The total number of nymphs produced/apterous adult was not significantly affected by temperature from 10°C to 25°C but adult reproductive lifespan was reduced by increasing temperature from 10°C and 12–22°C to 15°C, 20°C and 25°C. The daily intrinsic rate of increase changed from 0.11 to 0.25, and the cohort generation time decreased from 31 to 12 days, with increase of temperature from 10°C to 25°C. Reproductive rate was similar when the aphids were feeding on the flag, second or third leaves during booting to early inflorescence at 19°C. The reproductive rate was higher when the aphids fed from mid‐inflorescence to mid‐milky ripe stage than from mid‐milky to early ripe stage. These results were compared with those from other studies. Predictions from a simulation model using development and reproductive rates from this study and literature were compared and the former rates resulted in a more accurate prediction of field observations in 1979, an outbreak year.
Seasonal changes in primary and secondary inoculum during epidemics of leaf blotch (Rhynchosporium secalis) on winter barley
Authors: DAVIS HELENA , FITT B. D. L.
Published: February 2008

Seasonal changes in numbers of conidia of Rhynchosporium secalis on debris from previous barley crops infected with leaf blotch (primary inoculum) were monitored in 1985–86 and 1986–87. In 1986–87, changes in numbers of conidia on leaves of plants in the new winter barley crop (secondary inoculum) were also recorded. The greatest increases in production of primary inoculum were in early spring after rain, when temperatures were increasing after periods of sub‐zero temperatures when there was little conidial production. Subsequently, more conidia were recovered from this debris after cycles of drying and rewetting than when it remained wet. After January 1987, amounts of secondary inoculum produced on the crop were much greater than amounts of primary inoculum on debris. Most spores were produced on the basal leaves and more spores were present on the September‐sown than on the November‐sown crop. Thus, while primary inoculum was a source of disease when plants were emerging, secondary inoculum on basal leaves was the main source of disease at stem extension, especially on early‐sown crops.
Improvements in the detection of pea seed‐borne mosaic virus by ELISA
Authors: DING X. S. , COCKBAIN A. J. , GOVIER D. A.
Published: February 2008

The detection by ELISA of pea seed‐borne mosaic virus (PSbMV) in pea leaves and seeds was improved by the addition of cellulase or Triton X‐100 to the extraction fluid, probably because the additives aided the release of virus particles from host materials. With leaf extracts the additives were most effective at 0.1%. In initial tests cellulase was used with macerozyme, but the latter enzyme was then shown to decrease the effectiveness of cellulase. Triton X‐100 was as effective as cellulase and the absorbance values obtained in ELISA of infected leaf extracts, diluted to 1/10 in extraction fluid containing the additive, were about six times greater than those of infected extracts diluted in normal extraction fluid. Five named isolates of PSbMV, in addition to the homologous isolate, were readily detected in infected leaves extracted in fluid containing Triton X‐100.

In tests on seeds and seedlings of seven infected seed lots of pea cv. Waverex, using Triton X‐100 in the extraction fluid, PSbMV was detected in five times as many seeds as seedlings, probably mainly because in many infected seeds the virus was in the testa and not in the embryo. About 9% of infected seedlings were without recognisable symptoms 4 wk after emergence.
A study of the mode of transmission of maize streak virus by Cicadulina mbila using an enzyme‐linked immunosorbent assay
Authors: REYNAUD B. , PETERSCHMITT M.
Published: February 2008

Two batches of Cicadulina mbila were given two distinct acquisition access periods (AAP) (3 h and 50 h) on maize plants infected with maize streak virus (MSV). Infectivity assays on susceptible maize were carried out 1, 3, 10, 17, 26 and 35 days after the AAP. Transmission efficiency was significantly higher for C. mbila subjected to the 50‐h AAP. At the same time as the infectivity assays, the amount of MSV in each leafhopper was determined by an indirect double antibody sandwich (IDAS) ELISA. There were more ELISA‐positive insects after the 50‐h AAP than after the 3‐h AAP. In the group given a 3‐h AAP, only 7% of the insects tested between day 1 and 35 were found to be positive by ELISA. In contrast, after the 50‐h AAP, the majority of C. mbila were positive, yet a decrease in ELISA‐positive insects was noticed from day 17 onwards. Using a calibration curve obtained with purified virus, as little as 0.15 ng of MSV per insect could be measured by the IDAS‐ELISA. A mean value of 0.36 ng of MSV per C. mbila was found 3 days after the 50–h acquisition, whereas 14 days later there was only 0.20 ng of virus per insect. For comparison, when leafhoppers were kept on infected maize, they displayed substantial accumulation of MSV up to an average of 3.83 ng of MSV per insect after 35 days of continuous acquisition. The amount of virus per insect detected in females was usually greater than the amount detected in males. Our results suggest that MSV does not multiply in C. mbila and contribute to the understanding of the persistence of transmission efficiency in the absence of virus multiplication.
Cloned DNA probes for detection of grapevine Flavescence dorée mycoplasma‐like organism (MLO)
Authors: DAIRE X. , BOUDON‐PADIEU E. , BERVILLE A. , SCHNEIDER B. , CAUDWELL A.
Published: February 2008

Flavescence dorée (FD), a yellows disease of grapevine is caused by a non cultivable mycoplasma‐like organism (MLO) transmitted in vineyards by the leafhopper vector Scaphoideus titanus. In the laboratory, FD is transmitted from broadbean to broadbean by the leafhopper Euscelidius variegatus. Total DNA from FD‐diseased broadbean was centrifuged in a bisbenzimide‐CsCl density gradient. Low density DNA was collected from the gradient, digested with HindIII, ligated into plasmid pUC18 and cloned in Escherichia coli. Trans‐formants were differentially screened by colony hybridisation with 32P‐iabelled healthy and FD‐infected leafhopper DNA as probes. The selected clones were shown to carry inserts which all hybridised with FD‐diseased host DNA and not with DNA from healthy host. These 32P‐labelled inserts, used as probes in dot blot hybridisation, enabled detection of FD‐MLO in field‐collected samples of grapevine. However, because of the low MLO titre in this plant, an MLO enrichment procedure using tissue from main leaf veins was necessary to ensure efficient DNA extraction.
Broad bean wrinkly seed caused by artichoke yellow ringspot nepovirus
Authors: AVGELIS A. D. , KATIS N. , GRAMMATIKAKI G.
Published: February 2008

Artichoke yellow ringspot nepovirus (AYRV) was isolated from stunted broad bean plants in Crete showing leaf mottling and deformation and wrinkling of seed testas. AYRV identification was based on host range, behaviour during purification, electron microscopy and serology.

AYRV‐broad bean isolate was seed‐transmitted in broad bean, and embryo infection appeared to be a prerequisite for virus transmission to seedlings. Transmission through pollen was not detected in broad bean plants, although pollen grains were externally contaminated by the virus. Ovule infection occurred in a high proportion of seed and was independent of pollination.
Monoclonal antibodies to beet soil‐borne virus
Authors: BARBAROSSA L. , VETTEN H. J. , KAUFMANN A. , LESEMANN D.‐E. , KOENIG R.
Published: February 2008

Four monoclonal antibodies (MCA) were obtained to the ‘Ahlum’ serotype of beet soil‐borne virus (BSBV). On ELISA plates which had been precoated with polyclonal antibodies (PCA) all four MCA detected this serotype with a higher sensitivity than alkaline phosphatase‐labelled PCA. Three of the MCA were specific for the ‘Ahlum’ serotype, but a fourth one also detected the distantly related ‘Wierthe’ serotype. Cross‐reactions with wheat soil‐borne or oat golden stripe furoviruses were not observed. One of the MCA reacted with an epitope which is exposed along the entire length of the BSBV particles, whereas two others were specific for epitopes which are exposed on one particle extremity only. Although these latter two epitopes occur apparently on the same extremity of the particles, they seem to be different, because one is found only on the particles of the ‘Ahlum’ serotype, whereas the other one is present also on the particles of the ‘Wierthe’ serotype. The fourth MCA is specific for a cryptotope which is not exposed on the intact virus particles, but presumably on some degradation product or precursor of the viral coat protein present in crude sap preparations. All four epitopes are SDS‐labile; they are not detected on denatured viral coat protein on Western blots.
Influence of nematicide, resistant and susceptible potato cultivars and bare fallow on the population dynamics of Globodera rostochiensis Woll. Rol under field conditions in Spain
Authors: SALAZAR A. , RITTER E.
Published: February 2008

The susceptible potato cultivar Désirée and the resistant cv. Diamant were cultivated on untreated and nematicide‐treated plots on two fields in northern Spain infested with Globodera rostochiensis Rol. Initial and final infestations of cysts and viable eggs were assessed. Multiplication rates differentiated more accurately the effects of the different treatments than final number of cysts and eggs, due to the elimination of some of the errors associated with variability of the initial infestation. Many new cysts were observed on all plots where susceptible potatoes had been grown, whether they had been treated with nematicide or not, although significantly fewer cysts were actually found on the nematicide‐treated plots. With the resistant cultivar no significant effects of the nematicide were detected even though there was a noticeable reduction of viable cyst contents over and above the effect of the resistant cultivar.
Control of potato cyst nematode (Globodera pallida) by host plant resistance and nematicide
Authors: GURR G. M.
Published: February 2008

Seven trials conducted over four years on sites naturally infested with the white potato cyst nematode established that potato clones bred for resistance to Globodera pallida allowed significantly less nematode multiplication than conventional cultivars under field conditions. Nematode multiplication was inversely related to initial infestation level. The nematicide, aldicarb, significantly reduced nematode multiplication. However, nematode multiplication on nematicide treated susceptible cultivars was greater than on untreated partially resistant clones, indicating that resistance may offer more effective control of G. pallida than chemical treatment. Integration of host plant resistance and nematicide treatment is discussed.
Apple replant disease: the assessment and results of seedling bio‐assays of growth responses to soil fumigation with chloropicrin
Authors: SEWELL G. W. F. , ROBERTS A. L. , ELSEY R. F.
Published: February 2008

The effects of chloropicrin fumigation of field soils before replanting apple are frequently predicted from bio‐assays using pot‐grown apple seedlings. The results of 506 such bio‐assays carried out during 12 years are discussed with reference to modifications which were made to the test method. The interpretation of the most recent and valid bio‐assay results is considered in relation to the different purposes for which such tests may be conducted.

When all test soils were amended with phosphorus (to compensate for the eradication of vesicular‐arbuscular mycorrhizal fungi by fumigation) the proportion of old orchard soils yielding economically significant growth responses increased from 39% to 68%. When, additionally, plant growth was assessed by shoot fresh weight (rather than shoot length) the proportion further increased to 82%.

The traditional method of expressing growth responses to soil sterilisation, as proportionate growth increases, was found to be subject to skewing effects of non‐biological fertility factors; this feature was avoided when results were given as actual growth increases. The latter value therefore is considered preferable when assessing the relative disease status of soils for etiological purposes (as opposed to predicting the cost‐benefits of field soil treatment).

The data indicated that disease severity was on average diminished in the most acidic soils (pH 4.8–6.1), but did not support the generalisation that disease severity increases progressively with soil pH.
Comparative epitope profiles of the particle proteins of whitefly‐transmitted geminiviruses from nine crop legumes in India
Authors: SWANSON M. M. , VARMA A. , MUNIYAPPA V. , HARRISON B. D.
Published: February 2008

Geminiviruses associated with yellow or golden mosaic diseases of legume crops in two regions of India were compared by testing their reactivity with 27 monoclonal antibodies (MAbs) prepared to the particles of African cassava mosaic (ACMV) or Indian cassava mosaic (ICMV) viruses. The viruses fell into two main groups. Group 1 comprised isolates of dolichos yellow mosaic virus; these reacted with three or four ACMV MAbs and four ICMV MAbs. Group 2 comprised isolates of horsegram yellow mosaic virus, together with isolates from blackgram, cowpea, French bean, pigeonpea, soybean, Indigofera hirsuta and probably also isolates from mungbean. These reacted with three or four ACMV MAbs but with few or no ICMV MAbs. Isolates within each group differed slightly in epitope profile, depending on the source species (Group 2) or geographical origin (Groups 1 and 2). Isolates from lima bean resembled those in Group 2 but had some antigenic differences, and their status is uncertain. The poor detectability of geminivirus isolates in mungbean may reflect a low virus concentration in this species.
The restricted distribution of potato leafroll luteovirus antigen in potato plants with transgenic resistance resembles that in clones with one type of host genemediated resistance
Authors: DERRICK PETER M. , BARKER HUGH
Published: February 2008

The distribution of virus‐infected cells was examined, by fluorescence microscopy, within plants of a range of potato clones infected with potato leafroll luteovirus (PLRV). This range included nine PLRV‐resistant clones, of which four were transgenic lines carrying the PLRV coat protein gene and five were conventionally bred. Plants of these clones were resistant to PLRV multiplication and accumulated less virus antigen in leaf tissue than did susceptible clones. Indirect fluorescent antibody staining of thin sections from carbodiimide‐fixed petiole tissue revealed that in plants of PLRV‐susceptible clones, virus‐infected cells were abundant within both external (abaxial) and internal (adaxial) phloem bundles. In plants of the PLRV‐resistant conventionally bred clones and in resistant transgenic lines of cv. Pentland Squire, virus‐infected cells were much fewer in number and largely restricted to internal phloem bundles. In resistant transgenic lines of cv. Désirée, this restricted distribution of PLRV antigen was only detected in petioles of young leaves. The results suggest that the transgenic and a host‐mediated type of resistance that restricts virtis multiplication have underlying similarities.
Emergence of juvenile potato cyst‐nematodes Globodera rostochiensis and G. pallida and the control of G. pallida
Authors: WHITEHEAD A. G.
Published: February 2008

Speed of emergence of juveniles from cysts in potato root diffusate (PRD) in vitro differed between Globodera rostochiensis and G. pallida and between populations within each species. Early emergence in vitro was slower in most populations of G. pallida than in most populations of G. rostochiensis. Fewer G. rostochiensis juveniles emerged from 4 or 6 month old than from 4 yr old cysts.

More G. rostochiensis emerged in solutions of sodium metavanadate at concentrations of 10‐2 and 10‐3 M than in PRD and as many G. pallida emerged in the same solutions as in PRD. In plots of bare fallowed sandy loam, emergence of G. pallida was stimulated by 10‐‐3 M sodium metavanadate. The emergence of two populations of C. pallida in PRD was stimulated by the addition of benomyl at 0.1 ppm (3.4 × 10‐‐7 m). In microplots, cv. Cara potatoes grown for 8 wk decreased four populations of G. pallida by up to 93%. During a 4 wk period in PRD, more than 20 juveniles per gravid female emerged from five of 25 populations of G. pallida. In root observation boxes in which cv. Désirée was grown, oxamyl applied to the top 15 cm of a peaty loam soil greatly increased G. pallida in soil 1545 cm deep. In another peaty loam, but not in a sandy loam, the same treatment appeared to increase the nematode in soil 15–30 cm deep. Oxamyl incorporated in the uninfested top 15 cm of all three soils largely prevented nematode increase from juveniles migrating upwards from untreated heavily infested soil 15–30 cm deep.

These experiments suggest that inadequate control of G. pallida increase on susceptible potatoes by an oximecarbamate nematicide of short persistence, such as oxamyl, is primarily due to the slow rate of juvenile emergence in most populations of G. pallida, with a second generation and the upward migration of juveniles from deeper untreated soil later in the growing season as potential contributory factors.
The influence of temperature on leaf development and growth in potatoes in controlled environments
Authors: KIRK W. W. , MARSHALL B.
Published: February 2008

Three controlled environment experiments were conducted at different temperatures to determine the relation between temperature and leaf development and growth in the potato (cv. Maris Piper). Developmental stages are defined for the appearance and duration of leaf extension in the potato and comparisons made with other temperate zone crops.

The rate of leaf appearance was linear over the temperature range (9–25°C) and above 25°C there was no further increase in the rate. The temperature coefficient for the rate of appearance of leaves was 0.032 leaves (degree days)‐1 using a base temperature of 0°C. The duration of extension of an individual leaf decreased with increase in temperature up to 25°C such that the thermal duration was constant at 170 degree days using a base temperature of 0°C for leaf positions 4–10 on the main stem. At higher leaf positions the thermal duration was similar or greater. The advantages and limitations of controlled environment work as a parallel to field experimentation are discussed.
The prediction of leaf canopy expansion in the leek from a simple model dependent on primordial development
Authors: HAY R. K. M. , KEMP D. R.
Published: February 2008

In an analysis of leaf development of leek plants grown in the field in 1988, successive leaves initiated, appeared (tip and ligule) and senesced at equal intervals of accumulated temperature/thermal time. These intervals corresponded to a plastochron of 92°C days and phyllochrons of 135 (tip) and 233 (ligule) °C days. The rate of appearance of ligules was exactly equal to the rate of leaf senescence, with the result that the number of fully‐expanded leaves per plant remained constant at 1.4. These data, which were compatible with results from previous seasons, were used to develop a model of the interrelationships between primordium initiation at the shoot apex and subsequent events in the development of individual leaves. Primordium initiation is considered to be the primary controlling event in the life of a leaf, and the processes of tip appearance, ligule appearance and death can be predicted from knowledge of the number of primordia which have been initiated, without reference to the environment. A model of canopy expansion, based on the central role of the shoot apex, was developed using the temperature relations of primordium initiation and additional data on leaf expansion and leaf dimensions. Leaf area indices computed in this way provided a satisfactory simulation of the thermal‐time course of leaf area index observed in a previous season, 1985.
The effect of micronutrient supply on the growth and seed production of guayule (Parthenium argentatum Gray)
Authors: BECKETT R. P. , van STADEN J. , ALLEN SHIRLEY
Published: February 2008

The effect of micronutrient supply on the growth and seed production of guayule (Parthenium argentatum Gray) was investigated. A deficiency of boron, but no other trace element, significantly reduced the growth, seed production and the percentage of seeds that germinated. The optimum concentration of B for seed production was between 20 and 100 μM. Results indicate that guayule may benefit from B fertilisation.
The effect of starvation on size and survival of the terrestrial planarian Artioposthia triangulata (Dendy) (Tricladida: Terricola)
Authors: BLACKSHAW R. P.
Published: February 2008

Ten Artioposthia triangulata were kept without food at 5°C, 10°C, 15°C, 20°C and 23°C. Survival and weights were recorded weekly. All planarians died within one week at 23°C and within three weeks at 20°C. One individual survived for 60 wk at 5°C. A negative exponential equation was fitted to average survival times for planarians kept at 5°C, 10°C, 15°C and 20°C. Negative exponential models could also describe the pattern of degrowth by planarians deprived of food. The results are discussed in relation to possible survival of the planarian outdoors in Northern Ireland and the implications for earthworm populations.
Differentiation between larvae of Tipula paludosa and Tipula oleracea (Diptera: Tipulidae) using isoelectric focusing, and their occurrence in grassland in northern Britain
Authors: HUMPHREYS I. C. , BLACKSHAW R. P. , STEWART R. M. , COLL C.
Published: February 2008

Thin layer agarose isoelectric focusing (IEF) was used to separate proteins from the larvae of Tipula oleracea Linnaeus and Tipula paludosa Meigen (Diptera, Nematocera). Silver staining revealed protein banding patterns which consistently distinguished these two species at any stage in their life cycles. Within the pH range 5–6 Tipula paludosa contained one major protein band and T. oleracea two bands, with the pI value of the T. paludosa protein being slightly higher than those of T. oleracea. The IEF method is particularly useful for the larval stages of these species because they are often visually inseparable. Leather jackets obtained during a survey of Northern Ireland and north‐eastern and western Scotland were tested to determine the distribution and frequency of these species occurring in grassland. In each area surveyed T. paludosa predominated with only one field in Northern Ireland and north‐eastern Scotland found to contain T. oleracea. In western Scotland T. oleracea occurred in five fields each year of the survey, and was locally abundant on the Isle of Bute in the 1990/91 survey making up 15% of the total larvae tested.