bluuebunny/crossref_metadata_2025 huggingface dataset:
The dispersal and distribution of polyphagous predatory Coleoptera in cereals
Authors: COOMBES DAVID S. , SOTHERTONS NICOLAS W.
Published: February 2008

Observations were made on the phenology of the dispersal of polyphagous arthropod predators from their overwintering habitats in field boundaries into adjacent farmland in cereal fields in southern England from 1981 to 1984. Agonum dorsale, Bembidion lampros and Demetrias atricapillus dispersed from overwintering habitats into adjacent cereal crops by crawling. B. lampros was fully dispersed by early May and the other two species by late May. Tachyporus spp. were thought to disperse mainly by flight, T. hypnorum being fully dispersed by mid‐May and T. chrysomelinus by late May. A small proportion of A. dorsale marked in field boundaries in April before dispersal began were later recaptured up to 200 m into adjacent crops later in the season.

Areas of a crop, immediately adjacent to field boundaries in which high numbers of predators had overwintered, were found to have significantly (P<0.01) higher numbers of predators that disperse by walking (A. dorsale, B. lampros and D. atricapillus) moving through them towards the centres of fields. By mid‐summer, the mid‐crop density of D. atricapillus was correlated with its overwintering density in surrounding field boundaries the previous winter, but this was not so in the other species. Mid‐crop, mid‐summer densities of A. dorsale were significantly (P<0. 02) correlated with mean percentage weed cover in fields. The densities of the other species were not correlated with weed cover.

Analysis of data collected over a 10‐yr period on a Sussex study area in late June revealed that significantly more D. atricapillus were found in fields surrounded by hedgerows than fields surrounded by fence‐post and wire boundaries.
Diversity within two serogroups ofRhizobium leguminosammnative to soils in the Palouse of eastern Washington*
Authors: TURCO R. F. , BEZDICEK D. F.
Published: February 2008

The effect of plant genotype, soil temperature, and moisture on recovery ofRhizobium leguminosammserogroups WA01 and WA02 from soil, was evaluated in the greenhouse using three plant genotypes (Pisum sativumcv. Alaska,Pisum sativumcv. Paloma andLens culinariscv. Rechief), three temperatures (12, 20 and 24°C) and soil from two different slope positions. The impact of moisture was followed by assessing pea nodulation after incubation of soil at different preplanting moisture levels. Isolates were also evaluated for serogroup, response to low levels of antibiotics and efficacy of symbiotic characters.

Of the 33 antibiotic‐strain combinations showing growth, 10 permitted 50% or more of the isolates to grow. Of the 24 clusters obtained, all except one were dominated by isolates in either serogroup. WA01 or WA02. There was no relation between either serogroup or cluster groupings and N2fixation. Serogroup recovery was influenced by plant genotype and temperature. At root temperatures of 12 and 24°C, serogroup WA02 occurred in a significantly lower fraction of the lentil nodules as compared to the pea species. At 12°C, recovery of WA02 was higher for the Paloma than Alaska pea. Recovery of WA02 in pea nodules generally increased as the soil moisture was preconditioned to drier levels of ‐0.5 and ‐1.5 MPa water potential.
Epidemiology and control of virus diseases of vegetables
Authors: TOMLINSON J. A.
Published: February 2008

The diverse ecological and epidemiological factors which determine virus infection of vegetable crops are discussed. These include the sources and spread of viruses, together with some agricultural and horticultural practices which have influenced their prevalence. Control measures are described, demonstrating ways of avoiding or minimising infection. Developments are reported with insecticides, insect repellents, anti‐feedants, and fungicides for the control of virus vectors. Some of the successes and future requirements in breeding vegetable cultivars with virus resistance are listed.

An Appendix lists the economically most important vegetable virus diseases present in 28 countries or regions with temperate, Mediterranean‐like or subtropical climates. The five most important viruses in field‐grown vegetables are transmitted non‐persistently by aphids (cucumber mosaic, turnip mosaic, potato virus Y, lettuce mosaic and watermelon mosaic 1 (= papaya ringspot virus)). In contrast, with protectively‐grown vegetables, the most important are the mechanically‐transmitted tobamoviruses (tomato and tobacco mosaic, Capsicum mosaic and cucumber green mottle mosaic).
Apple replant disease: the influence of soil phosphorus and other factors on the growth responses of apple seedlings to soil fumigation with chloropicrin
Authors: SEWELL G. W. F. , PREECE D. A. , ELSEY R. F.
Published: February 2008

The effects of fumigating field soils before replanting apple are frequently predicted from bioassays where apple seedlings are grown in pots, some containing untreated soil and the others containing chloropicrin‐fumigated soil. The results from 418 such bioassays made during eight years are discussed with reference to the effects of certain physical and chemical soil features.

Soil phosphorus (P) content and pH had large effects on growth in fumigated (but not untreated) soils; they therefore had large effects on the growth response to soil fumigation. There were no indications of important effects due to soil content of potassium or magnesium or to soil texture.

In fumigated soils, the height of seedlings was generally greater, the greater the soil P content, but in untreated soils it was mostly independent of P (range 1 – 156 mg P litre‐1soil). The differing effects of native P on growth in untreated or fumigated soils were attributed respectively to the presence and absence of vesicular‐arbuscular mycorrhizas: their absence in fumigated soils was considered (for apple) to be an artefact in the seedling bioassay. The results for untreated soils indicated that the apple mycorrhizal system was very efficient in retrieving P when there was little available.

Growth responses to soil fumigation were usually greater in acidic than in alkaline soils for any given level of P. When soils were P‐amended before testing, the effects of native P and pH virtually disappeared and the proportion of orchard soils with economically significant growth responses increased from 39% to 67%.
Virus diseases of lupins
Authors: JONES R. A. C. , McLEAN G. D.
Published: February 2008

INTRODUCTION

APHID‐TRANSMITTED VIRUSES

Potyvirus group

Bean yellow mosaic virus

Clover yellow vein virus

Bean common mosaic virus

Peanut mottle virus

Bidens mottle virus

Cucumovirus group

Cucumber mosaic virus

Peanut stunt virus

Alfalfa mosaic virus

Fabavirus group: broad bean wilt virus

Pea enation mosaic virus

Luteovirus group: soybean dwarf virus

Rhabdovirus group: lettuce necrotic yellows virus

THRIPS‐TRANSMITTED VIRUSES

Tomato spotted wilt virus

NEMATODE‐TRANSMITTED VIRUSES

Tobravirus group: pea early browning virus

Nepovirus group: tomato black ring virus

VIRUS‐LIKE DISEASES

Lupin leaf curl ‘virus’

‘Lupin witches’ broom disease

CONTROL VII. CONCLUSIONS

CONCLUSIONS
Sporulation of Botrytis cinerea as affected by photoselective polyethylene sheets and filters
Authors: REUVENI R. , RAVIVM M. , BAR R.
Published: February 2008

Sporulation of Botrytis cinerea was studied in vitro under various filters and polyethylene co‐polymer (PE) sheets. It was found that continuous darkness blocked sporulation completely. Sporulation was inhibited by reduced ultraviolet (u.v.) radiation. Almost total inhibition of sporulation was also found when cultures were grown under a blue filter. The reduction of spore formation was negatively related to the ratio of transmitted blue/u.v. light. The possibility of using this effect to control the incidence of Botrytis cinerea in greenhouses is discussed. A brief report has been published (Reuveni, Raviv, Allingham & Bar, 1988).
Strain group specific and virus specific hypersensitive reactions to infection with potyviruses in potato cultivars
Authors: JONES R. A. C.
Published: February 2008

When 12 potato cultivars were inoculated with isolates (one each) of potato virus Y (PVY) ordinary (Yo), C (Yc) and tobacco veinal necrosis (Yn) strain groups, potato virus A (PVA) and potato virus V (PVV), none of them responded hypersensitively to Yn. However, with Yo, Yc, PVA and PW specific hypersensitive reactions developed depending on isolate‐cultivar combination which were all independent of each other. When field isolates of PVY thought to be Yoor Ycwere inoculated to the same 12 cultivars, two did not fit into either strain group giving hypersensitive reactions in only two cultivars instead of seven with Yoor eight with Yc. These two isolates may represent a previously unreported PVY strain group (Yz).

When Yowas graft‐inoculated to seedlings of the cross Desiree × Maris Piper (hypersensitive × non‐hypersensitive for Yo), the segregation ratio obtained for non‐hypersensitive:hypersensitive reactions was close to 1:1 suggesting that a single dominant gene (Nytbr) determining Yospecific hypersensitivity may be present in cv. Desiree (simplex condition). In tests using PVV and Desiree × Maris Piper (non‐hypersensitive × hypersensitive for PVV) seedlings, the segregation ratio obtained was close to 1:5 indicating that a single dominant gene (Nv) determining PVV specific hypersensitivity may be present in cv. Maris Piper (duplex condition).

Cultivars Corine, Pirola and clone G5457(4) which each carry one of the extreme resistance genes (Ry) from Solanum stoloniferum were graft‐inoculated with Yn, Yo, Yc, PVV and PVA. G5457(4) gave a strong localised hypersensitive reaction in all instances, while cv. Pirola did so with all except PVA to which it was immune. In cv. Corine a severe localised hypersensitive reaction developed with PVA, generalised hypersensitivity with PVV but an immune response with the three PVY strain groups. Large‐scale grafting of Ynto plants of cvs Corine and Pirola gave no evidence of selection of a strain which overcomes Ry genes.
The effect of cypermethrin on the feeding of mustard beetles Phaedon cochleariae (F.)
Authors: HAJJAR M. J. , FORD J. B.
Published: February 2008

Cypermethrin deposits on sprayed (3, 6, 9, 12 and 15 g ha‐1) radish leaves caused a significant antifeedant effect on third instar larvae and adults of mustard beetles.

There was a significant inverse relationship between feeding and dose for both stages. In the case of adults on deposits of 1, 3 and 6 g hafeeding was reduced by 60–75% but no mortality was recorded. Much less uniform feeding was associated with higher application rates (9, 12 and 15 g ha‐I) with low mortality at the two highest doses. The mean areas of the individual holes eaten by larvae or adults in either control or treated leaves, did not differ significantly. The number of holes eaten was negatively related to application rate. The antifeedant effect was observed with low concentration of both technical and formulated cypermethrin.
Slug foraging behaviour: Attraction to food items from a distance
Authors: HOWLING G. G.
Published: February 2008

Slug foraging paths recorded using time lapse video techniques under infra‐red light were fitted to a correlated random walk model. Analyses were carried out on slugs in arenas where no food was present, as well as those containing commercial molluscicides at two rates of application. Slugs were found to search randomly in empty arenas and those containing commercial metaldehyde baits, but deviated from random search patterns when in the presence of commercial methiocarb bait. Differential attraction from a distance is suggested as a cause of these differences.
Complementary video and acoustic recordings of foraging by two pest species of slugs on non‐toxic and molluscicidal baits
Authors: BAILEY STUART E. R. , WEDGWOOD MARILYN A.
Published: February 2008

The effects of adding the molluscicides methiocarb and metaldehyde to pelleted foods on the encounter, acceptance, feeding and post‐meal stages of the foraging sequence of the slugs Deroceras reticulatum and Arion distinctus have been studied using two complementary laboratory techniques ‐ video and acoustic recordings.

Whereas non‐feeding slugs encountered wheat grains at random, slugs which fed on wheat grains or pellets encountered them more frequently because of changes in locomotor pattern and olfactory attraction.

Slugs would almost always feed on the first pellet they found, regardless of the presence or absence of molluscicide: thereafter they fed on only one pellet in every four encountered. Far fewer slugs accepted wheat grains.

Slugs ate much less from pellets containing molluscicide, and meals were more irregular. The relative amounts of non‐toxic pellets of various types which were eaten gave no indication of the relative amounts eaten when molluscicide was added. Meal length did not correlate well with meal size on different pellet types because softer pellets were eaten faster.

Most Deroceras fed several times on non‐toxic pellets or pellets containing methiocarb, although subsequent meals were shorter than the first meal. Most returned to shelters by dawn. In contrast, metaldehydefed slugs were rapidly immobilised; they seldom fed again, moved little, and few regained shelter. Arion were also inhibited after methiocarb meals but Deroceras were not.

Arion distinctus moved less, ate less during a meal, and had fewer meals on nontoxic baits than Deroceras reticulatum.
Mango stem end rot pathogens — Infection levels between flowering and harvest
Authors: JOHNSON G. I. , MEAD A. J. , COOKE A. W. , DEAN J. R.
Published: February 2008

During flowering and fruit set of mango (Mangifera indica L.), colonisation by fungi (Alternaria alternata, Cladosporium cladosporioides, Dothiorella dominicana, Dothiorella mangiferae, Dothiorella sp., Epicoccum purpurascens and Pestalotiopsis sp.) increased as the flowers senesced and young fruit formed.

In the third week after flowering, the incidence of Dothiorella dominicana and Dothiorella mangiferae associated with mango fruit‐pedicel connection tissue declined coincidentally with early fruit‐fall, suggesting that early infections by Dothiorella spp. may cause fruitlet abortion. Dothiorella spp. levels in fruit‐pedicel connection tissue remained low for the subsequent 6 weeks, after which they increased. By 16 weeks after flowering, the incidence of Dothiorella spp., determined by isolation from fruit‐pedicel connection tissue, was similar to the incidence of stem end rot caused by Dothiorella spp., which developed in fruit harvested at that time. By contrast, the frequency of detection of Dothiorella spp. in peduncle tissue peaked 11 weeks after flowering, when the levels of stem end rot developing in fruit were already similar to the levels recorded in fruit harvested at 16 weeks and later.

The results suggest that in fruit and fruit‐pedicel tissue, colonisation might arise from Dothiorella spp. occurring endophytically in the peduncle. The earliest indicator of stem end rot incidence at harvest was the infection level in peduncle tissue sampled 11 weeks after flowering. Early assays of peduncle tissue for Dothiorella spp. might prove useful for selecting crops with low stem end rot infection levels.
A uniform decimal code for growth stages of crops and weeds
Authors: LANCASHIRE PETER D. , BLEIHOLDER H. , BOOM T. VAN DEN , LANGELÜDDEKE P. , STAUSS R. , WEBER ELFRIEDE , WITZENBERGER A.
Published: February 2008

A universal scale (to be known as the BBCH scale) using a decimal code for the description of the growth stages of most agricultural crops and weeds is proposed. The scale and codes are based on the well‐known Zadoks code for cereals.

Developmentally similar growth stages of different crops are given the same codes. The general scale provides a framework within which more specific scales for individual crops may be constructed. The uniformity of the scale makes it easy to remember and use in agricultural practice and simplifies storage and retrieval in a computer system.

A description of the general scale is given followed by specific scales for cereals, rice, maize, oilseed rape, field beans, peas and sunflower. Comparisons with scales currently in use are given where appropriate.
Detection of BMYV and BWYV isolates using monoclonal antibodies and radioactive RNA probes, and relationships among luteoviruses
Authors: HERRBACH E. , LEMAIRE O. , ZIEGLER‐GRAFF V. , LOT H. , RABENSTEIN F. , BOUCHERY Y.
Published: February 2008

In order to discriminate between sugar beet infecting beet mild yellowing virus (BMYV) and other isolates of beet western yellows virus (BWYV), monoclonal antibodies (MAbs) and radioactive riboprobes were used. With MAbs prepared against BMYV or potato leafroll virus (PLRV) no distinction could be established between BMYV and BWYV. Seven probes were synthesised from a lettuce infecting BWYV isolate; their localisation in the genome is known and they cover almost its entire length. Probes from the ′3 part of the genome hybridised with all BMYV and BWYV isolates whereas those from the ′5 part did not recognise BMYV isolates, showing that a divergent ′5 region exists in the genomes of BMYV and BWYV. Probes also readily detected the virus in single aphids. The relevance of this finding for epidemiological studies is discussed.

MAbs and riboprobes were also tested against other luteoviruses (PLRV; barley yellow dwarf virus (BYDV) MAV, PAV and RPV strains). The serological relationship between BMYV and PLRV was confirmed and an epitope common to PLRV and BYDV‐RPV was found. Using probes, PLRV and BYDV‐RPV were found to share domains of homology with BWYV. BYDV‐PAV showed weak homology with BWYV, while BYDV‐MAV showed none.
Localisation of coconut foliar decay virus in coconut palm
Authors: RANDLES J. W. , MILLER D. C. , MORIN J. P. , ROHDE W. , HANOLD D.
Published: February 2008

Coconut foliar decay virus (CFDV) occurs at a very low concentration in coconut palm. A 1203 nucleotide segment of the sequenced encapsidated circular single‐stranded 1291 nucleotide CFDV‐DNA has been amplified and transcribed for use as a 32P cDNA probe for the virus. A rapid method for the extraction of DNA from coconut palm has been devised for a dot‐blot hybridisation assay using this probe. An alternative non‐radioactive probe has also been developed for future use in CFDV diagnosis.

CFDV‐DNA was shown to be distributed unevenly in a range of infected palms, necessitating the use of multiple sampling to reliably detect infection in diagnostic tests. Viral DNA was detected in symptomatic and asymptomatic palms of both high and low susceptibility, in disease‐free tolerant cultivars, and in palms in remission from disease. Within the same palm, detectability of viral DNA varied little within leaflets, but varied more within and between fronds. CFDV‐DNA was detected 6–8 months after insect‐mediated inoculation, and symptoms generally appeared after another 1–4 months.

In situ hybridisation of rachis tissue showed localisation of DNA within the phloem, but its distribution in the phloem was uneven. CFDV‐DNA was detected in tissue adjacent to and within necrotic zones which develop into the petiolar lesions associated with the disease‐specific collapse of fronds.

Virus was detected in the body of the insect vector, and, where its distribution could be resolved, in the abdomen rather than the head.
Detection of maize streak virus antigens over time in different parts of maize plants of a sensitive and a so‐called tolerant cultivar by ELISA
Authors: PETERSCHMITT M. , QUIOT J. B. , REYNAUD B. , BAUDIN P.
Published: February 2008

Maize streak virus (MSV) capsid antigens were detected over time in different parts of maize plants of a sensitive (INRA508) and a so‐called tolerant (“tolerant”) cultivar (IRAT297) using a direct or an indirect double antibody sandwich ELISA. Based on three types of experiments, it was shown that the antigens were distributed in the plant according to the age of the tissues. When the virus was inoculated on a particular leaf of 18‐day old plants with infective Cicadulina mbila, only the young leaves above the inoculated one were positive by ELISA but not the older ones below. The antigens could not be detected in the inoculated leaf. At day 3 after inoculation, the antigens were detected in the sheath and/or in the whorl of the third leaf above the inoculated one but not in the oldest part of the leaf, the unfolded lamina. Plants of the sensitive cultivar were inoculated at 9 days with C. mbila deposited in the whorl. At 23 h after inoculation, the antigens were detected in the sheath but not in the whorl which was found to be positive only at 32 h. On the basis of these results, a hypothesis of the mode of virus infection is proposed. Our results contribute to a better understanding of the relationship between the age of the plant at inoculation and yield loss as well as secondary infection. By transmission tests with C. mbila, it was shown that virus could only be acquired from leaves exhibiting symptoms. Virus concentrations were measured in plant samples by ELISA using a range of dilutions of purified virus. The virus concentrations were higher in the sensitive than in the “tolerant” cultivar, but no difference in antigen distribution was observed between the two cultivars. The “tolerant” cultivar appeared to be resistant to virus multiplication.
Hybridisation and fruit formation in macabo cocoyam (Xanthosoma sagittifolium (L.) Schott)
Authors: ONOKPISE OGHENEKOME U. , BOYA‐MEBOKA MARY , WUTOH JOSEPH G.
Published: February 2008

Studies on the floral morphology of macabo cocoyam (Xanthosoma sugittifolium (L.) Schott) indicated that it required 50 to 70 days for flower formation while fruit maturity took 40 to 60 days after pollination. Among the three types of cocoyams (“white”, “red” and “yellow”), male flowers were more sterile in the “red” and “yellow” types. The spadix consisted of three parts, a bottom pistillate section, a central constricted region with sterile flowers separating the pistil from a third staminate section. The fruiting head formed as a result of hybridisation, is dome shaped and is comprised of a dense cluster of berries. Mean number of berries per fruiting head was 244 ± 40 while the weight of each head was 16.15 ± 6.38 gm. There were an average of 15 ± 6 seeds per berry with 100 seeds weighing 0.0266 ± 0.0048 gm. The longitudinally shaped seed is ridged and grooved like a pumpkin pod when observed under high magnification (400 ×)
Odour stimuli affecting autumn migration of Rhopalosiphum padi (L.) (Hemipter: ornoptera)
Authors: PETTERSSON JAN
Published: February 2008

R. padi gynoparae settling in the canopy of the winter host, Prunus padus, tended to form aggregations. Differences in the degree of exposure to wind, sun, etc., did not satisfactorily explain the aggregated pattern observed. In laboratory experiments, aphids did not distinguish between leaves taken from nearby aggregations and leaves taken far away from aggregations. The results of laboratory olfactometer tests and field trapping studies indicate that R. padi gynoparae produce an aggregation pheromone. Thus the aggregated settling pattern of gynoparae of R. padi can best be explained as a response to an aggregation pheromone.
Hatching of Globodera pallida juveniles by diffusate of potato genotypes, differing in tolerance to G. pallida
Authors: ARNTZEN F K , VISSER J H M , HOOGENDOORN J
Published: February 2008

Hatching induced by root diffusate, obtained from various potato genotypes, and by standard potato root diffusate, was determined in vitro. The used potato genotypes differed considerably in tolerance to Globodera pallida. A three parameter logistic model was used to describe the numbers of hatched juveniles in relation to time of exposure to root diffusate. Clear differences in hatching characteristics between genotypes were found. Some tolerant genotypes induced hatching of G. pallida juveniles relatively slowly, compared to intolerant genotypes. Other tolerant genotypes, however, induced hatching as fast as intolerant genotypes, and no significant correlation between hatching parameters and tolerance was found.
Crops that stay green1
Authors: THOMAS HOWARD , SMART CATHERINE M
Published: February 2008

Genetic variation exists for foliar senescence and has, usually incidentally or empirically, been exploited for crop improvement. We review the incidence of delayed or inoperative senescence in maize, sorghum, oats, rice, wheat, fescue, soybean, french bean, fruit crops, trees and other species. The insights such variants give into the genetic control of leaf senescence, and the practical implications of improved understanding of the stay‐green phenomenon are discussed.
A simulation model of competition between winter wheat and Avena fatua for light
Authors: WEAVER S E , KROPFF M J , COUSENS R
Published: February 2008

An eco‐physiological simulation model of competition between A vena fatua and winter wheat (Triticum aestivum cv. Avalon) for light was parameterised and tested. The model simulates growth of each species, in kg dry matter ha“1day‐1, from sowing to maturity as a function of irradiance, temperature and various species characteristics. Parameter values were derived from the literature and from field experiments with each species grown in monoculture. Model performance was tested against 50:50 mixtures of the two species grown at two sites in southern England. Sensitivity analyses were performed in which the canopy height of each species and the density and time of emergence of A fatua were systematically varied while all other parameters were left unchanged. Accurate simulations of growth in mixtures depended upon an accurate description of the canopy height of each species throughout the growing season. Model predictions of winter wheat yield losses in relation to A fatua density and time of emergence showed good agreement with previously published data.
Infection of wild and cultivated Vaccinium spp. with blueberry leaf mottle nepovirus
Authors: SANDOVAL C R. , RAMSDELL D C. , HANCOCK J F.
Published: February 2008

A field survey was performed during the summers of 1991 and 1992 to determine whether blueberry leaf mottle virus (BLMV) infects wild blueberry bushes surrounding commercial blueberry fields and might act as a reservoir of the virus. Leaf samples from wild blueberries growing in wooded areas surrounding commercial plantings in Western central Lower Michigan were taken from bushes radiating out from the border of the commercial field into the wooded areas at 5, 50 and 100 m. BLMV was present in native bushes of Vaccinium corymbosum, V. myrtilloides and V. angustifolium, and two hybrids of V. corymbosum V. angustifolium. BLMV‐infected pollen grains were detected in pollen traps located up to 2 miles from a source field.
Survival and seed to seedling transmission of Alternaria linicola on linseed
Authors: VLOUTOGLOU I. , FITT B. D. L. , LUCAS J. A.
Published: February 2008

Alternaria linicola survived as thick‐walled chlamydospores in hyphal or conidial cells on infected linseed stem debris, either on the soil surface or buried in the soil, during the period between the harvest of linseed and sowing of the following crop (September ‐ April). Conidia produced on these debris under favourable conditions were not only viable but also pathogenic to young linseed seedlings. Infected stem debris increased the incidence of infected seedlings which emerged from infected seed (incidence of A. linicola 1% to 28%), especially if the debris was on the soil surface rather than buried. A. linicola also survived between successive linseed crops on infected volunteer linseed plants which survived the low temperatures in winter and on the weed Veronica persica. A. linicola was more effectively transmitted from infected seeds to seedlings at temperatures 15–25°C than at 10°C. The incidence of the disease on seedlings which emerged from infected seed was positively correlated with the amount of seed‐borne inoculum, whereas the proportion of seedlings which emerged was negatively correlated with the incidence of A. linicola on the seed.
Variation in the occurrence of rust (Melampsoraspp.) and other diseases and pests, in short‐rotation coppice plantations ofSalixin the British Isles
Authors: HUNTER T. , ROYLE D J , ARNOLD G M
Published: February 2008

A proportional odds model was employed to analyse simple assessments of disease and pest severity in plantings of short‐rotation coppice willows at 18 sites in the UK over a 5‐year period (1987–1991). Of a wide range of fungal diseases and pests encountered, the most severe and damaging were rusts, caused byMelampsoraspp., and feeding damage due to beetles of the family Chrysomelidae. For rust, the model revealed highly significant (P< 0.001) interactions between the main factors, disease development within a season and between seasons, clones and sites. Within seasons, rust severity increased more at sites in the northern than in the southern UK, due mainly to low levels of occurrence at the northern sites early in the season. There was a gradual increase in rust severity over the 5‐year period, although clones differed both in terms of disease severity and the extent of change in severity in any one year. Beetle feeding damage was also analysed in a similar way, indicating a general increase from 1987–1989, but also revealing differential patterns over time and between sites.
The potential of hemp (Cannabis sativa L.) for sustainable fibre production: a crop physiological appraisal
Authors: WERF HMG VAN DER , MATHUSSEN E W J M , HAVERKORT A J
Published: February 2008

Hemp (Cannabis sativa L.) fibre can be used as a raw material for paper and textile production. A comprehensive research programme in the Netherlands has concluded that fibre hemp is a potentially profitable crop, having the right profile to fit into sustainable farming systems. This paper presents an appraisal of the crop physiological characteristics and the agronomic potential of hemp. Parameter values of basic crop physiological characteristics such as light interception potential, radiation use efficiency and dry matter partitioning coefficients are given. The effect of crop management decisions such as cultivar choice, sowing date, plant density, and harvest date on the value of these parameters is discussed. A simple crop growth model was used to assess the yield potential of hemp for the climate of the Netherlands. Calculations made for a non‐stressed late‐flowering hemp crop sown on 15 April and harvested on 15 September give a stem dry matter yield of 17.1 t ha‐1. The effects of advancing or delaying sowing or harvest date on stem yield were calculated. Crop physiological characteristics of hemp are compared to those of kenaf (Hibiscus cannabinus L.). Radiation use efficiency and dry matter partitioning coefficients of the two crops are similar. Base temperatures for development and growth are lower in hemp than in kenaf. In a temperate climate with cool springs, canopy establishment will be more rapid in hemp than in kenaf. Hemp seems an excellent candidate to fill the niche for an annual fibre crop in a temperate climate.
Crop borders reduce potato virus Y incidence in seed potato
Authors: DIFONZO C D , RAGSDALE D W , RADCLIFFE E B , GUDMESTAD N C , SECOR G A
Published: February 2008

Crop borders of soybean (Glycine max), sorghum (Sorghum bicolor), winter wheat (Triticum aestivum) and potato (Solanum tuberosum) were tested as a means of reducing potato virus Y (PVY) incidence in seed potato. Borders of fallow cultivated ground served as controls. Aphid landing rates were monitored weekly in plots using green tile traps, and PVY incidence was assessed by serologically testing tuber progeny from selected rows in each plot. Average weekly aphid landing rates in fallow‐bordered and crop‐bordered plots were not significantly different in 1992 (29.4 and 25.2 aphids, respectively) or 1993 (7.3 and 6.6 aphids, respectively). However, crop borders significantly reduced PVY incidence. In 1992, fallow‐bordered and soybean‐bordered plots averaged 47.8% and 35.0% PVY infection, respectively. In 1993, PVY infection averaged across all crop (soybean, sorghum, and wheat) bordered plots was 2.7% compared to 6.8% in fallow‐bordered plots. PVY incidence in the centre rows of fallow‐bordered and crop‐bordered plots was statistically equivalent, while outer rows of crop‐bordered plots had significantly less PVY than outer rows of fallow‐bordered plots. Crop borders apparently reduced the number of viruliferous aphids landing on the edge of the plot. The choice of crop species used as a border, or treating the border with a systemic insecticide, did not affect aphid landing rates or PVY incidence. In 1995, PVY incidence in the centre 10 row block of potatoes averaged 2.1% across all crop borders (potato and soybean). PVY infection in the four row potato border averaged 5.7%. Crop borders are readily adaptable to current production practices, although the greatest benefits in reducing PVY incidence would occur in average sized, generation 0 (< 0.2 ha), elite seed potato fields.
Prediction of a low dose herbicide effect from studies on binding of metribuzin to the chloroplasts of Chenopodium album L.
Authors: KETEL D H. , WIELEN M J W VAN DER , LOTZ L A P.
Published: February 2008

Chenopodium albumL. seedlings at the 4‐ and 8‐leaf stage were exposed to low concentrations metribuzin [4‐amino‐6‐(l, l‐dimethyl)‐3‐(methylthio)‐l,2,4‐triazin (4H)‐one] in nutrient solution to study herbicide uptake and the effects of low‐dose rates. Chlorophyll fluorescence was measured to relate the inhibition of photosynthesis to herbicide dose. The minimum rate at which metribuzin fully inhibited photosynthesis was less than 1μMfor seedlings at the 4‐leaf stage of development, and between 1 and 5μMfor the 8‐leaf stage seedlings. With isolated chloroplasts, experiments were conducted to establish the relationship between the amount of herbicide molecules bound to each chloroplast and the inhibition of photosynthesis. From the dose‐response curves obtained it was calculated that photosynthesis was fully inhibited when 7.5 105molecules metribuzin were bound to each chloroplast. This amount of binding was used to estimate minimum‐lethal dose rates of metribuzin required for seedlings differing in fresh weight of leaves and amounts of chloroplasts present. It is suggested that prediction of a low dose herbicide effect from studies on binding of photosystem‐II inhibitors in combination with chlorophyll fluorescence measurements may lead to the development of a new weed management strategy.
Elimination of apple stem grooving virus by chemotherapy and development of an immunocapture RT‐PCR for rapid sensitive screening
Authors: JAMES D. , TRYTTEN P A , MACKENZIE D J , TOWERS G H N , FRENCH C J
Published: February 2008

Ombuin (7,4′‐dimethyl quercetin) (10 μg ml‐1, for 12 wk), glycyrrhizin/quercetin (80 μg ml‐1and 10 μg ml‐1respectively, for 18 wk), ribavirin (10 μg ml‐1, for 12 wk) and quercetin/ribavirin (10 μg ml‐1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT‐PCR, and immunocapture RT‐PCR. A sensitive immunocapture RT‐PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.
The effect of the CpTi gene in strawberry against attack by vine weevil (Otiorhynchus sulcatusF. Coleoptera: Curculionidae)
Authors: GRAHAM J. , GORDON S C. , McNICOL R J.
Published: February 2008

The degree of protection against insect feeding conferred upon transgenic strawberry lines expressing the Cowpea trypsin inhibitor was evaluated under glasshouse conditions. Insect bioassays were carried out using vine weevil (Otiorhynchus sulcatus) in two experiments and in both experiments there was a highly significant reduction in damage by weevil larvae on the transgenic lines.
Arable weeds identified as new sources of beet mosaic potyvirus in Greece
Authors: KATIS N J , KOKINIS G. , ELEFTHEROHORINOS I. , JONES P.
Published: February 2008

Field and laboratory studies were carried out between 1992 and 1994 to assess the potential for arable weeds to act as reservoirs of beet mosaic potyvirus (BtMV) in fields where sugar beet is cultivated for seed. 933 weed samples were collected and tested by biological methods, while a representative number of weeds were tested by serological methods. The results showed that 97 samples, representing 14 weed species from eight families, were infected with BtMV. The following weeds were found to be naturally infected with BtMV for the first time: Bilderdykia convolvulus, Nonea pulla, Cerastium glomeratum, Galium aparine, Conyza (Erigeron) spp., Fumaria officinalis, Heliotropium europaeum and Rumex spp. The most common weeds found to be infected with BtMV in high percentage were members of the Papaveraceae.
The effect of field margins on the yield of sugar beet and cereal crops
Authors: SPARKES D L , JAGGARD K W , RAMSDEN S J , SCOTT R K
Published: February 2008

The effect of field margins on the yield of sugar beet, wheat and barley was studied on commercial farms and in a series of field experiments from 1992–1997. There was always a trend of increasing yield from the edge of the field to the centre, with a marked reduction around the ‘tramlines’ and the area where machinery turns. In the studies on commercial farms, headland yield loss varied widely. In sugar beet the headlands yielded 19–41% less than the centre, with a mean reduction of 26%. In cereals the range was 3–19%, with a mean loss of 7%. Headland yield reductions were generally smaller in the field experiments than those found on commercial farms. These headland effects did not move towards the centre of the field when grass margins were planted at the edge of the field; there was no significant effect on the yield of the adjacent crop. The presence of boundary trees had the greatest effect on yield: in the outer 9 m of the field, the area shaded by trees produced 4.4 t ha‐1 of wheat, and the area that was not shaded 8.1 t ha‐1. Turning of machinery also significantly reduced yield, while grazing by rabbits and hares surprisingly had no effect.

Following the reform of the Common Agricultural Policy in 1992, the main effect of which was to change from a price support policy to direct payments to producers, farmers in the European Union who produce more than a specified tonnage of ‘eligible crops’ per year, are required to fallow a given percentage of their land (currently 5%), to qualify for Arable Area Payments. Growers can elect to fallow fields on a rotational basis, or permanently. Headland set‐aside is a term used to describe strips of set‐aside, a minimum of 20 m wide around the edges of fields. In these experiments, the headland effect did not extend beyond 20 m from the field edge. Therefore, particularly in fields with boundary hedges or trees, headland set‐aside could effectively remove the poor‐yielding area at the field margin.
Intercrops, Cicadulina spp., and maize streak virus disease
Authors: PAGE W. W. , SMITH M. C. , HOLT J. , KYETERE D.
Published: February 2008

Intercrops of bean and finger millet were tested as a possible means of controlling maize streak virus disease (MSVD) in maize by disrupting the mating behaviour of the insect vectors of the maize streak virus, Cicadulina mbila and C. storeyi. A series of three trials were done. In the first, MSVD incidence 2 months after sowing was reduced to 14.9% and 17.4% in millet and bean intercrops compared to 29.5% in the pure maize stand. The number of male Cicadulina spp. caught on sticky pole traps was also significantly reduced relative to the control, but there was little effect on the catch of females. There was no significant yield penalty for the millet intercrop but maize yield was 49% lower in the bean intercrop treatment than in the pure stand. In the second trial, there were two millet and two bean intercrop treatments and a maize only control. Fewer male Cicadulina spp. were caught in the intercrop treatments relative to the control but MSVD incidence was reduced in one millet intercrop treatment only for which the associated maize yield penalty was 89%. In the final trial the bean intercrop was again tested but it had no effect on MSVD incidence. These experiments demonstrated that intercropping maize with bean or millet decreased vector activity and/or vector numbers. Vector catches were predominantly male, and catches of males but not females were reduced in the intercrop treatments compared with pure stands. However the lower vector catch was not consistently associated with a significant reduction in MSVD incidence, and when it was there was often an associated yield penalty in the maize due to the intercrop.
An investigation of the frost hardiness of grapevine(Vitis vinifera)during bud break
Authors: FULLER M. P. , TELLI G.
Published: February 2008

The aim of this investigation was to assess ice nucleation and frost resistance of two varieties of grapevine (Siegrebbe and Madeleine Angevine) during bud burst under radiative freezing conditions analogous to those during Spring in the UK.

During bud burst, grapevines were almost entirely resistant to freezing during frosts of less than ‐3°C by virtue of their ability to supercool. The risk of frost damage increased significantly as bud development progressed, and once buds had passed growth stage DS3 they became more sensitive to freezing and freezing damage was more extensive. The two varieties did not differ in frost resistance but, because of its earlier developing habit, variety Siegrebbe could be more prone to frost damage in the field.

Buds were more prone to damage after freezing once bud burst had commenced and the damage could not be reversed by acclimating plants for periods of 7 to 21 days at 4°C in an 8 h photoperiod. Such acclimation appeared to predispose frozen buds to more extensive damage.
Microbial population dynamics on Golden Delicious apples from bud to harvest and effect of fungicide applications
Authors: TEIXIDÓ N. , USALL J. , MAGAN N. , VIÑAS I.
Published: February 2008

The microbial population dynamics on apples cv. Golden Delicious were analysed every 15 days between bud and harvest in a fully replicated experiment in northern Spain in 1994 and 1995. The total microbial populations varied with developmental stage, and with prevailing climatic conditions. The predominant mycroflora were the filamentous fungiCladosporiumandAlternariaspp. and white and pink yeasts. Other genera isolated included mainly species ofEpicoccum, FusariumandAcremonium.However, the most important post‐harvest pathogensPenicillium expansumandBotrytis cinereawere seldom isolated from ripening apples. Maximum total filamentous fungal populations occurred after fruit set and during early ripening [2 × 104cfu (colony‐forming units) g‐1approximately] while those of bacteria were maximum at bud stage (3.5 × 105and 3.0 × 104cfu g‐1in 1994 and 1995 respectively). White yeasts were more numerous than pink yeasts. Endophytic infection of apple buds byAlternariaspp., responsible for core rot, was found in almost all bud tissue. By contrast,Cladosporiumspp. were initially isolated later from 12.5–50% of tissue samples during blooming and fruit set. The impact of a four‐spray fungicide regime during apple development significantly decreased the total filamentous fungal populations in both years, and that ofCladosporiumspp. in 1994. However, bacterial populations were often higher on apples from fungicide‐treated plots. Fungicide sprays decreased populations ofCladosporium, Alternariaand white yeasts for a maximum of up to 15–30 days after application. Fungicide application had little effect on endophytic infection of apples byAlternariaspp. between bud and harvest.
The response ofCuscuta planifloraseedlings to red and far‐red, blue light and end‐of‐day irradiations
Authors: HAIDAR M A , ORR G L
Published: February 2008

Irradiation of excised stem segments from de‐etiolated seedlingsof Cuscuta planiflorafor 24 h with mixtures of red and far‐red light with red to far‐red ratios between 0.02 to 1.0 enhanced coiling and formation of prehaustoria. Maximum number of prehaustoria were recorded when red:far‐red was near 0.1. Coiling and prehaustoria were observed whenever estimatedin vivoPfr/Ptotal at photoequilibrium was between 0.06 and 0.67. Irradiation of excised stem segments from white light grown seedlings with 12 h blue light also promoted coiling and prehaustoria formation after another 38 h in darkness. Coiling and prehaustoria were not observed in segments pulsed with 10 min red light at the end of 12 h in blue light. Coiling and prehaustoria were observed after photoreversible end‐of‐day far‐red/red/far‐red pulses but not after red/far‐red/red pulses. A far‐red pulse may not reverse inhibition by end‐of‐day red pulse when far‐red is given more than 12 h after the red pulse.
Use of resistant and susceptible potato cultivars in the trap cropping of potato cyst nematodes, Globodera pallida and G. rostochiensis
Authors: HALFORD P D , RUSSELL M D , EVANS K.
Published: February 2008

The effects of planting date and growing period of potato cultivars on their efficiency as trap crops for potato cyst nematodes (PCN) were studied. Plots were planted with susceptible or resistant cultivars in April, June and August and these were grown for 5, 6 or 7 wk before removal of the plants by hand lifting. Crops planted in June provided the best overall reductions in PCN population density of up to 95%, with cv. Santé significantly more effective than the other cultivars. Population reductions from the August planting were only slightly less than from planting in June but the tuber yields obtained were much greater: Maris Piper and Maris Bard produced 16.4 and 21.4 t ha‐1 respectively, with 37% and 43% respectively, of a size useful for canning (i.e. between 20 and 40 mm diameter).
Radial velocity study of the chemically peculiar star ε Ursae Majoris
Authors: Sokolov N. A.
Published: February 2008

In this Letter, the radial velocity variability of the chemically peculiar star ε Ursae Majoris (ε UMa) from the sharp cores of the hydrogen lines is investigated. This study is based on the ELODIE archival data obtained at different phases of the rotational cycle. The star exhibits low-amplitude radial velocity variations with a period of P = 5.0887 d. The best Keplerian solution yields an eccentricity e = 0.503 and a minimum mass of ∼14.7MJup based on the hypothesis that the rotational axis of ε UMa is perpendicular to the orbital plane. This result indicates that the companion is the brown dwarf with the projected semi-amplitude variation in the radial velocity K2 = 135.9 km s−1 and the sine of inclination time semimajor axis a2 sin (i) = 0.055 au.
Detecting early galaxies through their 21-cm signature
Authors: Naoz Smadar , Barkana Rennan
Published: February 2008

New observations over the next few years of the emission of distant objects will help unfold the chapter in cosmic history around the era of the first galaxies. These observations will use the neutral hydrogen emission or absorption at a wavelength of 21 cm as a detector of the hydrogen abundance. We predict the signature on the 21-cm signal of the early generations of galaxies. We calculate the 21-cm power spectrum including two physical effects that were neglected in previous calculations. The first is the redistribution of the ultraviolet photons from the first galaxies due to their scattering off of the neutral hydrogen, which results in an enhancement of the 21-cm signal. The second is the presence of an ionized hydrogen bubble near each source, which produces a cut-off at observable scales. We show that the resulting clear signature in the 21-cm power spectrum can be used to detect and study the population of galaxies that formed just 200 Myr after the big bang.