bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in glucosinolates during crop development in single‐ and double‐low genotypes of winter oilseed rape (Brassica napus): I. Production and distribution in vegetative tissues and developing pods during development and potential role in the recycling of sulphur within the crop
Authors: FIELDSEND JANE , MILFORD G F J
Published: February 2008

The distributions of glucosinolates and sulphur were measured in the vegetative and reproductive tissues in a series of single‐ and double‐low cultivars of oilseed rape (Bienvenu, Ariana, Cobra and Capricorn) grown on a sulphur‐sufficient soil at Rothamsted in 1987/88, and in crops of the cv. Libravo grown with none or 40 kg/ha of sulphur on a sulphur‐deficient soil at Woburn in 1990/91.

The glucosinolate measurements demonstrated large differences in the abilities of single‐ and double‐low cultivars to synthesise glucosinolates, and showed that the biosynthetic differences were associated more with the developing pods than the vegetative tissues. It indicated that potential contribution of intact glucosinolates from vegetative tissues to the seed was likely to be small, but did not preclude the possibility that the vegetative tissues were a source of glucosinolate precursors. The sulphur measurements showed that the glucosinolates contained only a small proportion of the crop's total sulphur and that they were unlikely to be a major source of recyclable sulphur, even under conditions of severe sulphur deficiency.
Changes in glucosinolates during crop development in single‐ and double‐low genotypes of winter oilseed rape (Brassica napus): II. Profiles and tissue‐water concentrations in vegetative tissues and developing pods
Authors: FIELDSEND JANE , MILFORD G F J
Published: February 2008

The concentrations of glucosinolates in the tissue water of leaves, stems, floral buds and developing pods were measured at defined stages of development in four oilseed rape cultivars known to have different seed glucosinolate concentrations (Bienvenu, Ariana, Cobra and Capricorn). Five alkenyl, two aromatic and three indolyl compounds were identified in the vegetative and reproductive organs. Substantial differences developed in the profiles of compounds present during vegetative growth. The 2‐hydroxy‐3‐butenyl glucosinolate was primarily associated with developing and mature seeds and germinated seedlings. The 4‐pentyl glucosinolate occurred mainly during the later stages of vegetative growth in spring, when leaves contained higher concentrations than stems, and during the early stages of flowering. The 2‐phenylethyl and 3‐indolymethyl glucosinolates were present earlier in vegetative growth when similar concentrations were present in leaves and stems. Differences between cultivars in the tissue‐water concentrations of individual glucosinolates were small during vegetative growth. The leaves of Cobra and Capricorn had smaller concentrations of the 3‐pentyl glucosinolate than Bienvenu and Ariana especially early in spring, and the stems of Capricorn had smaller concentration of the 3‐pentyl and 2‐phenylethyl glucosinolates. Greater differences between cultivars developed during pod growth and involved large increases in the concentrations of the 2‐hydroxy‐3‐butenyl and 3‐butenyl glucosinolates, especially in Bienvenu and Ariana. The implications of these changes in the types and concentrations of glucosinolates in the different organs for the incidence of pests and diseases are discussed.
Blackleg potential of potato seed: determination of tuber contamination by Erwinia carotovora subsp. Atroseptica by immunofluorescence colony staining and stock and tuber sampling
Authors: JONES D A C , HYMAN L J , TUMESEIT M , SMITH P , PÉROMBELON M C M
Published: February 2008

Two methods to determine numbers of the blackleg pathogen, Erwinia carotovora subsp. atroseptica, in tuber peel extract were compared; (1) growth and cavity formation on crystal violet pectate (CVP) medium (Pérombelon, Lumb & Hyman, 1987) and (2) immunofluorescent colony (IFC) staining (Van Vuurde & Roozen, 1990) using an antiserum against the bacterium conjugated with fluorescein isothiocyanate. Detection, identification and quantification of the bacterium based on the differential effect of temperature on growth in the CVP method were severely restricted and in some cases could not be done at low peel extract dilutions containing > 106 saprophytic bacteria ml“1 and > 103 cells ml‐1 of E. carotovora subsp. carotovora. In contrast, although recovery was c. 50% relative to growth of E.c. atroseptica alone on nutrient agar, numbers of the bacteria could be determined by the IFC method regardless of numbers of saprophytic bacteria and E.c. carotovora present. Moreover, the tedium of counting colonies on a UV microscope could be avoided by automation using an imaging system on photograph film negatives of the microscope fields.

Readily accessible tubers from the top layer of one tonne boxes in commercial stores were c. 10 times less contaminated than those from the middle of the boxes. For the two methods of peel extract preparation examined, the estimated sample size needed with an allowable error of log1010 E.c. atroseptica cells ml“1 extract with 95% confidence, was c. five tubers per box and 14 boxes for extract prepared from individual tubers and c. three lots of 10 tubers per box and 10 boxes for extract from 10 pooled tubers. A blackleg potential index for seed stocks was proposed based on the summation of the weighted number of individually tested tubers in different classes of contamination level.
Properties of an unusual isolate of raspberry ringspot virus from grapevine in Germany and evidence for its possible transmission by Paralongidorus maximus
Authors: JONES A T , BROWN D J F , McGAVIN WENDY J , RÜDEL MARIA , ALTMAYER B
Published: February 2008

An isolate of raspberry ringspot nepovirus (RRV‐P) commonly found infecting grapevine in localised areas of the German Palatinate, was serologically closely related to, but distinguishable from, the English type strain of this virus (RRV‐E) which is transmitted by Longidorus macrosoma. However, unlike RRV‐E, RRV‐P had a restricted herbaceous host range and produced symptoms reliably in only two hosts, Chenopodium quinoa and Nicotiana occidentalis‐accession 37B: these symptoms were a faint systemic vein clearing which, on most occasions in C. quinoa, was transient. In in vitro studies with herbaceous plant sap, RRV‐P infectivity was lost after diluting 1/100‐1/500, after storage at 20oC for 1–3 days and at 4oC for 45 days: for similar studies with RRV‐E, the values were 1/125 000, and more than 15 days at 20oC and 4oC, respectively. RRV‐P was difficult to purify in quantity and in most preparations seemed to sediment as a single component corresponding to ‘bottom’ component of RRV‐E. Purified particles of RRV‐P, like those of RRV‐E, contained a major polypeptide and two RNA species of Mx 54 000, 2.6 × 106 and 1.6 × 106 respectively. There was no evidence from RNA preparations from purified virus particles or, from analysis of dsRNA from infected plants, that RRV‐P contained a satellite RNA. The incidence of RRV‐P in vineyards was not associated with the presence in soils of Longidorus nematodes, but was associated with the distribution in the Palatinate of Paralongidorus maximus. Furthermore, results from an experiment in Germany in a vineyard planted with healthy grapevines in soil fumigated to destroy nematodes, showed spread of RRV‐P into these plants from an adjoining source of infected grapevines and soil infested with P. maximus. In laboratory studies, RRV‐P was transmitted by P. maximus at a very low level between grapevines (used as the virus source and test plants) but not to, or between, herbaceous hosts.
Partial replacement of local common bean mixtures by high yielding angular leaf spot resistant varieties to conserve local genetic diversity while increasing yield
Authors: TRUTMANN PETER , PYNDJI MUKISHI M
Published: February 2008

The effect of replacing proportions of local farmer bean (Phaseolus vulgaris) mixtures with varieties resistant to angular leaf spot on grain yield was evaluated under local disease pressure in the Kivu region of Zaire. Local bean mixtures in on‐station and in multi‐locational trials containing respectively 25%, or 50% of Centro Internacional de Agricultura Tropical (CIAT) breeding lines BAT76, or A285, resistant to angular leaf spot yielded significantly more than the local mixture alone. Yields exceeded expected values in three seasons of on‐station testing and in two seasons of multi‐locational trials. Yield over the expected was found to be a property of new mixtures not protected with fungicide and were attributed to disease control. Relative to expected yields non‐protected farmer mixture components performed 17% and 16% better than in protected plots and A285 components yielded 24% and 16% better at respectively 25% and 50% A285 supplementation levels. A285 increased yields of the local mixture components and benefitted from the local mixture when not protected by fungicide. Yield increases in multi‐locational trials were largely attributed to the higher yield potential of the resistant variety A285, although angular leaf spot severity was significantly reduced. It was concluded that high yielding, resistant varieties were able to increase bean yield in the region, but probably at a substantial cost in genetic diversity in farmer bean mixtures. That said, a partial replacement strategy is preferable to strategies which encourage complete replacement of local germplasm with one or few high yielding varieties.
Infection of cereals and grasses by isolates of Polymyxa graminis (Plasmodiophorales)
Authors: ADAMS M J , JACQUIER C
Published: February 2008

The host range of isolates of Polymyxa was tested in mono‐fungal sand cultures. Fourteen isolates of P. graminis, obtained from barley, wheat, oats or Poa annua and from several different countries, all infected barley and all but one infected wheat. Rye was also a good host, whereas oats (nine cultivars), Lolium multiflorum and Poa pratensis became only slightly infected. Wheat cultivars differed in susceptibility, with Galahad much more resistant than Avalon. Several common weed and pasture grasses were not infected by the two isolates tested. A range of wild Hordeum spp. were mostly susceptible to P. graminis and/or barley mild mosaic virus, which it transmits. An isolate of P. betae, used for comparison, caused slight infection on oats but not on other cereals. The variation within and between species of Polymyxa needs more detailed investigation.
Control of skin spot and silver scurf on stored cv. King Edward potatoes by chemical and non‐chemical methods
Authors: HIDE G A , HALL SHARON M , READ P J
Published: February 2008

In 3 years, seed tubers of cv. King Edward were planted in field experiments and diseases assessed on the daughter tubers after storage for 24–26 wk. In 1991 and 1992, the seed tubers were treated with a mixture of thiabendazole and imazalil at two rates. Tubers were harvested on several dates from late August to early October and dried under different conditions before storage.

In 1990, silver scurf after storage was decreased equally by dry curing for 2 wk and windrowing for 2 h whereas skin spot was decreased most by dry curing, and these effects were greater the earlier tubers were harvested. In 1991, dry curing for 2 wk decreased skin spot and silver scurf more than dry curing for 1 wk, and skin spot was slightly decreased by windrowing for 2 h; windrowing improved the control of both diseases when tubers were subsequently dry cured. In 1991 and 1992 fungicide treatment of seed tubers greatly decreased skin spot after storage and was also effective against silver scurf, but increased black dot when tubers were harvested in September or October.

Skin spot was controlled equally well by the two rates of fungicide but silver scurf was less well controlled when the dose was decreased by 75%. It is suggested that amounts of fungicide applied to seed tubers could be decreased provided that the efficiency of application is improved and that crops are harvested early and dried before storage.
A comparison of methods for inoculating bean plants with Elsinoë phaseoli and some factors affecting infection
Authors: PHILLIPS A J L
Published: February 2008

Bean (Phaseolus vulgaris) leaves were inoculated with a conidial suspension of Elsinoe phaseoli by spraying, by applying a 10 μl drop, by a cotton wool technique or by using a camel hair brush. Spray application resulted in a uniform distribution of lesions over the leaf surface and gave consistent levels of infection between repetitions. Drop application allowed good control of the amount of inoculum applied. Although brush or cotton wool techniques gave high levels of infection it was not possible to control the amount of inoculum. Only immature tissues were susceptible to infection.

Five cultivars were inoculated with two isolates and disease was scored on the basis of numbers of lesions and lesion type (scab severity). The small white cvs PAN 181 and Teebus were the most resistant; lesions were small and generally fewer than on the large‐seeded red speckled sugar bean cvs Umlazi and Umvoti. The value of the different inoculation techniques in studies on bean scab is discussed.
Inoculation and acquisition of maize bushy stunt mycoplasma by its leafhopper vector Dalbulus maidis
Authors: LEGRAND ANA I , POWER ALISON G
Published: February 2008

Maize bushy stunt mycoplasma (MBSM), a mycoplasma‐like organism, is transmitted in a persistent manner by the corn leafhopper, Dalbulus maidis, to maize (Zea mays). The influence of the duration of acquisition access and inoculation access periods on the transmission of MBSM by D. maidis was investigated. The proportion of plants infected by D. maidis increased significantly from 0 to 0.51 as the inoculation access time to a plant increased from 10 min to 72 h (X2= 101.5, P < 0.001). Likewise, the proportion of insects acquiring MBSM from infected plants increased from 0 to 0.19 as the acquisition access time to the source plant increased from 10 min to 72 h (X2= 53.2, P < 0.001). The data were fitted to a loglinear regression model. No significant association was found between the sex of the insects and vector ability.
Properties of a host range and coat protein variant of broad bean true mosaic comovirus from Vicia faba
Authors: JONES A T , MITCHELL M J
Published: February 2008

Unlike other described isolates of broad bean true mosaic comovirus (BBTMV), a variant, code name SB, infected some non‐leguminous plant species and, in N. benthamiana, induced systemic mottling and puckering of the leaves. However, like other described BBTMV isolates, purified SB particle preparations contained isometric particles c. 28 nm in diameter that sedimented as two nucleoprotein components with S20, w values of 90S and 109S; some preparations occasionally contained a component of c. 50S. Virus particles contained two ssRNA species which, when denatured in glyoxal, had estimated MT values of 2.1 × 106 and 1.3 × 106 and co‐electrophoresed with cowpea mosaic virus RNA‐1 and RNA‐2 respectively. Isolate SB was serologically indistinguishable from British and German isolates of BBTMV. However, SB virus particles contained a major polypeptide (L) of Mr between c. 31 000 and up to three minor ones (S) or Mr between c. 20 000 and 24 000. This contrasts with protein preparations from other BBTMV isolates that typically contain only two polypeptides of Mr c. 37 000 (L) and 21 000 (S). Following isopycnic centrifugation in CsCl, SB particles purified from pea separated into two major components with densities of 1.39 and 1.44 g cm‐3 and a minor component of estimated density 1.43 g cm‐3. In Cs2SO4, virus preparations separated into three major components with densities of 1.30, 1.32 and 1.36 g cm‐3 and a minor one of density 1.27 g cm‐3. In CsCl isopycnic gradients, SB particles purified from TV. benthamiana separated into two components with densities of 1.38 and 1.43 g cm‐3. During immuno‐electrophoresis in agarose gels, freshly prepared virus and preparations stored for up to 4 days at 4°C contained a single component that migrated rapidly to the anode, whereas similar preparations of an English isolate of BBTMV migrated as a single component that moved only slowly toward the anode but which, within 48 h, contained an additional component with a migration rate similar to that of isolate SB. Isolate SB is therefore a host range variant of BBTMV which, in comparison with previously described isolates of BBTMV, has an increased negative charge of its particles prior to any appreciable degradation of its S protein, and S protein that is degraded less rapidly. These features probably account for the anomalies observed in isopycnic centrifugation.
The development of plant‐parasitic nematode infestations on micro‐propagated banana plants following field control measures in Côte d'Ivoire
Authors: MATEILLE THIERRY , QUÉNÉHERVÉ PATRICK , HUGON RÉMI
Published: February 2008

Of the weeds that were found in banana production areas, only Asystasia gangetica was parasitised by Radopholus similis; Helicotylenchus multicinctus and Hoplolaimus pararobustus were able to parasitise all weed species. Field trials were carried out in Cote d'Ivoire to assess the potential for using nematode‐free micro‐propagated banana plants following cultural and chemical methods for nematode control. Banana (Musa acuminata) cv. Poyo was examined for nematodes after weed fallow, flooding and chemical treatment. Before replanting bananas, nematode assays showed that: i) all nematode species declined but were not eliminated after a 1,3‐dichloropropene soil treatment; ii) H. multicinctus, H. pararobustus and Cephalenchus emarginatus were still present after either a 2‐year weed fallow (dominated by Chromolaena odorata or Asystasia gangetica) or a 10‐week flooding; iii) R. similis did not persist after fallowing or flooding. All nematode species were found in plots treated with 1,3‐dichloropropene and that had been planted with bullheads, suckers or nematode‐free micropropagated plants. After both fallow and flooding, R. similis was reintroduced on infested planting materials (bullheads and suckers) even when they were pre‐treated with a nematicide. When fallow and flooded plots were planted with nematode‐free materials (vitro‐plants), R. similis did not appear in the roots for two vegetative cycles. The other species, still present in the soil, invaded the roots and increased slowly in numbers. These results were confirmed in commercial banana plantations.
The use of hydrogen peroxide to control postharvest decay on ‘Galia’ melons
Authors: AHARONI YAIR , COPEL AZICA , FALLIK ELAZAR
Published: February 2008

Sanosil‐25, a disinfectant containing 48% hydrogen peroxide and silver salts as stabilising agents, inhibited the mycelial growth of the two main decays causing fungi of melons, Alternaria alternata and Fusarium solani in vitro at concentrations between 5000 and 10 000 μl litre‐1. However, in in vivo experiments, Sanosil‐25 markedly decreased decay at a concentration of 5000 μl litre‐1 when incorporated into a wax treatment and produced no phytotoxic effect. This treatment may provide an alternative to imazalil which, although more effective, gives problems with residue levels. A concentration of 10 000 μl litre‐1 proved phytotoxic.
A decimal code describing the developmental stages of head cabbage (Brassica oleracea var. capitata)
Authors: EVERAARTS A P
Published: February 2008

The developmental stages of head cabbage (Brassica oleracea var. capitata) as a vegetable have been characterised by a decimal code. Five primary stages are recognised: germination, emergence and establishment, leaf formation, head formation and maturity. Each primary stage is divided into secondary stages, which apply both to single plants and to crops. Maturity is defined as the head having obtained a marketable weight and density. The standing ability is defined as the number of days from 90% of the crop being marketable to 25% of the crop having become unmarketable.
Falling aphids enhance impact of biological control by parasitoids on partially aphid‐resistant plant varieties
Authors: GOWLING G R , van EMDEN H F
Published: February 2008

Cage experiments, in which the population increase of Metopolophium dirhodum was measured either in the absence or presence of the parasitoid Aphidius rhopalosiphi, showed reductions of peak populations in the presence of the parasitoid of 30% on the susceptible wheat cultivar Armada, but of 57% on the partially resistant Rapier. On both cultivars, aphid population curves in the presence and absence of the parasitoid diverged before the first mummies were formed. The number of aphids leaving plants was measured, and was found to increase in the presence of the parasitoid, particularly with Rapier (almost double). Most aphids (about 75%) which left plants fell, and a smaller proportion regained plants when parasitoids were present than when they were absent. A field experiment with Brevicoryne brassicae and natural predation on Brussels sprouts also showed an increase in aphids leaving a less susceptible compared with a more susceptible cultivar.
The relationship between colonisation and crown rot symptoms in strawberry plants infected with Phytophthora cactorum
Authors: PETTITT T R , PEGG G F
Published: February 2008

Strawberry tissues infected with Phytophthora cactorum were comminuted and plated in a selective antibiotic agar medium to determine levels of tissue colonisation as indicated by the number of colony forming units (CFU) recovered per gramme of infected tissue. The number of CFU recovered per gramme of tissue increased logarithmically with the amount of necrosis in infected crown, leaf and petiole tissues. Under the conditions of enhanced susceptibility to infection and colonisation caused by cold storage treatments, this relationship between colonisation and necrosis was not significantly altered in the susceptible cv. Tamella. A recovery index was used to determine the effect of infected tissues on the recovery of CFU. This indicated that increasing levels of host colonisation stimulated CFU recovery and may partly explain the large increase in CFU g‐1 with larger amounts of necrosis.

The amount of tissue colonisation was greater in inoculated plants of the susceptible cv. Tamella than in less susceptible cv. Cambridge Favourite, although the necrotic tissues of the latter contained more CFU g‐1, indicating a greater level of tolerance to colonisation. In cv. Tamella small amounts of colonisation were capable of causing wilt symptoms, although no wilted plants contained less than 200 CFU g‐1. Conversely, plants containing more than 1000 CFU g‐1 always wilted. In the early stages of infection, low levels of colonisation could be detected in strawberry crowns in the absence of symptoms. Dormant strawberry plants of cv. Tamella were readily infected by P. cactorum zoospore inoculations but, unlike actively growing plants, the majority of infections remained latent. These latent infections exhibited little or no symptoms and CFU recoveries from infected tissues were always below 100 CFU g‐1.
Modelling the relationship between purple blotch and yield loss in garlic and effect of leaf damage on bulb yield
Authors: BISHT I S , AGRAWAL R C
Published: February 2008

An AUDPC model was developed to describe the relationship between Alternaria porri infection and yield loss in garlic. Percentage yield loss was regressed against AUDPC and gave an acceptable fit to a linear model with an intercept of ‐0.35, a slope of 0.09 and R2= 0.85 during 1990–91 and an intercept of 1.91, a slope of 0.08 and R2= 0.87 during 1991–92. The effect of various levels of leaf damage on garlic bulb yield was also studied to simulate damage caused by A. porri. Significant yield reduction by 25% defoliation at 5 wk, 50% defoliation at 4 wk and 75% defoliation at 3 wk before bulb maturity were recorded. No significant yield reduction from 2 wk before bulb maturity could, however, be noticed even at the highest levels of leaf damage. Linear regression models were fitted for predicting yield at various levels of defoliation at different weeks before bulb maturity.

These models can be used to describe the consequences of disease epidemics, projecting possible losses during the season and justifying the need for chemical disease control.
Differentiation of Erwinia carotovora subsp. atroseptica and carotovora by RAPD‐PCR
Authors: MÄKI‐VALKAMA T , KARJALAINEN R
Published: February 2008

Six different 10‐mer oligonucleotide primers were used to differentiate Erwinia carotovora subsp. atroseptica (Eca) and carotovora (Ecc) using RAPD‐PCR. All primers gave different banding patterns for Eca and Ecc indicating their value for identification. UPGMA clustering analysis clearly showed two separate clusters, one for Eca and the other for the Ecc group. Similarity within Eca strains was very high, over 85% among most isolates but within the Ecc group extensive genetic diversity was found and many of the Ecc strains were no more than 50% similar. Similarity between the 10 Eca and 10 Ecc strains was generally only 10–25% based on the results from six primers.

Three RAPD fragments from Eca group, which were amplified by three different RAPD primers, were isolated and used as probes for Southern hybridisation to test, if homologous fragments were amplified from Ecc strains. All these probes hybridised only with Eca isolates indicating that these fragments could be useful in order to develop a PCR‐based detection system for Eca strains.
Detection and differentiation of whitefly‐transmitted geminiviruses in plants and vector insects by the polymerase chain reaction with degenerate primers
Authors: DENG D , MCGRATH P F , ROBINSON D J , HARRISON B D
Published: February 2008

Degenerate oligonucleotide primers, designed for amplification of an approx. 500 bp fragment of DNA‐A of five well characterised whitefly‐transmitted geminiviruses, were used in the polymerase chain reaction (PCR) to detect known or putative geminiviruses infecting seven plant species and originally obtained from Africa, India, America or Europe. Although nucleotide sequences are published for only four of the viruses, all 13 were detected. Six of the viruses were also detected in single viruliferous whiteflies (Bemisia tabaci). Virus was detected both in fresh B. tabaci and in specimens that were frozen and dried before being dispatched from their country of origin. Individual viruses could be distinguished by the patterns of DNA fragments obtained by the action of restriction endonucleases on the PCR products. This approach also allowed six virus isolates from leaf curl‐affected tomato to be assigned to four country‐specific forms.
Antigenic analysis of potato virus A particles and coat protein
Authors: ANDREEVA LEENA , JÄRVEKÜLG LILIAN , RABENSTEIN F , TORRANCE LESLEY , HARRISON B D , SAARMA M
Published: February 2008

Five monoclonal antibodies (MAbs) were prepared to particles of potato virus A (PVA), isolate B11. In immunoblots, MAbs A1D8 and A5B6 reacted only with full length molecules of PVA coat protein (CP). Pepscan tests with overlapping octapeptides representing the whole sequence of PVA CP showed that the epitope detected by MAb A5B6 is contained in its N‐terminal octapeptide. MAbs A9A4, A3H4 and A6B8 reacted with CP molecules that lacked about 5 kD of sequence at their end(s) and detected epitopes at residues 52 to 62, 64 to 73 and 75 to 82 respectively, all of which lie in the protease‐resistant core of the CP. The epitope which reacts with MAb A3H4 is in a region predicted to be hydrophobic and is not detected in intact virus particles, indicating it is a cryptotope. In contrast, MAbs A6B8 and A9A4 reacted with freshly purified PVA particles but more strongly with partially degraded ones. Pepscan tests with polyclonal antibodies to PVA isolate B11 identified five additional immunogenic sequences in PVA CP and showed that regions at the N‐termini of the intact and core molecules are immunodominant.

PVA isolate B11 was not transmitted by aphids, and its CP N‐terminal octapeptide contains the sequence DAS, which is associated with aphid‐non‐transmissibility in other potyviruses. MAb A5B6, which detects this region, reacted strongly in ELISA with three out of four other aphid‐non‐transmissible PVA isolates but only weakly with three aphid‐transmissible ones, suggesting that differences in N‐terminal sequence may underlie most of the differences in aphid transmissibility.
Weed seed banks in arable fields under contrasting pesticide regimes
Authors: MARSHALL E J P , ARNOLD G M
Published: February 2008

Viable weed seed banks on a clay soil were estimated for five years from 11 arable fields receiving one of three levels of pesticide application. Low seed densities, averaging 2000 m‐2, were recorded, but dicotyledonous weed seed numbers usually increased following oilseed rape crops, reaching 26 000 m‐2 in one field. Field‐to‐field variability was large. Samples could be grouped using multivariate techniques into those dominated by grass weed seeds and those containing mainly dicotyledonous weed seeds. Within TWINSPAN classifications, most fields maintained similar seed banks during the study period, indicating relative stability of communities. Differences present at the outset of the experiment, including variation between fields in the same treatment area, were maintained for the five years. Patterns were not associated with straw disposal or spring herbicide application. Oilseed rape crops did not cause qualitative change in seed bank communities, but allowed certain species, notably Stellaria media and Sonchus asper, to increase seed numbers. Smaller and less diverse seed banks in the area receiving most herbicide were not statistically significant. Seed banks gave poor predictions of following weed populations.
The ploidy composition of offspring from Solanum tuberosum (4×) ×S. phureja (2×) crosses with special reference to triploid frequencies
Authors: DE M J
Published: February 2008

Data on the production of offspring of 4×× 2× crosses in potato are presented. The ploidy composition of seedlings varied from year to year and parent to parent. Products of dihaploid induction crosses were chiefly 2× or 3× whereas crosses between S. tuberosum cultivars and unreduced gamete‐producing S. phureja clones were mainly 3× or 4×.

Substantial percentages of 3× seedlings were produced by some crosses in some years. It was concluded that the so‐called ‘triploid block’ in potatoes is a variable phenomenon and that factors which increase seed production may suppress the proportion of triploids produced.
A description and code of development of evening primrose (Oenothera spp.)
Authors: SIMPSON M J A
Published: February 2008

A description and code of development is proposed which divides the life cycle of evening primrose (Oenothera spp.) into seven stages, namely germination and emergence, leaf production, stem extension, flower bud development, flowering, spike development in terms of seeds and spike development in terms of pods. The description and code are based on a system devised for oilseed rape but are modified to suit evening primrose growers and those who require simple and accurate identification of critical crop stages such as harvest stage. The relationship between the proposed code and the general BBCH scale is indicated.
Arable acronyms analysed – a review of integrated arable farming systems research in Western Europe
Authors: HOLLAND J M , FRAMPTON G K , ÇILGI T , WRATTEN S D
Published: February 2008

Arable production has come under increasing economic and environmental pressures, especially in the last decade. These have derived from over‐production, decreased farm incomes and a concern with the possible environmental effects of intensive pesticide use associated with such intensive cultivation. A number of long‐term research programmes on integrated farming systems and their sustainability have recently been completed or are currently under way. In the UK, these include the ‘Boxworth’ project, ‘SCARAB’, TALISMAN’, RISC, ‘LINK Integrated Farming Systems’, ‘LIFE’ and the demonstration‐only programme ‘LEAF’. These projects are reviewed in terms of their objectives, designs and results to date, and are compared with some parallel programmes in Germany, the Netherlands, Switzerland and France.
Interactions between the diamondback moth, Plutella xylostella L. and glasshouse and outdoor‐grown cabbage cultivars
Authors: VERKERK R H J , WRIGHT D J
Published: February 2008

Interactions between Brassica cultivars (cvs) and adult and larval stages of Plutella xylostella L. were examined. In six‐way choice oviposition experiments, glasshouse‐grown Chinese cabbage cv. Tip Top was preferred to five outdoor‐grown temperate cabbage cultivars but was similar to four out of five tropical cultivars. Bionomic studies with neonate larvae on temperate cabbage cultivars showed that mean larval duration was longer and percentage survival less on older compared with younger plants but that plant age or cultivar had little effect on pupal weight. The fecundity of P. xylostella reared on outdoor‐grown cabbage cultivars varied ten‐fold between the poorest and the best cultivar but plant age had little effect on P. xylostella reared on Chinese cabbage. In a glasshouse experiment, survival of P. xylostella on Chinese cabbage was significantly greater compared with field‐grown glossy‐leaved, normal bloom green cabbage and red cabbage. In bioassays with neonate larvae, when the leaves were placed vertically instead of horizontally a significant level of intrinsic resistance was revealed for glasshouse and field‐grown glossy‐leaved cabbage but not for Chinese cabbage. Observed differences in host status to P. xylostella are discussed in relation to the potential for partial plant resistance in control programmes.
Characterisation and pathogenicity of bacteria from shoot tips of the globe artichoke (Cynara scolymus L.)
Authors: PEŃALVER R , DURÁN‐VILA N , LÓPEZ M M
Published: February 2008

Bacteria have been isolated from shoot tips of symptomless globe artichoke plants. These were identified as Pseudomonas fluorescens, Pseudomonas marginalis, Pseudomonas spp., Serratia liquefaciens, Enterobacter agglomerans/Erwinia, Agrobacterium radiobacter, an unidentified member of Rhizobiaceae and another classified in the “corynebacteria” group. The most frequently isolated species was P. fluorescens, biovars II and III. The endogenous character of these bacteria was studied in plants growing in vitro and in the open field. P. fluorescens, P. marginalis, S. liquefaciens and E. agglomerans/Erwinia caused symptoms in plants growing in vitro, but only P. fluorescens biovar II and P. marginalis produced symptoms in plants growing in open fields. Differences in pathogenicity were observed on inoculated plants growing in vitro or in the open field. This suggests that several endophytic bacterial species may be responsible for the high levels of contaminants found during the micropropagation of globe artichoke.
Identification of a second distinct strain of beet mild yellowing luteovirus using monoclonal antibodies and transmission studies
Authors: STEVENS M , SMITH H G , HALLSWORTH P B
Published: February 2008

The variation among isolates of beet mild yellowing luteovirus (BMYV), collected from commercial crops of sugar beet during 1990, 1992 and 1993, was studied using monoclonal antibodies and transmissions to indicator species. The common strain of BMYV, which occurs throughout the sugar‐beet root growing area, reacts with monoclonal antibodies MAFF 24, BWYV‐BC‐510H and BYDV‐PAV‐IL‐1, and infects Capsella bursa‐pastoris. A second strain, which failed to react with monoclonal antibody BYDV‐PAV‐IL‐1 and which did not infect C. bursa‐pastoris, was identified in 11% of sampled infected plants. The implications of the properties of this strain for the epidemiology of BMYV are discussed.
The sealed storage of moist flax with and without the use of chemical preservatives
Authors: EASSON D L , ANDERSON R , SHARMA H S SHEKHAR
Published: February 2008

The suitability of ensilage as a means of preserving flax was investigated in a series of experiments in which 400 kg round bales of fresh flax were sealed in polyethylene film or plastic wrapped, with or without the addition of formic acid at 2.5 litre t‐1 or formalin at 5.6 litre t‐1 at the time of baling. Plastic wrapping provided a more effective seal than the bags which were easily punctured by the flax roots resulting in moulding and deterioration of the flax. Where the seal was not broken untreated flax underwent a clostridial fermentation and the pH fell to about 4.8. Cellulolytic activity degraded the flax fibre over a period of 3 to 6 months. The addition of formic acid reduced the cellulolytic activity provided the seal was not broken. In an experiment with 4 kg batches of flax of 65%, 40% or 25% MC sealed in polyethylene film, the addition of formic or propionic acids at 20 g kg‐1 DM did not prevent moulding and deterioration, but both NH3 and SO2 at 40 g kg‐1 DM preserved the physical structure of the flax. The NH3 darkened the flax and made it pliable and unscutchable while the SO2 bleached it and preserved the fibre without microbiological deterioration. The presence of acids on the moist stored flax appeared to inhibit the progress of normal water retting.
Inheritance of partial resistance to bean rust in the common bean (Phaseolus vulgaris L.)
Authors: EDINGTON B R , SHANAHAN P E , LEVIN J , RIJKENBERG F H J
Published: February 2008

The inheritance of partial resistance within eight bean cultivars to a single‐pustule isolate of bean rust was studied by means of a F1 diallel test. General combining ability (GCA) and specific combining ability (SCA) were very highly significant over two seasons and in interaction with seasons. The partitioning of the sums of squares indicated the greater importance of GCA in the inheritance of the resistance. Reciprocal effects were not significant. The estimates of narrow‐sense heritability in the two seasons were 0.899 ± 0.056 and 0.603 ± 0.065.
Immunological techniques used with fungal plant pathogens: aspects of antigens, antibodies and assays for diagnosis
Authors: WERRES SABINE , STEFFENS CLAUDIA
Published: February 2008

The present review surveys serological work with phytopathogenic fungi. Knowledge of antigenic determinants of fungi and the possibilities and problems of selecting and using fungal structures and metabolic products for the production of specific antibodies are considered. The paper is intended to be a source of practical information and literature for the active research worker.
Drought stress and cereal aphid performance
Authors: PONS X , TATCHELL G M
Published: February 2008

The performance of clones of Rhopalosiphum padi and Sitobion avenae from England and Spain was examined on drought‐stressed tillering winter wheat in an environment chamber at 14 ± 1°C. Two different levels of drought stress and an unstressed control were established by different watering regimes which resulted in drought‐stressed plants being smaller at the end of the experiment.

The effect of drought stress to plants on aphid performance was not significantly different between the clones tested. Drought stress had no effect on aphid development time, nymphal mortality, the weight of teneral adults and the number of embryos in teneral adults up to the onset of reproduction in the first F1 generation. The subsequent reproductive capacity, as measured by the effective and potential fecundity, and the reproductive rate, were much reduced on drought‐stressed plants. However, there was only a small decrease in the intrinsic rate of increase (rm). Overall the clone of R. padi from Spain performed better than that from England, the development and prereproductive times being shorter and the fecundity higher in the Spanish clone, giving a higher rm. There were no differences in the fecundity and the rm between the Spanish and the English clones of S. avenae. The proportion of the F2 generation that was alate differed greatly between clones, and only the English S. avenae produced significantly more alatae on drought‐stressed than on unstressed plants.
Effect of pea bacterial blight (Pseudomonas syringaepv.pisi) on the yield of spring sown combining peas(Pisum sativum)
Authors: ROBERTS S J , PHELPS K , McKEOWN B M , HEATH M C , COCKERELL V
Published: February 2008

Field trials to examine the effect of pea bacterial blight(Pseudomonas syringaepv.pisi) (Psp)on the yield of combining peas were carried out at five sites (HRI Wellesbourne, ADAS Rosemaund, ADAS Terrington, PGRO, SASA East Craigs) in the UK in 1990, 1991 and 1992. Healthy seed, cv. Solara, and seed naturally infected withPspRace 2 was sown in large plots (c.200 m2) in the open or under nets to prevent bird damage by pigeons. Despite relatively low disease severity levels (< 15% leaf area) and separation by at least 12 m of cv. Consort (resistant to Race 2) between plots there was considerable spread of disease into plots sown with healthy seed. Regression analysis demonstrated a significant relationship between yield and disease. Of the disease measurements examined, disease severity on the leaves (stipules) at growth stage 208 was found to be the best predictor of yield. A model containing environmental and bird damage terms, in addition to disease, suggested that a yield loss of 0.98 t/ha would be expected for a disease severity score of 1, equivalent to 5% leaf area affected, at growth stage 208.
Characterisation of a variant of zucchini yellow fleck virus (ZYFV), a potyvirus causing a wilt disease of melons in Israel*
Authors: ANTIGNUS Y , LEVY D , COHEN S
Published: February 2008

A flexuous filamentous virus 750 nm in length was isolated from field‐grown melons (Cucumis melo L.) and squirting cucumber (Ecballium elaterium L.). Infection of melon seedlings of most commercial varieties resulted in a lethal wilting, but late infections gave dieback. The virus infected systemically all economically important cucurbit crops. Its coat protein consists of a single polypeptide, 34 500 D in size, encapsidating a single stranded RNA genome of 10.1 kb.

Antiserum against the Italian zucchini yellow fleck virus (ZYFV) reacted specifically with the Israeli isolate in both ISEM and Western blot. The virus was aphid transmissible in a non‐persistent manner. Based on host range, host reaction and serological data, it is suggested that the virus described is an Israeli variant of ZYFV.
Resistance to cucumber mosaic virus in potato
Authors: VALKONEN J P T , SLACK S A , WATANABE K N
Published: February 2008

Reactions to two subgroup I isolates (Fny‐CMV and Pf‐CMV) and two subgroup II isolates (A9‐CMV and LS‐CMV) of cucumber mosaic virus (CMV) were studied in three non tuber‐bearing wild potato species (Solanum spp.) of the series Etuberosa, and in two tuber‐bearing interspecific potato hybrids and four potato cultivars using graft‐inoculation. Three classes of phenotypic reactions (susceptible, hypersensitive, extreme resistance) were observed in the tuber‐bearing genotypes. Susceptible genotypes developed mosaic or severe mosaic with leaf malformation and had high CMV titres. Hypersensitive genotypes developed either top necrosis or vein necrosis and/or necrotic spots on apical leaves, and had low CMV titres. Extremely resistant genotypes had no symptoms and no CMV was detected. The hybrid 87HW13.7 (S. tuberosum×S. multidissectum) developed top necrosis specific to infection with Fny‐CMV. The hybrid ‘A6’ (S. demissum×S. tuberosum cv. Aquila) was hypersensitive to all CMV isolates tested. Extreme resistance was not functional against all CMV isolates. Neither hypersensitivity nor extreme resistance were related to the CMV subgroup.
The effects of domestic compost upon the germination and emergence of barley and six arable weeds
Authors: LIGNEAU L A M , WATT T A
Published: February 2008

In a bioassay, leachate from composted household waste was found to decrease both cress germination and the germination of barley and six arable weeds, especially in the light. The effect of compost depth upon the emergence of these species was examined in a glasshouse experiment. Compost had no significant effect on barley emergence. However, weed emergence, particularly of those with small seeds, was reduced greatly by the physical effect of compost and, to a lesser extent, by its chemical effect. The emergence of the large‐seeded species was relatively unaffected by increasing depths of compost, whereas that of the smaller‐seeded weeds steadily decreased, being almost completely prevented by a 3 cm layer. The use of compost to control arable weeds in the field is discussed.
Somatic embryogenesis in pea (Pisum sativum L.): effect of explant, genotype and culture conditions
Authors: van DOORNE L E , MARSHALL G , KIRKWOOD R C
Published: February 2008

In this study 16 cultivars of pea (Pisum sativum L.) were screened in vitro for the formation of somatic embryos which were dependent on the genotype, culture conditions and explant source used. The cultivars Stehgolt, Maro and Progreta showed the highest tendency to form somatic embryos (c. 25%) while Alaska, Rondo and Ascona did not show any embryo production. Using the cultivar Belman, the highest embryo production was achieved by using nodal explants of shoots (10.6%) and a cotyledon‐free embryo as explant source (14.1%) in the light (15.8%) compared to using apices as explants (1.8%) and a seedling as the explant source (9.4%) in the dark (3.3%). Media containing picloram (0.75 mg/litre) followed by BA (1 mg/litre) or kinetin (1 mg/litre), each for four weeks gave the highest somatic embryo production. The development of embryos to whole plants was unreliable and some 90% of the embryos induced did not develop any further, died, recallused or formed secondary embryos. The size of the embryo at separation and the timing of the separation from the original callus were important factors determining success for complete development to whole plant. Regeneration of 184 plants was achieved with ensuing flowering, pod formation and viable seed production from the techniques described.
A survey of black dot and other fungal tuber blemishing diseases in British potato crops at harvest
Authors: READ P J. , STOREY R M J. , HUDSON D R.
Published: February 2008

Black dot and other fungal blemishing diseases were assessed on tubers from crops in eastern England in 1987 and 1988, and in 1989 and 1990 from crops throughout Great Britain.

Black dot was found on tubers in crops from all areas of the country, and was most common in those from eastern and southern England. The disease was scarce on most Scottish crops, but occasionally some were severely affected. In 1988 there was no consistent relationship between the amounts of disease on the seed and subsequent ware crop. On average, the disease was more prevalent in irrigated crops and where the interval between successive potato crops was short. In 1990 treating seed tubers with fungicide had no effect on subsequent levels of disease.

Few crops were unaffected by silver scurf, and it was most common in crops from southern and eastern England. In the national survey common scab was the most prevalent disease, black scurf was less common and skin spot and powdery scab uncommon except in some Scottish crops.