bluuebunny/crossref_metadata_2025_split huggingface dataset:
Races and virulence of Fusarium oxysporum f.sp. cubense on local banana cultivars in Kenya
Authors: KUNG'U JACKSON N , JEFFRIES PETER 
Published: July 2006

SummaryVirulence of 31 Kenyan isolates of Fusarium oxysporum obtained from bananas showing symptoms of Panama disease was tested against the differential banana cvs Bluggoe, Gros Michel, Dwarf Cavendish, and two other local cvs Muraru and Wang'ae. Seventeen isolates were assigned to either race 1 or race 2 of F. oxysporum f.sp. cubense (FOC). Race 4 was not apparent in this sample of 31 isolates from Kenya as none were pathogenic to cv. Cavendish, and no wilted Cavendish have been observed in field surveys in Kenya. Races could not be assigned to 12 isolates as they were virulent on more than one differential cultivar, and two were apparently not pathogenic. All isolates assigned to races 1 and 2 belonged to the VCG bridging complex 0124/5/8/20, but some other isolates belonging to this VCG complex could not be assigned to race. All five isolates assigned to VCG 01212 could not be assigned to known races. Considerable variability thus exists within FOC isolates within this region. Local cultivars of banana showed differential resistance to the pathogen. The interaction of cultivars and isolates on the level of disease was significant. Overall, cv. Wang'ae was the most susceptible to most of the isolates tested, regardless of their race, and could therefore be used as a reference cultivar in pathogenicity tests of isolates of FOC in the East African region. Of the cultivars tested that are widely grown on smallholder farms in Kenya, Muraru was the least susceptible.
A multivariate analysis of cropping effects on Irish ground beetle assemblages (Coleoptera: Carabidae) in mixed arable and grass farmland
Authors: PURVIS GORDON , FADL ABDOULLA , BOLGER THOMAS 
Published: July 2006

SummaryThe assemblage of carabid species trapped over a 3 yr period in eight separate but contiguous fields was analysed by Canonical Correspondence Analysis (CCA), Seven of the fields were subject to arable crop rotations involving a mixture of autumn and early spring‐sown cereals (wheat or barley), late spring‐sown crops (potatoes, sugar and fodder beet and maize) and short‐term uncultivated grass leys, The eighth field was an established ‘permanent’ grass pasture of at least 50 yrs standing, Pooled samples collected in the first half of the growing season (April‐June) showed clear evidence of soil cultivation effects on community structure, Systematic exclusion of samples and re‐analysis distinguished the fauna of firstly, old pasture samples, samples from ley pastures of increasing age and finally samples from fields with different times of soil cultivation, In the latter analysis, the main effects of soil cultivation were related to differences in ground cover over the winter and a direct effect of spring soil cultivation on autumn breeding populations, The ordination of pooled catches for the second half of the growing season (July‐September) could not be related to known year, field or crop cultivation variables, The underlying species ordination suggested that later in the summer the effect of crop cover on soil microclimate may mask cultivation effects by influencing the post‐emergence dispersal of autumn‐breeding populations and the reproductive success of spring‐breeders, The combination of earlier soil cultivation effects, and probably microclimatic influences later in the season, resulted in the strong distinction of whole season carabid catches from individual fields, It is concluded that the uniqueness of individual field histories may provide a mechanism to promote the co‐existence of ecologically similar species within the farmed landscape and enhance the abundance and bio‐diversity of species in the face of routine soil cultivation.
The influence of branches and leaf area on rooting and development of Cotinus coggygria cv. Royal Purple cuttings
Authors: CAMERON R W F , HARRISON‐MURRAY R S , VAN CAMPFORT K , KESTERS K , KNIGHT L J 
Published: July 2006

SummaryThe influence of branches and mature leaves on the rooting and subsequent development of cuttings was examined, using Cotinus coggygria cv. Royal Purple. A model system was developed, whereby branched cuttings could be harvested from stock hedges and manipulated to alter leaf area, the number of actively‐growing, lateral branches and thus the source: sink ratio for photoassimilates. Highest percentage rooting ((80%) was promoted by retention of branches and a full leaf area. Reducing leaf area resulted in a lower rooting percentage (44%); however, greatest reductions in rooting were associated with the removal of lateral branches ((22%). Applying exogenous auxin (indole‐3‐butyric acid) at the excision point where branches had been removed significantly improved rooting potential, but did not fully substitute for the presence of branches with active shoot tips. Negative effects associated with removing a proportion of mature leaves appeared to relate to alterations in carbon balance rather than an influence on the supply of endogenous auxin to the potential rooting zone. The use of branched cuttings accelerated root and shoot development and resulted in a finished plant being produced more rapidly than is achieved from conventional, non‐branched cuttings. The results presented indicate a means for improving the efficiency of production of Cotinus coggygria, which may be applicable to a wider range of ornamental plants.
Effects of illumination source, culture ventilation and sucrose on potato (Solanum tuberosum) microtuber production under short days
Authors: ALIX M J , SAVVIDES S , BLAKE JENNET , HERRMANN R , HORNUNG R 
Published: July 2006

SummaryThe culture yield of a simple method of microtuber production of potato was increased by assessing the interactions of illumination source (Thorn Lighting (Philips) “Colour 84” lamps (TL‐84) or Grolux lamps (Sylvania) in a conventional growth room or natural light in a glasshouse cabinet), type of vessel closure (unventilated or ventilated) and sucrose concentration (1%, 2%, 4% or 8%).Microtuber initiation and growth in unventilated cultures was 100% at 8% sucrose falling to 40–50% at 4% sucrose and was absent at 1% or 2%. With ventilation, rapid tuberisation (90–100%) occurred at initial sucrose concentrations of 2–8%, but only when the medium was allowed to dry before transfer of cultures to short days. Water supplementation of cultures at day 28 prevented tuberisation at 1–4% sucrose up to day 56.The fresh weight and dry weight of microtubers per plant increased significantly with sucrose concentration, with ventilation of cultures and under natural light. In ventilated cultures, the mean number of usable microtubers (± 0.1 g weight) increased from between 1.0–1.4 per plant at 8% sucrose to between 1.6–2.6 per plant at 4% sucrose, with the highest numbers (1.8–2.6 per plant) produced under natural light for the cvs Desirée and King Edward. The mean % dry matter content of microtubers was reduced to 11.3% at 4% sucrose compared with 17.3% at 8% sucrose, but the survival rate of microtubers after 6 months storage was unaffected.Microtuber production under short days was improved at a higher intensity of natural light with culture ventilation in a partially‐shaded glasshouse cabinet, whilst using reduced inputs (lower sucrose supply and no lamps).
Factors affecting development of phoma canker (Leptosphaeria maculans) on stems of winter oilseed rape (Brassica napus) in southern England
Authors: SUN P , FITT B D L , STEED J M , UNDERWOOD C T , WEST J S 
Published: July 2006

SummaryIn winter oilseed rape experiments at Rothamsted in 1997/98 (cvs Lipton and Capitol), 1998/99 (cv. Apex) and 1999/2000 (cvs Apex, Lipton and Capitol), development of crown canker and phoma stem lesions in spring was related to development of phoma leaf spot in the previous autumn/winter. There were differences in thermal time (degree‐days) from the first appearance of phoma leaf spot (autumn) to the first appearance of crown canker (spring) between cultivars (cvs Lipton and Capitol, 1220–1240; cv. Apex, 1120–1140 degree‐days) but not between growing seasons. In 1998/99 and 1999/2000, fungicide (November) treatment delayed the start of crown canker development in the spring but did not affect the rate of increase in severity. In 1997/98, fungicide treatments did not delay the appearance of crown canker but decreased the rate of increase in crown canker severity. In all three seasons, fungicide treatments generally decreased the proportions of plants at harvest with crown canker severity scores 3 or 4 and increased the proportions with scores 0 or 1. There were differences between seasons in the distributions of crown canker severity scores at harvest. The severity of both crown canker and phoma stem lesions increased linearly with accumulated degree‐days in plots with or without fungicide treatment in 1997/98 (cv. Lipton), 1998/99 (cv. Apex) and 1999/2000 (cv. Apex). Regressions showed that severity of crown canker at harvest in July was related to severity in the spring in 1997/98 (early June, cv. Lipton), 1998/99 and 1999/2000 (April, cv. Apex).
Mycelial growth inhibition of plant pathogenic fungi by extracts of South African plant species
Authors: EKSTEEN D , PRETORIUS J C , NIEUWOUDT T D , ZIETSMAN P C 
Published: July 2006

SummaryEleven plant species were collected from the Blyde River Canyon area, Mpumalanga, South Africa. Methanolic crude extracts of the plant samples were concentrated to dryness, dissolved in sterile distilled water and bioassayed in the laboratory for their fungicidal potential against seven plant fungal pathogens, namely Botrytis cinerea, Fusarium oxysporum, Sclerotium rolfsii, Rhizoctonia solani, Verticillium dahliae, Botryosphaeria dothidea and Pythium ultimum, at equal concentrations.A modified agar dilution method was used to determine the inhibitory effect of the plant extracts on the mycelial radial growth of the plant pathogens. Antifungal activity was confirmed in all the plants, but not in all plant parts and also not against all the test organisms. The crude extract of Eucomis autumnalis performed best of all the plant extracts tested, as it showed significant antifungal activity against all seven of the plant pathogenic test organisms and compared favourably to the inhibition of the mycelial growth by a broad spectrum synthetic fungicide (carbendazim/ difenoconazole). The crude extract of Schrebera alata came out second best, in the sense that at least one plant part inhibited the mycelial radial growth of four of the seven test organisms by at least 50%.
A rapid PCR method to discriminate between Tomato yellow leaf curl virus isolates
Authors: MARTÍNEZ‐CULEBRAS PEDRO VICENTE , FONT ISABEL , JORDÁ CONCEPCIÓN 
Published: July 2006

Summary Tomato yellow leaf curl virus (TYLCV) was recently divided into two different species: Tomato yellow leaf curl virus‐Israel (TYLCV‐Is) and Tomato yellow leaf curl virus‐Sardinia (TYLCV‐Sar). There are no rapid methods by which TYLCV viruses may be assigned to either TYLCV‐Is or TYLCV‐Sar species. In the present work, using an extensive alignment of begomovirus sequences, TYLCV‐specific primers were designed and tested which allow the specific amplification of DNA fragments from any isolate of TYLCV. Also, a primer was designed and tested which allows the specific amplification of TYLCV‐Sar. Furthermore, a combination of these primers was selected to develop a duplex PCR method, which has the potential to detect either TYLCV‐Is or TYLCV‐Sar. The PCR methods were also highly effective with minimal sample preparation and allowed direct amplification of TYLCV from infected leaf extracts. This approach may be used in the laboratory as a tool for rapid, large‐scale diagnostics of TYLCV‐infected samples.
Additional sources of resistance to groundnut rosette disease in groundnut germplasm and breeding lines
Authors: OLORUNJU P E , NTARE B R , PANDE S , REDDY S V 
Published: July 2006

SummaryGroundnut rosette, a virus disease of groundnut (Arachis hypogaea) transmitted by the aphid, Aphis craccivora Koch, reduces yield in susceptible cultivars by 30–100%. Additional sources were sought in germplasm accessions involving 2301 lines from different sources and from 252 advanced breeding lines derived from crosses involving earlier identified sources of resistance to rosette. The lines were evaluated in field screening trials using an infector row technique during 1996 and 1997 growing seasons. Among the germplasm lines, 65 accessions showed high levels of resistance while 134 breeding lines were resistant. All rosette disease resistant lines were susceptible to groundnut rosette assistor virus. This work identified germplasm and breeding lines that will contribute to an integrated management of groundnut rosette disease. These new sources also provide an opportunity to eliminate yield losses due to the rosette disease.
Influence of day length and temperature on number of main stem leaves and time to flowering in lupin
Authors: CHRISTIANSEN J L , JØRNSGÅRD B 
Published: July 2006

SummaryA growth chamber experiment was carried out to investigate the influence of day length and temperature on the development of flowering in eight varieties of the three grain lupin species Lupinus albus (Wat and C3396), L. angustifolius (Gungurru, Polonez and W26) and L. luteus, (Juno, Radames and Teo). The plants were grown at two temperatures, 10°C and 18°C, in combination with five daylength regimes: 10, 14, 18, 24 h day at full light intensity and 10 h full light extended with 8 h low intensity light. Increased daylength decreased days from sowing to flowering in all varieties, but had little effect on thermal time to flowering in most varieties. However, C3396, W26 and Radames had a significantly longer thermal time to flowering at high, non‐vernalising temperature (18°C) at short daylengths. Low light intensity daylength extension did not significantly influence thermal time to flowering. For flower initiation, measured as number of leaves on the main stem three types of response were found. All varieties formed fewer leaves on the main stem at 10°C than at 18°C, although the two thermo‐neutral varieties of L. luteus, Juno and Teo, gave only a small response to temperature and daylength. In Polonez, Gungurru and Wat, low temperature decreased leaf number, but there was only a small response to changes in daylength. Three varieties, C3396, W26 and Radames, showed longer thermal time to flowering at 18°C with short daylengths. This could be explained by a greater number of main stem leaves formed at short daylength at non‐vernalising temperatures. Increased daylength decreased leaf number in these varieties, but never to a smaller number than for plants grown at 10°C. In these varieties, low intensity extension of the daylength had a similar (W26, Radames) or decreased (C3396) effect compared to full light extension. The hastening of time to flowering by long days could be separated into two effects: a high light energy effect hastened development by increasing the rate of leaf appearance in all varieties, while low light energy in thermo‐sensitive varieties was able to substitute for vernalisation by decreasing leaf number.
Temporal dynamics of spread of four viruses within mixed species perennial pastures
Authors: COUTTS B A , JONES R A C 
Published: July 2006

SummarySix mixed species, perennial pastures at two locations, A (four pastures) and B (two pastures), were sampled at regular intervals over periods of 10 to 22 months. The predominant plant species present were white clover (Trifolium repens), perennial ryegrass (Lolium perenne) and kikuyu grass (Pennisetum clandestinum). To determine the extent to which incidences of viruses transmitted in different ways change in the same pastures over time, samples of each plant species were taken at random on every visit and tested for virus presence. To help identify factors that might explain changes in virus incidence, records were also made of aphid presence, pasture management practices, grazing regimes, sward height and the relative proportions of different plant species within the swards. Samples of white clover were tested for presence of Alfalfa mosaic virus (AMV) and White clover mosaic virus (WCMV), ryegrass for Barley yellow dwarf virus (BYDV) and Ryegrass mosaic virus (RyMV), and kikuyu grass for BYDV and potyvirus infection. AMV and WCMV were detected in white clover, and BYDV and RyMV in ryegrass at both locations but often with wide incidence fluctuations for the individual viruses. AMV incidences in white clover ranged from 0% to 19% at A, and from 27% to 100% at B. WCMV incidences in white clover fluctuated between 9% and 46% at B, but never exceeded 1% at A. RyMV incidences in ryegrass fluctuated between 3% and 34% at A, and 19% and 73% at B. BYDV incidences in ryegrass ranged from 0% to 6% at A and 4% to 17% at B. In kikuyu grass, an unknown potyvirus and BYDV were detected twice (1% incidence) and once (4% incidence) respectively at B, and the unknown potyvirus only once (2% infection) at A. During repeated trapping of aphids in four pastures (two each at A and B), numbers of aphids caught varied widely between trapping dates and between individual pastures on the same trapping date. The species caught were Acyrthosiphon kondoi, A. pisum, Aphis craccivora, Rhopalosiphum padi and Therioaphis trifolii. Except in summer, when only T. trifolii was caught, A. craccivora was the most abundant.The trends in incidence for each virus within each pasture were compared with those from the other pastures sampled over identical periods to determine whether there was any commonality. For RyMV in ryegrass, overall incidence trends within the different pastures at both locations resembled each other during the same sampling periods. Within pastures at the same location there was commonality in incidence trends for RyMV and BYDV in ryegrass, but with AMV in white clover periods of similarity were rare even when pastures were adjacent and managed identically. Unravelling the individual effects of alterations in season, vector numbers, mowing, intermittent heavy grazing and pasture species composition on virus incidence proved difficult due to complex interactions between these and other factors influencing new spread or declining virus occurrence.
Susceptibility of the eggs of the field slug Deroceras reticulatum to contact with pesticides and substances of biological origin on artificial soil
Authors: IGLESIAS J , CASTILLEJO J , ESTER A , CASTRO R , LOMBARDIA M J 
Published: July 2006

SummaryThe toxicity of 14 substances, including a number of pesticides, to the eggs of the pest slug Deroceras reticulatum was determined in laboratory experiments. Eggs were kept in contact with a precisely defined artificial soil to which a range of concentrations of the test substances had been applied. Mortality of the eggs was assessed every 24 h and the median lethal doses (LD50) were determined. The herbicides bromoxynil, ioxynil and pyridate + bromoxynil, the insecticides thiocyclam, diflubenzuron and azadirachtin, the molluscicides metaldehyde and methiocarb, and other compounds such as carvone, iron‐EDDHA, saponin, and an extract of Pongamia pinnata, killed the eggs after periods of exposure ranging from 2 to 14 days, depending on the compound and the dose. Only two compounds, the insecticides imidacloprid and teflubenzuron, failed to kill the eggs of D. reticulatum at any of the doses tested. Values of LD50 below 0.01 mg a.i. cm−2 were obtained for the herbicides bromoxynil, ioxynil and pyridate + bromoxynil, and for the biological pesticide azadirachtin. The feasibility of slug egg control in different contexts is discussed.
Deploying strain specific hypersensitive resistance to diminish temporal virus spread
Authors: CHENG Y , JONES R A C , THACKRAY D J 
Published: July 2006

SummarySpread of necrotic and non‐necrotic strains of Bean yellow mosaic virus (BYMV) was compared when aphid vectors moved both types from external or internal virus sources to plots of Lupinus spp. (lupin). Regardless of whether virus sources were internal or external, removed or left in place, and spread was within plots with homologous sources or across buffers to plots containing the opposite type of virus source, non‐necrotic BYMV always spread faster than necrotic BYMV in plots of L. angustifolius (narrow‐leafed lupin). When necrotic BYMV spread from external sources into plots sown with two L. angustifolius genotypes differing in their necrosis responses to different BYMV strain groups and one genotype of L. luteus (yellow lupin) giving only non‐necrotic responses, differing symptom reactions in the two L. angustifolius genotypes revealed presence of two distinct necrotic BYMV strain groups and overall virus spread was greater in this species than in L. luteus. Spread of non‐necrotic BYMV in L. angustifolius was always polycyclic in nature. However, when it came initially from external sources, spread of necrotic BYMV was largely monocyclic. This work demonstrates how temporal virus spread can be diminished when hypersensitive (necrotic) resistance is deployed and the limitations associated with employing hypersensitivity that is strain specific.
Cytopathology of Plgeonpea sterility mosaic virus in pigeonpea and Nicotiana benthamiana: similarities with those of eriophyid mite‐borne agents of undefined aetiology
Authors: KUMAR P LAVA , DUNCAN G H , ROBERTS I M , TEIFION JONES A , REDDY D V R 
Published: July 2006

Summary Pigeonpea sterility mosaic virus (PPSMV) is transmitted by the eriophyid mite, Aceria cajani, and is very closely associated with sterility mosaic disease (SMD) of pigeonpea (Cajanus cajah) in the Indian subcontinent. Antiserum produced to purified PPSMV preparations detected a virus‐specific 32 kDa protein in sap of SMD‐affected pigeonpea plants by ELISA and Western blotting. PPSMV was transmitted mechanically in sap of SMD‐affected pigeonpea leaves to Nicotiana benthamiana. Ultrastructural studies of symptom‐bearing leaves of two pigeonpea cultivars, (ICP8863 and ICP2376) and N. benthamiana infected with PPSMV, detected quasi‐spherical, membrane bound bodies (MBBs) of c. 100–150 nm and amorphous electron‐dense material (EDM). These structures were distributed singly or in groups, in the cytoplasm of all cells, except those in conductive tissues. Fibrous inclusions (FIs), composed of randomly dispersed fibrils with electron lucent areas, were present in the cytoplasm of palisade cells and rarely in mesophyll cells of the two pigeonpea cultivars but were not detected in infected TV. benthamiana plants. In the PPSMV‐infected pigeonpea cultivars and TV. benthamiana, immuno‐gold labelling, using antiserum to PPSMV, specifically labelled the MBBs and associated EDM, but not the FIs. The MBBs and associated inclusions are similar in appearance to those reported for plants infected with the eriophyid mite‐transmitted High Plains virus and the agents of unidentified aetiology associated with rose rosette, fig mosaic, thistle mosaic, wheat spot chlorosis and yellow ringspot of budwood. The nature of these different inclusions is discussed.