bluuebunny/crossref_metadata_2025 huggingface dataset:
A cohort study of pregnancy outcome after amniocentesis in twin pregnancy
Authors: Kidd Sharon A. , Lancaster Paul A.L. , Anderson John C. , Boogert Antheunis , Fisher C. Coll , Robertson Rob , Wass Debbie M.
Published: November 2003

We conducted a retrospective cohort study to assess the risk of amniocentesis in twin pregnancy for adverse outcomes. The study base consisted of women who had an amniocentesis performed during twin pregnancy and a comparison representative sample of women who carried a twin pregnancy, but did not have invasive prenatal diagnosis. The 227 women in each of the exposed and non‐exposed groups were residents of the state of New South Wales, Australia, over the period 1980–92, and were matched on maternal age and period of the infant’s birth. Nearly 10% of twin pregnancies among the women having an amniocentesis were affected by a stillbirth, and the stillbirth rate among exposed fetuses (5.3%) was nearly twice as high as among non‐exposed fetuses (3.1%). After adjustment for confounding and excluding abnormalities, there was a non‐significant elevated relative risk of stillbirth after exposure to amniocentesis. The analysis by type of amnio‐centesis (with and without methylene blue dye) was limited by small numbers, but the burden of risk was primarily among women who had dye exposure during amnio‐centesis (relative risk = 3.64, 95% confidence interval = 1.15, 11.48). This increase remained after adjusting for confounding, although the confidence interval was wide. In conclusion, we were unable to establish with certainty whether an increased risk of stillbirth could be ruled out among women who had any type of amnio‐centesis in twin pregnancy.
Infant mortality in Norway and Sweden 1975–88: a cause‐specific analysis of an increasing difference
Authors: Daltveit Anne Kjersti , Vollset Stein Emil , Otterblad‐Olausson Petra , Irgens Lorentz M.
Published: November 2003

In a previous article, a high infant mortality was reported in the 1980s in Norway compared with Sweden. The aim of the present study was to assess secular trends in this difference, and to clarify whether the difference was confined to particular causes of death. Mortality rates, ratios of mortality rates and numbers of excess deaths were calculated on the basis of birth records comprising all livebirths in Norway and Sweden during the two periods 1975–79 and 1985–88. From the first to the second period, the infant mortality ratio for Norway to Sweden increased from 1.22 to 1.45 for single births, and from 1.23 to 1.54 for twin births. Increasing mortality ratios were observed for all ages at death. These were lowest in the early neonatal period (1.09 and 1.20 respectively) and highest in the postneonatal period (1.53 and 1.78 respectively). Within each cause of death category, the mortality rate in Norway was equal to or higher than the rate in Sweden. The highest mortality rate ratios were observed for sudden infant death syndrome (SIDS), 2.44 and 2.46 respectively, for the two time periods. SIDS was also the single cause of death that gave the largest contribution to the Norwegian excess mortality (45% and 53% overall, 65% and 78% for postneonatal deaths, and 65% and 79% for birthweights above 2500 g). In the second period, the excess SIDS mortality in Norway pertained mainly to infants of young mothers, infants of birth order two or more and twin births. An adverse trend for infants of young mothers in Norway was also observed in non‐SIDS deaths. This suggests that in Norway, preventive health care should be improved, particularly for young mothers and their infants.
The effects of housing on the health of preterm infants
Authors: Emond Alan M. , Howat Pamela , Evans Julie‐Ann , Hunt Linda
Published: November 2003

Using a prospective study based on cases and controls selected from a geographical population, we have investigated the effects of housing on the health of very preterm infants ( 32 weeks’ gestation) during the first year of life. Information on health morbidity of the 117 preterm and 226 term babies was collected using a parent‐held record, and housing data by a validated self‐completion questionnaire. The most common health problems in the first year – upper (UR) and lower (LR) respiratory tract infection, otitis media (OM) and diarrhoea and vomiting (DV) – were all more frequent in the preterm group, There were no significant differences in the housing conditions to which preterm and control infants were exposed. Relative risks (RR) and 95% confidence intervals (CI) associated with each housing factor were calculated for preterm and control infants separately. Significant (P < 0.05) interaction effects were found for overcrowding and gas cooking. Overcrowding was associated with an increased incidence of LR [RR = 1.53; CI 0.96–2.42] and DV [RR = 1.57; CI 0.92–2.67] in the preterm, but with a decreased incidence of LR [RR = 0.28; CI 0.04–1.86] and DV [RR = 0.85; CI 0.30–2.38] in the term controls. The use of gas ovens was found to be associated in preterm infants with an increase in LR [RR = 1.48; CI 0.96–2.28] and DV [RR = 2.24; CI 1.28–3.93] but the controls did not show this effect for LR [RR = 0.67; CI 0.40–1.09] or DV [RR = 0.93; CI 0.56–1.56]. These associations are robust – even after allowing for confounding social factors – but causality has not been proved. This work suggests that preterm infants may be vulnerable to specific adverse housing factors, and further studies are now indicated to clarify potential mechanisms and interactive effects behind these associations.
Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking
Authors: Horta Bernard Lessa , Victora Cesar Gomes , Menezes Ana Maria , Halpern Ricardo , Barros Fernando C.
Published: November 2003

The association between the intensity and duration of cigarette smoking during pregnancy and the frequency of low birthweight, preterm births and intrauterine growth retardation was investigated in a historical cohort. All 5166 livebirths occurring in the city of Pelotas, Brazil, during 1993 were identified and mothers interviewed soon after delivery. Children whose mothers smoked during pregnancy had a birthweight 142 g lower than those of non‐smoking mothers. The odds ratio for low birthweight among children of smokers was 1.59 [95% CI 1.30–1.95]. There was no association between smoking and preterm delivery assessed by the Dubowitz score. In relation to intrauterine growth retardation, smoking was associated with an odds ratio of 2.07 [95% CI 1.69–2.53]. There was a direct dose–response association between the number of cigarettes smoked and the risk of growth retardation. Women whose partner smoked were also at higher risk of having a child with growth retardation. All the above results were adjusted for confounding factors. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth retardation rather than preterm delivery.
Evaluation of parental participation in a case–control study of infant leukaemia
Authors: Mertens Ann C. , Robison Leslie L.
Published: November 2003

This study was performed to evaluate participation rates and characteristics of participants in a case–control study of infant leukaemia. Eligible cases were identified throughout the United States, and two controls were selected for each case using a structured protocol for telephone random digit dialling. The non‐participation rate, once a household agreed to provide an address to receive a letter explaining the study, was 7.9% for cases and 19.8% for controls. When comparing demographic differences between participants and non‐participants, parents of eligible cases that participated were more likely than non‐participating case parents to be white (P = 0.01) and to be currently married (P = 0.03); parents of eligible controls who participated were more likely than non‐participating parents of eligible controls to have a higher education level (P < 0.01), more children under the age of 10 years (P = 0.05) and to be white (P < 0.01). These data have application for future studies involving infants with a serious disease and the use of random digit dialling for the selection of infant controls.
The effect of mode of delivery on neonatal mortality in very low birthweight infants born in Victoria, Australia: Caesarean section is associated with increased survival in breech‐presenting, but not vertex‐presenting, infants
Authors: Jonas Helen A. , Lumley Judith M.
Published: November 2003

To determine whether the improved survival of very low birthweight (VLBW) infants (< 1500 g) born in Australia can be attributed to currently high rates of Caesarean section, we examined the associations between neonatal mortality and Caesarean section in singleton liveborn VLBW infants (500–1499 g) born during 1986–93 in Victoria, Australia, using data from the Victorian Perinatal Collection Unit. The infants included in this study had completed > 23 weeks of gestation, had no life‐threatening malformations and had not been delivered by a repeat Caesarean without a trial of labour (n = 2763). For infants weighing 500–749 g, 750–999 g, 1000–1249 g and 1250–1499 g, the neonatal mortality rates were 56.1%, 25.7%, 13.0% and 4.3% respectively, and the Caesarean section rates were 33.1%, 42.3%, 54.8% and 55.8%. Nearly half of these births (n = 1269) were associated with one or more obstetric indications for Caesarean section (non‐breech malpresentaion, fetal distress, prolapsed cord, placenta praevia, pre‐eclampsia and hypertension). Overall, the odds ratio (OR) for neonatal death associated with Caesarean section was 0.92 [95% confidence interval 0.60–1.41], after adjustment for gestational age, birthweight, year of birth, type of hospital, presence or absence of labour, presentation and obstetric indications for Caesarean section. However, when the vertex‐presenting (n = 1702) and breech‐presenting (n = 746) infants were considered separately, the adjusted ORs for neonatal death were 1.98 [0.96–4.10] and 0.52 [0.29–0.96] respectively. For those infants without obstetric indications for Caesarean section, the adjusted ORs for neonatal death in vertex‐presenting (n = 950) and breech‐presenting (n = 446) infants were 3.80 [1.11–13.0] and 0.47 [0.23–0.6]. These recent population ‐ based data support the view that Caesarean section does not enhance the neonatal survival of VLBW babies when obstetric complications are absent.
The relationship of drinking and birth outcome in a US national sample of expectant mothers
Authors: Faden Vivian B. , Graubard Barry I. , Dufour Mary
Published: November 2003

Alcohol consumption by pregnant women and birth outcome were studied in 9953 livebirths, 3309 fetal deaths and 5332 infant deaths from the 1988 National Maternal and Infant Health Survey. In crude analyses, race, age, mother’s education, prenatal care, parity, low birthweight, gestational age, smoking and alcohol consumption during pregnancy were significantly related to the occurrence of fetal deaths and infant deaths. Among women having livebirths, race, age, mother’s education, prenatal care, prematurity, gestational age, smoking and alcohol consumption during pregnancy were significantly related to having a low birthweight baby (< 2500 g). In this group, women who drank more during pregnancy also smoked more, were younger and less educated than women who drank at lower levels or not at all. The relationship of alcohol consumption during pregnancy and infant birthweight for those women having livebirths was studied using multivariable linear regression. The results indicated that race, mother’s education, baby’s sex, parity, mother’s height, mother’s body mass index and smoking, but not alcohol consumption, were significantly related to birthweight. Multivariable logistic regressions were performed for the occurrence of low birthweight, fetal death and infant death. The effect of alcohol was significant in all these analyses. These results indicate that alcohol has an important relationship with birth outcome, but that for the drinking reported in this study, the alcohol effect on mean birthweight is small relative to that of other risk factors, accounting for the non‐significant result in the multiple linear regression.
Non‐radioactive molecular hybridization detection of carnation mottle virus in infected carnations and its comparison to serological and biological techniques
Authors: SÁNCHEZ‐NAVARRO J. A. , CANO E. A. , PALLÁS V.
Published: November 2003

A non‐radioactive molecular hybridization method was developed to detect carnation mottle virus (CarMV) in carnation plants. This method was compared to the standard ELISA test and biological assays. For crude plant extracts, the molecular hybridization technique proved to be at least 125 times more sensitive than double‐antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA). The method was adapted to avoid the necessity to clarify the samples by centrifugation and to use pipettes to load them. By introducing this modification, the hybridization assay was found to be a suitable method for routine virus detection. The relative benefits of using this procedure for large‐scale indexing are discussed.
The biology and pathology of the fungus Rhizopusstolonifer, cause of black mould disease of table grapes in Israel
Authors: LISKER N. , KEREN‐SHACHAM Z. , SARIG P. , ZUTKHI Y. , BEN‐ARIE R.
Published: November 2003

Rhizopus
stolonifer causes severe losses to Israeli grape exports. The fungus develops on mature berries in the field, during storage at temperatures above 08C and during shelf‐life. It was isolated from naturally contaminated soils throughout the year, and from fruits after mid‐June. The airborne spore population increased in vineyards at the time of fruit maturation and was related to the proximity of stone‐fruit orchards. The size of this population was highly correlated with disease incidence and thus may be a satisfactory tool for disease prediction. Intact young berries were more resistant than mature ones to Rhizopus inoculation, in both the vineyard and in the laboratory. Mechanical wounding, or chloroform dips, dramatically increased the susceptibility of young berries. The decline in acidity and the increase in the soluble solids content during growth and maturation of the berry were accompanied by an increase in susceptibility to inoculation. Scanning electron microscopy showed the fruit surface to be covered with white amorphous structures. At higher magnifications small cracks (approximately 1 μm in length) were observed on the surface but in no case was fungal penetration noticed through these cracks. In artificially inoculated fruits the fungus germinated near the wound and developed vigorously inside and around the fissure, producing sporangia. The young sporangium is covered by a smooth external layer which is compressed against the sporangiospores. After lysis of the cover, the young hexagonal sporangiospores can be observed. With maturation, the columella collapses and the mature sporangiospores are dispersed. In naturally infected berries, an important path for fungal penetration is the incomplete connection between the berry and the pedicle. Heavily infested berries become disconnected from their pedicles. Two chemicals applied to the surrounding atmosphere, orthophenyl phenate (as a fog) and calcium hypochlorite (as chlorine vapour), significantly decreased postharvest decay in artificially inoculated berries.
Degradation of stilbene‐type phytoalexins in relation to the pathogenicity of Botrytis cinerea to grapevines
Authors: SBAGHI M. , JEANDET P. , BESSIS R. , LEROUX P.
Published: November 2003

The ability of eight isolates of Botrytis cinerea to degrade the stilbene phytoalexins, resveratrol and pterostilbene, was compared with their pathogenicity to grapevines. All strains which degraded resveratrol and pterostilbene were highly or moderately pathogenic to in vitro cultures of grapevines (Vitis rupestris) after inoculation with agar disks containing mycelium, while those which were unable to degrade phytoalexins were non‐pathogenic. In all cases, the hydroxystilbene‐degrading activity was related to the presence of laccase activity in the culture filtrates, as shown by using syringaldazine as substrate. The role of laccase‐mediated degradation of phytoalexins in relation to pathogenicity of B. cinerea to grapevines in discussed.
Naturally occurring variants of citrus exocortis viroid in vegetable crops
Authors: FAGOAGA C. , DURAN‐VILA N.
Published: November 2003

Four viroids were isolated in crops of tomato, eggplant, carrot and turnip. They were detected only after inoculation of ‘Rutgers’ tomato with nucleic acid extracts from field plants and were characterized as variants of citrus exocortis viroid (CEVd). The size of the variants ranged from 371 to 374 nucleotides and they contained nucleotide exchanges and insertions affecting all structural domains. Symptoms were induced in tomato and carrot whereas eggplant and turnip responded as symptomless carriers. As the samples came from an area where no citrus is grown, it appears that these viroids have a reproductive cycle independent of this crop, and perhaps involving wild plants or other vegetables.
Field evaluation of a predictive model to control anthracnose disease of mango in the Philippines
Authors: ESTRADA A. B. , JEFFRIES P. , DODD J. C.
Published: November 2003

Infection estimates determined by a predictive model developed by Dodd et al. (1991b) were used to time fungicide sprays to control anthracnose disease of mango in the Philippines. For an amount of disease on fruits after harvest which was acceptable to growers, this approach resulted in the application of five fewer sprays compared with a standard spray programme used by the growers in a field trial conducted in 1991–1992. The model predicted only two high anthracnose‐risk periods (>40% of conidia forming appressoria) throughout the duration of the growing period. Rainfall intensity and its time of occurrence during fruit development was found to greatly influence the amount of anthracnose and stem‐end rot disease on fruits after harvest. Three relatively strong precipitations (>20 mm) within a month before harvest resulted in relatively high anthracnose infection of fruits after harvest. At a second field trial, rainfall periods during fruit development did not exceed 4 mm and resulted in virtually disease‐free fruits after harvest, including those not treated with fungicide. Again the use of the predictive model resulted in the elimination of five fungicide treatments compared with the standard programme. The amount of rainfall and the time of its occurrence should be considered when planning a disease management scheme for the control of anthracnose on mango fruit.
The effect of phenylamide fungicides on the control of potato late‐blight (Phytophthora infestans) in England and Wales from 1978 to 1992
Authors: BRADSHAW N. J. , VAUGHAN T. B.
Published: November 2003

During the period 1978–1992, phenylamide fungicides in co‐formulation with the dithiocarbamate fungicide mancozeb were tested for the control of potato late‐blight in 51 separate field experiments in England and Wales. Whilst there was a general trend over all the experiments which indicated that foliage blight was less severe where the phenylamide + dithiocarbamate mixture had been used, the benefit was more marked in some than in others. Despite the detection of phenylamide resistance, at some sites the mixture gave better control of foliage blight than the dithiocarbamate alone. At one site where continuous data were available, the additional benefit of the phenylamide compound for control of foliage infection was lost after 1986 coinciding with a rise in phenylamide resistance from 31.7% in 1986 to 81% in 1987. Where foliar blight epidemics occurred, yield responses to fungicide programmes compared with unsprayed controls ranged from 0 to +118.5% with a mean response of +30.2%. This is equivalent to 30.8 and 12.92 t/ha respectively. Standardized yield differences were calculated to allow inter‐trial and inter‐year comparisons and showed no benefit from the phenylamide fungicide applied at 14‐day intervals in 33 out of 38 experiments where foliar blight epidemics occurred. At one site, Cusum analysis of standardized yield differences following treatment with the phenylamide + dithiocarbamate mixture and the dithiocarbamate alone showed a mean benefit from the phenylamide mixture of 2.23 t/ha during the period 1978 to 1986. From 1987 to 1992, the yield benefit dropped to a mean level of 0.68 t/ha a decrease of 69.5%. In experiments where blight was not recorded, fungicide treatments had no deleterious effect on yields. Over all the trials, there was no effect of fungicide treatment on the incidence of tuber blight at harvest.
Sensitivity of South African Ramulispora herpotrichoides isolates to carbendazim and ergosterol biosynthesis inhibitors
Authors: ROBBERTSE B. , HOLZ G. , CROUS P. W.
Published: November 2003

In a survey conducted during 1991–1992, single‐spored isolates of the eyespot fungus from the Swartland area were characterized and tested for sensitivity to carbendazim and ergosterol inhibiting fungicides. The 100 isolates tested were all fast growing, even marginate, and designated as Ramulispora herpotrichoides. Fungal growth was completely inhibit on PDA amended with carbendazim (1 μg/ml), indicating that the local population of the fungus is still at baseline sensitivity to benzimidazoles. The mean concentration of prochloraz calculated to inhibited growth by 50% (IC50 value) was 0.043 ± 0.029 μg/ml, which is comparable with the baseline sensitivity reported for European isolates. Of the 36 representative isolates screened against 2 μg/ml triadimenol, 44% were sensitive, while 36% were resistant. The triadimenol‐resistant isolates were sensitive to propiconazole and flusilazole. However, four of the triadimenol‐resistant isolates were also resistant to tebuconazole. These results indicate that South African isolates of R. herpotrichoides are sensitive towards carbendazim, prochloraz, propiconazole and flusilazole. They were found to differ, however, in sensitivity towards triadimenol and tebuconazole, where some isolates had an IC50 value greater than 2 μg/ml.
Isozyme variability among isolates of Phaeoisariopsis griseola in southern Africa
Authors: BOSHOFF W. H. P. , SWART W. J. , PRETORIUS Z. A. , LIEBENBERG M. M. , CROUS P. W.
Published: November 2003

Angular leaf spot caused by Phaeoisariopsis griseola is an economically important disease of beans (Phaseolus vulgaris) in southern Africa. The success of local programmes breeding for resistance to this disease depends to a large extent on the genetic variation within the pathogen population. To assess variability within the pathogen, 28 isolates of P. griseola from various localities were compared using isozyme analysis by means of starch gel electrophoresis. Thirteen loci were identified in 10 enzyme systems. Using UPGMA, three electrophoretic types were detected. The most common type included the South African isolates, namely seven from the Mpumalanga and KwaZulu‐Natal provinces, respectively, 10 from Malawi, and one from Portugal. Two isolates from Bembeke in Malawi, and one from the Netherlands, differed from the rest. An isolate of Phaeoramularia angolensis, used as an outgroup, differed from the P. griseola isolates in all enzyme systems tested. The high homology of banding patterns among isolates of P. griseola from southern Africa suggests the local population to be uniform.
Relationships between populations of Pseudomonas syringae pv. persicae determined by restriction fragment analysis
Authors: YOUNG J. M. , JONES D. S. , GILLINGS M.
Published: November 2003

Pseudomonas syringae pv. persicae, the pathogen causing bacterial decline of stone‐fruit, was first noted almost simultaneously in France and in New Zealand, together with a closely related pathogen from myrobalan plum in England. The relative similarity of 31 strains from these three countries was examined by comparing DNA restriction endonuclease fragment patterns. Fragment patterns produced from digested DNA samples which were electrophoresed on polyacrylamide gels and visualized by silver‐staining, were analysed using the software package Gelcompar. The fragment patterns produced by strains from France and England formed homogeneous but separate groups, while those from New Zealand were relatively heterogeneous. This finding suggests that the New Zealand population of P.s. persicae is older than those found in Europe. Problems in explaining the distribution of the pathogen are discussed.
Differentiation of Xanthomonas albilineans strains with monoclonal antibody reaction patterns and DNA fingerprints
Authors: ALVAREZ A. M. , SCHENCK S. , BENEDICT A. A.
Published: November 2003

Thirty‐eight strains of the sugarcane leaf scald pathogen, Xanthomonas albilineans, were compared using a series of seven species‐specific monoclonal antibodies as well as genomic DNA fingerprint patterns. The strains, which were obtained from 13 countries and states in the USA, were placed in three major groups with approximately eight subgroups based on similarity of their serological reactions. The serological groupings correlated strongly with groupings based on DNA fingerprint patterns. The groups of strains that were genetically and serologically related did not necessarily come from nearby locations but were usually from widely separated regions. Thus, it appears that disease transmission occurred by means other than natural spread. The methods used in this study are useful for comparing relationships among strains of X. albilineans. A combination of the monoclonal antibodies could be used in a serodiagnostic‐based method to test for the presence of leaf scald disease.
Biological control of Botrytis stem infection of greenhouse tomatoes
Authors: EDEN M. A , HILL R. A , STEWART A
Published: November 2003

Botrytis cinerea infects stem wounds of greenhouse tomatoes and can cause serious economic losses. A bioassay using stem sections was developed to study wound infection and to screen potential fungal antagonists for activity against BotrytisCladosporium cladosporioides reduced infection from 80–100% to 0–10%. A much smaller proportion of Trichoderma harzianum gave this reduction. Similar results were obtained on whole plants. Penicillium isolates varied widely in activity. The concentration of Cladosporium and Trichoderma which gave the highest level of protection was c. 108 cfu/mL. When only half the wound was treated, simulating poor spray coverage, Cladosporium isolates still prevented infection. By contrast, Trichoderma isolates and four fungicides failed to give the same level of protection. The ability of certain fungal isolates to colonize the wound surface was thought to be partly responsible for this activity. The successful application of antagonists to whole plants using both aqueous suspensions and gel secateurs is described.
Inoculum potential of Pythium arrhenomanes in soils from three crop rotation experiments
Authors: OLSSON S.
Published: November 2003

Soil from crop rotation experiments at three different sites was tested by using bait plants and a most probable number (MPN) method to estimate the inoculum potential of Pythium arrhenomanes in terms of the density of infective units. Recorded values varied between 0 and 85 infective units/kg soil. In soil from one of the sites the inoculum densities following barley monoculture were significantly higher than those from crop rotations, whether sampled in the spring or autumn. At the other two sites, which had consistently lower inoculum densities, small effects of rotation treatment were also recorded when they were sampled in the autumn. However, the results did not support the tentative conclusions of earlier studies, that inoculum of P. arrhenomanes could be a major cause of yield reduction in barley monoculture. The MPN method cannot be recommended for predicting expected disease levels of P. arrhenomanes, unless the infective unit can be carefully defined and its relation to yield loss reliably established.
Red leaf blotch (Dactuliochaeta glycines) of soybeans (Glycine max) and its relationship to yield
Authors: HARTMAN G. L. , SINCLAIR J. B.
Published: November 2003

Red leaf blotch of soybeans, caused by Dactuliochaeta glycines, was evaluated on soybean plants in field plots located in Zambia. Two experiments were conducted in each of two seasons. Experiment 1 had four cultivars that were either fungicide‐sprayed or not sprayed. Disease severity was greatest on leaves at the lowest nodes from early vegetative through the reproductive growth stages. Area under the disease progress curve (AUDPC) values and percentage of nodes defoliated at growth stage R5 were significantly (P = 0.05) greater in unsprayed plots for all cultivars in both seasons. Yield losses ranged from 8 to 37% while reduced seed size ranged from 21 to 29% for the four cultivars. Number of pods per plant in fungicide‐sprayed plots did not differ from those in unsprayed plots. However, the number of seeds per plant and seeds per pod were significantly (P = 0.05) greater in sprayed than unsprayed plots for some cultivars. In experiment 2, cultivar Tunia was either fungicide‐sprayed at different times or not sprayed. The lowest attached leaf had the most variation in the amount of disease while ratings of the most median leaf in the canopy were generally less variable. The AUDPC values calculated from the lowest attached leaf, the mean of all attached leaves, and the median attached leaf differed significantly (P = 0.05) the number of times plants were sprayed with fungicide. Defoliation and vertical incidence of red leaf blotch from lower to higher nodes were significantly (P = 0.05) reduced in fungicide‐sprayed plots in one season, but not the other. One thousand‐seed weight and yield differed significantly (P = 0.05) with treatment as one application of triphenyltin acetate increased yields by 18% over unsprayed plots in season 1. One thousand‐seed weight and yield, regressed on the AUDPC for the median leaf in the canopy, explained 92 and 72% of the variation, respectively.
Theoretical approach to the dynamics of the inoculum density of Verticillium dahliae in the soil: first test of a simple model
Authors: MOL L. , HUISMAN O. C. , SCHOLTE K. , STRUIK P. C.
Published: November 2003

A mathematical equation was developed that describes the inoculum densities of microsclerotia of Verticillium dahliae in the soil over a long time span. The equation was based on measurable parameters and ecologically meaningful principles. In the model, the number of systemic infections of plant roots during crop growth was related to soil inoculum density. In turn, formation of microsclerotia in debris and reduction of the amount of crop growth were related to the number of systemic infections. Finally, a gradual release and mortality of microsclerotia in the soil were included to calculate subsequent inoculum densities in the soil.

Fitting the function to experimental data of potato cvs Element, Ostara, Mirka and Astarte, flax, pea, barley, sugar beet, onion and faba bean gave a very high correlation between observed and predicted soil inoculum densities. The clear differences in inoculum production among potato cultivars and other crops were expressed in quantitative terms. The highest inoculum density after incorporation of the debris of a susceptible crop was estimated to occur at 2.3 thermal time units of 3600 degree days (base 0°C). Ten per cent of the initial input of inoculum was still present after 4.5 thermal time units. The model was used to predict the dynamics of soil inoculum densities for V. dahliae under various cropping frequency schemes and performed satisfactorily.
Effects of crop species, crop cultivars and isolates of Verticillium dahliae on the population of microsclerotia in the soil, and consequences for crop yield
Authors: MOL L. , VAN HALTEREN J. M. , SCHOLTE K. , STRUIK P. C.
Published: November 2003

In a micro‐plot experiment the development of the inoculum density of Verticillium dahliae in soil was studied and consequences for yields of potato cvs Element, Ostara, Astarte, and Mirka, faba bean, flax, pea, barley, sugar beet and onion were evaluated. In May 1991, 75‐litre containers were filled with sterile soil. Soil was infested with 2 or 200 microsclerotia per g of a potato isolate or a faba bean isolate of V. dahliae . The same crop species and cultivar was grown on the same plot in 1991 and 1992. For flax, a non‐pulled crop was compared with a pulled crop. Fallow plots were included as a control. In 1993, potato cv. Element was grown on all plots. During 3 years the soils were sampled, and the soil inoculum densities were assessed by plating the soil on a semi‐selective medium.  In 1991, yield differences in dry matter per plot between isolates were only significant for potato cv. Element (lower yield when infected with potato isolate), and potato cv. Astarte, faba bean, and sugar beet (lower yield when infected with faba bean isolate). In 1992, isolates and infestation levels did not affect the dry matter yields per plot. In 1993, haulm dry matter yield per plot of potato cv. Element was affected by the isolate, the inoculum density and the crop grown in the previous years. Plots previously cropped to potato cvs Element, Astarte and Mirka gave the lowest dry matter yields in 1993.  No decrease of inoculum density occurred under any crop species or cultivar grown. Increase of inoculum densities was significant for potato cvs Element, Ostara, Astarte, and faba bean at the low initial soil infestation level. At the high initial soil infestation level the effect of crop species and cultivar on the inoculum densitiy depended on the isolate used. Potato cultivars seemed to be more susceptible to potato isolate than to faba bean isolate and faba bean seemed to be more susceptible to faba bean isolate than to potato isolate. Removing flax culms from the field diminished the increase of the inoculum density in treatments infested with potato isolate at a high level.  In 1993, the concentration of microsclerotia in the haulm debris was positively related to the inoculum density in the soil, and the haulm dry matter yield was negatively related to the inoculum density in the soil.
Production of syringomycins and syringopeptins by Pseudomonas syringae pv. atrofaciens
Authors: VASSILEV V. , LAVERMICOCCA P. , DI GIORGIO D. , IACOBELLIS N. S.
Published: November 2003

All virulent strains of Pseudomonas syringae pv. atrofaciens produce in vitro substances with syringomycin‐like features. All strains inhibited the growth of Geotrichum candidum in the plate assay although the extent of their growth inhibition was variable.

Purification of bioactive culture extracts of a highly virulent strain by ion exchange chromatography (Whatman CM52) yielded a main fraction which inhibited the growth of Rhodotorula pilimanae and Bacillus megaterium, and was phytotoxic to tobacco and wheat plants. In particular, the injection of this fraction in the culm of wheat plants caused phytotoxic symptoms on leaves similar to those caused in nature by the pathogen. The further purification by HPLC of the above fraction gave rise to four main bioactive substances which have been identified by spectroscopic methods (FAB‐MS) and amino acid analysis as syringomycin E, syringomycin G, syringopeptin 25A and syringopeptin 25B, toxic lipodepsipeptides thus far recognized to be produced by most strains of P. syringae pv. syringae. The injection of both syringomycin E and syringopeptin 25A in wheat leaves caused necrotic symptoms; however, syringopeptin 25A was at least six times more active than syringomycin E. The possible role of the toxins in the disease development on cereals and the need for a careful examination of pathogenetic and biochemical features of P. syringae pv. atrofaciens to establish the relationships of the two pathovars in the ‘syringae group’ are discussed.
Reproductive fitness and pathogenicity of selected Radopholus populations on two banana cultivars
Authors: HAHN M. L. , SARAH J.‐L. , BOISSEAU M. , VINES N. J. , WRIGHT D. J. , BURROWS P. R.
Published: November 2003

Ten populations of Radopholus similis from various locations and one population of Radopholus sp. from Indonesia were tested for their reproductive fitness and specific pathogenicity on Musa AAA, Cavendish cv. Poyo under controlled experimental conditions in a constant environment chamber. In addition, five of these populations were tested on Musa AAA, Ibota cv. Yangambi. Reproductive fitness of the populations tested on the two cultivars, measured as the ratio of the final number of nematodes per root system (Pf) to the number of nematodes inoculated (Pi), differed significantly. Greatest fitness was observed among R. similis populations collected from banana in different African countries (Cameroon, Uganda and the Ivory Coast) and one population from arecanut in Sri Lanka. In contrast, a population from tea in Sri Lanka and the population of Radopholus sp. from turmeric in Indonesia were the least fit. Specific pathogenicity was estimated at 8 weeks and 12 weeks after inoculation using three plant growth parameters: fresh root weight, fresh shoot weight and plant height, compared to uninfected control plants. Reduction in plant root weight was the best indicator of pathogenicity. While the R. similis populations from Uganda and the Ivory Coast were highly pathogenic, other populations with great reproductive fitness (i.e. isolates from Cameroon and Sri Lanka) did not significantly reduce root weight. In cv. Poyo, no linear correlation was found between final numbers of nematodes per gram of root (Pf) and the decrease of root weight.
The relationship between virulence and cytokinin production by Rhodococcus fascians (Tilford 1936) Goodfellow 1984
Authors: EASON J. R. , MORRIS R. O. , JAMESON P. E.
Published: November 2003

Qualitative and quantitative analyses were made of cytokinins secreted into liquid culture by virulent and avirulent strains of Rhodococcus fascians, and of the endogenous cytokinins in pea plants inoculated with the same strains. Both virulent and avirulent strains secreted a range of cytokinins into liquid culture. The non‐hydroxylated cytokinins were present in the liquid cultures at levels up to 1000‐fold higher than hydroxylated cytokinins, but the virulent strains secreted only slightly higher levels of isopentenyladenine (iP), isopentenyladenosine (iPA) and the tentatively identified methylthio‐isopentenyladenosine (ms‐iPA), than the avirulent strains. Pisum sativum cv. Novella plants that were inoculated with virulent strains contained only slightly higher levels of iP and ms‐iPA but had lower levels of the cytokinin nucleotides than those plants that had been inoculated with the avirulent strains. The origin of the cytokinins secreted by avirulent and virulent strains is discussed, as is the significance of the cytokinin content of fasciated plants.
Occurrence of anthracnose (Colletotrichum acutatum) on ornamental lupin in the United Kingdom
Authors: REED P. J. , DICKENS J. S. W. , O'NEILL T. M.
Published: November 2003

The first recorded outbreak of anthracnose (Colletotrichum acutatum) on ornamental lupin in the United Kingdom occurred in 1989. Seedborne infection by Colletotrichum acutatum was investigated after seed was implicated in the origin of the outbreaks and infection was found on seed of three of 14 cultivars tested. In pathogenicity tests, typical anthracnose symptoms developed only on plants of Lupinus spp; there were slight symptoms on Pisum sativumVicia sativa and Lathyrus odoratus, but none on Vicia faba, Phaseolus coccineus, P. vulgaris and Onobrychis viciifolia
Enhanced field control of wheat take‐all using cold tolerant isolates of Gaeumannomyces graminis var. graminis and Phialophora sp. (lobed hyphopodia)
Authors: WONG P. T. W. , MEAD J. A. , HOLLEY M. P.
Published: November 2003

Cold tolerant isolates of Gaeumannomyces graminis var. graminis (Ggg) and Phialophora sp. (lobed hyphopodia), which produced at least comparable growth rates at 5°C to those of pathogenic G. graminis var. tritici (Ggt), were shown to control take‐all disease in wheat effectively in 2 years of field experiments in New South Wales, Australia. The addition of oat inoculum of these fungi at the rate of 60 kg/ha to the seeding furrow significantly (P ≤ 0.05) reduced disease and increased grain yields by 33–45% compared to the Ggt alone treatment. The use of 30 kg/ha of oat inoculum also significantly (P ≤ 0.05) reduced disease and increased grain yields by 21–44%. These high levels of take‐all control were obtained consistently from four field experiments on three different soil types with different pHs. A treatment inoculated with Ggg alone showed no disease symptoms and produced grain yields similar to that of untreated wheat. This fungus is, therefore, non‐pathogenic to wheat. At high rates of inoculation of Ggg and Phialophora sp. (lobed hyphopodia), 65–80% of tillering wheat plants (GS 32) had root systems colonized by these fungi. In contrast, two Pseudomonas spp. and an isolate each of Ggg and Phialophora sp. (lobed hyphopodia), which did not grow at 5°C, were ineffective in controlling take‐all. Take‐all assessments during heading (GS 61‐83) were highly correlated (R2=0.6047, P≤0.0005) with the relative yield increase or decrease of inoculated treatments compared to the Ggt alone treatment. The use of a Ggg isolate (90/3B) and a Phialophora sp. (lobed hyphopodia) isolate (KY) for take‐all control has been patented. These fungi are being developed for commercial use.
On estimating non‐linear response of fungal development under fluctuating temperatures
Authors: XU X.‐M.
Published: November 2003

Published research concerning disease development often shows that the response of fungal development to temperature is non‐linear. Unfortunately, this non‐linear response has often been ignored when predicting fungal development under varying temperatures using non‐linear models and when deriving fungal development models from data collected under fluctuating temperatures. In this paper, the magnitude of non‐linear effects on fungal development is shown to depend on the types of non‐linear models and on the extent of temperature fluctuations. A method is described, which has been used in other disciplines to fit non‐linear models directly to varying temperatures. Hypothetical data were generated to demonstrate the usefulness of this method. With the underlying rate equation being non‐linear, models derived from average temperatures underestimate the rates at intermediate temperatures; the greater the temperature fluctuation, the greater this underestimation.
Assessment of Phaeotheca dimorphospora for biological control of the Dutch elm disease pathogens, Ophiostoma ulmi and O. novo‐ulmi
Authors: BERNIER L. , YANG D. , OUELLETTE G. B. , DESSUREAULT M.
Published: November 2003

The antagonistic fungus Phaeotheca dimorphospora was tested as a biocontrol agent against the Dutch elm disease pathogens, Ophiostoma ulmi and O. novo‐ulmi, on Ulmus americana seedlings in the glasshouse. Curative inoculation of seedlings with P. dimorphospora had no significant effect on disease development. Conditioning inoculation of seedlings with the antagonist protected them against O. ulmi but not against the more aggressive O. novo‐ulmi. In seedlings challenged with both the antagonist and either one of the pathogens, P. dimorphospora only spread locally around the inoculation point; however, the pathogens spread systemically throughout the whole plant. O. novo‐ulmi survived in the region colonized by P. dimorphospora, whereas O. ulmi did not.
Aetiology and biological control of Fusarium wilt of pinks (Dianthus caryophyllus) using Trichoderma aureoviride
Authors: CARVER C. E. , PITT D. , RHODES D. J.
Published: November 2003

Fusarium oxysporum f.sp. dianthi (F.o.d.) was the species isolated most frequently from wilted glasshouse‐grown pinks in south‐west England, whereas F. avenaceum was less prevalent and F. culmorum was not found. Although infections by F. avenaceum, via the roots or through a cut‐stem wound, caused symptoms identical to those characterizing mild infections due to F.o.d., the former was always pathogenically weak relative to the latter. Of several organisms screened for potential antagonistic capacity towards F.o.d., using an in‐vitro dual culture plate technique, Trichoderma aureoviride, isolated as an endophyte from healthy pinks, proved most effective. Elevated temperatures substantially reduced the antagonistic capacity of micro‐organisms in both in‐vitro and in‐vivo screens, except in the case of T. aureoviride where maximum antagonism occurred at 28°C, which was near the optimum for wilt disease in pinks. The tolerance shown by T. aureoviride to a wide range of pesticides used in commercial production of pinks under cover indicated its potential in a proposed integrated disease control programme.
The influence of inoculum concentration, relative humidity, and temperature on infection of greenhouse tomatoes by Botrytis cinerea
Authors: EDEN M. A. , HILL R. A. , BERESFORD R. , STEWART A.
Published: November 2003

Botrytis cinerea causes serious crop losses in greenhouse tomato crops through infection of flowers and stem wounds. Experiments were carried out to determine the effects of inoculum concentration, relative humidity (RH), and temperature at these two infection sites. Infection of permanent flower parts increased as a function of inoculum concentration and both length of exposure to high RH (approximately 100% for 0–36 h) and specified continuous RH (56–100%). A low level of infection was still evident under continuous 56% RH. Interruption of periods of high RH with breaks of low RH did not reduce infection. Infection of stem wounds was less dependent on inoculum concentration or RH. Factorial combinations of inoculum concentration, RH, and temperature produced significant interactions. Higher temperature increased infection of flowers but reduced infection of stem wounds. The main implications for control in commercial crops are as follows. Lowering the aerial spore concentration by maintaining the disease at a low level will reduce flower infection. Lowering RH will reduce but not eliminate flower infection but will have only a small effect on stem infection. Raising the temperature (from 15 to 25°C) will reduce stem infection, and whilst flower infection increases, this is counteracted by increased flower production and a decrease in the proportion of infections reaching the peduncle and stem.
Genetic variation in Danish populations of Erysiphe graminis f.sp. hordei: estimation of gene diversity and effective population size using RFLP data
Authors: DAMGAARD C. , GIESE H.
Published: November 2003

Genetic variation of the barley powdery mildew fungus (Erysiphe graminis f.sp. hordei) was estimated in three Danish local populations. Genetic variation was estimated from the variation amongst clones of Egh, and was therefore an estimate of the maximum genetic variation in the local populations. The average gene diversity, Ĥ, was estimated as 0.84. The effective population size was estimated as: log10 (N^e) = 0.64 − log10(μ), or 4.4 × 109, assuming a nucleotide mutation rate ( μ) of 10−9 per base per generation. There was no significant genetic differentiation between locations.