Imperial College London

Michael J Jeger

Faculty of Natural SciencesDepartment of Life Sciences (Silwood Park)

Emeritus Professor of Horticulture
 
 
 
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Contact

 

+44 (0)1398 332 941m.jeger Website

 
 
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Location

 

Home working 13 Brook Street, Bampton, Devon EX16 9LUSilwood ParkSilwood Park

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Summary

 

Publications

Publication Type
Year
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271 results found

Allen EJ, Howell R, Fernández-Fernández F, Jeger MJet al., 2012, The use of microsatellite markers and morphological traits in characterising and maintaining genetic diversity in a cultivated apple germplasm collection, Apples: Nutrition, Consumption and Health, Pages: 141-158, ISBN: 9781619427099

The consumption of apple has demonstrated benefits for human nutrition and health which make the characterisation and maintenance of genetic diversity of the utmost importance. The aim of this study was to investigate whether multivariate analysis of characterisation data obtained using microsatellite markers (SSR) provided useful information for the management of a field gene-bank collection of apple varieties; and as a subsidiary aim, the effectiveness of this approach was compared with a similar analysis of morphological traits. SSR characterization data at 12 loci collected from 85 accessions in the UK National Fruit Collections were analysed along with morphological character scores that were available for a subset of 28 of those accessions. In addition, the application of SSR polymorphisms for resolving queries that cannot be answered on the basis of morphological data alone, e.g. identification of duplicates and relationships between accessions of unknown origin, was investigated. For the SSR loci tested there was generally a high level of heterozygosity, but at some loci alleles were not associating randomly. Sets of diploid varieties that were clonally derived were identified. Fifteen of the varieties were revealed to be triploids, some not previously known. Multivariate analysis using Principal Co-ordinate Analysis presented a reasonable model for the genetic data, but did not reveal groupings of the apple accessions. Similarly there were no discernible groups formed with the morphological data and the positioning of accessions differed from those formed with the genetic data. The uses of such analyses in management of genetic diversity is discussed in relation to historical literature, parentage analysis and the use of collection by plant breeders in improving nutritional quality and other traits in cultivated apple. © 2012 Nova Science Publishers, Inc. All rights reserved.

Book chapter

Hughes DJ, West JS, Atkins SD, Gladders P, Jeger MJ, Fitt BDLet al., 2011, Effects of disease control by fungicides on greenhouse gas emissions by UK arable crop production, PEST MANAGEMENT SCIENCE, Vol: 67, Pages: 1082-1092, ISSN: 1526-498X

Journal article

Xu X-M, Jeffries P, Pautasso M, Jeger MJet al., 2011, Combined Use of Biocontrol Agents to Manage Plant Diseases in Theory and Practice, PHYTOPATHOLOGY, Vol: 101, Pages: 1024-1031, ISSN: 0031-949X

Journal article

Xu X-M, Jeffries P, Pautasso M, Jeger MJet al., 2011, A Numerical Study of Combined Use of Two Biocontrol Agents with Different Biocontrol Mechanisms in Controlling Foliar Pathogens, PHYTOPATHOLOGY, Vol: 101, Pages: 1032-1044, ISSN: 0031-949X

Journal article

Jeger MJ, Chen Z, Powell G, Hodge S, van den Bosch Fet al., 2011, Interactions in a host plant-virus-vector-parasitoid system: Modelling the consequences for virus transmission and disease dynamics, VIRUS RESEARCH, Vol: 159, Pages: 183-193, ISSN: 0168-1702

Journal article

Jeger MJ, van den Bosch F, Madden LV, 2011, Modelling virus- and host-limitation in vectored plant disease epidemics, VIRUS RESEARCH, Vol: 159, Pages: 215-222, ISSN: 0168-1702

Journal article

Mills P, Dehnen-Schmutz K, Ilbery B, Jeger M, Jones G, Little R, MacLeod A, Parker S, Pautasso M, Pietravalle S, Maye Det al., 2011, Integrating natural and social science perspectives on plant disease risk, management and policy formulation, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 366, Pages: 2035-2044, ISSN: 0962-8436

Journal article

Wilkinson K, Grant WP, Green LE, Hunter S, Jeger MJ, Lowe P, Medley GF, Mills P, Phillipson J, Poppy GM, Waage Jet al., 2011, Infectious diseases of animals and plants: an interdisciplinary approach <i>Introduction</i>, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 366, Pages: 1933-1942, ISSN: 0962-8436

Journal article

Moslonka-Lefebvre M, Finley A, Dorigatti I, Dehnen-Schmutz K, Harwood T, Jeger MJ, Xu X, Holdenrieder O, Pautasso Met al., 2011, Networks in plant epidemiology: from genes to landscapes, countries, and continents, Phytopathology, Vol: 101, Pages: 392-403, ISSN: 1943-7684

Journal article

Lebeda A, Holmes GJ, Mauch-Mani B, Jeger MJet al., 2011, "The downy mildews-Biology, mechanisms of resistance, population ecology" Foreword, EUROPEAN JOURNAL OF PLANT PATHOLOGY, Vol: 129, Pages: 129-129, ISSN: 0929-1873

Journal article

Pautasso M, Moslonka-Lefebvre M, Jeger MJ, 2010, The number of links to and from the starting node as a predictor of epidemic size in small-size directed networks, ECOLOGICAL COMPLEXITY, Vol: 7, Pages: 424-432, ISSN: 1476-945X

Journal article

Pautasso M, Dehnen-Schmutz K, Holdenrieder O, Pietravalle S, Salama N, Jeger MJ, Lange E, Hehl-Lange Set al., 2010, Plant health and global change - some implications for landscape management, BIOLOGICAL REVIEWS, Vol: 85, Pages: 729-755, ISSN: 1464-7931

Journal article

Salama NKG, Edwards GR, Heard MS, Jeger MJet al., 2010, The suppression of reproduction of <i>Tragopogon pratensis</i> infected by the rust fungus <i>Puccinia hysterium</i>, FUNGAL ECOLOGY, Vol: 3, Pages: 406-408, ISSN: 1754-5048

Journal article

Xu X-M, Salama N, Jeffries P, Jeger MJet al., 2010, Numerical Studies of Biocontrol Efficacies of Foliar Plant Pathogens in Relation to the Characteristics of a Biocontrol Agent, PHYTOPATHOLOGY, Vol: 100, Pages: 814-821, ISSN: 0031-949X

Journal article

Dehnen-Schmutz K, Holdenrieder O, Jeger MJ, Pautasso Met al., 2010, Structural change in the international horticultural industry: Some implications for plant health, SCIENTIA HORTICULTURAE, Vol: 125, Pages: 1-15, ISSN: 0304-4238

Journal article

MacLeod A, Pautasso M, Jeger MJ, Haines-Young Ret al., 2010, Evolution of the international regulation of plant pests and challenges for future plant health, FOOD SECURITY, Vol: 2, Pages: 49-70, ISSN: 1876-4517

Journal article

Xu X, Robinson J, Jeger M, Jeffries Pet al., 2010, Using combinations of biocontrol agents to control <i>Botrytis cinerea</i> on strawberry leaves under fluctuating temperatures, BIOCONTROL SCIENCE AND TECHNOLOGY, Vol: 20, Pages: 359-373, ISSN: 0958-3157

Journal article

Pautasso M, Xu X, Jeger MJ, Harwood TD, Moslonka-Lefebvre M, Pellis Let al., 2010, Disease spread in small-size directed trade networks: the role of hierarchical categories, Journal of Applied Ecology, Vol: 47, Pages: 1300-1309, ISSN: 1365-2664

Summary 1. Small-size, directed networks are relevant for many biological applications, from meta-populations to food webs, from transport flows to evolutionary trees, from epidemics within households to outbreaks of emerging plant pathogens (e.g. Phytophthora ramorum). However, little attention has been paid to dynamic processes in these networks.2. In the horticultural trade, structural change in hierarchical categories, i.e. the proportion of producers, wholesalers and retailers, can influence the likelihood that plant epidemics will take place in such systems, but it is unclear how.3. We model disease spread and establishment in directed networks of 100 nodes at four connectance levels in six network structures [local, small-world, random, and scale-free (SF) networks with positive, no, and negative correlation between in- and out-degree (number of incoming and outgoing links)], and study the role of hierarchical categories.4. For non-SF networks, the correlation coefficient between number of incoming and outgoing links is negatively correlated with the proportion of producers and retailers, and positively correlated with the proportion of wholesalers. Given the previously reported negative correlation between the in–out degree correlation coefficient and the epidemic threshold, adding producers/retailers and removing wholesalers can contribute to making epidemics more difficult in non-SF networks. For SF networks these associations are not generally present, as in these structures epidemic development is driven by the presence of hubs, rather than the features of the majority of the nodes.5. Synthesis and applications. despite the importance of trade movements of plants for plant epidemics and the emergence of new plant pathogens, little is known about the current contact structure of horticultural networks within and among nations, and about how this is changing. Such information is important for risk assessment and management in plant health regulation.

Journal article

Harwood TD, Xu X, Pautasso M, Jeger MJ, Shaw MWet al., 2009, Epidemiological risk assessment using linked network and grid based modelling: <i>Phytophthora ramorum</i> and <i>Phytophthora kernoviae</i> in the UK, ECOLOGICAL MODELLING, Vol: 220, Pages: 3353-3361, ISSN: 0304-3800

Journal article

Moslonka-Lefebvre M, Pautasso M, Jeger MJ, 2009, Disease spread in small-size directed networks: Epidemic threshold, correlation between links to and from nodes, and clustering, JOURNAL OF THEORETICAL BIOLOGY, Vol: 260, Pages: 402-411, ISSN: 0022-5193

Journal article

Barlow S, Chesson A, Collins JD, Flynn A, Galli CL, Hardy A, Jany KD, Jeger MJ, Knaap A, Kuiper H, Larsen JC, Lovell D, Schlatter J, Silano V, Smulders F, Vannier Pet al., 2009, Guidance on safety assessment of botanicals* and botanical preparations** intended for use as ingredients in food supplements, EFSA Journal, Vol: 7

In this opinion, EFSA’s Scientific Committee provides guidance on the scientific data needed to carry out a safety assessments of a botanical or a botanical preparation. It also proposes a two-tiered scientific approach for the safety assessment depending on the available knowledge on a given botanical and the substance(s) it contains. The guidance also provides a set of criteria to help prioritise the safety assessment of botanical ingredients which are in use. EFSA has also compiled the available information on a large number of botanicals which have been reported to contain substances that may be of health concern when used in food or food supplements. The resulting compendium, which will be regularly updated, should be considered as part of this guidance document and is intended to assist manufacturers and food safety authorities by highlighting possible safety issues which may require further consideration.

Journal article

Xu X, Harwood TD, Pautasso M, Jeger MJet al., 2009, Spatio-temporal analysis of an invasive plant pathogen (<i>Phytophthora ramorum</i>) in England and Wales, ECOGRAPHY, Vol: 32, Pages: 504-516, ISSN: 0906-7590

Journal article

Jeger MJ, Madden LV, van den Bosch F, 2009, The effect of transmission route on plant virus epidemic development and disease control, JOURNAL OF THEORETICAL BIOLOGY, Vol: 258, Pages: 198-207, ISSN: 0022-5193

Journal article

Bannon F, Gort G, van Leeuwen G, Holb I, Jeger Met al., 2009, Diurnal patterns in dispersal of <i>Monilinia fructigena</i> conidia in an apple orchard in relation to weather factors, AGRICULTURAL AND FOREST METEOROLOGY, Vol: 149, Pages: 518-525, ISSN: 0168-1923

Journal article

Jeger MJ, Jeffries R, Elad Y, Xu X-Met al., 2009, A generic theoretical model for biological control of foliar plant diseases, JOURNAL OF THEORETICAL BIOLOGY, Vol: 256, Pages: 201-214, ISSN: 0022-5193

Journal article

Robinson-Boyer L, Jeger MJ, Xu X-M, Jeffries Pet al., 2009, Management of strawberry grey mould using mixtures of biocontrol agents with different mechanisms of action, BIOCONTROL SCIENCE AND TECHNOLOGY, Vol: 19, Pages: 1051-1065, ISSN: 0958-3157

Journal article

Jeger MJ, Pautasso M, 2008, Comparative epidemiology of zoosporic plant pathogens, The Downy Mildews - Genetics, Molecular Biology and Control, Pages: 111-126, ISBN: 9781402089725

Loss of zoospores has happened independently several times in different phylogenic lines and has, it is claimed, no major phylogenetic significance. But whether or not, how, and under which conditions plant pathogens retain the ability to produce motile asexual spores has fundamental importance from an ecological and epidemiological perspective. Recent molecular investigations of the early evolution of fungi and oomycetes are shedding light on the issue of zoospore loss in organisms able to cause plant diseases. Zoospore loss may have accompanied the development of new forms of dispersal adapted to the terrestrial environment, or the simplification processes which often follow the shift to parasitic or biotrophic life-forms. In this review we consider hybridisation events between Phytophthora species, long distance dispersal of oomycetes, sporangia and zoospore survival, direct and indirect infection processes and newly observed sporulating structures. These aspects are all relevant features for an understanding of the epidemiology of zoosporic plant pathogens. Disease management should not be based on the presumption that the zoosporic stage is a weak link in the life cycle. Oomycete plant pathogens show remarkable flexibility in their life cycles and ability to adapt to changing environmental circumstances. © 2008 Springer Netherlands.

Book chapter

Jeger MJ, Termorshuizen AJ, 2008, Strategies of soilborne plant pathogenic fungi in relation to disease suppression, FUNGAL ECOLOGY, Vol: 1, Pages: 108-114

The purpose of classifying pathogens based on ecological traits is that certain generalizations can be made beyond the specific or “model” pathogen that has been investigated. Usually this is done at the taxonomic level of species, but infraspecific variation in ecological traits frustrates such classifications. Moreover, shifts in traits can take place during the life cycle of the pathogen, and plant-mediated rhizosphere effects affect the ecological traits of pathogens. It is therefore useful to separate management of the pathogen, leading to pathogen suppression, from management of the disease, which is essentially plant-mediated. Both approaches may act via specific or general suppression, although the latter mainly acts in the bulk soil. An ecological classification of a given pathogen isolate needs to take into account host range, host sensitivity, host species (in relation to systemically acquired resistance (SAR)/induced systemic resistance (ISR) and host-affected rhizosphere communities), sensitivity to fungistasis, ability to compete for organic matter, sensitivity to specific disease suppression and survival capability. We conclude that generalization at the species level is imprecise and often misleading

Journal article

Jeger MJ, Pautasso M, 2008, Comparative epidemiology of zoosporic plant pathogens, EUROPEAN JOURNAL OF PLANT PATHOLOGY, Vol: 122, Pages: 111-126, ISSN: 0929-1873

Journal article

Jeger MJ, Wijngaarden PJ, Hoekstra RF, 2008, Adaptation to the cost of resistance in a haploid clonally reproducing organism: The role of mutation, migration and selection, JOURNAL OF THEORETICAL BIOLOGY, Vol: 252, Pages: 621-632, ISSN: 0022-5193

Journal article

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