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
to

271 results found

Vereijssen J, Schneider JHM, Termorshuizen AJ, Jeger MJet al., 2003, Comparison of two disease assessment methods for assessing Cercospora leaf spot in sugar beet, CROP PROTECTION, Vol: 22, Pages: 201-209, ISSN: 0261-2194

Journal article

van Leeuwen GCM, Holb IJ, Jeger MJ, 2002, Factors affecting mummification and sporulation of pome fruit infected by <i>Monilinia fructigena</i> in Dutch orchards, PLANT PATHOLOGY, Vol: 51, Pages: 787-793, ISSN: 0032-0862

Journal article

Bock CH, Jeger MJ, 2002, The distribution and spread of sorghum downy mildew in sorghum and maize fields in Nigeria and Zimbabwe, EUROPEAN JOURNAL OF PLANT PATHOLOGY, Vol: 108, Pages: 745-753, ISSN: 0929-1873

Journal article

Lamour A, van den Bosch F, Termorshuizen AJ, Jeger MJet al., 2002, Quasi-steady state approximation to a fungal growth model, IMA JOURNAL OF MATHEMATICS APPLIED IN MEDICINE AND BIOLOGY, Vol: 19, Pages: 163-183, ISSN: 0265-0746

Journal article

Pielaat A, van den Bosch F, Fitt BDL, Jeger MJet al., 2002, Simulation of vertical spread of plant diseases in a crop canopy by stem extension and splash dispersal, ECOLOGICAL MODELLING, Vol: 151, Pages: 195-212, ISSN: 0304-3800

Journal article

Jeger MJ, van den Bosch F, Dutmer MY, 2002, Modelling plant virus epidemics in a plantation-nursery system, IMA JOURNAL OF MATHEMATICS APPLIED IN MEDICINE AND BIOLOGY, Vol: 19, Pages: 75-94, ISSN: 0265-0746

Journal article

van Leeuwen GCM, Baayen RP, Holb IJ, Jeger MJet al., 2002, Distinction of the Asiatic brown rot fungus <i>Monilia polystroma</i> sp nov from <i>M-fructigena</i>, MYCOLOGICAL RESEARCH, Vol: 106, Pages: 444-451, ISSN: 0953-7562

Journal article

Tumwine J, Frinking HD, Jeger MJ, 2002, Tomato late blight (Phytophthora infestans) in Uganda, INTERNATIONAL JOURNAL OF PEST MANAGEMENT, Vol: 48, Pages: 59-64, ISSN: 0967-0874

Journal article

Tumwine J, Frinking HD, Jeger MJ, 2002, Integrating cultural control methods for tomato late blight (<i>Phytophthora infestans</i>) in Uganda, ANNALS OF APPLIED BIOLOGY, Vol: 141, Pages: 225-236, ISSN: 0003-4746

Journal article

Segarra J, Jeger MJ, van den Bosch F, 2001, Epidemic dynamics and patterns of plant diseases, PHYTOPATHOLOGY, Vol: 91, Pages: 1001-1010, ISSN: 0031-949X

Journal article

Yu DZ, Yang XJ, Yang LJ, Jeger MJ, Brown JKMet al., 2001, Assessment of partial resistance to powdery mildew in Chinese wheat varieties, PLANT BREEDING, Vol: 120, Pages: 279-284, ISSN: 0179-9541

Journal article

Lamour A, Van Den Bosch F, Termorshuizen AJ, Jeger MJet al., 2001, Erratum: Modelling the growth of soil-borne fungi in response to carbon and nitrogen (IMA Journal of Mathematics Applied in Medicine and Biology (2000) 17 4 (329-346)), IMA Journal of Mathemathics Applied in Medicine and Biology, Vol: 18, ISSN: 0265-0746

Journal article

Lamour A, Van den Bosch F, Termorshuizen AJ, Jeger MJet al., 2001, Modelling the growth of soil-borne fungi in response to carbon and nitrogen., IMA J Math Appl Med Biol, Vol: 18, Pages: 329-346, ISSN: 0265-0746

Growth of soil-borne fungi is poorly described and understood, largely because non-destructive observations on hyphae in soil are difficult to make. Mathematical modelling can help in the understanding of fungal growth. Except for a model by Paustian & Schnürer (1987a), fungal growth models do not consider carbon and nitrogen contents of the supplied substrate, although these nutrients have considerable effects on hyphal extension in soil. We introduce a fungal growth model in relation to soil organic matter decomposition dealing with the detailed dynamics of carbon and nitrogen. Substrate with a certain carbon : nitrogen ratio is supplied at a constant rate, broken down and then taken up by fungal mycelium. The nutrients are first stored internally in metabolic pools and then incorporated into structural fungal biomass. Standard mathematical procedures were used to obtain overall-steady states of the variables (implicitly from a cubic equation) and the conditions for existence. Numerical computations for a wide range of parameter combinations show that at most one solution for the steady state is biologically meaningful, specified by the conditions for existence. These conditions specify a constraint, namely that the 'energy' (in terms of carbon) invested in breakdown of substrate should be less than the 'energy' resulting from breakdown of substrate, leading to a positive carbon balance. The biological interpretation of the conditions for existence is that for growth the 'energy' necessary for production of structural fungal biomass and for maintenance should be less than the mentioned positive carbon balance in the situation where all substrate is colonized. In summary, the analysis of this complicated fungal growth model gave results with a clear biological interpretation.

Journal article

Lamour A, Van den Bosch F, Termorshuizen AJ, Jeger MJet al., 2001, Modelling the growth of soil-borne fungi in response to carbon and nitrogen (vol 17, pg 329, 2000), IMA JOURNAL OF MATHEMATICS APPLIED IN MEDICINE AND BIOLOGY, Vol: 18, Pages: 213-+, ISSN: 0265-0746

Journal article

Gilles T, Fitt BDL, Jeger MJ, 2001, Effects of environmental factors on development of <i>Pyrenopeziza brassicae</i> (light leaf spot) apothecia on oilseed rape debris., PHYTOPATHOLOGY, Vol: 91, Pages: 392-398, ISSN: 0031-949X

Journal article

Gilles T, Fitt BDL, Welham SJ, Evans N, Steed JM, Jeger MJet al., 2001, Modelling the effects of temperature and wetness duration on development of light leaf spot on oilseed rape leaves inoculated with <i>Pyrenopeziza brassicae</i> conidia, PLANT PATHOLOGY, Vol: 50, Pages: 42-52, ISSN: 0032-0862

Journal article

van Leeuwen GCM, Baayen RP, Jeger MJ, 2001, Pest risk assessment for the countries of the European Union (as PRA area) on Monilinia fructicola, EPPO Bulletin, Vol: 31, Pages: 481-487, ISSN: 0250-8052

A pest risk assessment was performed according to the EPPO Standard PM 5/3 to determine the probability of introduction of Monilinia fructicola into the countries of the European Union (EU) and its potential economic impact. Data on the biology of the pathogen were combined with trade pathways and information on the use of commodities in order to quantify risk. On the basis of the EPPO Standard, we concluded that there is a serious risk that M. fructicola could become established in the EU, with significant economic losses as a result. This justifies the phytosanitary measures currently in place in the EU. © 2001 Wiley. All rights reserved.

Journal article

Lamour A, Van Den Bosch F, Termorshuizen AJ, Jeger MJet al., 2001, Modelling the growth of soil-borne fungi in response to carbon and nitrogen, Mathematical Medicine and Biology, Vol: 18, ISSN: 1477-8599

Journal article

Jeger MJ, Viljanen-Rollinson SLH, 2001, The use of the area under the disease-progress curve (AUDPC) to assess quantitative disease resistance in crop cultivars, THEORETICAL AND APPLIED GENETICS, Vol: 102, Pages: 32-40, ISSN: 0040-5752

Journal article

Bock CH, Jeger MJ, Cardwell KF, Mughogho LK, Sherington Jet al., 2000, Control of sorghum downy mildew of maize and sorghum in Africa, Tropical Science, Vol: 40, Pages: 47-57, ISSN: 0041-3291

In Africa, sorghum downy mildew (SDM), caused by Peronosclerospora sorghi, infects both sorghum and maize. Systemic infection can result in severe yield loss. The effects of seed treatments and foliar sprays of metalaxyl on the disease were determined on maize in Nigeria (1992) and sorghum in Zimbabwe (1993/4). Seed treatment at 1.0 g a.i/kg or a foliar spray at 0.96 g a.i./l significantly reduced the incidence of the disease, although the latter was less consistent. The effect on yield was less clear. In Nigeria, severe stem borer damage in some plots prevented definitive yield assessment in response to fungicide. In Zimbabwe, there was no effect of fungicide on sorghum yield due to the overriding influence of insect damage (1993) and drought (1994). Planting density of sorghum in Zimbabwe did not appear to influence disease incidence at the densities used. Metalaxyl can be used to control SDM effectively on sorghum and maize in Africa.

Journal article

Jeger MJ, 2000, Theory and plant epidemiology, PLANT PATHOLOGY, Vol: 49, Pages: 651-658, ISSN: 0032-0862

Journal article

Lamour A, Van den Bosch F, Termorshuizen AJ, Jeger MJet al., 2000, Modelling the growth of soil-borne fungi in response to carbon and nitrogen, IMA JOURNAL OF MATHEMATICS APPLIED IN MEDICINE AND BIOLOGY, Vol: 17, Pages: 329-346, ISSN: 0265-0746

Journal article

Jeger MJ, 2000, Bottlenecks in IPM, CROP PROTECTION, Vol: 19, Pages: 787-792, ISSN: 0261-2194

Journal article

Gilles T, Evans N, Fitt BDL, Jeger MJet al., 2000, Epidemiology in relation to methods for forecasting light leaf spot (<i>Pyrenopeziza brassicae</i>) severity on winter oilseed rape (<i>Brassica napus</i>) in the UK, EUROPEAN JOURNAL OF PLANT PATHOLOGY, Vol: 106, Pages: 593-605, ISSN: 0929-1873

Journal article

Gilles T, Fitt BDL, Kennedy R, Welham SJ, Jeger MJet al., 2000, Effects of temperature and wetness duration on conidial infection, latent period and asexual sporulation of <i>Pyrenopeziza brassicae</i> on leaves of oilseed rape, PLANT PATHOLOGY, Vol: 49, Pages: 498-508, ISSN: 0032-0862

Journal article

van Leeuwen GCM, Stein A, Holb I, Jeger MJet al., 2000, Yield loss in apple caused by <i>Monilinia fructigena</i> (Aderh. & Ruhl.) honey, and spatio-temporal dynamics of disease development, EUROPEAN JOURNAL OF PLANT PATHOLOGY, Vol: 106, Pages: 519-528, ISSN: 0929-1873

Journal article

Madden LV, Jeger MJ, van den Bosch F, 2000, A theoretical assessment of the effects of vector-virus transmission mechanism on plant virus disease epidemics, PHYTOPATHOLOGY, Vol: 90, Pages: 576-594, ISSN: 0031-949X

Journal article

Tumwine J, Frinking HD, Jeger MJ, 2000, Isolation techniques and cultural media for Phytophthora infestans from tomatoes, Mycologist, Vol: 14, Pages: 137-139, ISSN: 0269-915X

The lack of a standard procedure for isolation of Phytophthora infestans from tomatoes has been a major problem for researchers working on tomato late blight. There is an associated problem of culturing, especially in the tropics where standard media such as Rye A agar are not readily available. Efforts were made to try and develop isolation and culturing techniques based on tomato and locally available tropical cereals respectively. Two techniques for isolating P. infestans from tomato tissue were successfully developed. The first was by placing young sterile healthy tomato slices on infected tomato leaves. A second technique was developed in order to make use of already diseased fruits. For both techniques, P. infestans grew well on tomato slices and subculturing was successfully made onto Rye A agar without the need of antibiotics.

Journal article

Hoffland E, Jeger MJ, Van Beusichem ML, 2000, Effect of nitrogen supply rate on disease resistance in tomato depends on the pathogen, Plant and Soil, Vol: 218, Pages: 239-247, ISSN: 0032-079X

The aim of this study was to investigate the effect of tissue nitrogen concentration, as a consequence of nitrogen supply rate, on the susceptibility of tomato plants to three pathogens. We varied tissue N concentration by supplying N at different rates by adding nitrate in different, exponentially increasing amounts to the nutrient solution on which the tomato plants were grown. Separate experiments were carried out to test susceptibility of tomato plants to the bacterial speck-causing Pseudomonas syringae pv tomato, to the wilt agent Fusarium oxysporum f.sp. lycopersici and to tomato powdery mildew caused by Oidium lycopersicum. The effect of tissue N concentration appeared to be highly pathogen-dependent: there was no effect on susceptibility to F. oxysporum, but susceptibility to P. syringae and O. lycopersicum increased significantly with increasing N concentration. We have previously demonstrated the opposite for susceptibility to Botrytis cinerea: decreasing susceptibility with increasing N concentration. The apparent contradictory effects are discussed in relation to the effect of N supply on both the nutritional value of the plant tissue to the pathogen and on the concentration of resistance-related compounds. We conclude that the effect of changing both characteristics on disease susceptibility is highly pathogen-specific and is probably dependent on differences in resource requirements of the pathogen or the sensitivity of the pathogen to plant resistance reactions or on both these factors.

Journal article

Bock CH, Jeger MJ, Mughogho LK, Cardwell KF, Mtisi E, Kaula G, Mukansabimana Det al., 2000, Variability of <i>Peronosclerospora sorghi</i> isolates from different geographic locations and hosts in Africa, MYCOLOGICAL RESEARCH, Vol: 104, Pages: 61-68, ISSN: 0953-7562

Journal article

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