The Importance of Dispersal Mechanisms in the Epidemiology of Phytophthora Blights and Downy Mildews on Crop Plants

Epidemics of plant diseases share a basic structure with those of human and animal diseases; however, unlike most epidemics of people and animals, fungi or fungi-like organisms are of major importance as pathogens. Because of the relatively low value of an individual in most plant populations, botanical epidemiologists perform observational as well as designed studies repeatedly on epidemics in large populations. Plant disease epidemics develop from overlapping cycles of propagule dissemination, host encounter and infection, pathogenesis (including symptom development), and pathogen reproduction. Initial infective units, or propagules, originate from survival structures formed between cropping seasons or during periods when weathers conditions are not suitable for disease initiation. Propagules may also arrive by long-distance transport from other geographic areas where conditions are suitable for the occurrence of continuous epidemic cycles. The importance of dispersal mechanisms in epidemic development are illustrated with three solanaceous pathosystems: Phytophthora blight of pepper (caused by Phytophthora capsici), blue mold of tobacco (caused by Peronospora tabacina), and late blight of potato (caused by Phytophthora infestans).

[1]  J. Ristaino.  The importance of archival and herbarium materials in understanding the role of oospores in late blight epidemics of the past. , 1998, Phytopathology.

[2]  F. Govers,et al.  Development of potato late blight epidemics: disease foci, disease gradients, and infection sources. , 1998, Phytopathology.

[3]  S. B. Goodwin,et al.  Re-emergence of Potato and Tomato Late Blight in the United States. , 1997, Plant disease.

[4]  S. B. Goodwin,et al.  Sensitivity to Protectant Fungicides and Pathogenic Fitness of Clonal Lineages of Phytophthora infestans in the United States. , 1997, Phytopathology.

[5]  S. B. Goodwin,et al.  Resurgence of the Irish Potato Famine Fungus , 1997 .

[6]  J. Ristaino,et al.  Suppression of phytophthora blight in bell pepper by a no-till wheat cover crop. , 1997, Phytopathology.

[7]  S. B. Goodwin,et al.  Widespread distribution and probable origin of resistance to metalaxyl in clonal genotypes of Phytophthora infestans in the United States and Western Canada , 1996 .

[8]  B. Cohen,et al.  Panglobal distribution of a single clonal lineage of the Irish potato famine fungus. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[9]  B. Cohen,et al.  Migration from northern Mexico as the probable cause of recent genetic changes in populations of Phytophthora infestans in the United States and Canada. , 1994 .

[10]  J. Ristaino,et al.  Spatial dynamics of disease symptom expression during Phytophthora epidemics in bell pepper , 1994 .

[11]  Barak A. Cohen,et al.  Historical and recent migrations of Phytophthora infestans: chronology, pathways and implications. , 1993 .

[12]  J. Ristaino,et al.  Spatial and temporal dynamics of Phytophthora epidemics in commercial bell pepper fields , 1993 .

[13]  D. Neher,et al.  Dispersal of Phytophthora parasitica in tomato fields by furrow irrigation , 1992 .

[14]  L. L. Wilson,et al.  Epidemiology and control of leather rot of strawberries , 1991 .

[15]  L. Madden,et al.  Effect of ground cover on splash dispersal of Phytophthora cactorum from strawberry fruits , 1990 .

[16]  J. H. Bowers,et al.  Path coefficient analysis of the effect of rainfall variables on the epidemiology of Phytophthora blight of pepper caused by Phytophthora capsici , 1990 .

[17]  D. Aylor,et al.  A framework for examining inter-regional aerial transport of fungal spores , 1986 .

[18]  C. E. Main,et al.  Applying atmospheric trajectory analysis to problems in epidemiology , 1986 .

[19]  C. E. Main,et al.  A regional analysis of the meteorological aspects of the spread and development of blue mold on tobacco , 1984 .

[20]  W. Fry,et al.  Interplot interference: a model for planning field experiments with aerially disseminated pathogens , 1983 .

[21]  D. Aylor,et al.  Escape of Peronospora tabacina spores from a field of diseased tobacco plants. , 1983 .

[22]  G. B. Lucas.  The War Against Blue Mold , 1980, Science.