Author
 |
Pfender, William |
|
Submitted to: Plant Disease Epidemiology International Workshop Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/28/2005 Publication Date: 6/30/2005 Citation: Pfender, W.F. 2005. Importance of plant phenology to temporal scale in epidemics of ryegrass stem rust. Plant Disease Epidemiology International Workshop Proceedings. p.61. Interpretive Summary: The severity of stem rust disease on perennial ryegrass during the growing season is determined, in large part, by the amount of rust disease present in the early spring. Springtime disease severity, in turn, is determined by the ability of the pathogen to survive over the winter in plants that were infected in the fall. In this research we developed a mathematical model to describe the ability of the pathogen to overwinter, as a function of weather conditions and timing of fall infections. We used information about the effects of weather on the reproductive rate of the pathogen and on the growth of the plant, including development of new leaves and death of older leaves that may have harbored the pathogen. Testing of the model showed that it accurately estimated the level of springtime disease in plants that were intentionally inoculated at various times in the fall. Technical Abstract: In the Puccinia/grass pathosystem, host phenology strongly affects temporal development of epidemics. After infection of seedlings in the autumn, persistence of the fungus through the winter depends on the temporal interplay between pathogen life cycles and grass phenology. Overwinter survival of Puccinia graminis subsp. graminicola (the stem rust pathogen) was effectively modeled based on growth rates, duration and senescence of sequential host leaves interacting with pathogen infection efficiency, latent period and pustule duration. Cycles of pathogen appearance (pustules) and absence (present as latent infections only) observed in field experiments were simulated with the model. The manner in which winter weather conditions can affect epidemic survival through effects on interacting host phenology and pathogen biology was demonstrated. Equations for stem extension were used to model the rapid increase in stem rust that occurs during and after tiller extension. |
