The Chestnut Blight Fungus and its Viruses: An Example of Murphy's Law for Introduced species?

Saturday, April 13, 2002 - 9:00am - 9:50am
Keller 3-180
Michael Milgroom (Cornell University)
Chestnut blight is one of the most ecologically devastating plant diseases known to result from the introduction of an exotic pathogen. Countless millions of chestnut trees died as a result of the introduction of the chestnut blight fungus into North America and Europe from east Asia. Before this introduction, the American chestnut was the dominant tree in the Appalachian region; sprouts from old root systems are now killed by blight before they can fruit or reach canopy height. Along with the fungus, however, fungal viruses were also introduced into Europe from Asia. Unlike most fungal viruses, these viruses cause marked reductions in host fitness and have invaded some European fungus populations, exerting some degree of biological control on chestnut blight. Attempts to introduce these viruses into North America for biological control have failed despite some aggressive strategies. This system will be discussed in relation to the evolution of virulence, founder effects in introduced populations, and the interaction of ecological or demographic factors.