Title: Risk Assessment of Exotic Plant Pathogens
Student: Chandalin Bennet
Department: Forest Resources
Exotic plant pathogens have been the cause of many devastating disease epidemics in America’s forests and agriculture. Famous examples include chestnut blight and white pine blister rust, both cases of native plants showing catastrophic susceptibility to the pathogen of a congener. This project tries to understand this phenomenon of resistance and susceptibility to pathogens of congeners by performing host-range inoculation experiments using a speciose plant genus and multiple isolates of its most common pathogen.
The plant genus Salix (willows) was chosen as an ideal group for inoculation experiments because in North America there are over one hundred native species and are commonly host to a rust fungus in the genus Melampsora. Twenty-six different Salix species were inoculated in three separate experiments with isolates from different hosts of this pathogen. Results from these experiments show that in each case greater than 80% of the plants were resistant to the pathogen of a congener. Extreme susceptibility of congener species occurred in less than 5% of plants in each experiment. This susceptibility occurred at the greatest frequency in small Southwestern populations of Salix and to a lesser extent a few isolated Pacific Northwest populations. One of the Salix species that showed this extreme susceptibility was Salix arizonica, which just recently was taken off the endangered species list.
For more information, email the PI: Dr. George Newcombe