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blink211j2
Guest
American chestnut trees once made up more than 25% of the hardwood forests of the eastern United States. These trees were wiped out by a fungus accidently introduced on imported Asian chestnuts, which are not affected. More recently, a fungus has killed many eastern dogwood trees; some experts suspect that the parasite was accidentally introduced from somewhere else. Why are the plants particularly vulnerable to fungi imported from other regions? What kinds of human activities might contribute to the spread of plant diseases? Do you think introductions of plant pathogens such as chestnut blight are more or less likely to occur in the future? Why?