At a recent APS Northeastern Division meeting, plant pathologists highlighted several types of diseases that are of growing concern, including:
First reported in Wisconsin in 1967, butternut canker is a fast moving, virulent disease that is killing butternut trees at a rapid rate throughout their range in North America. Butternut canker is caused by a fungus that infects the trees through wounds or natural openings in the bark. Infections kill the inner bark and create dark-colored, elongate cankers (dead patches) on woody tissues of exposed roots, stems, and branches. Infected trees are eventually killed due to multiple cankering that girdles the tree. In 2004, a survey of 1,384 permanently marked butternut trees in Vermont found that about 82 percent were diseased and that 41 percent had been killed. This level of mortality is about a 30 percent increase since the initial survey was completed in 1996. Forest pathologists at the University of Vermont have found that insects are involved in the dissemination of spores of the fungus. They are also using a Geographic Information System (GIS) to investigate geospatial patterns of disease development and tree mortality on the landscape.
SUDDEN OAK DEATH AND RELATED DISEASES
Since it was discovered in 1995, Sudden Oak Death (SOD) has killed tens of thousands of oaks in forests of California and Oregon. The fungus-like organism that causes SOD, Phytophthora ramorum, appears to be an exotic species that is not native to North America. The pathogen infects a large number of plant species, but mortality in forests is primarily restricted to oaks and tanoaks. While many of the non-oak plants do not die as a result of their expos
Contact: Amy Steigman
American Phytopathological Society