Global warming: Forest Service researchers examine the role of pathogens in a world that’s heating up

Forest Service scientists say warmer and drier conditions could lead to more Armillaria root disease in some conifers and hardwoods, as well as more Cytospora canker on aspens and dwarf mistletoe, which poses a high risk under drought conditions. Under a warmer and wet climate change scenario, sudden oak death and other Phytophthora tree diseases could become more common, as the pathogens reproduce and spread quickly under favorable moist and warm conditions. The report from the agency’s Pacific Southwest Research Station surveyed existing scientific literature to try and rate potential risks to forests under different climate change scenarios, looking specifically at eight diseases that affect forests in the Western United States and Canada. The results suggest that climate change will affect forest health, but there is still some uncertainty about the degree of climate change and how it will affect pathogen biology, the potential direct impacts to host species and the interactions between the pathogen, host, and climate. To read the full report, “A Risk Assessment of Climate Change and the Impact of Forest Diseases on Forest Ecosystems in the Western United States and Canada,” go to: http://www.fs.fed.us/psw/publications/documents/psw_gtr236/