Pacific Southwest Research Station

Sudden Oak Death (Phytophthora ramorum)

Over the past ten years, significant mortality of oaks and tanoaks has occurred in the coastal areas of central California. Commonly called Sudden Oak Death, this epidemic is viewed as a serious threat. Tree losses are occurring in both wildland and urban-wildland interface areas, with up to 80 percent of susceptible trees being affected in some stands. This oak loss is unprecedented in recent California history, and there are concerns that the mortality is affecting ecosystems, increasing fire and safety hazards, and reducing land values. In response, federal, state, and local agencies, as well as non-profit groups and concerned citizens, formed the California Oak Mortality Task Force to better coordinate research, education, management, and funding efforts.

In 2008, the USDA Forest Service is awarding approximately $1.5 million for Sudden Oak Death/Phytopthora ramorum research. Projects are being carried out at 15 research institutions, in 7 states, the United Kingdom and Germany. The information is being used to guide development of regulatory policies, monitoring programs, and management and treatment strategies, to minimize spread and impact of this quarantine pathogen. Read about this topic.

Insect and Disease Response to Climate Change

• Forest Disease (Contact: Susan Frankel, sfrankel@fs.fed.us) Sudden Oak Death

Forest plant diseases are heavily influenced by weather and climate. For forest pathogenic fungi, bacteria, viruses and other microorganisms, the temperature and moisture conditions interacting with the host determine infection severity and disease distribution. Extreme weather, i.e. drought or typhoons, can kill large expanses of trees directly by overwhelming tree physiological and structural strength. Patterns and rates of wood decay, caused by forest fungi, are also expected to change in response to climate changes which will influence forest carbon cycles. Expected changes in climate coupled with the increasing stresses of invasive species, lack of fire, and forest fragmentation are creating conducive conditions for many forest plant diseases.

• Kliejunas, J. T.; Geils, B.; Glaeser, J. M.; Goheen, E. M.; Hennon, P.; Mee-Sook K.; Kope, H.; Stone, J.; Sturrock, R. and Frankel, S.J. In preparation. Climate and Forest Diseases of Western North America: A Literature Review. February 22, 2008. General Technical Report. PSW-GTR-XXX. USDA Forest Service, Pacific Southwest Research Station, Albany. 36 p.
• Annotated Bibliography

White Pine Blister Rust in Western North America

A disease native to Asia, white pine blister rust was introduced separately into both eastern and western North America early in the 20th century. In both cases, the vector was seedlings of native eastern white pine imported from European nurseries, where they had become infected. Blister rust had first appeared in Europe in the mid-nineteenth century, and within three decades had spread across the continent wherever the popular eastern white pine had been planted.

Research is being conducted by: