Second Science Symposium
January 18 - 21, 2005
Phytophthora Species Associated with Forest Soils in Central and Eastern U.S. Oak Ecosystems
Yilmaz Balci, West Virginia University, Morgantown, WV 26506-6058; (304) 293-3911 ext: 2234; firstname.lastname@example.org; Kurt Gottschalk, USDA-Forest Service, Northeastern Research Station, Morgantown, WV 26505-3180; (304) 285-1598; email@example.com; William MacDonald, West Virginia University, Morgantown, WV 26506-6058; (304) 293-3911 ext: 2236; firstname.lastname@example.org; Jennifer Juzwik, USDA-Forest Service, North Central Research Station, St. Paul, MN 55108-1099; (651) 649-5114; email@example.com; Robert Long, USDA-Forest Service, Northeastern Research Station, Delaware, OH 43105-8640; (740) 368-0052; firstname.lastname@example.org
The existence of native and exotic species of Phytophthora
in soils of eastern and central oak ecosystems is largely unknown. This
informational void and the potential threat of P. ramorum to
eastern oak species provided the impetus for a multiple state survey of
soils associated with oak cover types. The initial survey was conducted
from April-June 2004 with the assistance of state and federal cooperators
from IL, IN, MD, MI, MN, OH, PA, WI and WV. Sampling sites were chosen
to avoid areas impacted by oak wilt, recent storm damage or defoliation.
Most stands contained a diverse population of species; stands were generally
greater than 40 years of age and located on moist sites. At each site,
four soil samples were taken 1.5 m from the base of the tree in four directions.
Samples from each tree were bulked; generally five trees were sampled
per site. To date, a total of 79 sites were surveyed and soils from 410
oak trees sampled. An oak leaf baiting procedure was used whereby soils
from each tree were placed in a container, flooded with distilled water
and three-to-seven day old Quercus robur leaflets were floated
on the water surface to bait Phytophthora. Leaf samples that
trapped Phytophthora and produced sporangia were plated on PARPNH-medium.
When initial isolations attempts failed, soils were dried at room temperature
and the isolation procedure repeated. Twenty-eight percent of the samples
from individual trees yielded Phytophthora; P. cinnamoni was
the most frequently recovered species (77%). Other species recovered included
P. europaea and P. citricola and several yet unidentified
or undescribed species. These findings suggest that Phytophthora
species are common to oak forest types in the eastern and central U.S.
A comparable survey will be conducted during the fall of 2004 to establish
a more complete assemblage of Phytophthora species so that studies
of their role in forest health can be initiated.
| Coordinated by:
USDA Forest Service Pacific Southwest Research Station
University of California Integrated Hardwood Range Management Program,
Center for Forestry, Division of Agriculture and Natural Resources, and
California Oak Mortality Task Force
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