Thought this might be of interest to you professional caregivers, if this isn't already old news.
Harv
Thursday, March 11, 2004 (SF Chronicle)
CALIFORNIA/Nursery reports oak disease/Infested plants have been sold
out of state -- scientists shocked
Peter Fimrite, Chronicle Staff Writer
Ornamental plants in the largest nursery in California -- a place
that distributes flora around the country -- have been infested with
spores from the tree-killing disease known as sudden oak death, it was
revealed Wednesday.
The discovery of Phytophthora ramorum in camellias at Monrovia
Growers in Azusa (Los Angeles County) means that the highly contagious
disease has been transported to other states and may have been
introduced into highly susceptible oak forests in places like the
southeastern United States.
The news hit like an earthquake as forest pathologists from around
the world gathered Wednesday at Sonoma State University for a California
Oak Mortality Task Force meeting.
"It's a huge nursery with thousands of plants that went all over the
place," said Susan Frankel, a U.S. Forest Service plant pathologist who
is working with the state Department of Food and Agriculture on the
problem. "Hundreds of nurseries are now going to require inspections.
Hundreds of thousands of plants will have to be destroyed. We're very
concerned for the forests of the United States, for the nursery industry
and trade. It's terrible."
The news of yet another infestation was a major setback after two
years of progress fighting the fungus-like scourge that has killed tens
of thousands of California's majestic oaks. The widening swath of
destruction seemed to have slowed in the past two years, especially in
the Bay Area, and an effective phosphite treatment was developed and
approved for use on private trees.
But there were signs of trouble last year when Phytophthora ramorum,
which is the scientific name for the disease, was discovered in
camellias in a small nursery in Washington.
It meant the disease had spread to another state -- but infestations
had been found before in nurseries and isolated, so it wasn't yet a
disaster. However, Frankel said, the camellias were eventually traced
back to Monrovia. Testing of plants there confirmed Monday that six
varieties of camellias were infected, the first such infestation in arid
Southern California.
The major concern is that the 500-acre nursery does $30 million
annually in out-of-state shipments, Frankel said, and many of the plants
sent out over the past year may have been infected. That means they may
serve as hosts and spread the disease to wildland areas.
Steve Oak, a forest pathologist for the North Carolina office of the
U.S. Forest Service, said a great many of Monrovia's plants are shipped
to the southeast, including places near the southern Appalachian
Mountains, where Northern red oak trees make up 80 percent of the forest
canopy in some places.
"We have a pathway that was theoretical before, but is now likely,"
he said during a break in Wednesday's conference. "The threat is very
real."
It is especially troubling in that region because the oaks there
replaced the forests of American chestnut trees killed in one of the
worst blights in world history.
The chestnut blight, first discovered in 1904, killed some 3.5
billion trees in 50 years, essentially wiping out the entire species.
Steve Lyle, spokesman for the California Department of Food and
Agriculture, said lab samples are being taken and analyzed to determine
how extensive the Monrovia infestation is. "Surveying is ongoing at
other nurseries in California as well to see if the fungus has spread
even further," Lyle said. Katie Bloome, the spokeswoman for Monrovia
Growers, said shipments of all plants that are susceptible to sudden oak
death have been halted and she is confident the problem can be
eradicated. "We're on top of it," she said.
Meanwhile, forest pathologists from the United Kingdom and the
Netherlands outlined during the conference how Phytophthora ramorum has
spread from nursery plants to forested areas. It seems to be especially
deadly for beech and red oak trees in Europe.
Curiously, the microbe in Europe -- which was recently also found in
the Pacific Northwest -- is a different mating type from the one that
dominates in the United States. Scientists are desperately trying to
keep the two types apart for fear that they will mate and create an even
more virulent form of sudden oak death.
Dave Rizzo, an associate professor of plant pathology at UC Davis,
said the latest news shows how important it is to stay focused and keep
up the fight. "We've had a couple of years where we haven't had much
die-off, probably because of the weather," Rizzo said. "But remember,
chestnut blight took 50 years to kill every tree. So we still need to be
cautious."
