The
Problem Facing Connecticut
- By Donald H. Smith, Connecticut State Forester
Since 1995, large numbers of oaks and tanoaks
have been dying in the coastal counties of California. Since then,
many other types of plants have been found to be infected or associated
with this disease, referred to as Sudden Oak Death, Phytophthora
ramorum (Pr). Phytophthora ramorum was first seen
in 1995 in Mill Valley (Marin County) on tan oak. Since that time,
the disease has been confirmed in twelve coastal California counties
and in localized areas of Oregon and Washington. There is no known
practicable control for forest environs. The nation has known other Phytophthora
species (root rot and potato blight) for a while. With those species, the
means of spread has been through rain splash or other mechanical
means. This species seems much more dangerous because it can be
airborne. That means that spread can be accelerated via severe
weather events that may coincide with spore production. Several
tree species are vulnerable to this disease - most notably many
red and black oaks - especially northern red oak. Many shrubs species
such as rhododendron, laurel, and viburnum are also hosts to this
disease. On oak trees, it seems the infected tree may
appear healthy to the casual observer and suddenly wilt and die
within two to four weeks. In actuality, infected trees will show
evidence of infection that is observable by inspection, (cankers,
seeping, etc.) for several years before the final collapse. The disease was found on stock in numerous commercial
nurseries in California and eradication efforts were well under
way. Unfortunately, it was announced in early March that one of
the largest nurseries in the nation has shipped infested camellias
to 1700 retail points across the nation. It is suspected that shipments
of rhododendron, laurel, and viburnum landscape stock may have
already exposed several regions of the country to the disease,
as well. This is just the latest in a series of "leaks" through
the containment net that have been discovered, but this is a big
one. In northern climes, camellias are indoor plants and the risk
of escape to the forest is small. But, for southern states, the
risk is significant. At least seven states have now taken the dramatic
step of banning any plant material from California from entering
their states. The rhododendron and viburnum stock is of concern
to Connecticut - especially since it is so widely available through
chain department stores (and then there is the issue of mail order
sales). The Connecticut Agricultural Experimental Station
is very concerned about this disease and is gearing up to be able
to culture samples and identify the species by DNA analysis. 112
addresses in Connecticut received these camellia plants by mail
order. The CT Agricultural Experiment Station (CAES) has sent letters
to these people and reports good cooperation. They have been taking
samples to determine if the plants are infected. To date, CAES
has not found any infected plants and none have been disposed of
into the environment. Follow ups will be made to all who failed
to respond to the letter. CAES has also notified all of Connecticut
's 900+ registered nurseries of the danger of SOD and is instituting
an inspection/monitoring program for SOD at and around nurseries. USDA Animal and Plant Health Inspection Service
(APHIS) has instituted a quarantine on all SOD host material originating
from the state of California . Approximately 1500 nurseries in
the state are affected by the quarantine. A statewide survey of
nurseries has found two nurseries in California with infected host
plants and an additional 11 have tested positive for the molecular
test for the organism. As part of their comprehensive response
plan, APHIS has set up a dedicated hotline for SOD issues to be
available immediately at (888) 703-4457. SOD has now been confirmed on nursery stock
in Florida , Georgia , Alabama , Virginia and Maryland. To date,
it has not been determined if infected plants have been planted
out and no infestation of woodland plants has been found. That's worth repeating: Sudden
Oak Death has never been found in the wild in the eastern United
States. To date, it has been found only on
nursery stock in nurseries. I strongly advise anyone reading this article
to go to the APHIS web site for this disease http://www.aphis.usda.gov/ppq/ispm/sod/ and
familiarize themselves with it. A web search for Sudden Oak Death
will yield much information - most of it from the west coast.
This is an important emerging issue and you can expect that there
will be new material posted (especially on the APHIS site) almost
daily. It would behoove all of us to become as knowledgeable about
Sudden Oak Death as possible - and to be observant. You should
report any suspected cases of infected trees to the Entomology
Dept. at the Connecticut Agricultural Experiment Station in New
Haven (203-974-8606). So, does this mean the demise of oak in eastern
US forests is imminent? It is true that researchers and foresters are
concerned that sudden oak death has the potential to have a catastrophic
impact similar to that of Dutch Elm Disease or Chestnut Blight
(i.e., elimination of oak from the forest within just a few decades.)
If this were to happen, the economic impact would be staggering,
but the economic impact would be dwarfed by the ecological impact.
However, it is much too early to push the panic button and, certainly, NO
ONE should be rushing to liquidate the oak from their
forests.
The facts are:
-
SOD has been on the west coast of the United States for 12
years.
-
West coast nurseries have been shipping stock throughout the
country for those 12 years.
-
This is the first time SOD has been found in the east – and
only in nurseries.
So, it is more than possible that the east coast
has repeatedly been exposed to SOD throughout the past decade or
so. If that's the case – and SOD has not appeared in the wild – one
might take some comfort in the hope that the environmental conditions
and species mix in the east is inhospitable to SOD. It may not
be able to gain a foothold here. Only time will tell.
Advisory
prepared by:
Donald H. Smith, Connecticut State Forester
CT DEP Forestry
79 Elm Street
Hartford , CT 06106
860-424-3630
860-424-4070 (fax)
don.smith@po.state.ct.us
CONNECTICUT FOREST FACTS:
- There are 819,628,631
t rees in Connecticut 's forests. (9.9%
State, 6.8% City, 82.8% Private)
- Of those, 145,170,522 are of species known to
be s usceptible to SOD. (17.7% of all
trees)
- There are no figures
on the number of susceptible trees in yards or on city streets.
(Source: USDA Forest Service, Forest Inventory
and Analysis)
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