A forest with 90 percent of its dogwoods dead by the end of the 1980s, due
to anthracnose, was in 1990 found to have one tree barely afflicted, being
highly resistant to the fungus, growing on Catoctin Mountain in Maryland.
The tree was closely scrutinized & cuttings started from it by Professor
Windham of the University of Tennessee. Read about Professor Windham he
http://eppserver.ag.utk.edu/personnel/windhamm.htm

That tree & its cloned & seed-grown offspring are now called "Appalachian
Spring." In Autumn 2001, young specimens of "Appalachian Spring" were
re-introduced into the Catocin forests. The long-term plan is to
re-introduce the eastern dogwood into other forests where it naturally
grew but has died out due to anthracnose.

The university's horticultural extension and experimental station in
Knoxville had the resistant dogwood under production & ready to release by
1998. The experimental station is also using "Appalachian Spring" to
create other strains of resistant dogwoods, though no others are thus far
released. Budwood is also being supplied to commercial nurseries in
Tennessee under special liscense. Growers outside of Tennessee are on a
waitlist and when budwood comes available, there will be increasing
numbers of growers, and the eastern dogwood will be guaranteed a
continuing presence among gardeners.

One source that ships "Appalachian Spring" nationwide even to individual
gardeners is a central Tennessee grower:
http://greenwoodnursery.com/page.cfm/1
and there are others, but ask your local tree sources foremost. The young
trees are not terribly pricy as the goal is to get the dogwood back into
the wild & the gardened environments, not to service rich people only.

Korean dogwood is not very susceptible to the fungus & other gardened
varieties are also relatively safe. Hybrids of of the Korean with the
Eastern dogwood have been developed for gardeners, but these do not help
save the trees in the wild. Some C. florida x kousa dogwoods now being
produced for gardens bare the cultivar names "Celestial" "Aurora"
"Stardust" & "Ruth Ellen," among others released from the Rutgers
University experimental station. They're bred for both mildew &
anthracnose resistance, but as young trees most of them have been found to
be a little less resistant than would be optimal, & for a serious level of
resistance, "Appalachian Spring" is thus far the ONLY reliable cultivar,
with U.of T. expecting other resistant strains to be developed from it &
not with the assistance of C. kousa hybridization.

The western dogwood, alas, is very susceptible, & Northwest forests were
afflicted slightly earlier than the eastern (but by a strain of
anthracnose distinct from that in the east & believed to have been
independently introduced into North America). No one is as yet producing
a western dogwood equivalent of "Appalachian Spring." There is some fear
that the C. nuttallii could eventually be extinct without herculean
efforts to save it, and micropropogation of several strains from several
location is being undertaken by a C. nuttallii gene preservation program
in British Columbia. More research into the problem has been done in the
east not because C. florida is more susceptible, but because it had become
a major multi-million dollar component of the nursery industry, whereas C.
nuttalli seemingly does not have the same degree of economic significance.
However, on the plus side, anthracnose decimation seems to have peaked in
the late 1980s and early 1990s, and surviving trees today are a LITTLE
less susceptible to the disease. In some forests only 15 to 20% of the
dogwoods were killed, in other areas nearly all were killed, so degree of
decimation is not uniform. Usually the remaining trees in a wild dogwood
population WILL be infected but the hope is that enough will survive &
reproduce in the wild to perpetuate their own generations until eventually
only resistant trees remain, at which point they may be able to increase
in number rather than continue to decline in numbers. Natural regeneration
of self-seeding infected dogwoods has been observed in a limited sort of
way in the east, and may be happening with the western dogwood too.

Wild trees in the more sun-exposed sites last longest (despite that the
tree would prefer to be sub-story) because the disease spreads more slowly
in dry heat. Gardened cultivars can sometimes be saved if the fungus is
spotted soon enough, if infected branches are removed and properly
disposed of, if the tree is not watered in the spring time when the fungus
is most active, but not permitted to experience drought in the summer, and
by watering exclusively in the morning as the fungus can be assisted in
its spread by evening watering even in summer. Fungicides are not
ineffective on their own, but are nevertheless sometimes used as a
confinement technique & to stop spread of spoors at time of spring
budding.

Another disease has of late been introduced into the Pacific Northwest
which afflicts rhododendrons and oaks is Phytopthera ramorum. In Oregon a
serious attempt is being made to nip it in the bud so to speak, but the
disease is also making inroads into Washington state without much being
done. In Oregon rhododenron growers have a bit more political power
because they contribute more profoundly to the state economy; Washington
rhody growers are not so empowered. And unless both states get on top of
it together, everyone may be very sorry a few years from now, if one of
the greatest symbols of the northwest begins to die off. The disease has
some capacity to afflict Douglas fir, which has a mightier economic power
in Washingotn, but for so long as it seems mostly to be restricted to
garden ornamental shrubs & oaks, Weyerhauser is not going to be pressuring
the economically strapped state into doing something about Phytopthera.
Some of us northwesterners who always loved dogwoods & rhodies are already
pondering what we're gonna have to love instead!

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/