Marty said:
I dunno, Nina. Every year there's a new plant enemy. Has this always

been the case, or is the cause increased accessibility? Are we too
civilized? Sooner or later, each of these insects and diseases seems
to win out over the best efforts to control them. That's why I think
we should concentrate on developing disease-resistant varieties rather
than focusing on preventative measures. IMHO we have very little
choice.

I reply:

The problem in England is the "Historic gardens". For about a hundred
years, intrepid gardeners have gone exploring and bringing back plants
without thought to the diseases they might harbor. The world is now a
very small place, and there are few parts of it that don't interact
with the rest. We haven't found the native habitat of SOD yet;
probably China. At any rate, we can expect to see a faster and faster
rate of introduction of exotic diseases.

It's fine to develop resistant stock of cultivated plants, but SOD and
now P. kernovii are not simply attacking nursery stock, they are
killing native forests where neither spraying with fungicides or
resistant stock will do any good. To protect forests, you need
preventative measures or ugly clean-up measures.

Just as a history lesson: Chestnut blight took out the Northern
chestnut forests, but Phytophthora cinnamomi, introduced into the US in
the 1870's, wiped it out in the South. None of us remember this, but
the chestnut was the dominant tree in eastern forests and its timber
and nuts were a major economic force in Colonial America. It was a
major food source for birds, deer and swine. Now, the chestnut has
vanished. Cultivars resistant to chestnut blight have been bred, but
none of them can survive for long in the south, because P. cinnamomi is
still in the soil, and nothing has resistance to *it*. Our Eastern
forests can never go back to what they were.

A more recent history lesson: P. cinnamomi was introduced to
Australia, and has wiped out whole ecosystems. Any aussies who want to
comment, please do, because many people can remember the "before" and
"after" in Australia. Eventually a new equilibrium will be reached,
eventually no one will remember the "before", but Australian forests
will never be the same.

If you're suggesting that we sit back passively and watch the red oak
go exinct as well, well.... I don't think many people will agree with
you. And it's sad to visit California and see the land dotted with
dead oaks, to hear how this is affecting the bird and animal
populations, to hear how it's affecting the risk of major forest fires,
etc. etc. This is not just a problem of gardens. This is a potential
ecological disaster. We have to try and limit spread, even if it is
ultimately futile. At the very least, the study of Phytophthora is
undergoing a renaissance it hasn't seen since potato blight. We are
learning a tremendous amount, perhaps which can be applied to the
*next* disaster.

Nina