Wow, interesting article. So it really isn't nice to fool with mother nature, although you may not see the results of your actions for years.
This sort of leads one back to the idea of planting native species. The next step would seem to be planting native species obtained from local stock.

"(soon be placed in separate genera)"

The trend now is strongly to put them all (including Nootka Cypress) into Cupressus; see e.g. here and here (pdf file)

"however it is strange that the majority of California's 12 distinct cypress species are not affected by it"

Not surprising, as having been in contact with it for the longest, they've had the best opportunity to evolve resistance. Monterey Cypress is susceptible though, as the disease doesn't do well in the coastal fog belt so Monterey Cypress hadn't been exposed until it was planted inland.

Resin

That first link is a pretty great explanation of the matter, but I would beg to differ that it is not possible to differentiate between old and new world Cupressus by looking at them alone. Also, Cupressus abramsiana is completely extinguished as a species and lumped into Cupressus goveniana, despite the article by Adams and Bartel which describes abramsiana as a separate (albeit closely related to Goveniana) species, and which describes the Butano Ridge grove as possibly warranting yet another separate species designation. After having seen all of the three "varieties" of goveniana in the wild, I am completely averse to the idea of the Butano trees being classified as a variant of Goveniana - they have much blue-er foliage, the cones are enormous for a Cypress, and they reach massive sizes compared to goveniana. The growth and branching patterns are completely different, as well.
What's your take on this, Resin? I guess in the end it doesn't really matter much, but is certainly quite interesting to think about.

Maybe a little test? To tell which cone belongs to which world?

Here is a link that might be useful:

Hi Shastensis - most cases, it is possible to tell between old and new world Cupressus by looking at them alone, but I've known cases where it couldn't be done reliably. I've also seen herbarium specimens that were clearly C. lusitanica, but with determination labels (from notable names in conifer taxonomy!) saying "C. torulosa" ;-)

I'd agree lumping abramsiana into goveniana isn't a good idea; they're distinct in cultivation in Britain, and I've also read a suggestion that abramsiana may be closer to sargentii (or be of ancient hybrid goveniana ÃÂ sargentii origin??). I've not seen any of the Butano population, any chance you could spare some cones?

Nice challenge from Nothotsuga, still thinking about it!

Resin

Resin, No problem on the cones. Email me your address again.
Nothotsuga, I'll take a shot at it, for what it's worth. The cone on the left, if not a bakeri (which would be easy to tell if I could smell it or see a larger picture, but as it stands now it looks more like a funebris and I can't load a larger photo on my phone), 2nd from left is an old world, 3rd from left is a new world, 4th from left is a nw, 5th from left is an ow, and the last one is a new world species. How'd I do?

How'd I do?

Congratulations! Except for the first one which is not a bakeri nor a funebris, the others are correctly placed in the right part of the world.

What about the species?