Re: Sudden Oak Death linked to rhodendrons
Julie wrote:
>
> I found this news release extremely interesting; has ramifications galore.
> Subject: Sudden Oak Death
This seems to send a clear message for the value of monitoring all
movement of plant material around the earth and the sad fact that the
general public in its ignorance will often frustrate the best efforts of
the biosafty authorities because they fail to understand the hazards
involved.
It remains to be seen whether the disease whiich has been found on
Rhododendrons in Europe will in fact eventually spread to oaks.
I don't know if anybody is clear in which direction the disease is
spreading.
If originally a European disease I suppose it could have suffered a
mutation after crossing the Atlantic increasing its pathogenicity and
allowing it to increase its host range..
Conversely, if it has come in the other direction there is no particular
reason to believe it has changed and maybe it is only a matter of time
before European oaks begin to fall victim.
We have both exotic Rhododendrons and many oaks from both hemispheres
here, but no natives from either family. A species of Phytophthora has
long been known here as an occasional killer of Rhodos., but it
certainly doesn't seem to affect oaks.
In fact a rather old checklist I have gives Phytophthora as an ocasional
disease of a great many imported species but not a single oak of any
sort among them. Apparently also native species are generally resistant
as I could only find one reference to Phytophthora causing trouble and
that was on a hebe.
We have a great many very fine specimen oak trees here, both European
and American, many now well over 100 years old, and it would be a great
pity if their days should be numbered while they are still at the height
of their vigour and beauty.
Moira
--
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata (near Wellington, capital city of New Zealand)
