Re: Some musings on current local tree diseases/Pinus radiata

Hello Mark,

The article you forwarded from your local paper did a
much better job of reporting the facts than our local
San Francisco Chronicle, but that isn't saying much,
as our local paper just isn't in the real news
business anymore, (sadly...).  There has been some
local speculation that hybrid rhododendrons might have
been the original source of the disease here as well.


A few of the "facts" quoted in the article are also
not quite right.  Coast Live Oaks are by no means
rare, they are still abundant along most of the
coastal ranges, and one of the most common oaks in
California.  There are several other Live Oak species
such as Q. chrysolepis in inland areas and Q.
engelmannii in southern California which tend to
replace Q. agrifolia, the most common species in the
San Francisco Bay Area.  Tanbark Oaks, Lithocarpus
densiflorus, is also quite common here, as a redwood
forest associate.

Coast redwoods also are not an endangered species, the
secondary growth of Sequoia sempervirens still covers
the same original range of the species prior to
logging, and most of these trees are genetically
related to the old growth trees, as they are basal
sprouts from the logged trees.  This accounts for the
appearance of "Fairy Rings" of new trees around the
base of the originals.

However, mature old growth trees not already protected
in reserves are still under considerable logging
pressure, and there doesn't seem to be the political
will in California to spend the money to purchase the
remaining tracts of old growth forest. The money
required would be substantial.  The larger issues of
logging of Coastal Redwoods has much more to do with
improper control of erosion on often very steep slopes
and resultant silting of steel head trout and salmon
habitat in local coastal rivers, and the use of
herbicides to control deciduous species considered as
competing weeds.  The value of old growth trees as
habitat for certain bird species which require them is
also a large issue.  The trees themselves are not
scarce or becoming more so, just the most valuable old
growth trees.

The case wtih many of California's native oaks is more
threatening.  Many species are not regenerating well
due to changes in land use,  heavy grazing pressures
and rodents are also a major cause of young seedling
oaks nonsurvival for species such as Valley
Oaks(Quercus lobata), in particular.  Attempts are
often made to retain old trees in new suburban
developments, but often without proper regard to
retaining enough undisturbed soil.  Many times the
"saved" trees will slowly decline, due to changes in
grades, lack of undisturbed roots, added summer
irrigation which encourages root rot, etc.

I've been involved, as a landscape architect, with
development projects in prime oak country such as the
Napa Valley, and even when the county planning
department is relatively enlightened, the controls are
not sufficiently strict to save habitat, development
always takes precedence.  The current laws to preserve
existing oaks at least take into account the current
knowledge of what works; such as fencing off large
areas around groves during construction to minimize
root compaction, maintaining minimum distances away
from trees without disturbing grades, and mulching at
the perimeter of the tree canopy to encourage
seedlings at the prime location for their best
survival.  Old trees stand a much better chance of
survival and regeneration amongst development when
preserved as groves rather than isolated specimens.
Seedling germination of most oak species is very high,
as anyone who gardens near one can attest, and the
local wildlife is very efficient at spreading them
around.

Warm regards,
David Feix


> David,
>
> Might be of interest to you (and others) but the
> following is the web
> address of a news report from my daily newspaper,
> The Independent,
> concerning the interest in the plight of the
> Redwoods in California and the
> threat from Phytopthora,
>
> www.independent.co.uk/story.jsp?story=113831
>
> if this fails go to the site and search for Andrew
> Gumbel, a fairly
> entertaining and reasoned journalist responsible for
> the story. Quite
> interesting to see a  report of 'footbaths' being
> used at one place. As I
> say, I'm not sure where all this is leading but I
> guess the increasing
> rapid movement of plant material and timber imports
> from different regions
> must have a significant bearing on the problem if a
> disease slips through
> the net. It hadn't occured to me before but I have
> seen the demise of a
> couple of Sequiodendron giganteum (the Sierra
> Redwood) in these parts - one
> is but a few yards away on the site of the old
> Treseder Nursery here in
> Truro. Another I saw felled on an estate close to a
> local town, the owner
> told me that a local expert had considered the cause
> of death to be "old
> age"! - it was probably 120 yrs old.
>
> Interesting reports coming through to me from the
> Yahoo Rhodo group
> connected to the same problem which you may like to
> take a look at. Seems
> Rhododendrons have been placed in the frame as a
> possible culprit, with
> their export to Canada being placed under control?..
>
> Thanks for the inf. on the Monterey Pine, a tree
> that the local county
> landscape dept have been keen to preserve since its
> become such a feature
> close to coastal towns and on headlands. The
> rapidity of its establishment
> here is quite amazing - we're currently looking at
> taming some we planted 15
> yrs ago, they've gone from 12" to 40' in that period
> with a girth and spread
> to match.
>
> Found a UK Arboricultural report in some old notes
> concerning Oak dieback
> (was looking for something else, I assure you!),
> seems the trees were
> predisposed to attack by various pests including
> Honey Fugus due to a run of
> droughts in the 1980's which brought about water
> stress. However some Oak
> decline in parts of Eastern Europe inc. Romania and
> the former USSR may have
> been caused by a vascular wilt type disease
> involving various fungi in the
> Ophiostoma , Data relevent circa 1992. (phew, you
> never realise just how
> much stuff you've forgotten until you dig around in
> a box of old college
> papers).
>
> kind regards, Mark.
>
> Mark Brent, Lamorran House Gardens, St. Mawes,
> Cornwall.
>


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