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Sudden oak death

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Offline nick

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« on: November 10, 2009, 12:35 PM »
Does anybody know any more about this topic? I guess those of you living in dehesa areas have been witnessing it for some time.


The holm oak and with it that unique ecosystem the dehesa are under threat. A invasive fungi phytophthora from Australia is ravaging across the dehesa causing a disease known as sudden oak death, aided by a deadly cohort of drought, several insects and other fungi. There are currently some 500 foci but scientists believe the worst is yet to come and that the production of Iberian ham could be seriously affected, not to mention the biodiversity based around this habitat. Regeneration and the more sustainable use of the system are seen as the only remedies.

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Offline Dave

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« Reply #1 on: November 10, 2009, 13:15 PM »
Hi Nick
A Wiki on this disease, which has been rampant in the USA and in England

Offline andyj

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« Reply #2 on: November 10, 2009, 21:01 PM »
HI all, that bloody phytophthora gets everywhere!
Here is a bit of what i know.
Phytophthora was thought to be spread from plant to plant mainly via deer carrying the spores and rain splash transferring spores in the droplets as they hit a leaf or ground. Now it appears that the phytophthora can be spread under ground making it much more difficult to eradicate. There are numerous theories to the reason it suddenly changes to plague type proportions as there are several native species and strains of phytophthora in the UK, presumably the same in Spain. In the UK phytophthora seems to affect species such as bilberry (Vaccinium myrtillis), birch (betula species) and Rhododendron very easily. Oak does not seem to be as easily affected though is of course a target for phytophthora, maybe bark thickness helps? It was thought that the wet summers (in the UK) contributed to it spreading. In Spain, i guess that is less of an issue, BUT a long drought may have the same affect since it could be environmentally-related stresses that make plants more susceptible to attack rather than one particular  environmental factor (ie. Rain or sun) but too much of one element.
From what I know it also evolves quickly and therefore the Australian species (or strain or whatever it is) that has got established in Spain may have evoled into a new strain and like lots of other invaders, find is easy to attack native species since resistance is usually low to non-natives. In the UK, the main protagonist is a strain from the USA that may have evolved, I’m not sure where they are with all that now. Native species, although affect plants, are not notifiable to Natural England as it is a continual presence in plants.
The scarmungering in the UK has died down a little now (it was massive this time last year) but as the conservationists and Natural England have learnt more about it there appears to be less worry….not to be confused with complacency. A lot of work is still being done on the ground to destroy it.
An interesting aside to this is one way it appears to have spread. Most places that reported phytophthora were National Trust properties. It appears that the movement of people from one place to another on a Sunday day out has helped the spread of phytophthora far and wide.

I would say that, although this could be devastating, from the experiences of here, only small areas have had significant changes and luckily many of the large oaks have been retrained and saved and it has been less important species that can regenerate more quickly that have been affected to a greater extent.

Please keep us all informed over this.