Musings on Tree diseases
- Subject: Musings on Tree diseases
- From: G* B*
- Date: Mon, 14 Jan 2002 22:29:29 +0200
Hi all
I've been lurking here for a long while following my return from an extended
circum Australia trip.
Whilst in SW Australia I tried my damnest to understand what was happening
with the dieback there. The whys & wherefores are very confused & nobody
seems able to clearly state what the causes are. They seem reasonably sure
now that the main fungi species involved are not introduced - as was first
thought - but have always been present in the ecosystem. It was probably
always in balance in an undisturbed system & what we are seeing now is the
dieback organisms expressing themselves due to some imbalance, probably
precipatated by man. Think, perhaps, of your body in its normal
( hopefully ) healthy state under constant bombardment by disease & your
immune system throwing it off. Then maybe you come under extreme personal
stress & it can't cope so well anymore, so that the flu or something similar
gets a grip. It strikes me that this could well be what we are seeing with
the dieoff diseases world wide.
An associated problem that exists in SWA is massive areas of farmland being
lost to salination. What happened was the forests were cleared for pasture,
but cognisance wasn't taken of watertable levels. The eucalypt forests acted
as massive water pumps pulling water up from deep underground via osmosis.
Remove the trees & the water now comes to the surface by evaporation &
deposits the salt on the soil surface & leaving huge areas of saltpans.
What does all this mean for the forested areas adjacent to the agricultural
land.? What happens to overall watertables & salt levels there ? What stress
does this place on the trees ? I think if you want solutions these are the
sort of questions which should be answered first.
Someone noted earlier here of air sampling while ascending in a balloon & of
all the fungi spores etc naturally wafting around at higher altitudes. Can
anyone honestly tell me that these don't go worldwide ? The human influenza
virus , for instance, is cross carried by waterfowl so that even without
human contact & airtravel they can contaminate every waterway in the world
in their migratory travels.
I visited a protea farmer there who had massive dieback problems on his
farm. He maintained the South African proteas were every bit as susceptible
as the native Banksias. South Africas quarantine protection is laughable /
nonexistent so even without these pathogens occuring naturally we should be
seeing it here - but we're not. Believe me - if theres a system under stress
its got to be this one. So why don't we have it ?
I don't know where this is heading. Just musing out loud. Any insights
appreciated.
Regards
Glenn Breayley. Ragnarok & Valhalla Research.
POBox 26158, Hout Bay, 7872, Capetown, South Africa
Ph/Fax SA 021 7904253 E-mail valhalla@iafrica.com
Wholesale nurseryman & Tillandsia specialist wholesale & retail grower.
