I think that if the roots died as a result of a repotting injury a year ago,
they would be mostly gone, and only the thin, wiry core would remain (anyone
know what that's called, by the way?). The fact that fungi were growing on
the dead roots indicates that it's much more recent.

You must keep in mind that having the roots submerged in any medium is most
unnatural in the first place. For the most part the plants we grow are
epiphytes that have their roots clinging to tree branches and hanging right
out in the air, where the types and reactions of fungi are WAAAYY different.
Surrounding the root system with a potting medium is for OUR benefit, not
the plant's, so we have to keep it in a condition that is not detrimental to
the plant.

Being a scientist and engineer by background, I hesitate to make even
marginally unequivocal statements when I do not observe something first
hand, but I'd be willing to put money on the fact that your decomposing
medium led to the loss of roots.

While related mostly to semi-hydroponics, you might find this of interest:
http://www.firstrays.com/roots_and_culture.htm

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!

.. . . . . . . . . . .
"Ben Lurkin" wrote in message
hlink.net...
OK, at this point, the fungus was growing only on the media and dead
roots.
I still believe that the roots died as a result of a bad transplant job a
year ago last fall. I have kept potted plants for 60 years, but I still
consider myself a newby with orchids. I cut away the dead roots rinsed
with
water and planted in new media.



Would your experience indicate that the fungi begins in the media and then
moves to the roots?? Saprophytic fungi excrete digestive enzymes to break
down the dead organic matter, and then absorb the nutrients. Some of
these
enzymes could damage [read kill] roots of some plants. Of course I am
speculating here. The fungus would grow on dead roots.



In the organic garden; decomposition and disease fungi are different
species. But, for anything in biology every rule has an exception. It is
never safe to say always. Also in the crowded conditions of pots and a
greenhouse, miner infestations can become epidemics. I never have a
problem
with cottony aphis outdoors, but when the plants come in, in the fall I
must
be observant. Some years one gets in and will multiply very rapidly
without
the predators that are outdoors.



There are compounds available for killing fungi on some vegetables and
roses
at the organic gardening supply houses. These fungi live on the leaves
defoliating and killing the plant. I use one on roses and another on
cucumbers. As I have not previously had a root problem, I have not looked
into a safe way of dealing with them. Many fungicides are extremely
poisonous and not acceptable to me as an organic gardener.



I will try and do more research in the coming weeks.



Ben




"Wendy" wrote in message
news:AYWUb.16475$fD.2336@fed1read02...
Interesting stuff Ben & if this fungus isn't detrimental to the plants,
then
it's not what some of my plants have.
There was a time where it was so bad, I could pick out which
cymbidiums'
had
the flak, (my word for this), just by how they looked. The roots were
definately decomposed & a strong
mushroom odor! It would be attached to everything, the pot, pseudos,
roots
&
potting medium! I have lost a few plants too.
So now everything gets a bath in Physan, before repotting.
I would still like to try the recommended PrimaStop but as I mentioned
they
will not
ship it to Calif.?
--
Cheers Wendy
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