Plant disease question

[Steven Bach <moof1138 at mac_com>]

I think that some of my plants are getting some sort of disease.  I put some
E. tenellus in the tank a few weeks ago which I think might have been
infected with something.  It had a few browning leaves, but I figured that
once I got it established it would be fine.  I cleaned it up pulled the bron
leaves, and planted it next to some E. quadricostatus 'magdalensis.'  Over
the next few days, the tenellus got a few more brown leaves, and then at the
points where the quadricostatus and browning telellus leaves contacted the
browning moved onto the quadricoastatus.  The affected area turned a light
brown and essentially melted away, spreading along the leaf very quickly.
In many cases a leaf went from healthy to half melted in less than a day.  I
did not leave any long enough to see if the whole leaf would melt away, but
I expect it would have.  I pulled all the browning leaves off both plants.
But then on a leaf of a Java Fern that was nearby a brown soft patch
appeared in the middle of the leaf and spread.  I pulled that leaf, but it
spread to a few other leaves which I pulled as well.  Things settled down
for a week and I did not notice any more browning.  Then today I noticed
that another Java Fern in the back corner of the tank on some driftwood near
the PowerHead had the same browning going on.  It had pretty much taken over
the plant so I pulled it and threw it away, but it had contacted my African
Bolbitis which was slowly growing in the flow of the PowerHead, and a few
new fronds had browned in the middle.  I cut those off at the Rhizome.

Does anyone know of aquatic plant diseases like this? If so, are there any
ways to treat this sort of thing?  Is pulling the affected leaves adequate
or should I be pulling the whole plant?  I would not care so much about
trashing some of the Swords or Java Fern, but I really do not want to lose
the Bolbitis - it is a really nice one I have been nurturing for almost a
year.  Is this the sort of thing where eventually every plant in my tank
will melt into oblivion until I have to empty the tank and wash it all down
with bleach?  So far only certain Swords, African Bolbitis, and Java Fern
have shown any effects - I have a lot of species in the tank that don't seem
to have been affected.

Any advice appreciated,
Steven Bach