"......... The armpits on our plant have gradually darkened with some
kind of residue or mold. Now on top of the black residue are smaller
white patches of residue that look like mineral deposits but may have
no mineral elements whatsoever. What lead me to a closer look at the
armpits is a steady trail of ants. It appears that the ants find
something of immense value in these armpits where they congregate en
masse. Do you think it is a mold and if so have you any experience
with a black/white mold?"


Sounds like sooty mold which doesn't damage the plant except to make it much
less attractive.

Aphids get on the plant and secrete a honey dew type of substance which ants
are attracted to. The ants then take over and leave the black "stuff" in
the "armpits." Spraying the plant with a horticultural oil spray will help
prevent aphids and without the aphids to attract the ants, the situation
should improve.

On the leaf fall problem ... it could be too much water. No, bamboo can't
swim. It likes lots of water, but needs to be well drained, not standing in
water. The thing that concerns me is "all the leaves have fallen off."
However, on many varieties it is normal in the spring to have a large number
of yellowing leaves and dropping leaves as new leaves are forming to replace
old ones, but generally they all don't fall off at once. Check the branches
to see if there are tiny leaf buds. If so, you should see new leaves soon.

Good luck.

Mary Ann