Re: Fungus

on 12/16/03 6:19 PM, JanetTerVeen at terveen@comcast.net wrote:

> My neighbor has a question for the group.  Two years ago her neighbor cut down
> a Calodendrum capense leaving the stump which is now covered with flat topped
> light tan mushrooms. Above the ground in various places along the root runs
> there are groups of white round topped mushrooms.  At a place where the round
> topped white mushrooms are happy a Buff Beauty rose on it's own root was
> planted 2 years ago so it's still pretty fragile.  It has suddenly died.  Is
> it likely that the fungus caused the death of the rose?  Both neighbors are
> concerned as they both have other roses in this area.

Janet,

Your neighbors have every right to be concerned.  This sounds like a perfect
example of Armillaria mellea (oak root fungus--in England they call it
"honey fungus") taking advantage of the cellulose of the Calodendrum trunk
and roots.  Unfortunately, the mycelium also feeds on live wood, and rose
roots are one of its favorite foods.  If the roots of the now-defunct tree
reach out into the area where the roses are growing, chances are good that
the fungus will spread to them.  Even if there is no actual contact between
the tree roots and those of the roses, any one of the billions of spores
that are being let loose by the mushrooms may lodge on or near the roses and
send out mycelium that may not show up for a year or two, but eventually
will cause the roses to sicken and die.  As far as I know, there is no
effective treatment for a an established infection of Armillaria.  It might
be useful to excavate and remove the remaining roots to dry up the fungus's
food supply, but there can be no guarantee that the mycelium or spores will
not remain in the soil.

One encouraging note.  Armillaria melea mushrooms are delicious.  But you
would be well advised to verify their identity before eating.

John MacGregor
South Pasadena, CA 91030
USDA zone 9   Sunset zones 21/23
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