Nina,
Are you the Nina Shishkoff, plant pathologist from the LIHRL, that wrote
"Using Fungicides to Control Bonsai Diseases" at:
http://www.evergreengardenworks.com/fungicid.htm?
That article talks about using "An ERADICANT" to "...kill fungi that
have already invaded the plant." Later in the article several
fungicides are mentioned, including Fosetyl-A1 and Metalaxyl for water
molds and thiophanate methyl for other fungi, but fails to distinguish
if these are systemic fungicides or eradicants.
Has more recent work invalidated portions of that article? Would
sustained, judicial, treatment of all three types of fungicides
(protectant, systemic, and eradicant) not slow or halt progression of
the infection allowing more time in which to perform repots and
continued isolation and removal of the infected tissue.
I've also read that the use of thiophanate methyl will affect the
mycorrhizal fungi. Should new colonies be introduced after any use of
this fungicide?
This tree was a gift from my wife and it was immediately obvious that
the organics in the soil had broken down and the soil compacted. I
repotted the tree but the only soil I had available was shohin soil -
low organic and free draining but the particle size could have been
larger. The roots looked a little thin but otherwise ok at that time.
I trimmed them back to about half their length - about 18", still too
long but I was considering the overall quantity of roots tips and
figured I could adjust at the next potting - then treated with rooting
hormone to increase root mass near the base.
That was several months ago and now I'm getting suspicious that the tree
may have root rot. I've had a couple of limbs die and while I'm getting
new growth the old growth seems to be suffering. I'm planning to repot
to an inorganic soil (lava) of the appropriate particle size and want to
be prepared for what I find.
Thanks,
Don
-----Original Message-----
From: Internet Bonsai Club
] On Behalf Of Nina
Sent: Saturday, April 09, 2005 9:33 AM
To:
Subject: [IBC] Root Rot-TREATMENT
Does anyone have any suggestions for a systemic fungicide
for use on a
Texas Ebony (Pithecellobium flexicaule) with root rot?
I can answer this question with absolute certainty, because I
just finished a study of the effects of systemic fungicides
on Phytophthora ramorum on Rhododendron (come to Austin,
Texas this August for the American Phytopathology Society
meeting, and you can watch my Powerpoint Presentation!)*.
The answer:
Systemic fungicides do NOTHING for an existing infection.
They aren't fungi-CIDES (i.e. fungal-killers), they are
fungistatics (fungal growth inhibitors). The pathogen will
stop growing for a couple of weeks, then it will start up
again. The only way to use a systemic is as a preventative
measure, and I don't recommend that for a hobbyist- only for
a professional with thousands of plants.
My reason for looking at this is because nursery retailers in
California are suspicious that big wholesalers are treating
plants with systemic fungicides to arrest "sudden oak death"
long enough to sell them. But my findings are pretty clear:
they symptoms are still visible, even if the pathogen isn't
growing, and a PCR molecular test will detect the pathogen.
Nina, who infected 30 plants last week in order to look at
the effect of systemic fungicides on antibody-based detection methods.
*Any bonsai-related stuff to do in Austin?
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