I got a chance to talk to Dr. Griesbach as he was leaving NCOS judging last
week. He said microfungus is a real thing and a couple of species are know
to inflict orchids. I did not ask for species names, I knew I would never
remember. Sorry Al, I forgot to ask what the difference was between a
microfungus and a fungus.

Dr. Griesbach said claims of microfungus infections are not as common as
they were 5 - 10 years ago for a couple of reasons. First, when microfungus
was first being discussed, a lot of plants with false spider mite damage
were being labeled as microfungus. Second, it seems that virus tests from
this time period had problems and a lot of false negative results were
reported. Based on these false negative reports, viruses plants were being
reported to have microfungus. Dr. Griesbach said that today's virus testing
antigens are much better and have greatly reduced the number of false
negative results.

Dr Griesbach said most microfungus problems resulted as a secondary
infection. I asked if curing microfungus required the approach recommended
by Gordon or if newer fungicides such as Clearies 3336 would work. He said
fungicides such as 3336 should work but you had to follow the label in terms
of both strength and minimal time before respraying. We both agreed it was
a hard, but not impossible, thing to get completely cured.

Pat


"Pat Brennan" wrote in message
...
BobGordon "Culture of the Phalaenopsis Orchid"

. . ."sometimes a condition prevails that is caused by a systemic
infection of microfungi. As there are literally hundreds of these, the
symptoms vary from plant to plant.

Some of the more common are a spotty, ill-defined chlorosis; a streaky
chlorosis beginning at the edge of the leaf where it looks as if the leaf
edge had been burned with a match or candle; a red-brown coloration
appearing at the apical third or half of the lower leaves followed by a
dehydrated and senescent (old) appearance and also mesophyll tissue
collapse where deep pitting becomes apparent on the surface of the leaves.
This latter condition can also be caused by cold water and by virus
infections. However, in the latter instance, the pitting is usually
dark-brown to black in appearance rather than the white to light fawn
caused by fungi.
.
.
.
We still don't have a handle on what is causing the disease yet or even
what it is, but efforts are underway at two state universities. It may be
a fungal disease and virus in combination, confusing the diagnosis, but
there is little question that the disease weakens the plant and leaves it
susceptible to more common ailments such as Pseudomonas cattleyae.

Bayleton may be the agent that is correcting the problem, however, There
have been reports that the Bayleton alone will correct the problem. There
is one report that Subdue alone corrected the problem.

Symptons of the problem are similar to those of a photo of a specimen of
fungal leafspot caused by Guignardia sp. shown on page 84 of the 1986
edition of the AOS's Handbook on Orchid Pests and Diseases. However, to
date, that disease only has been reported in vandas and ascocendas. If
the disease is fungal in nature, it does not respond to the standard
culture tests. At least three efforts have resulted in no germination."


BobGordon '"Phal Cultu A Worldwide Survey."

"Microfungus Phal growers may be facing a major newly-discovered
(observed?) problem. This is the yellow pitting, necrotic spotting of the
leaves, preliminarily diagnosed by John Miller and Rob Griesbach as a
micro-fungus.
. . . Growers who have followed various recommendations on ridding their
collection of this problem have largely been unsuccessful. Nothing
sprayed, drenched or applied in any manner seems to make any inroads on
the disease. . . .--T. Happer"

"Systemic Microfungus To my knowledge, Ernie Campuzano of Butterfly
Orchids in Newburry Park Ca, was the first grower to experience the
microfungus problem on a large scale. . . . Ernie had all the symptoms Tom
Harper talks about above and related the problem to John Miller, who in
turn related it to Don Baker of Stoufer Labs. Don identified the problem
as a systemic microfungus and developed the following therapy. . .
.-editor"

I would say symptom are, in the order of appearance, yellow chlorosis,
more defined yellow spotting, pitting, large areas of grayish brown tissue
collapse.

Pat