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.
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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