Al, I thought it was mites to begin with, because of the pattern of damage.
I cannot see anything, even with a magnifying glass, but we did treat for
mites and will do it again. It could be a combination of factors.

Diana

"al" wrote in message news:rigdh.1997$g_3.1810@trndny02...
just a small side question for Pat:
I thought Daconil (Chlorothalonil) was a contact chemcial, not a systemic.
It is a curative agent, but may not act to prevent infection. I had just
looked through my grower catalogs to answer this very question for a
customer, so it was fresh in my mind. The grower catalogs can be wrong...
I was just wondering if this were the case.

In contrast, the Cleary's 3336 is listed as a systemic that has both
curative and preventative action.

According to one of my charts, between these two chemicals, you catch
every listed fungus your orchids are likely to encounter except a Pythium
infection. Add the Phyton (Preventative, curative contact) and you still
miss Pythiums

At least one Pyhtium species (P. ultimum?) causes what we commonly call
"Black Rot" in orchid plants. Turban, Subdue, and Aliette are listed for
Pythiums. (Of course a lot of fungus and bacterial organisms can be
behind what we call "Black rot" and frequently one organism opens the door
to others and probably several are ultimately involved in any large scale
infection as the tissue starts to die.)

Phyton is a copper based chemical. (Copper sulphate? in some kind of
polymer carrier) It is really helpful for bacterial problems. However,
make sure you know how the other chemical and fertilizers you may be
spraying on your plants will interact with it. Most labels tell you if
you need to take extra precautions with copper the based products in your
arsenal.

For gene's suggestion, you might verify if the pool installation has put
anything caustic in the environment by checking other plants in the area
(besides your orchids) for similar damage patterns.

If you want to rule out mites for some of that tip damage, get a
magnifying glass and look for them. Mites can open wounds that serve as
entry points for fungal and bacterial infection just like all the other
beasties that feed on leaves. Even with a magnifying glass some species
of mite instars and eggs look like tiny semi-opaque dots that are sunken
into the pits of plant tissue; not like insects at all, especially if you
have already killed off the larger easier to spray population. Phals tips
and leaf margins are places where you often find newly planted mite
colonies.

"Pat Brennan" wrote in message
...
Hi Diana,

I do not know what is going on. I, like Rob, Gene, and Ray, wonder if it
is not some culture issue. Hard, dry and very fast moving is not your
normal creeping crud. I do not think it is the Steve infliction, it is
moving too fast. I checked the weather for you for the past month, it
sounds like it has been lovely and not a single night would have cause
this. The sun is at a very low angle now. I would carefully check to
make sure shading is still right. Has anyone been using roundup or grass
weed & feed?

Do you have a bush snail problem? I have seen bacteria/fungus problems
show up very quickly moving into plants via open bush snail wounds.

If these were my plants here is what I would be doing:

First Day,

First, depot one or two and make sure the roots are ok. Since one of the
plants was mounted, I know this is not a problem. But one of the first
things I always do is check roots.

Second, I would flush everything. A real good flushing of two or three
passes.

Third, I would spray with a systemic fungicide cocktail. There are a
couple I use, Spectro (Cleary's 3336 and Daconil) is very good and the
components should be available in consumer sizes. This spraying will be
absorbed into the plant and remain effective for about a month.

Fourth, I would put out something if bush snails might be an issue.

In a couple of days, I would spray down the plants. After the leaves are
dry, I would start a weekly spraying of Phyton 27. The first couple of
times I would use it at the higher recommended level and after that move
down to the lower recommended level. Phyton 27 is also sold in consumer
size.

After the flush, the next time the plants needed water, I would do it
with a weak fertilizer solution. The time after that I would use a trace
mix. Trace mixes can be found at the local garden center as an Iron
supplement. Read the labels, many of the iron supplements are really
formulated to address all trace problems.

Lastly, I would isolate. Put everything with any signs of the problem in
one area. The bad leaves are not going to get better and dieing tissue
is going to continue to die. But over a short period of time we would
like to see problem areas quit growing with no new ones showing up.
Plants in the healthy area should stay healthy. If healthy plants
continue to get sick, we have not addressed the problem and it is time to
move to plan B.

Pat