I have a few dendrobiums plants that appear to have leaf spot (small black
spots on one side, visible through the leaf on the other side). They do not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray. I have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho Rose
Disease ) and baking soda, mainly becasue I have them. They have nothing
about orchids or ornamentals, although they can be used on Chrysanthemums
and snapdragons which are fairly sensitive .

Bruce,

If they aren't getting worse then why spray. Was there something in your
culture that caused it and now you've changed? Perhaps a very wet period
during a cool period?

Good growing,
Gene

"Bruce Musgrove" wrote in message
news
I have a few dendrobiums plants that appear to have leaf spot (small black
spots on one side, visible through the leaf on the other side). They do
not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray. I
have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho Rose
Disease ) and baking soda, mainly becasue I have them. They have nothing
about orchids or ornamentals, although they can be used on Chrysanthemums
and snapdragons which are fairly sensitive .

The spots may have been there when I bought them. Figured it was better to
be proactive than reactive, so a quick spraying program may be in order. I
will be taking them outside anyway for Proactive spraying for Mites (My
African violets nearby have them)


"Gene Schurg" wrote in message
news:9HPEg.71906$MW.3762@trnddc04...
Bruce,

If they aren't getting worse then why spray. Was there something in your
culture that caused it and now you've changed? Perhaps a very wet period
during a cool period?

Good growing,
Gene

"Bruce Musgrove" wrote in message
news
I have a few dendrobiums plants that appear to have leaf spot (small
black
spots on one side, visible through the leaf on the other side). They do
not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray. I
have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho Rose
Disease ) and baking soda, mainly becasue I have them. They have nothing
about orchids or ornamentals, although they can be used on Chrysanthemums
and snapdragons which are fairly sensitive .

On Tue, 15 Aug 2006 18:27:36 -0500, "Bruce Musgrove"
wrote in
:

I have a few dendrobiums plants that appear to have leaf spot (small black
spots on one side, visible through the leaf on the other side). They do not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray. I have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho Rose
Disease ) and baking soda, mainly becasue I have them. They have nothing
about orchids or ornamentals, although they can be used on Chrysanthemums
and snapdragons which are fairly sensitive .


My experiences are rather limited.

Recently I started using Harry Philips' method of watering mounts in
the evening, so that their roots are in contact with moisture longer.
Now I'm beginning to notice black spots on the underside of my
reed-stem Epis growing beneath the hanging mounts.

I spoke with a long-tine commercial grower today, and he had just
purchased a gallon of Daconil (Chlorothalonil) for use against fungus.
However he thought the spots were a result of genetics, poor cultural
practices (potting medium breakdown), stress induced by periodic
draught, and wasn't sure exactly what the black spots were. It seems
pretty obvious to me its Black Spot Fungus.

I can caution you against the use of Ortho Rose Disease on orchids; it
can cause leaves to yellow and drop off. I think I'll try the Ortho
Garden Disease you mentioned.

(Uh oh. Larry is a good, long-term customer, so I hope I don't **** him
off!)

What you've described is, in my opinion, a bad cultural practice that leads
to a disease that you then have to fix with chemistry. (Not that I'm
against chemicals, mind you. I DO work for a chemical company.)

In a short time period, there is a limit to how much water and nutrient ions
a plant can absorb. If a morning watering does not wet the roots long
enough for the mounted plants to fully absorb their fill, then I would
suspect that you're not watering long enough, or as frequently as the plants
need.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!


"Larry Dighera" wrote in message
news
On Tue, 15 Aug 2006 18:27:36 -0500, "Bruce Musgrove"
wrote in
:

I have a few dendrobiums plants that appear to have leaf spot (small black
spots on one side, visible through the leaf on the other side). They do
not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray. I
have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho Rose
Disease ) and baking soda, mainly becasue I have them. They have nothing
about orchids or ornamentals, although they can be used on Chrysanthemums
and snapdragons which are fairly sensitive .


My experiences are rather limited.

Recently I started using Harry Philips' method of watering mounts in
the evening, so that their roots are in contact with moisture longer.
Now I'm beginning to notice black spots on the underside of my
reed-stem Epis growing beneath the hanging mounts.

I spoke with a long-tine commercial grower today, and he had just
purchased a gallon of Daconil (Chlorothalonil) for use against fungus.
However he thought the spots were a result of genetics, poor cultural
practices (potting medium breakdown), stress induced by periodic
draught, and wasn't sure exactly what the black spots were. It seems
pretty obvious to me its Black Spot Fungus.

I can caution you against the use of Ortho Rose Disease on orchids; it
can cause leaves to yellow and drop off. I think I'll try the Ortho
Garden Disease you mentioned.

Question:- If it rains at night in the forest do the leaves get black spots
if nobody sees them? *G* Got to get my java!

--
Cheers Wendy

No Spam Email Address Invalid

Ray wrote:
(Uh oh. Larry is a good, long-term customer, so I hope I don't ****
him off!)

What you've described is, in my opinion, a bad cultural practice that
leads to a disease that you then have to fix with chemistry. (Not
that I'm against chemicals, mind you. I DO work for a chemical
company.)
In a short time period, there is a limit to how much water and
nutrient ions a plant can absorb. If a morning watering does not wet
the roots long enough for the mounted plants to fully absorb their
fill, then I would suspect that you're not watering long enough, or
as frequently as the plants need.

"Larry Dighera" wrote in message
news
On Tue, 15 Aug 2006 18:27:36 -0500, "Bruce Musgrove"
wrote in
:

I have a few dendrobiums plants that appear to have leaf spot
(small black spots on one side, visible through the leaf on the
other side). They do not
appear to be getting worse and only a few plants have them.

What are your experiences for good fungal control?

It is possible for me to take them out to a shaded porch and spray.
I have
considered Chlorothalonil (Ortho Garden Disease) , Triforine (ortho
Rose Disease ) and baking soda, mainly becasue I have them. They
have nothing about orchids or ornamentals, although they can be
used on Chrysanthemums and snapdragons which are fairly sensitive .


My experiences are rather limited.

Recently I started using Harry Philips' method of watering mounts in
the evening, so that their roots are in contact with moisture longer.
Now I'm beginning to notice black spots on the underside of my
reed-stem Epis growing beneath the hanging mounts.

I spoke with a long-tine commercial grower today, and he had just
purchased a gallon of Daconil (Chlorothalonil) for use against
fungus. However he thought the spots were a result of genetics, poor
cultural practices (potting medium breakdown), stress induced by
periodic draught, and wasn't sure exactly what the black spots were.
It seems pretty obvious to me its Black Spot Fungus.

I can caution you against the use of Ortho Rose Disease on orchids;
it can cause leaves to yellow and drop off. I think I'll try the
Ortho Garden Disease you mentioned.

The problem would seem to be having the dripping mounts over other stuff
that doesn't want to have water on the leaves at night. Adding another fan
in that area might help. Many people can't spend enough time in the morning
watering mounts. There's really nothing wrong with watering plants in the
evening. You just need to make sure you have good air movement and don't
have too much water standing on the foliage.
-danny

"Ray" wrote in message
news:nEl0h.9050$PA3.4173@trndny04...
(Uh oh. Larry is a good, long-term customer, so I hope I don't **** him
off!)

What you've described is, in my opinion, a bad cultural practice that
leads to a disease that you then have to fix with chemistry. (Not that
I'm against chemicals, mind you. I DO work for a chemical company.)

In a short time period, there is a limit to how much water and nutrient
ions a plant can absorb. If a morning watering does not wet the roots
long enough for the mounted plants to fully absorb their fill, then I
would suspect that you're not watering long enough, or as frequently as
the plants need.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!

On Fri, 27 Oct 2006 10:59:31 GMT, "Ray" wrote
in nEl0h.9050$PA3.4173@trndny04:

(Uh oh. Larry is a good, long-term customer, so I hope I don't **** him
off!)

You must have me confused with someone else.

What you've described is, in my opinion, a bad cultural practice that leads
to a disease that you then have to fix with chemistry. (Not that I'm
against chemicals, mind you. I DO work for a chemical company.)

That's what the professional grower said too. But I didn't get it.
Now that you too have mentioned it, I took a good look, and the spots
do seem to be occurring primarily on the plants that the potting
medium has broken down resulting in an over wet condition. This may
not have been as big an issue in the warmer months, but now that it's
getting colder, it's starting to manifest itself. My plants are grown
outside under 55% shade all year long, so it's difficult for me to
exercise much environmental control other than irrigation and feeding.
In a short time period, there is a limit to how much water and
nutrient ions
a plant can absorb. If a morning watering does not wet the roots long
enough for the mounted plants to fully absorb their fill, then I would
suspect that you're not watering long enough, or as frequently as the plants
need.

So you don't subscribe to Harry Philips' nighttime mount irrigation
advice?

Another issue, is the plants growing beneath the mounts get extra
water, because the mounts need more frequent irrigation than they do.
So I've started repotting with lots of sponge rock and large bark in
the hope that the open mix will tolerate more frequent irrigation.

Thanks for your help. It got me thinking in the right direction.

That's what the professional grower said too. But I didn't get it.
Now that you too have mentioned it, I took a good look, and the spots
do seem to be occurring primarily on the plants that the potting
medium has broken down resulting in an over wet condition.

Hello Larry!
I agree with Ray and Danny - the spots are from the leaves of the
plants in question being wet too much, or remaining wet too long. If
those conditions are removed the spotting should stop. If the spots
aren't spreading, you may not have to spray with anything. Spraying
won't make the spots disappear, I don't think. I have had a similar
problem with both Bollea violacea and Cochleanthes amazonica. On the
Cochleanthes the spots didn't grow, but on the Bollea they did. I
tried using one of the liquid 'hand sanitizers' applied with a Q-tip,
directly to the spots in question. They (the spots) stopped growing,
no new ones showed up (because I became much more careful with watering
those particular plants), but the existing spots remained. I put the
Bollea outside this past summer, under a Maple tree, and although it
got plenty of rain, and tap water as needed, only a couple very small
spots showed up. I believe it was due to the increased air movement
available outside as opposed to my windowsill.

Another issue, is the plants growing beneath the mounts get extra
water, because the mounts need more frequent irrigation than they do.
So I've started repotting with lots of sponge rock and large bark in
the hope that the open mix will tolerate more frequent irrigation.

Thanks for your help. It got me thinking in the right direction.

Again, with the Cochleanthes, I overpotted it in very chunky bark and
then watered it every day or two. I had found, under my conditions,
that while fine bark seemed the way to go, it remained too wet, held
too much water (or not enough air) and the roots rotted. Potting it in
a fast draining mix, and increasing the frequency of watering, allowed
it to flourish. I was getting eight to ten flowers from it evey year.
I have just repotted it (I wanted to divide it and get more orchids for
'free'), and have followed the same plan. We shall see if it works
again.
G
Bob - Philadelphia, PA

On 30 Oct 2006 18:42:14 -0800, "bobc" wrote in
. com:

Spraying won't make the spots disappear, I don't think.

Now that you mention it, I do recall using Neem Oil on this condition
in the past, and it did reduce the appearance of the spots. Perhaps
I'll give that a try again, and see if it is effective.

Thanks for your comments, Bob.