Black Rings on Dendrobium-Phalaenopsis Hybrid

[KristenJ]

There were 3 simultaneously yellowing leaves. These rings only appeared on 1 of those leaves. The rings do not appear on the green leaves. However, on one cane, on 2 of its top-most leaves, there are brown spots near the tips of the leaves. I was advised to snip the leaf tips and treat with cinnamon, which worked for awhile, but then the spots reappeared. But for a few months now, the spots haven't gotten worse. I can attach a picture if that would help. The rest of the canes and leaves appear normal. It is currently growing a new cane, which it does every year around this time. But it hasn't flowered in about 3 years. I have it in its own room, away from my other orchids and indoor plants.

[james mickelso]

Go to the website noted, drop down to row 17 and look for yourself.

[RosieC]

James can you post a link of the website you mean. In different countries and even different areas we get different results from google so it's hard to be sure we are seeing the same page.

I can't find the one you mean when I do the search here in the UK.

[King_of_orchid_growing:)]

1. Winter rest is only 3 - 4 months.

2. Winter rest has nothing to do with your possible problem. Some leaves can drop as a result of winter rest, which is to be expected with certain Dendrobiums including yours.

3. Test for virus if possible. Ask for test kits if they are available for the disease that it is diagnosed as possibly being.

Testing is better than guessing whether it's fungal or viral.

4. Yes, fungal problems can also cause similar symptoms. This is why written descriptions from forum members can often be difficult to diagnose. Subtle differences can mean all the difference between one disease and another, which is why pics are preferable over written descriptions.

5. If it is fungal, it is usually a cultural problem that caused the plant's immune system to decline just enough for the fungus to attack.

6. If it is viral, there is no known cure for a virus.

Viruses are transmitted through various means.

a) Using unsterilized tools to cut into living tissues on the plant.
b) Insects transporting the disease from one plant to another.
c) The virus, if present in your surroundings, can enter the plant through damaged tissues.

7. Virused plants must be destroyed to prevent the spread of the viral particle to other neighboring plants.

It sounds cruel, but your virused plant is not worth keeping around anymore. It will eventually die. There are no medicines made for plants to keep the symptoms of the virus from occurring. Neither are there medicines made for plants to disrupt the virus' protein coat or disrupt viral DNA/RNA production.

8. I know you provided a pic of a dried portion of affected leaf, but do you have photos of green portions of leaves that have been afflicted? Are you able to post those?

9. Please also provide information on how you're growing the orchid.

In order to properly find out what's going on, it is important to post info such as:

a) Length of time you've owned the orchid for.
b) Day/night temperatures.
c) Seasonal temperatures.
d) Light.
e) Humidity.
f) Air circulation.
g) What kind of potting media the orchid is potted in.
h) What kind of pot the orchid is growing in.

10. Have you checked the plant's roots?

[Orchid Whisperer]

Hi K.o.o.g.

If you look back through KristenJ's posts, the rings only appear on the one leaf, not on any green leaf, and only appeared after the leaf turned yellow.

Based on that, I can't rule out that this is merely fungus moving into tissue that is already undergoing a natural leaf senescence (leaf naturally dying due to old age). I think it is a bit premature to conclude it is virus & "throw the baby out with the bath water". I agree that isolation, observation, and testing might be in order.

Brown spots on the tips of some of the leaves may be due to her using softened water at one point.

I am no expert on Dendrobiums, but maybe the next best step is for someone (that is not me) to offer KristenJ some care tips for this type of Dendrobium?

[King_of_orchid_growing:)]

If these rings are showing up after the leaves have turned yellow and have fallen off, and is not showing up on healthy, young, intact green leaves, no matter whether the concentric rings are caused by fungus or virus, there's nothing to worry about.

The leaves are already dead and whatever pops up on dead material usually have no direct association or effect on the living tissues of the plant.

Like it was mentioned prior, winter rest will prompt certain Dendrobiums to drop leaves either partially or completely depending on the type of Dendrobium, and that is normal for the growth cycle of the plant.

If there is any doubt, I agree, isolation and observation is best to see whether or not there really is a concern for a pathogenic organism that is causing actual damage to the living portions of the plant.

Like it was mentioned before, testing is also another possibility before chucking a plant out in the trash or burning it.

Understanding an orchid's life cycle is, to me, far more important than blooms. If you don't understand the orchid's life cycle, you're missing out on one of the bigger elements of how to successfully grow an orchid for long-term success. This is why I don't always talk about flowers much. Sure, flowers are one of the reasons why I bought the plant, but there's also a reason why I bought the plant and not just the cut flowers or the photos of the flowers.

[james mickelso]

I agree King. There is a lot of enjoyment and satisfaction growing orchids aside from flowers. Getting a sick diseased orchid healthy is a really rewarding effort. I'm glad you brought it up.

[KristenJ]

Sorry for my lack of response, finals week!

King_of_orchid_growing:

I attached pictures of the whole plant, last year's cane with the brown spots on the leaf tips, and the roots (new cane's roots on the left, old cane's roots on the right). The tallest canes are the older canes from when I first bought it. One currently has a yellowing leaf with no black rings. As Orchid_Whisperer mentioned, the previous picture was of a yellow leaf that yellowed first for several days, then the black rings appeared. I should also mention that the leaves have never yellowed and fallen off until I tried this winter rest for about a month or 2.

Here is the additional information you asked for:

a) Length of time you've owned the orchid for: Purchased June 2011
b) Day/night temperatures:
Day temperature: around 76 if the AC is being used; about 78 - 80 with the windows opened
Night temperature: around 73
c) Seasonal temperatures: If it's nice outside, we don't use the AC or heater. During winter, we keep the house around 78 day/74 night and during summer it's more like 76/73. During fall we do keep the windows open more, so evening temperatures can sometimes be around 68-70.
d) Light: Sits in a South facing window, blinds up. Just got moved to a West facing window so I could isolate it from the other plants.
e) Humidity: I don't have an exact estimate. I have little humidity trays around all of my plants because it can get dry during winter.
f) Air circulation: Unfortunately our new house has no ceiling fans, so there is only air circulation when we have the windows/doors open (around May to early November).
g) What kind of potting media the orchid is potted in: Repotme.com's Dendrobium Classic Orchid Mix; repotted February 2013
h) What kind of pot the orchid is growing in: Repotme.com's Oxygen Core Dual Orchid Pot

10. Have you checked the plant's roots?
The roots are strange. Roots on the old cane are black at the surface, brown/tan underneath - but not mushy. Roots on new canes are mostly white at the surface, with a few black spots, but completely white under the surface with green tips.

Thanks to everyone for all of the advice!

[King_of_orchid_growing:)]

Originally Posted by KristenJ

Sorry for my lack of response, finals week!

I understand. I have one coming up myself and I work full-time.

Originally Posted by KristenJ

King_of_orchid_growing:

I attached pictures of the whole plant, last year's cane with the brown spots on the leaf tips, and the roots (new cane's roots on the left, old cane's roots on the right). The tallest canes are the older canes from when I first bought it. One currently has a yellowing leaf with no black rings.

Judging from the photos, it is clear the plant is infected with fungus.

You might want to give it some good air circulation.

It would also be good to start growing this orchid warmer because it is spring. So provide proper spring time temperatures and do not continue with winter rest temperatures and conditions anymore. Winter rest will have to come again during mid-November of 2014.

You will also want to water the plant more, because the roots seem like they are beginning to wake up and grow.

Originally Posted by KristenJ

As Orchid_Whisperer mentioned, the previous picture was of a yellow leaf that yellowed first for several days, then the black rings appeared. I should also mention that the leaves have never yellowed and fallen off until I tried this winter rest for about a month or 2.

Winter rest is normal for this plant. It should've been 3 - 4 months long. Yours was started too late. You were probably better off not giving it one this season, and providing the plant with a proper winter rest starting around the middle of this Novemember.

During winter rest, this plant will drop the older leaves. This is natural.

Even so, the leaves would have dropped off eventually. This is how the species is. It will not keep the leaves forever. Older leaves will eventually drop, winter rest or not.

If you were eventually coming up with problems regarding re-blooming this plant, winter rest was the best thing you could do for this plant. Often times what people tend to do is not provide winter rest to a Dendrobium that needed to be given a winter rest, and what ends up happening over time is that the orchid starts to not want to put out flowers anymore or the blooms get poorer and poorer in quality and quantity. If it continues, the plant will eventually, slowly, and mysteriously, die off little-by-little.

How do I know this?

I, myself, did not provide winter rest to a Dendrobium species that needed it, and that is exactly what happened. That's how I know. I didn't just dream it up or just say it to sound smart/like I know what I'm talking about, or because I'm some "armchair grower". It really happened. I no longer have this orchid because of my mistake. Similar things started to happen to other Dendrobiums that also needed a winter rest - so, yes, I saw a pattern.

A word about providing a proper winter rest…

Winter rest does not = keeping the plant bone dry for the 3 - 4 months duration. Watering only gets reduced drastically to about once to twice a month. During this time, fertilization is not necessary. Slight shriveling of the canes/pseudobulbs are normal. Heavy shriveling during dormancy is a sign that it might be too dry and the plant may need a little bit more moisture than provided.

If the plant was stubborn in giving you flowers before - with proper winter rest and proper lighting, it will give you the blooms you're looking for.

Again, how do I know this?

I currently own a Dendrobium amabile. The grower had admitted to not giving this orchid a proper winter rest, so the plant didn't really put on much of a show, in terms of flowers. That is pretty much what the guy who sold it to me said, and I knew he was being honest.

I gave my Dendrobium amabile a proper rest period this past winter of 2013, and sure enough, I got 2 full spikes of flowers instead of the 2 puny few flowered spikes I had when I bought it.

Originally Posted by KristenJ

Here is the additional information you asked for:

a) Length of time you've owned the orchid for: Purchased June 2011

Since you've been growing this orchid for a while, it shouldn't be too big of a problem for you to get this guy going again.

Originally Posted by KristenJ

b) Day/night temperatures:

Day temperature: around 76 if the AC is being used; about 78 - 80 with the windows opened

These are acceptable ranges for winter, spring, and fall.

Summer could go as high as 90 F without a problem. Shoot for a summer daytime temperature of 80 F - 90 F if possible.

Originally Posted by KristenJ

Night temperature: around 73

This is fine for the summer. For all other seasons, it could probably drop down to 60 F without a problem.

Originally Posted by KristenJ

c) Seasonal temperatures:

If it's nice outside, we don't use the AC or heater.

During winter, we keep the house around 78 day/74 night and during summer it's more like 76/73.

Winter temperatures at night of 74 F - 78 F is too warm.

Summer temperatures of 73 F - 76 F during the day is too cool, these would be acceptable night time temperatures.

Originally Posted by KristenJ

During fall we do keep the windows open more, so evening temperatures can sometimes be around 68-70.

This is an acceptable daytime temperature for fall. Nighttime temperatures during the fall can go down to 60 F, no problems.

Originally Posted by KristenJ

d) Light:
Sits in a South facing window, blinds up. Just got moved to a West facing window so I could isolate it from the other plants.

Be careful of the different lighting exposures. If you're moving from bright location to shadier location, that's not as problematic as moving from a shadier location to a brighter location.

If you're moving from a shadier location to a brighter location, the plant will need to be adjusted to the brighter conditions or it will burn.

Originally Posted by KristenJ

e) Humidity: I don't have an exact estimate. I have little humidity trays around all of my plants because it can get dry during winter.

As long as the humidity doesn't drop below 50%, you're fine.

I recommend getting a hygrometer. It will be important later on when you start getting into plants that love humidity.

Originally Posted by KristenJ

f) Air circulation: Unfortunately our new house has no ceiling fans, so there is only air circulation when we have the windows/doors open (around May to early November).

As long as there is a slight breeze coming from those windows, your orchid is fine.

Originally Posted by KristenJ

g) What kind of potting media the orchid is potted in: Repotme.com's Dendrobium Classic Orchid Mix; repotted February 2013

Check this out…

Remember a couple of us mentioned that this orchid is a lithophyte?

This is what we mean…

"lith" + o + "phyte" = "rock/stone" + connective conjunction + "plant"

This orchid grows on rocks in the wild. Specifically, granites, (they come from Australia - where granites are common).

If you can get a hold of some granite rocks that are about 0.5" across, you will not have to change the potting media out often (actually, probably not for a very, very long while). You will also not have to worry about rotting the roots out or the potting media going bad or whatever else is associated with organic material decomposing.

Originally Posted by KristenJ

h) What kind of pot the orchid is growing in:

Repotme.com's Oxygen Core Dual Orchid Pot

That's acceptable.

Originally Posted by KristenJ

10. Have you checked the plant's roots?

The roots are strange. Roots on the old cane are black at the surface, brown/tan underneath - but not mushy. Roots on new canes are mostly white at the surface, with a few black spots, but completely white under the surface with green tips.

This is not strange to me. It is very familiar. The roots on the old cane are most likely dead. They don't have to be mushy. If the roots were long dead, the brown/tan roots may just be hollow. When they are wet, the velamen layer of the roots will just slough off when you pull on them slightly.

The white roots with the green tips are the ones that are alive. If they have green tips, that means the roots are in active growth. If the roots have black tips, that could mean that the root tips were damaged or that the roots may be in dormancy - it is usually difficult to tell apart from each other. At any rate, it is safer to back off of watering a bit should you see black tips on the roots anyways.

This particular orchid has green roots, which means that the roots have the ability to photosynthesize. If allowed to photosynthesize, the roots will produce more food for the plant to use.

Originally Posted by KristenJ

Thanks to everyone for all of the advice!

You're welcome.




I've posted a pic of my Dendrobium amabile in bloom right now. I don't know if I have a photo of the same individual when I first got it. The photo might be on a different SD card or something. I'll try to post the pic of when I first got it when/if I find it for a good comparison, and to illustrate what I'm talking about.

Btw, the difference between the true Dendrobium amabile and Dendrobium thyrsiflorum is visible with the degree of coloration of the lip. Dendrobium thyrsiflorum has a completely yellow lip. The true Dendrobium amabile has white edges or is white with a pinkish flush around the margin of the lip.

I'm unclear about the difference between Dendrobium farmeri and Dendrobium amabile at the moment. I think the difference between the 2 species is the sizes of the plants. I believe Dendrobium amabile is the bigger of the 2. If so, then my plant definitely fits with the description of being large. My Dendrobium amabile is roughly about 2' and 3" long for the largest growth. The spike in the foreground is about 1' 3" long. Each bloom is about 1" tall.

[King_of_orchid_growing:)]

Looked through both SD cards I own…

Can't find a photo of the previous bloom, so just imagine the previous bloom having a flower spike that was anywhere from 1/2 to 3/4 the size of the one I described to you. While the previous 2nd spike only had around 5 - 7 flowers on it.