Dowiana seedling rotting!! Need help to treat it

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Malipoense

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I have 2 dowiana seedlings, and unfortunately have discovered one of them seems to have black rot. The other seedling is okay. One growth has turned brown/black and spread to the leaf which has fallen off. The red circle in the picture shows affected part. It doesnt seem to have affected the other growths or the current newest growth coming out. What do I need to do to treat it?
 

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I don't have an answer and this may not be relevant, so apologies in advance.

Do you think your temperatures are appropriate?

I ask because I just encountered similar looking damage in one of my Cattleya alliance plants. It occurred on a cold tolerance test subject after a spell of cold weather. The plant wasn't C. downiana, but I bring it up because if I recall correctly, isn't dowiana one of the species that has fairly warm growing requirements?
 
I don't have an answer and this may not be relevant, so apologies in advance.

Do you think your temperatures are appropriate?

I ask because I just encountered similar looking damage in one of my Cattleya alliance plants. It occurred on a cold tolerance test subject after a spell of cold weather. The plant wasn't C. downiana, but I bring it up because if I recall correctly, isn't dowiana one of the species that has fairly warm growing requirements?
Actually, I think that has helped because the area I have been keeping it in at the moment has a fan near it keeping good air circulation for other plants. It probably has been a little too cool for it and I have moved it to a much warmer area, and I will be keeping it more dry for the time being during the winter. And yes, dowiana is one of the warm growing species. I was just caught off guard because the room where it was in was always above 70 degrees and it was completely fine when it was outside in the summer, and it loved getting watered. Thanks for the reply.
 
I hate to be a pessimist but if it is black rot, in a plant that small, it might be tough to save.
Check out Saint Augustine Orchid Society website about pests and diseases. Lots of information and pictures.
In Florida, this wrecked havoc with my Cattleya Alliance stuff! I lost dozens of plants! It develops so quickly, spreads unchecked in the rhyzome, by the time you see the blackness, it is too late.
The only thing that helped me down there was: #1 24/7/365 air movement
#2 buy less Cattleyas

Edited to add:
In NY maybe three cases in 38 years!!
In Florida, maybe 200 dead plants in 9 years!!!
In Michigan, maybe 5 lost plants in 6 years!!!
Draw your own conclusions. Too wet, too humid, poor air movement = death.
 
It is pseudomonas, spread quickly in rhizome as bigcattl wrote. If ph is high, at around 7, ca is too low and water is not cleaned and sterilized, it develops quickly. I don t belive that air circulation can help....air change can help!!!Water is can t be problem , in rainy season plants get plenty of water continously, they can t chance to dry but there is no rot....infected water is another question...i use uvc water sterilizer and a 20 um prefilter to keep my water clean. Don t use copper on catts, it is higly toxic for catts!!!! This case prevention is the only chance, infected plants usually die....
 
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I hate to be a pessimist but if it is black rot, in a plant that small, it might be tough to save.....
It is pseudomonas, spread quickly in rhizome as bigcattl wrote.....
It might be both of them .... you can't distiguish it exactly by the photos.
But there is a great difference in the cause between the both of them. Whereas black rot is caused by fungis is Pseudomonas (Bacterial brown spot) caused by bacteria(s). You can read more here about both deseases.
 
It might be both of them .... you can't distiguish it exactly by the photos.
But there is a great difference in the cause between the both of them. Whereas black rot is caused by fungis is Pseudomonas (Bacterial brown spot) caused by bacteria(s). You can read more here about both deseases.
Thank you Rudolph. I ve been suffering for many years and belive me, i had many many problems....I can say, pseudomonas for catts is the same as Erwinia for paphs. A red many many literatures, not just here, but elsewhere i can. And as i learnt more and more, i understood, this problem is very difficult. We say, air movement is important....where? In a closed gh????Air exchange, this is very important!!!!We fear the water...why? Catts have no problem in pouring rain at all for many days in their habitat. Why? We use stagnant water full of bacterias, we don t care about ph, nutritients, ratios....I belive, if we care about them, we won t have problems with bacterias.
 
The question of Malipoense is: What I need to do !!!!
I've had this problem before. I cut the leaf a few mm below the black part (with a hot disinfected blade) and immediately put some cinnamon powder on the freshly cut part. I'll be watching to see if it continues to develop. If so, .... cut again and add more cinnamon.
You can also use a decoction of cinnamon powder (at saturation) in 70% isopropyl alcohol (IPA).
 
The question of Malipoense is: What I need to do !!!!
I've had this problem before. I cut the leaf a few mm below the black part (with a hot disinfected blade) and immediately put some cinnamon powder ......
Yes, and what to do stands written under treatment in the link I put in my post #6. Cinnamon powder has fungicidal characteristics and therefore it works well against deseases caused by fungis, like e.g. black rot. I also use it but it wouldn't be my first choice against a bacterial infection.
 
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Strange but in the past when i suffered with the same problem i tried to treat my plants with wide spectral fungicide( Amistar).Is was absulotely ineffective....
 
I can't advise what to use as everyone has different access to systemic fungicide bactericide. Below is a nbs dowiana I had that became infected, It died within two weeks. A Dr. told me that some growers use intermittent preventative treatment for this species. I am determined to grow and bloom dowiana, so my next course of action was to buy a flask, which had approx.18 seedlings. So far 17 are still here and several are absolutely growing gangbuster. Law of the jungle. Just my means of attack, offence beats defence.
Any sign of this disease, IMMEDIATELY quarantine the plant, or invite it to get warm by a fire. Cheers.
 

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Would physan 20 work to treat it? The physan website has a treatment for orchids with rot, such as erwinia. It states to "remove compost from plant, then soak entire plant 10 minutes or more. Cut away all rot with treated tool. Soak plant wounds again for 10 minutes. Repot in physan 20 soaked compost." It sounds reasonable. Thanks for all the tips and replies!
 
I think physan -as a desinfect- has no effect on sick plants. Physan can be used for desinfection water and media. I tried it, too, i could not see good results. If i can give you a good tip for the future ( ok, i know your question was what to do now...), desinfect your water everytime before use. Chemicals are not the best imho, try this, simple, cheap, no chemicals and very effective : uvc water sterilizer with a filter, as pic shows. And worth to adjust ph around 5,6-5,8, pathogenes like higer ph, around 6,5-7. And sad to say, but i d throw this sick plant, it is just a source of microbas in your collection.
 

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