Brown/tan band on Paphiopedilum callosum's developing leaf

[Kostas]

Hello,

Since the past Fall,i am growing a Paphiopedilum callosum. It was growing very well and the leaf it had half grown when it arrived,grew fine and at a good pace. The a new leaf started developing and at some point,as it was growing out,a solid redish-brown area started revealing itself. It appeared almost like healthy tissue and(after panicking a few days)i thought the problem was over as it was continuing to grow the new leaf fine. Its still(or at least i am sure it was till a few days ago,cant be sure now)growing the new leaf and the new leaf,even the brown area of it,is tough and like healthy tissue,not soft or anything,and the tough leaf epidermis is continuous and not any different on the brown area. I was waiting for the band to finally end and healhty tissue be revealed but still nothing. That didnt worry me too much but today,i noticed the brown spread a bit upwards on the right half of the leaf and that got me really worried.
I have no idea what might have caused this redish-brown area. I think i may have been overwatering it but when i noticed the brown area,i immediately cut down on watering and even left it dry out a couple of time,something i think isnt ideal though either. I noticed the damage spread today,in a period inbetween the waterings and it had a week or more without water and was almost completely dry today before watering it. Its growing by a windowsil receiving reasonable light even with the cloud cover we have been having for a month now. Below the windowsil is a heating element which provides warm and dry but not overly hot, passive air circulation. It doesnt seem negatively effected from lack of humidity and its probably kept more humid from the tray its growing it and the cool of the window and windowsil its sitting on,although insulated by bubble wrap to minimize the cooling.

Here are some pictures:






Why did it got this brown area,what is it caused by and what can i do for it?

Thank you very much in advance!

[Leafmite]

Could it be crown rot? Here is a good site to look for probable causes: Orchid Pests, Orchid Diseases

I am not really able to tell for certain or know what is best for the paph. I have only had a paph for a few months and just recieved a second. Some paphs need calcium as they grow on limestone, some don't. Do you know the name of the paph? Hopefully others can help you. Good luck!

[glengary54]

Kostas - From what I can see in your picture, your plant looks to be infected with erwinia cypripedii, a bacterial rot. With it being in the crown I don't really see anyway to save the plant. If you can cut the leaf off below the infection, you may have a
chance.

[Kostas]

Thank you very much for your replies!

Glen,

Thank you very much for the diagnosis. The description that the distal tissues are unaffected from the disease fits perfectly with my case but it seems to not be spreading rapidly,at least to my knowledge. There has not been much worsening since i first saw it,that is as far as i can see since i cant see how far down it goes on the newest leaf. The newest leaf is not mushy or anything but about as tough and strong as normal leafs are. The plant looks healthy in general with the only abnormal to be seen being this brown area which has been there for a month or more. Do the above fit with Erwinia cypripedii?

Btw,in the photos above it appears like the disease has spread really deep in the crown of the plant. That may or may not be correct(i cant tell with any certainty from up close) as what you see as dark area can just be the newer leaf blocking the light which easily passes through the thinner leaf bases surrounding it.

What would you suggest me do to help the plant recover? I think that trying to remove the infection mechanically would do quite some damage to the plants older leafs and will have a great risk of reinfecting it in multiple areas through the cuts,bruises,crashes that would inevitably be made on the older leafs. Is there any chance the plant is fighting the disease on its own and can win it? What can i do to help it?
What does this disease dislikes that Paphiopedilum callosum likes? Shall i be keeping it on the dry side or shall i be offering it a moist medium to lessen any additional stress? Warmer or cooler?

Thank you very much in advance!

[BikerDoc5968]

Kostas, it is definitely crown rot. Try to remove the leave and wash the crown with H2O2 (Peroxide); it should foam when you do this. Then powder the crown with cinnamon and keep it DRY!!!!!!! Dry is SOOOOOO very important. When watering try not to water late in the day and try to keep water out of the top of your chids. Next see if you can find SA-20 or Physan-20 and spray your plants.


While this plant will not flower from this fan, if it lives it may grow a new fan from the base which is what Paphs do, so I wouldn't toss it just yet. Certainly, if the entire plant rots out, well..... sorry.

[Kostas]

Thank you very much for your replies all of you!

I never let water in the crown,i water carefully and if any water gets on a leaf or leaf base,i use a tissue paper to dry it.


My affected P.callosum has remained the same till now. I didnt remove the newest leaf because although i tried pulling it out with a considerable amount of force,it refused to snap or even get any kind of damage. That leaf is hard and the normal leafs and very firmly attached to the plant. I was afraid i would damage the rest of the plant if i pulled with more force,so i left it be. There has been very slight progress of the brown area upwards,just on the lower lobe of the brown area by about 1-2mm at most. The rest of the leafs remain healthy and unaffected but there is no growth at all on the newest affected leaf unfortunately. I have been waiting for a new side growth given that the growth center of this growth is probably damaged by the disease,but nothing visible yet.
I poured hydrozen peroxide on the crown today to see if it would fizz and do something with the leaf still there,but there was no fizzing at all there,only with a soil saprophytic fungus did it fizz...

When should i expect to see a new side growth emerging given that the plant isnt dying so far?
Is the disease this plant has readily infectious to other orchids or Paphiopedilums or not? If this disease is just opportunistic as for example dampening off is in seedlings of palms(and other seedlings),i want to ground plant it already and leave it there be,either to recover or die,but if this is an infectious and dangerous disease,i want to keep it away from my garden(where i also grow orchids all year outdoors). Ground planting it would be much more convenient than having to care and hand water a plant doing nothing at home till it recovers or dies....

Thank you very much in advance!