Phal orchid leaves suddenly turning yellow from the middle out and orchids rotting :(

[Tia Rio]

Hi,

My name's Tia, I'm from southwestern Canada, and my orchids desperately need your help! I have about forty plants, seven of which are phalaenopsis orchids whom I've had for between two and five years depending on the individual plant. Within the last couple months most of my orchids have had at least one leaf turn yellow (from the base of the leaf and spreading to the outwards edges) and eventually fall off. At first I didn't think much of it but today, when I picked up one of my phals all of it's leaves came off with the slightest touch and when I gently pulled on the base it came apart to reveal black rotting inside I was hoping someone might have an idea of what is happening and what I can do to help it. I fear this particular orchid is dead though it sadly has a half formed baby on top. I've included pictures of that orchid and an example of a leaf that's turned half yellow. Some other information that could be important is my orchids are kept about seven feet from a southeast facing window, the temperature in the room they're in is kept quite high, around 23 Celsius and the humidity is around 20% in the room. My main questions are:

1) What is wrong with my orchids?
2) What can I do about it?
3) Could my other plant species catch it?

Thanks so much in advance for helping me out, I'm really worried here.

[Ray]

I would say your plant has contracted black rot from phytophthora and/or pythium fungi.

Frankly, I think that particular plant is beyond hope, but considering the ubiquitous nature of fungi, I would treat your entire collection with a decent fungicide.

[silken]

Welcome. It certainly looks like crown rot from some cause. It seems from the photo that you may have your plant in a pot larger than what most recommend. It should just barely fit the roots and be rather under-potted compared to most house plants. Many people feel just using sphagnum moss causes rot although it depends on your conditions as to what works. Do you get water in the crown of the leaves when you water? Leaving water in the crowns will cause them to rot also.

I agree with Ray that you should treat them as a pre-caution since it is showing up in more than one in a short time. In Canada it is rather hard to get decent fungicides so I would suggest gardening sulfur (yellow powder) or possibly using hydrogen peroxide or some alcohol and also plain brown Listerine has some anti-bacterial properties and won't hurt if put on the leaves.

[Tia Rio]

Thank you so much for the quick responses! I do only use sphagnum moss, do you have any suggestions on what to use instead? Thanks about the pot info, that one actually came in that pot... stupid plant store. Though it did look a lot bigger when it had all it's leaves, I think I'll probably throw that one out I make sure to water around the plant when I water though I do mist my orchids to add humidity about once or twice a month, would you suggest I stop this? And when you say to treat my entire collection I assume you mean the other orchids not the thirty other plants right? Thanks again!!

[Bill U.]

Tia,

There are many orchid-growers who do only use sphagnum moss, however, there is a majority of growers who use a bark mixture that is appropriate for your orchid type (some different genera have different preferences in regards to water retention). Or something that you can do is use a bark/sphagnum mix in which you use a about 90-95% bark : 5-10% sphagnum, to help increase water retention or time between waterings. I personally used to use only sphagnum, but I have since switched over to bark and S/H (if you don't know what that is, check out the S/H forum here on the OB!). I also have a very low humidity environment in my house, so I mist all of my plants (orchid and non) just about every day early in the morning, taking care to make sure that there is not water sitting in the crown.

If I interpret Ray's comment correctly, I would say that he is recommending that you treat all of the plants that are within any sort of contact range (growing environment) as the affected plant, due to fungi being able to spread rapidly and indiscriminately.

Keep us posted!

[silken]

I like a mix of moss and medium bark chunks for my Phals. I put them in clear pots with holes in them so they can drain well and get air to the roots. They do well, but everyone has to figure out what works in their environment. Many people struggle with root rot but in your case the crown seems to be causing the leaves to fall off. You may also want to check the roots.

I agree with Bill U that any plant in a close area could be susceptible to whatever is happening to these orchids. So if there are other plants near by treat them as well. You might want to isolate any affected ones to a separate area too.

[Stray59]

Tia Rio:
Welcome to the Orchid Board; as you see there is always someone ready to help.
I think we all agree - use a fungicidal treatment. Is you decide to remove the plants from the moss and replant, you can dust the roots with cinnamon. It does seem to help with bacterial infection and also seems to keep the fungus at bay.
As for your plant, I do believe it to be too late for the orchid you show in the pics. If you do throw it out, you might want to remove the peat moss from around the roots (throw all of it away!!) and inspect the base and roots of the plant. Sometimes this will show fungus growing or give you better indications of perhaps insect damage. I have learned a lot from looking over old root systems of dead plants, but be sure and wash your hands very well before you touch any other plants.
At this point, I would try and root the kieki - this should be pretty easy with the development that you already have. There are various ways you can do it, but I would just sterilize the stem with hydrogen peroxide, cut the stem into sections with sterile tools; leave the kieki in a section of the stem that is about 3-4 inches long with the plantlet in the middle. Lay the stem on sterile peat moss and keep it humid. Some rooting hormone or Kieki paste would help the roots to develop.
There have been a lot of posts lately about rooting the flower stems in sections like this and you might look some of them over as they really go into detail. The Advanced Discussion currently has one post that is named "method for obtaining 12...."; there are some tips there you could use.
Is there any way you can put your plants on humidity trays or place a humidifier near them? 20% is sooo low for most orchids..Your temps seems rather warm, so the trays could help you a lot!
Hope some of this helps - Best of luck
Have a great day and Happy New Year!
Steve

[bballr4567]

20% humidity? Is that a typo?

[Tia Rio]

So I have sprayed all my orchids with fungicide. I have also bought some new potting material that's a mix of bark chunks, perculite and sphagnum moss that says it can be used for all orchid species. I was wondering though should I replant the orchids after I've finished treating them for fungus or can I replant them during the treatment? Also how oftern should I spray them with the fungicide and when I do replant them should I take the opportunity to spray the fungicide on their roots as well? I've also attached a picture of the roots of the orchid that died already and that is pictured above. Thanks again!