Black leaves on vanda/neofinetia

[SundayGardener]

Hello,
I'll attach a picture later. What might cause blackening of the newest leaves on neofinetias?

I had one where one leaf after another turned black and fell off, starting at the top. It still has a few viable roots, so I haven't tossed it yet, but I did find some rot at the bottom and removed that. This one was pretty much bareroot because that is how I received it, and I soaked it 2-3 times a week. I also had a wick on the outer roots (not close to the main stem of the plan, and these are the roots that are still alive).

Another is showing the same pattern with the newest growths being black. I really think it is more black than purple...with purple, I would reduce light. But I had already done that with the first neo and it didn't help. This second one is in a coir-lined basket with tree fern and gets soaked 2x week.

I read about fusarium on the vanda threads, but couldn't find a purple ring on the now leafless one...

[Shoreguy]

Do you water early enough in the day for the leaves to be completely dry by nightfall? New growths are even more vulnerable when being wet as night approaches.

Drenching neos 2 or 3 times a week seems highly excessive even if leaves are dry going into the evening.

[estación seca]

What are your temperatures? Neos need next to no water all winter, and often rot quickly when cool and moist.

[stonedragonfarms]

Reading the above, I'm an outlier, but here it goes:
In the greenhouse (cool/alpine), I'd grow with the parameters that have been mentioned above; ie cool/cold and watering about twice a week, but never so much so as to saturate the moss. Think of it like the plants getting dew in the morning, but no rain.
Inside under lights though, totally different culture [for me]; temps are much higher, and I run lights 14 hours/day. Under those conditions, I water [ie fully saturate the moss] 2x a week, and spray [both foliage & root zone] 2x a day [usually about an hour before lights turn on, about 5.30am, and again about an hour before lights out]; I fertilize year round indoors. Given the temps that I am growing under and circulating fans running 24/7, my neos are usually dry 48-60 hours after their watering.
That said, what you are describing I have seen under a couple different situations:
1. If new growth starts to emerge and plants are then not watered for a long period [under lights and intermediate temps, about 5-7 days], I have had plants abort the developing leaf. It will usually rapidly turn black from the tip down; if you wait about a week, you can typically gently tug it out. If the plant continues to be dry, the roots will start drying near the plant and continue down the length of the root, and the leaves will start to drop from the plant, usually after turning black at the tips or at intermittent points along the leaf. Once the leaves start to fall, just compost the plant--it's almost impossible to save them.
2. There are a few plants in my collection that are sensitive to the combination of high night temps and excessive dryness--any of the Aojiku type varieties can behave this way for me; the developing leaf will rapidly turn black and die. Different from above though, the rest of the plant will keep chugging along; once culture is corrected, another new leaf will grow opposite of where the dead one was.
All that said, what conditions are you growing under? What are your day/night temperatures? What type of pots are you using?

[SundayGardener]

I'm sorry, my home computer stopped working (which means I've been window shopping for power supplies instead of orchids) and I don't think I can post pictures from my phone.

So conditions. I have 3 recently purchased neos that are in moss. Two are in plastic neo pots, and the other is in a plastic net pots. All the others are in tree fern in plastic net pots lined with coir. So far this has worked well.

Current conditions, a few are directly by (about 12" away) a southern window. These are old glass windows without any filters. The others are in my main shelving unit under plastic with humidifier and T5HOs. The ones in moss typically dry within 24-48 hours. For the most part, the ones in tree fern (which I drain thoroughly) have been doing quite well, but there are a few that aren't doing well.

Temps in the house range from 68 to 75 F, under the lights it is warmer but I've noticed that anything wet still feels cold to the touch, so not THAT much warmer.

I would be delighted to not water them 2x week. This is the first time I have been told to water less, hurray for me! My concern has been that my newest neos are quite small and I thought they might need more nurturing.

Now I still have a holcoglossum hanging in there after having a terrible summer and it recently put out a massive new root. I treat it the same as the neos, maybe a little drier.

I do have pictures, I just need to get it together and upload them.

[estación seca]

In habitat they have cool to cold winters with next to no rain. People grow them cool and dry all winter.

[SundayGardener]

I've been following this guidance from New World Orchids:

Neofinetia Care: now that it's winter... - New World Orchids

So I water, and let them fully dry out, but then I water again within a few days of their drying out. They tend to dry completely out within 24 hours (less if not in any kind of medium). I don't let them stay crunchy dry for more than 2-3 days because if I do, then I start to see problems. Right now, with the heat cranking, I'm having to water phals in bark twice a week and keep a close eye on everything in semi-hydro.

[Shoreguy]

Completely “dryed out within 24 hours” in sphagnum???

Are you referring just to the top surface? If so, that’s not completely dryed out.

It is often regarded as proper to water when completely dryed out in the winter although many may disagree and say don't let it dry out completely. During the growing season, you must water before then.

[SundayGardener]

No the spaghnum is dried top to bottom, not just the top. I check it frequently because I am not really comfortable with moss. I didn't want to repot the ones in moss at this time of year. It gets crunchy within 24 hours, then I let it stay that way for 2 days.

That's right now, I think because it has been very cold outside, and hot and dry inside.

[Shoreguy]

I'm not comfortable with moss either and have been using for over 45 years seedling bark mixed with shredded tree fern and larger bark pieces at the bottom of the pot for drainage. I have always repotted immediately any neos that way upon receipt of those in moss regardless of time of year with no problems.

An advantage of bark with tree fern is that you can get away with repotting every 5 or so years assuming you don't over water or over feed whereas sphag requires frequent repotting.