Phal. seedling leaves yellowing/dropping
 

I have a few Phal. seedlings in 2-3 in. pots that have been growing well, but recently I've had some of the newer leaves gradually yellow and fall off. The fact that they are new leaves worries me.

The plants appear healthy in all other respects. I know there are many possible causes for this, namely root loss and crown rot, but I havent overwatered them and I've used preventative fungicides.

Any ideas on what I can do? Thanks.http://img.tapatalk.com/32712476-5683-e87a.jpghttp://img.tapatalk.com/32712476-568e-07a4.jpg

Are you sure you're not overwatering? I also use the same media you have for my phals and I let it get completely crispy before I water again. I make sure my pots have bottom holes and slits in the side to let a lot of air in. Haven't had any problems doing it this way. I usually have to water a 2-3" pot about every 5 days.

Cathy

No air for the roots ?
Get them out of the crappy plastic pots and, from what I can see in the photo, the clay I see are no better.
Get a real clay pot with slots. Clean those slots with a putty knife to remove the burrs and restart.If these aren't in a fully controlled environment (without anynatural rainfall) ditch the sphagnum. That's for greenhouses........and swamps.

I use spaghnum moss on all my orchids. Catts, Laelias, mini catts, Sophronitis, and a lot of others. It works great for me and I don't grow in a greenhouse. I grow inside under lights. I use mostly clay pots and use packing peanuts in the bottom. The trick is to pack the moss loosely. But I do grow my Phals in spaghnum moss in plastic clear pots and they have slits in the sides. They grow great. You don't HAVE to grow in a green house to use moss. I also use well water and not rain water.

I agree with Wynn Dee. I also use mostly spaghum in my phals, water with well water and grow in my windows in the house with no problems. I've been doing this for over 12 years now and my plants grow and bloom consistently. I also put the moss in very loosely and change it every year. I have over 30 phals growing this way. The picture above just seems like they are over watered or not draining and drying well between.

I would agree that they could be over-watered. Another thing to watch is whether it get's water sitting in the crook of the leaves when you water. I've had this happen sometimes and I'm pretty sure it was that combined with either too cold or too dark (so that water doesn't dry quickly). For the same reason you should water in the morning so it has plenty of time to dry before night. Also if you notice water sitting in the crown or in the crooks of leaves you can dry it with paper towel.

I agree with those suggesting a root problem. Either overwatered or otherwise. Often, phals will shed leaves for which they dont have the roots for. This is especially prominent in early seedlings if any roots is lost, as there are so few. You really need to check those roots. If sphag is working for you, maybe loosen the sphag ball up a bit so it holds less moisture, or add in some aeration media (bark/LECA/perlite) so it holds less water.
Rosie could be also onto something if you are not a morning waterer. If any decent amount of water is left at the leaf bract, this can also cause the leaf to rot. Tough to say though

Thanks for everyone's input! I repotted the plants in question; one of them did appear to have a little rot in the leaf axil and the other one's roots didn't look great.

I think possibly the medium was packed too densely and air wasn't getting to the roots. And as someone said, with seedlings any amount of root loss can have an effect on the plant because of its small size.

Proper Phal. watering can be such a tricky balancing act. My conditions here are fairly dry and windy, so plants dry out very quickly. And with seedlings I was under the impression that they should stay fairly moist to ensure good growth. I guess the key is to find a medium that retains some moisture but also allows good air flow to the roots.

I am not saying it is this, but be aware.
A grower informed me:

Be very careful with big box plants as many harbor a new disease called Taiwan yellows, a very bad type of pseudomonas that can kill all of the plants in your collection. The leaves will sometimes turn yellow and fall off or become watery inside.

the context was a conversation about Taiwan imports