Phalaenopsis leaves turning yellow - fast

[wetfeet101b]

Of the 30+ Phalaenopsis orchids that Katie gave me some time ago, three of them started turning yellow really fast. The smallest one had all but one leaf turn from light green to bright yellow in a span of 5 days.

These were originally in S/H when I got them and when they started turning yellow I thought it might have been nitrogen deficiency due to the inert media. So I repotted them in my own mix of orchid bark just to eliminate the S/H as a possible cause.
All the other phals that were in S/H are still green and growing well.

Possible causes that I am thinking of:
1. Nitrogen deficiency
2. Sunburn (it is possible, but unlikely since all the other phals in the same area would have been burned as well.
3. Cold damage (again it is possible but unlikely or else all the other phals would have shown the same symptoms.
4. Relocation stress.
5. These phals had spider mite problems in the past so they may have already been weakened and are not able to cope with the new environment as well as the other phals from Katie that were not touched by the spider mites. But there are a couple of other phals that were spider mite cases and are not showing the yellowing leaves.


Here are the pictures:

This is the smallest of the ones turning yellow. The top leaf does not appear to be affected yet. And the roots were healthy when I repotted. There were only a couple of really old, rotten roots that I cut away.


This is the biggest of the three, and the second leaf on the right is starting to turn yellow. The newest emerging leaf however, is green and does not yet show any signs of yellowing - similar to the first plant.


This may or may not be the same problem, but looks like it could be early symptoms of the above cases. The bottom leaf is slowly turning yellow and the other leaves appear to display some yellow coloration as well. But it is progressing much slower than the previous two plants.


Another leaf problem I noticed on another phal is pictured below. The edges of the leaves appear to be turning white. At first glance they look like the edges are drying up but they are not. It is almost like the chlorophyll is being sucked towards the middle of the leaves, away from the edges.
Any ideas on what is happening here?


For comparison, here is a picture of an old timer phal that I have. The top leaves are light green with purple tints due to the sun and only the bottom leaf is slowly aging and will eventually drop.


Here is a group shot of the other phals from Katie that do not exhibit the yellowing of the leaves - although the one in the extreme right appears to be showing signs of brown rot on the leaves (I am addressing that one now).


I do not have extensive experience with phals and would appreciate any input regarding these leaves.

~John

[sadie]

John -- Hey there. It sounds like these couple are going down hill quickly. My best guess would be a combination of a couple of your suggestions. It looks like it could be sunburn--which perhaps affected the weakend plants more than the others. I recently had some seedling sitting side by side, out of the same flask in the same media and some burned while others didn't. Go figure. Maybe these few were more suceptible because of the mites and the shock of relocation.

Let me know how it goes.

[Molly Taco]

No offense to you ,John but maybe they are just pining for Katie.
Cin

[wetfeet101b]

No offense to you ,John but maybe they are just pining for Katie.
Cin

Yeah it could be that too. I'm sure they miss their mommy.

~John

[clintdawley]

That looks like waayyy too much sun to me. Katie was probably growing them on a windowsill and you plunked them in the greenhouse without any acclimation time.

The older leaves will turn yellow because they are not used to such high light. I would shade them for a while and give them some Epsom salts.

[magooba]

Epsom salts would be my guess too. Sounds like chlorosis, a magnesium deficiency. Notable for greenness near the veins and yellow in between. Good luck with them..J

[ariamia@comcast.net]

Hi, I'm new to orchids and have just joined the forum. I am so pleased to know that my best phal is not dying, thanks to one of the pictures you posted of the bottom leaf turning half yellow due to aging. Just wanted you to know. Looks like you have been given some good advice here, and I am more than anxious to learn more. . .

alicia

[wetfeet101b]

Well, I took care of the sun part.
I pulled in some clouds from Colorado and they are now sitting steady over my yard (I apologize to the rest of California for the solid overcast - I may have overdid it a bit)

Thanks for the info. I have already moved them to the bottom shelves so the sun will pass through 3 shelf grilles and other plant leaves first before touching these phals.

~John

[Abby]

This is a test. Just figuring out how to ask a question about my phal.

[Mehera]

John, since it seems to be happening in the plants that have been moved from s/h, do you suppose that the roots are having a hard time getting used to the change? On Ray's site there is information about how when they are put in s/h, plants grow a different type of root than in other media. Maybe roots grown in s/h conditions have a hard time switching back? No doubt a big bump in light would add to the stress....