Weird yellow leaves

[jmrathbun]

I got this Phal from a commercial grower... no tag on it... and it has declined over several years. Recently it put out a mediocre spike and then suddenly the leaves turned yellow. Two leaves have fallen off, one of the remaining two is on its way out by the same door. The green leaf appears to have poor turgor. I had potted this into an appropriate-sized clear plastic pot with good drainage. The medium bark chips appear solid and there was no area of excessive moisture in the pot. The roots look healthy and I could find no insect pests. It was getting well water, moderate light, and temps in the 70 to 80 degree range with high humidity. Any clue?

[zxyqu]

You have a serious case of mites on pic 4. Note the silvering on the underside of the leaves. Tell tale sign of mites. I'd check your other plants for this as well to be sure. You'll need a good 20x loupe or so to be able to see them.
The roots look good on this one, but unless it's sentimental, it may not be worth keeping as recovery time will take a couple years.

[jmrathbun]

Interesting! With my best hand-magnifier I can barely make out something that might be mites. Many of my other phals have had plenty of exposure to the sick one in the past few months. Is there something I should use as a preventive? How did they get into my collection, I wonder? The last time any of my orchids was out of the house was in March and this one wasn't among them. It didn't start to look ill until this month.

[Leafmite]

Mites were always an indoor problem for me on my plumaria in the winter. They seem to like dry conditions. I now use granular Bayer 3-in-1 for roses on the plumaria. Any systemic that is said to kill mites should rid your orchids of mites and, yes, I would treat them all if you can. The other method I use to get rid of mites is to completely submerge plants for an hour in clean water once a week (to kill those that hatch) for a few weeks. Good luck!

[sweetjblue]

I totally agree with Jarad, mites!! As said it will take years for the plant to recover from this kind of damage but it can be done as you have a good root system, it will just take time and patience. Its ultimately up to you if you think it's worth it.
Mites multiply faster as the weather gets warmer as they love hot, dry conditions so that may be why it appeared to decline at such an alarming rate. If your other plants are in close proximity to this one you should check them for mites also, there is a very good possibility they will have them as well.

Just this morning I noticed one of my equestris in spike and upon examining the plant I saw what looked like mite damage to a few of the lower leaves. (Just what yours looks like but not as bad) Using a 10X loupe that diagnosis was confirmed.
What I did was to take the plant, turn it upside down in the kitchen sink (its planted in moss so no fear of the potting mix dropping out) and under warm running water and using a old soft toothbrush gently brushed the leaves starting from the lowest and worked to the newest. I did this so any mites (eggs or other critters) would be washed away from the plant and not into the mix. Checking afterwards with the loupe I didn't notice any mites . That's not to say there isn't any, but what could be seen before are now gone. Once the plant dries I'll follow up with a spray of a neem oil mix. I plan to check it in another week or so and redo the same treament if need be until their gone. I've used this method in the past and it works pretty well, at least for me.

Good luck with whatever you do decide to do!!

Judi

[jmrathbun]

I found this reference helpful:
http://www.sdstate.edu/ps/Severin-Mc...ed-Orchids.pdf

Now that I understand them, I think spider mites may account for a lot of mysterious problems in my collection here to fore. I sprayed my orchids with insecticidal soap today and already they look better!