Question
Help,  I have 2 phalenopsis that have developed clusters of
elevated spots--mostly on the undeside of leaves but now on
the blooms.  They seem to start of as a yellow drop of sap--
thick and gooey and over time they become hard.  I'm able to
flick off the spots once they've gotten to this stage.  They're
multiplying and have actually taken over one of the plants.

Is this fungi, are they mites?  What's the treatment.
Thanks

Answer
Hello Lily,

From your description of the spots, I'm afraid they may be scales. I'm also afraid that scales are very difficult to get rid of once they have established such a large colony as you've described.

What you might try doing (other than throwing the infected plants away) is to unpot the phals, remove all potting media from the roots, remove as much of the scales as you can see, treat the entire plant including the roots with a product called Ortho Rose Defense. Be sure to follow directions on the label for use and safety precautions. Repot them into new pots and potting media. Do NOT reuse the old pot or media as they may have some scale hiding on them.

Phalaenopsis orchids seem to attract scales and mealybugs, almost like a magnet, so you will have to keep an eye on them for any sign of them, especially on the underside of the leaves.

I hope this helps you save them.  Good luck!!!  

Jim Kawasaki
San Jose, Ca.