Question
Hi!  I just sent the question about the leave.  Today I noticed that the one with brown/red color, have white stuff at the back of the leaf.  The bottom of leaf are brown/red color, it spread when leaf grow, but edge always have dark color.  Now, they have white stuff at the back of leaf.  Is it bacterial or fungus?

Thanks
Evelyn

Answer
Evelyn, I think there is a good chance that the "white stuff" is an infestation of mealy bug.  These are small sucking insects that, when mature, are cottony in appearance.  If you have a magnifying glass, look at a colony of these and see if you can detect any movement.  Let's hope that it isn't mealy bug as these multiply rapidly and can quickly spread from plant to plant.  You should isolate the plant and check any nearby plants for similar symptoms. Isolate any others also from unaffected plants.  Once you have isolated any affected plants, remove the plant from its pot and discard all potting mix and the pot.  Then, spray all parts of the plants with water (outside) and let dry.  Purchase an insecticide effective against mealy insects (one is Bonide's "Eight") and prepare a drench consisting of a water dilution of the insecticide plus water at the recommended dilution rate.  This should be in a large enough container to be able to submerge all parts of the plant.  Be sure to wear chemical gloves.  This is best done outside, upwind from the drench.  Repot the plant in fresh orchid potting mix in a clean plastic pot and let it remain outside in a semishaded location for at least a week before bringing it in.  If you can attach a picture, I may be a able to confirm my suspicions.