Question
QUESTION: Hi Wayne King,

How can I tell if spider mite are gone from my Phalaenopsis which has badly attacked by mite recently?

Thanks,
Nwe Lay

ANSWER: You didn't mention what you have done to treat the infestation.  If you spray for them, continue weekly spraying until new growth appears healthy.  Also, be sure that your plant is isolated or it may become reinfested from nearby plants

---------- FOLLOW-UP ----------

QUESTION: Hi Wayne King,

Sorry, I forget to mention the treatment. I spray everyday with mild liquid soap. But, it doesn't seem to be effective. I can't use the miticide as they are placed indoor.

Any safe solution to get rid of them effectively?

Thanks,
Nwe Lay

ANSWER: Spider mites are, indeed, difficult to eradicate without use of miticides.  Kelthane is only one of a very few miticides that are effective against the most common mites.  If you use a miticide, you should place the plant in its pot inside of a plastic bag before spraying.  Then seal the bag for several days.  Repeat this in a couple of weeks.  Another product is Safer's insecticidal soap.  This is a contact miticide and the spraying should be repeated every 2-3 days for two weeks.  Unlike household soap, this is formulated to suffocate the mite.  However, repeated spraying is required to kill young mites that are continually hatching.  The latter soap is less toxic to humans and may be sprayed in the room.

Low humidity is needed for mites to thrive so once you have established control, you should mist the plant daily.  My guess is the low humidity is caused by the air conditioning.

---------- FOLLOW-UP ----------

QUESTION: Hi Wayne King,

After I used insecticidal soap, next day the leaves become floppy. Is the soap too strong? Or any other thing that cause the leaves floppy?

I think the floppy leave can't be stiff again,right?

Thanks,
Nwe Lay

Answer
If you followed the directions for use of the insecticidal soap, it should not cause droopy leaves. It is made from naturally occuring plant oils.  I suspect that you may have a root problem causing those droopy leaves.  Check the roots first and repot if necessary. If floppy leaves are the result of a root problem, they will be lost and you will need to grow new leaves and roots.  One other, less likely possibility, is that these leaves are not receiving the structure building elements of calcium and magnesium.  Dynagrow markets a product called "Protek"  which can sometimes rebuild the leaf structure using the missing elements.  I would not go to Protek unless the roots are fine.