Question
My phalaenopsis has two beautiful long stalks right now, but the stalks started to pearl with sticky clear drops after a few weeks and now about one inch below the top, the stalk is beginning to wither and dry out.  It happened with the last blooming effort in December and I finally had to cut the stalk off. I was so happy when it shot two more stalks last month!  I have been watching it like a hawk and it just started again. It breaks my heart... The stalks are about 18 inches long and the buds are still inside the stalk.
I repotted the orchid last fall in a medium that is not bark, but soil (it is said to be an orchid medium).  I do not see evidence of pests on or around the orchid.  I have not changed its location.  I just rotate the pot so the stalk grow straighter.  I have never had this problem with any of my orchids.
I feed the orchid once a month - twice when it blooms.  It is indoor on my kitchen windowsill.   I have not seen this symptom described on any websites and would really appreciate your help!
Thank you

Answer
Michele, there are several explanations possible but my first choice of suspects is the potting mix. One reason to suspect the potting mix is that the problems seems to have started not long after you repotted and has continued as long as your plant is in that potting mix. Some potting mixes contain fine particles which tend to trap moisture in the root zone and allow little aeration of the roots. In nature, orchids often have their roots exposed to the air and a potting mix should mimic that to the extent possible.  One of the reason for incorporating fir bark in an orchid potting mix is to create air spaces at the root zone.  At the same time, finer particles such as perlite are introduced to help prevent the potting mix from drying out too quickly. Fir bark, when dry, repels water-- so any potting mix containing it, must be soaked for at least an hour prior to use.  When there is excess water in the root zone, the water pressure in the plant's conductive tissue increases and may cause "weeping" from the plant tissues as it escapes through the pores.  This could explain the sticky drops that you observed.  These drops are sticky because the plant sap contains sugars it is carrying to the tissues-- especially newly growing tissue. As plant sap leaks out of the pores, there may be less nutrients available for parts of the plant above the leakage of the sap. If my guess about the root zone is correct, this could also lead to root rot and compromise the plants ability to supply nutrients.

If this speculation is correct, you will need to repot to a fir-bark based orhid potting mix. Usually, I don't recommend this for a plant in spike as it can disrupt the flow of nutrients to the buds.  However, in your case, this is happening anyway. If you elect to repot, rinse the roots thoroughly so you can identify if any rot is setting in (rotting roots are mushy) before repotting. Also, be sure to use a plastic pot with lots of drainage holes. With this improved root condition, you may water weekly and not be concerned about a root zone that remain too wet and that has sufficient air flow. After the roots re-establish their connections in the root zone, the flower spike production may resume.  Any flower spike that continues to die back can be cut off below the die back but above a node (ie joint) in the flower spike.