Probably so, Lisa. Trim that yellow leaf completely back to green tissue, sprinkle with cinnamon, and try not to get any water on the leaves. The best way to keep water controlled is by bottom-watering. This was most likely crown-rot, likely caused by the plant being planted too upright, and water stayed in the crown (where the new leaves formed). If there is no sentimental value, you might just want to toss it and get a new plant. If you have a "nursing-instinct", baby the plant for a few months and see what happens. By the way, Phal. are very prone to crown-rot. You might get some Cattleyla alliance orchids instead. They don't have this problem. Also for me, scale seems to be attracted to some of my Phal. as well as snails. Neither nuisance seems to bother my Cattleya orchids.
Good luck.
