[brookn]

Hi,

Phal type dendrobium refers to the type such as yours that do not generally lose their leaves in the winter, and do not need a true resting period in the winter such as a nobile dendrobium or nobile hybrid. I cannot remember all the details presently (sorry) so someone else will have to give you more specifics ( I have worked a lot lately, and exhaustion makes my brain kinda fuzzy).
I do know that when Catts lose leaves it can mean they are in shock, they generally do not lose too many. I cannot tell from the pic very well, but it doesn't look like a sheath which sometimes brown and dry (I could be wrong that it is not a sheath). If the leaves on the Dend are on the oldest cane no big deal, but if they are not, you might want to check for bugs. I would do a careful inspection of both plants for sure. There is a good thread by Cynthia in the pests and disease section.