Leaf-tip dieback (from AOS film on website)
 

Greetings -
I was very excited to see a film on the AOS site about this subject, as I have this problem with both Den. palpebrae and Enc. garcinia. This link may/may not work for the film:
AOS | Leaftip Dieback
Anyway, short story long, the narrator points out that this is caused by a problem with nutrition, but gives no clue as to what nutrients are present or absent that might cause this unsightly and slightly unnerving problem.
Clues? I'd certainly like to fix it before any new foliage is affected!
Thanks - Nancy

In my experience , it is sometimes too much salt in the pot (over fertilization). Some plants are more sensitive to salts than others. This why I have found it better to feed at a lower rate with each watering.

Good point Des, I agree with you - slow and steady is the best way to avoid some of the dark tips we see in out orchids.
I've also learned that keeping the media too dry can also cause black tip leaves.

I agree completely Des & Gloria. One question I have though regarding Phrags, how long does it take from the time of exposure to high salt concentrations until the leaf tip die back shows up? How long does it take after reducing the salt concentration for the problem to disappear? I'd sure like to hear your thoughts on the time frame.

Jerry,

I've got a few phrags that do have this leaf tip burn. It takes about 6 weeks to see paleness then about 8 weeks for light yellowing color. Then a bit longer to finally turn fully dark brown - 10 weeks maybe.

As for the reverse, I'd suspect it takes about the same about of time providing the new leaf growth is finished.
I'm still working on knowing more about that, time will tell :)