OTB usually no. But in any online site (such as this one) it does apply.
Fifty-move rule

It would apply OTB if there was a way to prove it. Since there's usually no scoresheet, that makes it difficult.
As a TD, if one of my players claimed a 50 move draw, I would at least investigate the claim, and do the count myself if at all possible.
Interestingly, the 6th edition of USCF Blitz rules do not list the 50-move, or the Triple Repetition of Position (TRP) rules as a drawing method. The 5th edition did list TRP as a method, however.
As a TD, if one of my players claimed a 50 move draw, I would at least investigate the claim, and do the count myself if at all possible.
The reason I'm asking is that I've made, like, 100 moves - but the game was not drawn. Do I have to claim a draw?
Quick question to connoisseurs:
Does fifty-move rule apply to blitz and lightning games?