Lilies do this when they are too dry or stressed in other ways. Has it been getting plenty of water? Does it have good drainage? Has a dog been peeing on it? Check the stem where it goes into the ground for signs of borers. Report back you findings and maybe someone here can help.

Lainey

If anything I water too much. All the other lilies parked next to the sick on are doing fine. There's no evidence of borer activity at the base but I did not try to dig down around it... should I?
Drainage is great in that part of the garden. Water seeps in right away, and I add compost and mulch every year.
We have had a few weeks of unseasonably hot dry weather (I watered often)
This particular lily is one I bought last year, different from the others, which all came from Costco 4 or 5 years earlier.
I swept up all the fallen leaves... many are yellow, others are black.
I'm guessing this one won't make it through the winter, since it has'nt had the whle summer to gather nutrient. Is that a safe bet?
Thanks

It sounds doubtful, especially if the bulb is rotting or diseased. It could just come up very small. It depends. I'd dig it up, keeping a bunch of soil around the roots and put it in a pot, and watch it, just in case it's diseased. If it smells bad when you dig it up, then the bulb is rotting and you need to throw it out (but not in your compost.) Watch it throughout the season, and if it makes it, replant in the fall.

I might add that I recently read an research report that tied bud blast to very high temperatures, but I don't think that's what you've got here.

Lainey