Ken, thank you for your post. I did give a bit of granular fertilizer, half dose than what the producer says. But it begun some day before of it. It's bad to see all that beautiful foliage that wilt in few days.
Here it's warm by day and slightly fresh at night, it's humid too. The soil keeps well moisture except for the firts centimeter that gets dry quickly.
The man I'm talking about it's an italian grower and started hybridizing and registering his daylilies two years ago, he lives in center/south and he has warmer temps than me. If someone wants to check his registration these can be found under the name of E. Rossi.
Arlene, good to know it's a common "symptom". and don't worry about the email, there's no rush!