I wish I could answer your question, but I can't. I'll post a link to what the AHS says about the fungus that causes leaf streak, but it doesn't talk about hybridizers who are working on the problem. There are two diseases of daylilies, rust and leaf streak, and many, myself included, consider rust more of a threat then leaf streak. Of course, it's whatever bothers you the most that counts. Not to be overly cynical, but there are only a hand full of hybridizers that are seriously trying to eliminate rust as a problem, I don't think too much effort has been made with leaf streak. Or at least I am not aware of it. Maybe someone else can help in that regard. Personally, if I've got a streaky leaf, I just pull it off. I've never had much problem with leaf streak compared to last years infestation of rust.....I know this isn't much help, but you weren't getting much response so I thought I'd at least give you the small amount of information I have....Good luck in your quest....Maryl

Here is a link that might be useful: Disease information-further on down the page

Any daylily advertised as resistant to daylily rust, I believe, will also resist leaf streak.
Any particular color you are looking for?
Ed