There was some testing of fungicides including bio-products for leaf streak, the fungicide Julie uses was one of the best ones but is not organic. There's a link to the study and also an article on leaf streak from the AHS daylily dictionary page for leaf streak, scroll to the bottom for the links:
http://www.daylilies.org/ahs_d...
Another problem that surfaces early in the year is spring sickness, which I've seen mistakenly called leaf streak, so just to differentiate here are some pictures of that (I know that's not what Becky has, but it might be of interest to others who aren't sure what they're seeing):
http://web.ncf.ca/ep568/galler...
