This has shown up again this year - see attachment also notice the yellow blotch. Any suggestions? Bob
Could the powder be pollen? The yellow spot looks burnt, maybe from water salts, or fertilizer burn? (These are just from looking at the picture you have provided, not based on my knowledge of day lilies.)
The yellow spots are daylily rust, which is caused by a fungus, I had it on several of mine, the best solution is to remove the infected lily because it will spread to others. The white spots might be mildew,
