My suggestion would be that you submit one or more (tissue) samples of your affected daylilies to the laboratory in Alabama that does plant tissue analyses.
You can find more information at this web page
https://offices.aces.edu/plant...
and this one
https://www.aces.edu/blog/topi...
You should phone the laboratory to get details about how to take the tissue sample, what tissues to sample and how to send the sample(s) to the lab. There is a charge for each tissue sample to be analyzed and that seems to be $10 for each sample of plant tissue to be tested for all of these - Ca, Mg, K, P, Cu, Fe, Mn, Zn, B, Al, Cd, Cr, Pb, Na, and Ni. The information the lab provides you about your daylily tissue(s) should give you an idea whether there is too much of any of the tested compounds (or too little).
You can download the form that needs to be sent with the tissue sample(s) from the second web page listed above.
You should also have a sample of your soil (taken from as close as possible to several of the most affected daylilies and mixed together) tested by the same laboratory. That would be especially important if the plant tissue test indicates that some compounds are too high, or some are too low or there are both.
