Q: I collect daylilies and my ‘Pandora’s Box’ and ‘TC Red’, do not seem to be doing too well this year. Is this daylily rust and, if so, is it curable?
A: Daylily rust is a relatively new disease but it has been studied extensively by Dr. Jean Williams-Woodward at the University of Georgia. This fungus requires green leaves and high humidity to germinate and cause a yellow fuzz on the underside of daylily leaves. Rub a piece of white tissue under your infected leaves. If it has lots of orange powder on it, you have daylily rust.
Control is possible but persistence is the key. Cut off all of the infected leaves and remove them from your garden. Begin spraying with a contact fungicide like chlorothalonil (Daconil) to kill the visible spores and alternate every week with a systemic fungicide like myclobutanil (Immunox) to kill the fungus in the leaf tissue.