My first job was at a local nursery where we only sold daylilies (Hemerocallis). And the first sales pitch I had for a potential customer was simply, “There’s nothing that can hurt a daylily.” Despite these perennials being resilient plants, that absolute reassurance changed in 2000 when a new disease called daylily rust (Puccinia hemerocallidis) was introduced in the Southeast.
These spots are a sign of daylily rust.
Photo Credit: Daniel Overcash
Daylily rust is often mistaken for leaf streak (seen here), a common daylily disease.
Photo Credit: Daniel Overcash
Native to Asia, daylily rust has spread quickly since its introduction and can now be found in at least 30 states. One of the trickiest aspects of this disease is identifying it on an infected plant. Many devoted daylily gardeners confuse the signs of daylily rust with leaf streak, a more familiar fugal disease.
Daylily rust can be recognized by the presence of raised, yellow pustules on the leaves and flower stalks. These pustules look very much like pollen. The sure test to determine if your plant has daylily rust, and not leaf streak, is to take a white cloth or tissue and pull it over the infected leaf. If the tissue picks up a yellowish-orange powder, then it’s rust.
An infected plant may not show signs of rust immediately. Daylily rust spreads and shows symptoms when temperatures are mild – neither extremely cold nor extremely hot. Garden centers sell what appear to be healthy plants in late winter and early spring, then occasionally, as summer progresses, customers will discover their plant is infected with daylily rust.
Like other rusts, daylily rust is spread by spores carried by the wind, so there’s little you can do if your neighbor’s plants have it. If you have a susceptible plant, your daylilies will eventually be infected. The good news, though, is that daylily rust only affects daylilies – not other plants.
And there are prevention and treatment options. First, try to purchase cultivars that aren’t susceptible to the disease. The University of Arkansas has developed a website, (http://daylilies.uaex.edu), with good information about the disease including daylily cultivars it has tested.
If you identify daylily rust on your plants, check with your local Cooperative Education Office or state pesticide regulatory office for a suggested treatment, including what fungicides are approved for use in your area. If you’d like a professional to identify any diseased plant material for you, always transport the diseased plant in a sealed plastic bag. You might suggest that the plant professional join you in the parking lot to examine your plant problem so the chance of infecting healthy nearby plants is minimized. (Photos and a plant history are often sufficient for disease or pest identification.)
The easiest and quickest way to rid your garden of daylily rust, though, is to destroy the infected plant before it has time to spread. (When disposing of these plants, don’t just place them in the compost pile, because the spores on the pulled plants still have the potential to spread to healthy daylilies. The preferred method of disposal is to seal the diseased material in a garbage bag and dispose of it at the landfill.)
When it comes to daylily rust, doing nothing is not an option. If this disease is allowed to thrive, the daylilies in your garden will become unsightly and have fewer flowers. Daylilies are mainly appreciated for their colorful blooms, but paying close attention to the foliage is key to catching an infection from this exotic pest.
