My first job was at a local nursery where we only sold daylilies ( Hemerocallis spp.). 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.
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.
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