Garden Pests and Diseases: Need help diagnosing Daylily problems, 3 by robbie_1234

robbie_1234 wrote:
I have more than a dozen Stella D'Oro and Happy Return daylilies in my landscaping. The plants are several years old and were moved 3 years ago to their present locations. Some are on the east side of the house while others are on the southwest and west sides of the house. All are in full sun or receive sun for most of the day. All have been blooming and I see new growth along the edges. I do have heavy clay soil and the areas were amended with topsoil prior to planting. The plants are also mulched with wood chips. I do have heavy clay soil that I amended with topsoil before planting the daylilies. I also clean up all of the dead leaves in late fall or early spring.

The plants had been doing well this spring and only since July have they looked bad. The old flower stems are dried and there are a number of leaves that are dead or yellowing with orange. I started to pull out the old flower stems today trying to clean up the plants and numerous green leaves broke off at the base. The base of the leaf is also yellowed with orange areas. There is no "foul" odor to the crowns. New flower stems are curled up bent. There are also orange areas near the tips of the leaves, although nothing that "rubs off." The yellowing on the leaves is on the edge rather than the center. All of my daylilies seem to be affected. I live in mid-Michigan and we have had quite a bit of rain this summer.

I did some research and leaf streak, rust, and crown rot could be potential causes. I am hesitant to employ any treatment though until I have a better idea of the cause. I have not yet dug up the crown to inspect the roots, although that is next on my list.

Thank you