Many of my lilies look to be diseased—some Asiatics are the worst. Usually they make it through flowering without much of a problem, but then the leaves start dying from the bottom up. Now the infected ones are just ugly stalks with no green. They are often right next to others that are just fine or have little damage. For example, the dead “Roma” or “Lollipop” lilies are next to “Sunray” or “Anaconda” which are still in good shape. I assume if they are pretty much dead looking, I could dig, divide, and replant now rather that late fall, right? But the real question is what should I do next year to prevent this from happening? I have a lot of lilies and many, many varieties. If a photo would help, I could easily send one.
Thank you for the question. The three diseases that can be problematic for lilies are lily mosaic, Botrytis blight, and basal rot. Lily mosaic, a virus disease spread by aphids, usually produces streaking or mottling of the leaves, followed by distortion. Affected plants produce few flowers, and they may be deformed, or buds may fail to open properly. Plants affected by this should be dug up and discarded. Botrytis blight is a fungal disease that begins on lower leaves and ascends the stem. Orange-brown spots spread and merge together, and spores form a gray mold. If it infects the flowers, a messy decay results. Although wet weather is conducive to the development of fungal diseases, many factors affect the extent and severity of infection from year to year. Basal rot, also caused by a fungus, can be serious, infecting both roots and bulb. Fortunately, hybrids and species vary in their susceptibility to this disease. Infected lilies simply disappear or plants may emerge later in spring, growth is stunted, and foliage may yellow and die prematurely. This information taken from: http://ohioline.osu.edu/hyg-fact/1000/1237.html
You can divide lilies now that have no green growth left. Be sure to plant them where the soil is well drained, in full sun, and where there is plenty of air circulating around them to minimize the growth of fungal diseases. Replant using compost and bone meal.
If you think your lilies are having some other problem than the common ones listed, submit your question again along with photos of the entire plant and up close on the affected areas.
Here are two more publications for your information:
Thank you for contacting Extension.
Thanks for the info. I'm sure my problem is Botrytis. I've been looking around in garden stores for "over the counter" sprays to control this next year. Since my lilies are spread throughout my garden with a lot of other plants, I really don't want to use stuff that colors everything. Don't lily growers use something like Bonide Fruit Tree spray? It lists Botrytis for fruits, but I don't know how good it might be for lilies. Any other product suggestions you can make?