One again I am asking our Lilium experts for advise.

The foliage of the Oriental Lilium(?) in the picture corresponds to a pot with 3 bulbs of white flowered lilies (maybe Casablanca).
All were planted at the same time in specially purchased acidic soil, bloomed simultaneously as well and are located in dappled shade.

As you can see, one stem is wilted while the other 2 are still green. I also observed that the brown one aquired that colour almost over night, but the leaves' tissue remained soft for several days (not papery as regular).

Please let me know if this is a disease and, being this the case, if the other bulbs are in danger and what I should do.

Thank you very much beforehand.

Yes, this is a form of botrytis that affects the stem. It can start anywhere on the stem but usually starts a few cm above ground and progresses rapidly to the top. There is a name for it, too, but it escapes me at the moment. I don't think your other bulbs are in danger but this one may sulk next year. Work a small amount of Captan into the soil.

I was afraid of reading your answer. The same problem has shown up on other Lilies.

When Botrytis appeared on my Liliums on early spring the sympthoms were different.

I will proceed with Captan tomorrow morning.

Thanks!

This problem would come up with some of my species lilies from time to time in my earlier years as I learned how to grow them. At that time, the garden was rich clay, exactly what lilies (especially species lilies) hate, and many lily experts were surprised I could get them to grow at all. The secret was that the clay was never water logged, except in early spring when species lilies have greater tolerance to excess moisture. This was because the garden was bordered with lilacs and a huge Norway maple that sucked up water like sponges. Even after the occasional summer downpours, the clay was wet only briefly before the lilacs and maple mopped up the excess water. The other "secret" was that the soil was never cultivated, except to plant the bulbs themselves. (Due to the complicated regime of soil physics and soil flora involved, you'll just have to believe me, here.)

But then something started happening: climate change. I could no longer depend on seasonal ranges of norms. The occasional downpours could turn into torrents, and my natural "sponges" were beyond capacity. I had not changed my growing method to fit the new weather regime.
As Lorn says, my infections originated at or just above the soil line, and would manifest themselves just when soils started drying out, and just as I began to think I might have escaped the bad weather without casualties. Then I would see the symptoms, and once I had a tall stem just topple over. The bulbs were never affected by this disease, although sometimes they were consumed by an unrelated basal rot.

But we shouldn't confuse this with the normal phenomenon of natural senescence: when a lily stem may die back in late summer or fall. When this happens, the progression is slow, and you won't detect any evidence that the lower stem near the soil surface is different from the rest.

Rick, the soil I purchased for my OL comes from a reputed supplier and is supposed to be disease free. I added coarse sand to improve drainage. The bulbs were bought in early spring. But then we had this persistent dew during spring ......

Thanks for sharing your knowledge and experience.

"Botrytis is one of the most common fungal diseases of lilies and it can cause serious problems. The early symptoms usually include wet-looking spots on the upper leaves. Severe infections can result in practically every leaf turning brown and dry. Worst of all, it can mar the flowers with unsightly brown spots and rotted petals. The fungus gets its start in spring when spores that overwintered on plant debris blow in the wind onto susceptible foliage. Later in summer, spores produced in affected leaves spread the fungus throughout the plant and to neighboring lilies. To control this disease, remove affected leaves. Even if you have to remove every leaf, your lily will survive and flower. When you cut it back in fall, make sure to remove all debris from the garden. In winter, dig and move the bulb to an area with better air circulation, or remove surrounding plants that are crowding it. If your lily is heavily infected, be prepared to apply fungicides registered to control botrytis at the first sign of infection next spring. Be sure to thoroughly wet the lower side of the leaves in the process. If you follow these steps, the prognosis is good that your lily will once more grace your garden with beauty and fragrance." - Ciscoe Morris, Seattle Master Gardener

Jason, thanks for the additional information.

During spring I had those ugly botrytis marks on my lilies - at that time it only affected L. asiaticums and species lilies (mostly the yellow and some salmon coloured ones). I carefully removed the affected leaves and burned them - also applied some Captan. I was warned at that time by our experts that the battle was not won, and informed how to proceed at this time (autumn for us), but I did not expect the OL to be affected and in this very unusual way (for me).

This Lilium forum is far better than 100 books! Books contain good information, but they do not answer when you have questions.