After raining almost the entire day yesterday, one of my Lilium lijiangense very suddenly shows infection in the upper half of the stem. It must have been initially infected prior to the long rain, as the constant rain would have washed any germinating spores right off the plant. This particular plant is relatively small and would only produce one flower this year, so I am just going to cut that half off. The sun is shining now, so hopefully the wound won't be a new infection point.
Remember to disinfect your pruners if you are working with botrytis.