Oncidium with discoloration from top down

[Patrique]

Oncidium lemon drop with discoloration on stem. One spur stem had turned white already and I removed it. However, it seems to be spreading, and from one point outward. Has been outside and in some direct sunlight since it has gotten above 80, but leaves do not show any sign of light stress. Temps outside have been in the mid to high 80s here during the day with mid to high humidity.

Possible pest attack? I don’t see any evidence of pests other than some spider webs. Base is growing aggressively and has some new bulbs and roots.

Thoughts appreciated.

[estación seca]

After the flowers fall, the stem will die also. This is normal. New flowers can form on new growths.