'srooms in the door frame

[dshogman]

OK, I know I'll be able to ask this question to this Alpine group without being raked over the coals or experiencing gales of laughter.
That being said, there's a spot on the inside of the door frame, right where the stairwell side carpet meets the frame, that more than once, particularly after a heavy rain (like yesterday) that this one spot shows either mushrooms or the flowers preceding a mushroom (I think) growing. The carpet spot, about 2" long, is severely discolored.
SO any thoughts on what to do about this - cut out the section of carpet, spray it with something?? Any suggestions appreciated.

[EngineerMike]

Dude- Like totally drop them shrooms man!! Its gunna be like far out trippin man.

Wow, that was a wierd flash back from the '60's.
Probably most important thing is to locate the leak & get it patched. I worked on an 08 coach that had mushroom like fruiting bodies growing out of the floor "strand board" under the fridge. Stank like crazy. IIWMI'd not want things to progress to that level.
If you can stop the water feeding the infection, the infection won't progress. After that its whatever cosmetic & olfactory clean up works for you. IIWMI'd think remodel the stairwell w/new covering.

[Jeff and Cheryl]

While finding/fixing the problem, either replace any wood that may have become soaked as well as carpet. Anything that has not been replaced, wash throughly with bleach and let it dry before covering it over. 'Shrooms first but mold likely hiding, just waiting to come out to play.