Is dry stem rot fusarium on vandas?

[tyjch]

TLDR
I got this vanda from Home Depot a little more than a week ago. It was buried in moss and has been dropping leaves and has a hard, woody, dry section at the base of the stem. Is this fusarium stem rot ? And if so, how do I treat it at this point?

in advance




Culture
Temp: Days were around 95 and now about 80, nights around 60-65
Humidity: 50-60%
Light: 15ft or so from window inside Home Depot with little supplemental lighting, I put it outside in a NW-facing with 70% shade cloth to acclimate it for about a week. Today I put it in SE-facing porch that gets maybe 3 hours in the morning
Water: With moss, I sprayed once in the morning. After I took the moss off, I would dunk at around 9 am for 15 minutes and then mist at around 2 or 3 if it was dry, which it usually was.

Timeline
9/2
Bought the vanda with two yellow-green bottom leaves but I figured it was just stressed from being in Home Depot.


9/8?
A third leaf began to yellow overnight. I pulled out all the moss I could, figuring it was causing poor ventilation. Figured moss acts similarly to velamen so upped watering to 2x a day to compensate.



9/9
I noticed brown forming on the stem. I pulled back the dried out sheath at the base of the stem and saw even more brown. It wasn't wet or squishy though. And almost everything I read online said that meant it wasn't rot. Spent a lot of time watching videos and reading articles on how to determine orchid disease and how to treat them.




9/10
Ended up wiping brown/black stuff off with 3% h2o2 on q-tips, as much as I could. I wanted to get Phyton 27 from a local nursery but they were closed.

9/11
Brown spots seemed to have expanded since the previous night. Got Phyton 27 from the nursery and applied it at around 4:00 pm when it cooled off. I dunked the roots for 10 minutes in a solution of 1 tsp phyton in 1 gal of water

9/12
The bottom two leaves had turned a darker yellow and snapped off pretty easily near the base. The inner part had these black/brown specks inside. I don't know if that's just debris that gets caught by the leaves or a symptom of a disease.



Maybe this was a mistake, but I felt that I had to get the basket off so I could get the remaining moss out and cut off the rotting roots. I soaked the roots well beforehand and cut off the basket, I think with minimal damage to the roots.

9/13
Today, the brown seems to have slowed down a bit. I just noticed a flower spike; I have no idea how long that's been there.



I pulled the third yellowing leaf down, it did not snap off. I used 3% h2o2 again to clean the inside of the leaf as well as the part of the stem that it was covering



Questions
I have not been fertilizing since I noticed the brown spotting because I heard that nitrogen encourages fusarium. Should I apply another round of Phyton, this time dunking the leaves too? Or should I attempt to cut the stem somewhere and discard the bottom half?

THANKS SO MUCH FOR YOUR ADVICE!!!
Sorry about the length of this post ; I care a lot about my plants and just wanted to provide as much detail as possible so that hopefully it can be saved