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

[Roberta]

First, Welcome!
Where do you live? Fusarium is most common in humid, tropical environments. If that doesn't describe your situation, it likely is something else. There are other Board contributors far more knowledgeable than I am about this particular issue.

[tyjch]

I’m in inland Orange County, CA; right on the line between 10a and 10b. I do have foggers and misters I can use to raise humidity a bit but I don’t want to encourage more fungal/bacterial growth.

The tag says the nursery it came from is in Hawaii, so I assume fusarium is still a possibility.

[Roberta]

Hawaii, maybe but even there, while it is tropical it isn't really all that wet...Home Depot, anything is possible. I would not worry about losing those oldest leaves that were yellow. Is that area at the base mushy? If not you'll likely be OK, it is likely to scab over. Hopefully one of the Board contributors with more experience with these will jump in.

[tyjch]

The base is hard, so I guess I’ll hold off on doing anything drastic until those more experienced members you mentioned can chime in.

Thanks for the welcome and the advice! Off-topic but your website is absolutely amazing!

[Roberta]

Glad you enjoyed my website! We're neighbors, I'm closer to the coast but climate is similar to yours.
I don't think you need to do anything more to treat the plant, other than to keep it well watered. You should be able to keep it outside until nights get down to 55 deg F or so, then you'll likely want to bring it in It's a lot easier to manage the watering outside, indoors you'll need to come up with a different scheme. To make it easier to keep it hydrated without suffocating roots, you could put it in a pot (don't bother to try to remove the plastic basket, no way of doing that without damaging roots) with large bark (or an inorganic material such as volcanic rock or LECA) to give more surface to hold water while providing lots of air.

[estación seca]

I suspect it wasn't watered at all at the store, which caused the damage. Bare-root or near bare-root Vandas need watering every day. Being so far from a window was also a problem.

At this point I would get the roots wet every day, begin fertilizing at every 5th watering with a tablespoon per gallon of any balanced fertilizer you might have, and hope for the best. That is a long time for a Vanda to go without water and survive.