Dark spot on Phalaenopsis crown

[Wade Coleman]

Hey y'all, so I got back from vacation today and noticed that one of my phals has a large dark patch on one of its leaves near the crown. It's just one leaf that is showing this coloration. I also noticed a small tan colored bug crawling on the affected area. I sprayed the entire crown of the plant with hydrogen peroxide in an effort to help kill whatever is causing this, but I really don't know what I'm dealing with here. Any ideas?

[King_of_orchid_growing:)]

Beginnings of crown rot. Unpot and check the roots. Cut back on watering the plant. If leaves fall off, don't panic. As long as the plant has a lot of healthy roots, the leaves will grow back slowly.

[Wade Coleman]

Thanks so much. It’s in a clear plastic pot and the roots look very green and plump. Crown rot happens because water collects in the crown of the plant and bacteria colonize and eat away at the tissue right? So I just should be more careful to not get water in the crown?

[BotanicaExotica]

You need to be careful about water getting in the crown if you have insufficient air movement. With enough air movement it does not matter if you get water in the crowns.

[Wade Coleman]

I have no A.C., so the windows are always open and there is almost always air movement circulating around the plants. Even when there isn't a breeze I have a fan running 24/7, so why did my plant get crown rot then?

[BotanicaExotica]

Originally Posted by Wade Coleman

I have no A.C., so the windows are always open and there is almost always air movement circulating around the plants. Even when there isn't a breeze I have a fan running 24/7, so why did my plant get crown rot then?

I would still venture to guess not enough direct air movement. This in of itself can also be an issue if you have too much as it can dry out your plant very quickly.

I grow indoors under lights, but never have to worry about crown rot in my phals. The only ones I am more cautious with are my paphs, but even still, I get water in their crowns frequently.

---------- Post added at 05:17 PM ---------- Previous post was at 05:15 PM ----------

In situ, or in nature, they are in the trees so unless your house has conditions similar to be in the trees you may have to exercise more caution with your crowns.

[Wade Coleman]

Are some paphs more susceptible to crown rot than others? This is the only one so far to ever do this. I live on the windward side of Oahu, so the conditions are pretty similar to what I imagine they'd experience in the tropics where they come from. I treat this one just like my others and the others seem to be thriving, but this guy is just not doing too hot all of a sudden

[BotanicaExotica]

It could be location compared to other plants. Yes, your conditions should be prime, but perhaps this plant is sheltered in some way. My phals are only rescue phals from friends, and I usually give them back once they are in good condition so I would not consider myself an expert in phal species, even though I have grown hundreds of them from box stores. There could be some species which are more prone to rot, but in my experience I have not had an issue. My growing style provides a lot of air movement, more than most other growers I know, and then top with live moss I wild collect here to conbat the quick drying that usually takes place with as much air movement as I provide.

[Wade Coleman]

So I did a little more research and I think I may be dealing with Stem Rot, not Crown Rot. The crown of this orchid (or the little "cup" in the middle) does not look like it is rotting. The infection seems to be in the middle of the plant a little farther down the stem. What do y'all think?

[King_of_orchid_growing:)]

I tell a lot of people a lot of things that sound very counterintuitive and it doesn’t always make sense at first.

Crown rot is not always the result of having water collect in the crown. It can be. It does not always have to be.

It can also start because the plant is being watered a little more often than it can handle. It can result from the roots staying too wet for too long, which in turn results from air that remains a little bit too stagnant as well.

Regardless of whether it is called stem or crown rot, (they're similar enough to each other in the case of Phals, and the end result for a Phal is the same if they're severe enough - leaf loss), it is the result of a/a set of cultural problem(s). It needs to be addressed promptly.

Technically, that spot that can readily be seen is not even on the Phal's actual stem. It is on the Phal's petiole. The Phal's true stem is obscured by the petioles. If you dissected the plant, you'll find that the damage is pretty close to the apex of the stem. The apex of the stem is deep inside that new leaf. It might as well be called crown rot.