Moth Orchid: Difference between rot and natural leaf falling?
 

Hi All,

Thank you for all of the help on my last thread on possible crown rot.

Is there any easy way to tell if leaves are falling off from stem rot or being dehydrated? Should the edge of the fallen off leaf be all yellow instead?

I noticed some black splotches in the area leaves have come off and wondered if that is normal or is that something else.

So far most of the leaves have fallen off from my trimming of what I thought to be rotting roots/repot but would like to know if there was any stem rotting.

It doesn’t seem like I can do that much anymore but hope that the crown is still good for regrowth. All advice is appreciated.

Thanks,

J

Leaves can fall off because the leaf is just old, and it's time to die.

They can fall off when the leaf is not getting enough water. This can be caused by not enough watering, not enough roots to take up the water or dead tissue in the stem that should transport water. The last is called crown rot, but often the entire stem is rotting, not just the crown.

Falling leaves usually look about the same, no matter the cause. So you need to look and think to figure out why they are falling

Mature, healthy Phals, watered properly in humid, warm environments, can easily carry 8-10 leaves on each crown. In homes, where humidity is usually lower, they tend to have 4-6 healthy leaves. Any time the plant is shedding leaves to get below those numbers you should investigate. Either the grower isn't watering enough, or the roots are inadequate.

With crown (stem) rot, the stem or top of the stem turns mushy so rapidly the leaves usually fall off of the stem while they are still green. They can come off if you just bump the pot. I don't think that's what is happening with your plant.

I think your plant lost so many roots it isn't able to keep up the water supply needed in your conditions. It is probably dropping all those leaves at once to preserve the one leaf it can supply. As you water the plant, and it grows more roots, I expect it to grow more leaves.

The photos show a very dry plant in very dry medium, with very dry roots. I would not let this plant dry that much. You are using an open medium, with plenty of air spaces, and you've just repotted the plant. Soak it now, then water again before it becomes dry again. I expect it will recover if it gets enough water on a regular basis.

Totally agree with ES.

Also, check the roots in the pot ---- underneath the media, which means an unpot --- to see if the roots are ok or not.

See if the roots are very dry. If very dry, then you need to alter the watering schedule. If roots are rotted - then also need to alter the watering schedule or method.

I agree with the above, but in the first image, there looks to be a brownish discoloration at the base of the upper most yellowing leaf. If this isn’t just shadow, I suspect you're also dealing with some kind of stem rot.

I agree with Alice. Better take a close look at that darker region.

If it really is a sign of rotting - then it could be helpful to apply some sort of treatment - eg. monterey garden phos (aka agri-fos), or maybe thiomyl (aka cleary's 3336).

And provide gentle air-movement in the growing environment - which can help cut down on nasty activity on leaves and stems.

I tried the watering route and the plant is down to its last leaf. I am thinking it may have exacerbated the process and is probably rot.

Anything left I can do to save my plant? Hydrogen Peroxide? I tried to fix it early to no avail.

It seems pretty extensive. It seems many of the roots have discolorations.

The three photos from 8/5 don't show crown rot. That damages the center of the plant while the outer leaves look OK. The roots in the most recent photo are mostly healthy. I don't think it was a rot issue.

More photos of the roots.

Should I cut the brown ones?

What about the ones with brown on top and green still on bottom?

No, those roots don't look that bad. I would not cut off any of them.

I still suspect stem rot especially from the last photo. You can try to products recommended by SouthPark. Keep it warm, don’t cut any roots, and water appropriately. When the roots look silver: water.

Hydrogen peroxide will only affect the surface and it will kill the plant tissue along with the fungus. A good dousing with 3% hydrogen peroxide to the roots seems to be enough to kill all but healthiest orchids: orchids that are already struggling don’t have the resources to heal/recover from peroxide to the roots.