masdevallia leaf drop, without signs of rot
 

I'm sort of new to growing masdevallia, but I'm trying to find information on why a masd. (Bella Donna) would drop leaves with no visible signs of stem rot. All of the leaves are a healthy green color, but periodically two to three leaves fall....the only thing I can think of that might cause this is heat spiking during the day...

The confusing this is, where the stem of the leave separates from the rest of the plant....it looks like what I would think stems would look like if a tiny animal had chewed on them (wish I had a photo) to separate them. There is no discoloration, and the leaves do not appear to be wilting or under and other sign of stress.

I'm hoping someone else has had this problem, or knows what could be going on. thanks in advance.

Have you been having spikes in temperature lately? This can most definitely cause leaf drop. However, if you don't think that's what's causing it, maybe it's a big drop in humidity? I'm sure there could be other possible reasons, so hopefully some more people will weigh in here soon.

I agree, temperature spikes will cause leaves to drop suddenly and without warning. Humidity is a big issue, if the climate is very dry for long periods and you have a thin leaf variety then it can't hold enough moisture for the plant.

Depends on your situation but temp increases and drops in humidity can make a difference. Mine seem to take a bit of variation, can you tell us more about your conditions?

Oh and welcome to the forum.

I've had them drop when the temps were too warm.

The seemed to break at a natural joint in the leaf stem near the bottom, straight through with both sides looking healthy.

Since I've had mine in cooler conditions this has not happened again and it's instead growing lots of new leaves.

Hello , i would agree high temps with low humidity will stress the plant and can cause sudden leaf drop ,which can be alarming.
But it can be other things , i had one lose approx 8 leaves last month overnight ,now i know it isn`t due to low humidity/high temps .
The only thing i can think it was is that i watered them that day so maybe caused sudden rot/stress to this one plant .
Or maybe a tiny snail has been on the rampage ,but you would think they would prefer leaf over stems ?
Regards Keith

I know that Masdies can react very negatively to excessive fertilizer or build up of salts in the medium. I usually associate browning of the leaves with this, but perhaps it could also result in leaf drop??

Your right , ruling out pests the plant has been stressed causing the leaf drop .Why ? who knows .

I've not seen this with anything other than heat or dryness, myself. Usually excess salts buildup will produce pleating or distorted leaves (at least that's my experience.) Low humidity or moisture in the pot (underwatering) will cause leaf drop, but from what I've seen, the leaves dropping off are dried and green. Lots of times excess heat will produce weird brown spots before the leaves drop. Best way to grow these is cool as possible (even the warm-tolerant) with plenty of water (not like Phrags, though) and lots of air movement. They dislike stagnant air and will not grow well in terrariums unless there is plenty of air movement. They tend to rot if the medium doesn't dry a bit overnight. I use Paph mix for mine in really small pots (underpotted) to accelerate the nightly drying.