Advice for a struggling bicalcarata

[Dragoness]

A few months ago,when my bicalc outgrew the small terrarium, I set it up in one that was larger, but had less ventilation. I made the mistake of setting the pot in the water, and proceeded to neglect my poor nep for several months. (I also made the mistake of setting the terrarium up in a room I rarely visit.) aside from making sure it had water, I wasn't paying attention as I should have.

This is the result.
image by Jerabudragoness, on Flickr

About half of the lower/older leaves look like this. Newer larger leaves are relatively untouched.

I'm assuming fungal, and have bought some Concentrated propiconazole. I have not yet started treatment.

When I first realized my mistake, I took the following actions:

I repotted it in a net pot with clean media, a blend of perlite, dried spag, and cypress mulch. I do not have live spag, or I would have used that. The old media was similar, but not in a net pot, and did smell sulfurous upon removal.

I also moved it into a smaller, but better ventilated terrarium, sitting on egg crate raised above the water. There is an ultrasonic fogger in there keeping things humid, but it is allowed to ventilate as well.

While repotting. I noticed the roots and stem look fine and healthy, with no signs of rot or disease. Nothing mushy, and after washing the old media from the roots, no smell.

My quiestions are

1 does this look fungal?

2 would it be advisable to prune off the worst of the leaves? Leaving the plant with approximately half of its leaves?

3 do I dilute the propiconazole according to package directions, or is there a recommended dilution? Package directions say 2-4 ounces per 100 gallons, so literally a few drops for one gallon, or do I go stronger?

 

[theplantman]

Yes, it looks like a disease. I can't say which for certain, but looks like possibly Sclerotinia (White Mold). Obviously, I'm just making an educated guess though. Until you know for sure, just adding fungicide for the sake of adding fungicide may not even be effective. At the very least, you always, always, always use the recommended label rate with pesticides. Any less and you risk not killing the pest/pathogen. Any more and you risk phytotoxicity. The vast majority of stuff I've used exhibits no phytotoxicity to CPs. Orthene and Safer Soap have been the only things I've noticed damage from.

The leaves appear to definitely have fruiting bodies, which equal more fungi. Clip every bit of the dead stuff off and wash the rest of the leaves in a DILUTE 10% bleach solution. That'll work better than any fungicide. If you have this plant in an enclosed environment, every last square inch of it is probably covered in spores. Lower humidity significantly for a while, and increase ventilation as much as you can. Honestly, I wouldn't even throw it in a terrarium at all unless it begins to immediately wilt outside a terrarium. If you make the plant healthy, it'll start fighting this stuff better.

 

[Dragoness]

Thanks for responding!


Bicalcs tend to sulk when Anything about their environment changes (at least in my experience). I can increase ventilation considerably in the terrarium, if necessary. I don't think removing it from the terrarium is a good idea for such a fussy plant, unless it's for short periods of time, maybe a day or two at most.

When you say 10% bleach, do you mean diluting household bleach with water, one part bleach to ten parts water? Or finding a bleach that is 10% sodium hypochlorite (most household varieties are around 3%) which would be considerably stronger than household bleach... I'm assuming the former.

On a bright note, I have seen no further spreading of the diseased sections since putting it in the terrarium about a week or two ago.

Would adding bleach to the reservoir in which the fogger sits be an effective way of getting the bleach on everything? Or am I better off simply making a bath and dunking the plant, or hand washing the leaves gently with a towel?

 

[theplantman]

I would dilute non-concentrated household bleach with 9-10 parts water, wetting a paper towel, and wiping off the healthy leaves. 75-100% ethanol is also a great sterilant, and I recommend it over bleach because it has a lot less phytotoxicity to plants. Regardless of what you choose, leave for 10-15 mins, then take a towel soaked in water and wipe it all back off. Wiping it back off isn't always necessary, but it's a surefire way to prevent any bad effects. And of course, wiping down your growing environment also can't hurt. While sterilizing the humidifier is a good idea, I wouldn't let it blast bleach water everywhere. That might be overkill. Do not get bleach in any form on the roots or dunk the plant at all, period. That's a humongous no-no for 100% of all plant life.

IME, bicals are only fussy insomuch as they're heavy, heavy feeders and intolerant of cold. Lowering the humidity and bumping ventilation will be your best choice for making the growing environment less conducive to fungi, so I'd hit a happy medium between your plant's happiness and the happiness of the disease. I'm by no means saying 0% humidity and roaring 50mph winds or anything, but just enough so that new spores won't germinate. It seems to me that 90% of your problems are cultural and can be solved culturally rather than chemically.

 

[Dragoness]

Well, I'll trim the dead stuff, wipe down the healthy stuff, bump the ventilation (they also make nice aquarium fans that are low power, but good for moving air around. My brother swears by them for his orchid terrariums) and see what we can accomplish. It has either dramatically slowed, or stopped altogether since I moved it out of the unventilated terrarium.

 

[DragonsEye]

PC fans work quite well in terrs, too.

 

[Dragoness]

PC fans work quite well in terrs, too.

Might actually have some of those laying around thanks to hubs computer building hobby.