Having problems with my Promenea

[Angurek]

Have you unpotted the plant to check the roots?

From my experience, members of this alliance start doing this when their roots have gone south and can no longer support the growths. I haven't grown this genus personally, but if it's anything like Zygopetalum, it probably needs to be kept evenly moist (not sopping wet or bone-dry). They also start shedding leaves if the ambient temperatures are not right. Try growing it under intermediate temperatures (with night temperatures that do not dip any lower than 55 degrees fahrenheit, and daytime temperatures that do not go above 80 degrees fahrenheit).

[camille1585]

Originally Posted by Angurek

Have you unpotted the plant to check the roots?

Yup, see my previous post. They're beautiful healthy roots.

As for the temperature, I also posted that it's been growing at 18-22°C (65-75°F) since I got it.

I got home from work to discover more leaves yellowing....

[camille1585]

OK, whatever is going on is not culture related. There are more leaves yellowing, and I just noticed the same thing starting to happen on my Propetalum (Promenea x Zygo)....

[Discus]

Oh dear time to sacrifice a leaf and take it to the nearest dissecting microscope?

[camille1585]

That won't help much, I doubt it's insect related. Seeing how quickly it progresses, I'm guessing it's bacterial.

[RosieC]

That really sucks Camille. I've had my Miltoniopsis do somthing similar this year and I've given up on it. I removed all the dying growth and it still kept spreading, all the new growths are browning now and it's actually by the back door waiting to be chucked out. I just don't know what caused it either and I've been watching the others closely to check it doesn't start on them.

It started on my Miltoniopsis when it was in low light while flowering but putting it back in it's usual spot didn't help

Sorry I can't be more help.

[camille1585]

I don't care if the Promenea dies, it's easy to replace. But the intergeneric hybrid is another matter, the Netherlands Orchid Society had obtained seedlings for all members attending their annual national show. It's nowhere else in Europe, so irreplaceable!!!

[Discus]

Preventative Spray time? Maybe a broad spectrum fungicide/bactericide?
Drastic action on any yellowing leaves to stop spread to rest of plant?

[camille1585]

I'm going to go look for something at the garden center tonight, but I doubt I'll find anything, there are extremely few pest/disease control products sold here.
I'll start by removing everything yellow and other suspicious leaves, and at least spray with listerine. Maybe the antimicrobial action of it may help. It certainly can't hurt.

I have an entire arsenal of chemicals in France, but I left everything with my mother sicen she's more likely to need them in the yard than me with the orchids.

[camille1585]

I had no luck finding anything, there are very very few products. Lots of weed killers, 2 insecticides, and 1 fungicide. None of the things I was looking for though.