Black rot in collection

[Silje]

I'm sorry, I can't take pictures at the moment, but I'm pretty sure that I've diagnosed the problem.

My entire collection is dying of black rot, and at such speed I'm unable to keep up with it.

I don't have a large collection (50 or so plants), and I also don't have anything very valuable, except that some of the plants are personal favorites of mine.

Here is the problem. I live in Namibia and our humidity is around 5% at the moment, so the plants need to be in a room with a humidifier. I live about 500 km away from the nearest town where I can get a humidifier, so I'm stuck with whatever I have available on the farm. That goes for chemicals as well. Since I live on a farm and we're vegetable producers I've been scrimmaging through our chemical room searching for possible fungicide alternatives to the ones I've found on the list of the sticky post on top in this forum, but so far...no luck.

The main problem is that it's freaking impossible to see which plant that is infected until it's too late. Plants have beautiful green tips on the roots, look healthy and well in the morning and in the afternoon the roots have darkened and are drying up. The next morning the rot has reached the pseudobulb. It's incredibly aggressive. This is also why I probably responded a bit slow when the first plant keeled over. I didn't quite understand the severity when the first dendrobium lost a couple of pseudobulbs. Within a couple of days though, it became crystal-clear that I have a huge problem.

Obviously I remove plant immediately when I see sign of infection, but by then it's already too late. I've tried to take them out of the pots, cut the rhizome until it's nice and green (there's no purple ring), put on cinnamon and repotted them in new, sterilized growth medium in a clean pot, but it just seems to speed up the process of rot and until now I haven't had a single successful rescue.

It took my dendrobiums first. Within a week, 8 of them rotted from the bottom. Healthy plants with new growths and good-looking roots. Poff! Dead, gone in a blink of an eye.

They were dispersed in my growing area so it didn't jump from one plant to the neighbor, but the dendrobiums were much more susceptible than the others. Now the cattleyas are starting. The only plants that seem to be immune (at least to now) are the super market phals.

I've reduced the humidity in the my growing room to 40-50% and temperature down to 20-22 Celsius. It's the best I can do. It's 38 degrees outside.

I'm keeping the plants drier and I've spread them out as much as possible to make sure they're not in physical contact with each other. I've disinfected all surfaces with agri disinfectants, I'm using new scalpel blades every time I cut a plant and I work with them outside my growing area. I'm making sure there's no water standing anywhere in the growing area.

I am at a complete loss as to what else I can do that is within my capacity at the moment.

Help..!