Terrarium mold, Infections, and Algae

All,

This seems to be the last of many posts in regard to my struggles as an amateur orchid grower, and I'm grateful for the advice and identifications I've already received.

This time I'd like to address what appears to be a fungal infection on the leaves of two of my miniatures and what appears to be mold and algae growing on the bottom of their container. From what Both the H. nitidus and D. aberrans produce new growth at a healthy rate, but the former seems to grow relatively slowly and is thus unable to keep up with its fungal attackers. There are currently just two leaves left, but close to ten pseudobulbs.

The miniature orchids are in a shared enclosure with some humidity loving carnivorous plants, which have never been infected and are in fact becoming too large. The temperatures in the enclosure, although a bit hot for the carnivores, are well within the preferred range for both orchid species. The same is true with the humidity.

Before proceeding with the orchids, I should mention that I went on a trip to Colorado in the fall with a caretaker at the house and returned to find all my miniature orchids very unhappy (the R. sanguinea turned dark purple, but has recovered well since then). The only plant out of the four miniatures that never seemed to improve is the H. nitidus, which still has yellow tips and a tendency to lose leaves. The D. aberrans produced a great deal of new growth after I returned, but repeated infection has forced me to cut leaves...

If I have to guess why my orchids have been plagued with so many infections, it's probably because I have very poor air circulation in their container in addition to relatively high temperatures and humidity. I have a small (but powerful) fan for the R. sanguinea and B. tingabarinum that improves air circulation and humidity (due to a small water tray), and neither has ever gotten leaf infections like the two orchids this post is about. That being said, the humidity is somewhat lower and the temperature cooler...

So, should I a fan for the H. nitidus and D. aberrans? Is it time to use Physan 20 or other fungicides? Might the leaf spotting be due to a bacterial infection instead?

As this is the last of my issues for the time being, I'd like to like to thank the members of this forum who helped me with previous posts. With luck I'll have some flowers to show for it this year, and will be sure to post them here.

 

It looks like I accidentally posted without adding any images. They've been included in this reply.

 

I've always been very, very careful not to get any water on the leaves. It's only occurring to me now that the source of the water droplets might be the condensation on the walls of the tank, which form very large droplets that make their way to the bottom. Perhaps some of these land on the leaves of the orchids.

I water in the afternoon, but perhaps I should work to water earlier in the day. When I talk about adding a fan to the setup, it will be indirect and won't be focused on the plants themselves. I guess the verdict then is that watering earlier and providing more air circulation will prevent these infections from occurring so frequently. I'll be sure to look into buying the Inocucor Garden Solution you mentioned before using Physan 20 on the plants and the terrarium itself.

The carnivorous plants I mentioned are actually Heliamphora hybrids, which are growing tall enough that the nectar spoons now reach the terrarium ceiling. I grow Nepenthes as well (seven total) and at least one representative from almost all carnivorous plant genera. I keep my miniatures in two separate terraria, both of which are located in a plastic greenhouse that contains my other orchids and carnivorous plants. I suppose the air circulation is better there, as I've never experienced any mold or bacteria problems with my non-terrarium plants.

Thanks for the advice

 

Got it. Thanks.