Phal and oncidium leaf spots identification

[shadowteme]

Hi everyone!

I need some help again I have three orchids with spotting/discoloration on their leaves (two phals and one oncidium type, all of them no ID), and the ones on the two phals are especially concerning to me. Some disease or fungal infection has recently killed a phal in a matter of days, and even though these spots look a bit different, they are spreading and I can't help but worry. They did share space and the small phal also shared water with this sick orchid before I noticed and started using separate containers.

Big phal:


Mini phal:


Oncidium:


There are no pests on any of them, no webbing no nothing. My growing conditions are on the dry side with 50% humidity, temperatures now ranging between 23-20°C. I water with rain water once a week and I never spray my orchids because I’m paranoid about causing crown rot.

Any advice/input is appreciated!

[estación seca]

This looks like bacterial brown spot, though that is more common at high temperatures. Have a look at the St Augustine Orchid Society page on diseases.

[Roberta]

As you have noted, sharing water is a really, really bad idea. That would have provided the route for the infection to get from the bad one into all the good ones. (Like sharing a toothbrush with random strangers... )

[shadowteme]

Originally Posted by Roberta

As you have noted, sharing water is a really, really bad idea. That would have provided the route for the infection to get from the bad one into all the good ones. (Like sharing a toothbrush with random strangers... )

Well it was more like sharing a toothbrush with a lover both orchids have been in my care for over a year, repotted in the same mix and thriving. It was all very random and quite sudden. Obviously I don't share water between new orchids and my established collection, but I can't keep a separate water container for 16 orchids.

---------- Post added at 08:26 PM ---------- Previous post was at 08:20 PM ----------

Originally Posted by estación seca

This looks like bacterial brown spot, though that is more common at high temperatures. Have a look at the St Augustine Orchid Society page on diseases.

Thanks! Unfortunately this looks very similar... I will def keep a close eye and start cutting if it gets any worse.

[Roberta]

Since orchids need to drain, perhaps consider a different approach. When watering, the water should flow through the pots - which pulls air into the root zone and flushes out crud. When I kept large numbers of orchids in the house, I used "egg crate" light diffuser (source, Home Depot or similar "home improvement" store) over bins to catch the water, The water in the bins raised humidity a bit, as it evaporated. Cleaned out the algae about every 6 months... not a big issue. Here's a picture of the setup: http://orchidcentral.org/GrowingAreas/indoor.jpg

[shadowteme]

Originally Posted by Roberta

Since orchids need to drain, perhaps consider a different approach. When watering, the water should flow through the pots - which pulls air into the root zone and flushes out crud. When I kept large numbers of orchids in the house, I used "egg crate" light diffuser (source, Home Depot or similar "home improvement" store) over bins to catch the water, The water in the bins raised humidity a bit, as it evaporated. Cleaned out the algae about every 6 months... not a big issue. Here's a picture of the setup: http://orchidcentral.org/GrowingAreas/indoor.jpg

That is a cool setup and a lot of orchids, wow. I usually soak them for about 5-10 mins then drain the pots and reuse the water a couple times. This method has been working perfectly for 10 years when I got my very first phal - which is still alive and well, currently in bloom - but it seems the more orchids I have and the more I feel I know about taking care of them, the more problems keep cropping up

Anyway, thanks for the tips, I'll be brainstorming alternative watering methods

[Diane56Victor]

I understand the risks of sharing water.
I use rain water for my orchids and after one unusally dry summer by the end of autumn I was really running low on rain water so I grouped plants together. I figured there was less risk sharing between the plants that had grown together for several years than subjecting them all to the rigours of town water.
I put maybe half a dozen in each group and shared water between them. I figured if anything were to happen at least it would be restricted to that particular watering group.
As soon as my water supply was restored I went back to individual watering but I would do the group watering again if needed.