Small dark spots on Dendrobium Phalaenopsis leaves
 

Hi!
I have this Den Phal for 2 years now, and it has grown a nice new Pseudobulbs this season. But I noticed some spots on the leaves of the newest and the other growths. Not sure whet these can be, and how to treat it... any thoughts? Maybe Bacterial Brown Spot or Leaf Spot?
I live in Canada so I’m not sure what product I can use - we don’t have systemics.

Additional culture information: It spent summer outdoors (which explains the big brown patch, this is a sunburn) but I moved a month ago and it is now growing indoors under lights. I don’t see spots on other orchids near this plant. Temps vary between 23 and 28C And there’s a fan running all day, everyday. The roots look really healthy to me, but maybe the media doesn’t dry out entirely in between watering.

Thank you!

Everything I see is probably caused by mechanical damage, not fungus.

The first photo shows large patches of sunburn or heat damage.

The smaller spots are common on Dendrobiums grown in less than perfect conditions. It might be left-over damage from insects biting the leaves, or scraping the leaves when you moved them. I get them sometimes when I don't water soon enough.

Thank you!
I’m less worried now. I’ll spray with some,hydrogen peroxide just in case and try to provide better care. 🤞

It spread fast
 

Here’s a follow up on this - the plant quickly declined in a week and the leaves started to yellow and rot. I covered the whole plant in cinnamon until I could buy a fungicide I found locally, and sprayed the plant down. I cut the affected leaves.
Another Dendrobium got affected by something on the leaves and I sprayed it too.

Not sure what’s it is but I will be careful. Any advice appreciated!

The plant in the second photo isn't getting enough water. How long have you had it? When did you repot? How are you watering?