What is causing this?

[Susie11]

Just today I noticed these strange markings on the bottom of the oldest leaves on my new Phalaenopsis amabilis grandiflora.







If anyone knows what is causing this I would love hear from you. There is no web that I can see however the other day I did see a tiny little red spider crawling up the spike. It looked like a spider and not a mite. It was last week and so far there has been no sign of any nest or any others that I can see. I would think that it was harmless. I often find spiders in my pots. I wonder if it might be mechanical damage? Humm....

[dounoharm]

it looks almost like the leaf was pinched together then released when it cracked......very odd, what does the top look like? have there been children around the orchids?

[Susie11]

The top looks fine -normal. There are no children here. As long as it's not a virus or a pest I don't mind. Thanks for your reply.

[Ray]

It does look like mechanical damage, but with some potential infection settling into the wounds.

[Susie11]

Thanks Ray. Oh dear. Shall I cut out the marks and rub cinnamon on it?

[PaphMadMan]

Unless you see it spreading I wouldn't worry about an infection. If you do see it spreading though, don't try to cut around it, just remove the leaf to about an inch below the lowest spot. Then brush the cut edge with cinnamon if you like. You're much better off removing the leaf than risking the whole plant by halfway measures.

[Susie11]

Thanks for the advice PaphMadMan! I shall keep an eye on it and remove if necessary.

[james mickelso]

It looks suspiciously like the tunnel of a leaf miner. My japanese maples and roses get damage just like this although I've never had any attack my orchids. just a thought.

[james mickelso]

Uhh....do you have a cat??? Bad kitty, bad kitty. 'Whack, whack'.

[Trini Kjeldz]

looks mechanical but like slight leaf miner but i wudnt worry too much if the problem doesnt continue