Phal Amadeus leaf lumps

[Kelo]

There are two leaves developing hard lumps or nodes on the under side of them. Any ideas why this is happening or what causes this?

[Bud]

If its spreading, it is scale infestation. Have an old soft toothbrush and a butter knife to scrape and clean it with alcohol or listerine(original)...

[Kelo]

I thought scale was only found on the surface of the leaves and brownish in colour? These lumps feel like they are plant tissue growth. I'll treat them anyway. Thank you!

Sorry, neglected to say that it's only on the keikis on a spike.

[tucker85]

I have those on a couple of orchids also. I don't believe it's scale but I don't know what it is. I would be interested to find out.

[Kelo]

I wonder if it's just a slight deformity?

[glengary54]

Kelo - If I assume that your temps in Scotland have gotten cooler, my first guess would be Oedema. A condition caused by overwatering during cool temps in which the plant roots take up more water than they can respire causing the cells to swell and extend. There is nothing that can be done, the bumps will not go away but as long as you correct the conditions it will not be an issue. If you do some research you will find that the bumps most times are described as blisters but in minor cases that is not always so, the plant simply form a "bump".

[Kelo]

It could well be oedema. I've been giving the spikes with keikis and flower spikes a little extra water so as they wont be stressed. There's one 1 inch root on this particular keiki so I may pot it up in the next week or so. I'm not unduly bothered about it, I was just wondering what it could be. Thanks for the information. I'll have a hunt around and see what I can find on line.

[Kelo]

Oedema is exactly what it is.

PP244/PP164: Physiological Disorders of Orchids: Oedema

[glengary54]

Glad I could help.