Oncidium Yellow Leaf

[Josh]

Hello,

This smaller leaf in my Oncidium is turning yellow. What may this indicate? Too much light or too few? It's near an East facing window. This is a plant I rescued a month ago from a local greenhouse. I already repotted it and wasn't in very good shape as the wrinkly pseudo-bulb shows.

Attached photo as reference.

[Carkin]

Hi Josh,
I bought a couple oncidiums that were in rough shape too. I soaked the roots for a couple of hours and that helped plump up the old psuedobulb but even after that it still had a few wrinkles. My leaves leaves went yellow too but I think that is just the natural process of the old bulbs. Someone with more experience may correct me if I am wrong. But those old bulbs still have stored nutrients that will give energy to the new growth, which will be lush and green. I have mine in front of a southern window and they are very happy there, but I live in Canada were the sun is not too strong.

[Brooke]

Usually when you have a leaf turn yellow at the base rather than the tip, it indicates a slight bacterial infection. There could have been trapped water and an opportunistic bacteria set up housekeeping.

Remove the leaf, pour peroxide over the area and keep your fingers crossed it hasn't entered the pbulb.

Brooke

[Dendian]

I agree with Brooke - yellowing at the base is not good. I have had many many yellow from the tip back - but when they yellow from the base (and I see brown down there too) then it sounds more like rot. you might want to unpot and take a closer look at that side of the pbulb. If it is mushy then remove the whole bulb - hopefully the other bulbs will not be infected.

[Carkin]

Good observations Brooke and Dendian. I did not even notice where the yellow was starting from! You guys are real experts.

[orchidmainia]

how do you remove the mushy bulbs from the others?

[Dendian]

You would remove the plant from the pot - and cut off the mushy bulb with a sterile instrument dipped in Physan 20 or anti-fungal/bacterial solution. You can use cinnamon to seal off the cut area. However, if the rot is down in the base of the bulb on the other side - I would take off an additional pbulb that is not rotten - and be on the lookout for any dark spots where you cut - it could be a sign the rot has gone further than you can tell on the outside.
Then repot - keep on the dry side and