Yellowing leaves on Onciduim? - Orchid Board

greenpassion · #1 09-07-2011, 02:54 PM

I am almost sure that the orchid in question is an oncidium. That said, I think I may have a problem. Several leaves have begun to yellow. I don't think they're new leaves, which is a good sign, but I worry I'm doing something wrong.

I repotted it in a good mix made for oncidiums, and have it under LED 60 diode grow lights, on a humidity tray. (I don't have window light) Am I overwatering it? I think oncidiums like more water than phals, but I'm wary of sticking something down into the pot to check for moisture-I'm afraid I'll hurt the roots!

Wjs2nd · #2 09-07-2011, 08:02 PM

I believe they grow pretty much like phals. Is the yellowing starting at the tips or the crown? How close is it to the grow light? I wonder if it's getting to much light.

silken · #3 09-07-2011, 11:15 PM

Some pictures would help. A kabob skewer gently pushed into the pot won't do damage and can tell you a lot about how wet it is in the centre and bottom of the pot.

camille1585 · #4 09-08-2011, 04:25 AM

Do you have any photos? Oncidiums will lose a few leaves once in a while, so it could be normal.
Don't be afraid to put a wooden skewer in. If you wriggle it in gently the damage will be minimal, and then each time you take it out you just put it back in the same hole.

greenpassion · #5 09-08-2011, 10:53 AM

Quote:

Originally Posted by Wjs2nd

I believe they grow pretty much like phals. Is the yellowing starting at the tips or the crown? How close is it to the grow light? I wonder if it's getting to much light.

There are 2 leaves now that are yellowing all along one side of the leaf. I can't tell if it's starting at the crown or not, but it's happened pretty quickly. Yesterday they were nothing like this...

silken · #6 09-08-2011, 11:06 AM

They can also turn yellow quickly. How long have you had this plant? How were the roots when you re-potted? Oncidiums usually do like to be watered just before drying out, but they still need a well draining media. It depends on the hybrid as some like more light than others.

As already mentioned, some photos of the plant and media might help. they will lose the outer leaves on the oldest pseudobulbs first usually.

tucker85 · #7 09-08-2011, 11:49 AM

Oncidiums do not need more water than phals.. As a general rule orchids with psuedobulbs come from environments where they need to get through periods with little or no water. Oncidiums prefer to get fairly dry between waterings but not for as long as cattleyas. They have thinner roots and they don't appreciate long periods without water. I let my oncidiums dry completely before watering again but I don't let them stay dry long. Having said that, most oncidiums do occasionally have leaves that turn yellow even when the plant is well grown.

greenpassion · #8 09-10-2011, 10:28 AM

I was told by someone that it could be spider mites. I've got 2 pics but I don't know if they're helpful...

RosieC · #9 09-12-2011, 09:48 AM

I'm not expert on this, so really just giving you a

However the second picture looks just like normal browning I get on older Oncidium leaves.

tucker85 · #10 09-12-2011, 10:35 AM

It certainly couldn't hurt to spray for spider mites. A routine that I do twice a year now is to spray all parts of the plant (including both sides of each leaf) with a horticultural oil. I use one called Organicide. Then a week later I spray the same way with a horticultural soap. I use Safer's Insecticide Soap. Good luck.