Yellow spots forming on leaves of Howarea

[Keiki Paste]

This has been progressing. I've had it outside in shade/dappled sunlight for about 6 weeks. The brown specks extend under the leaf a bit, but do not correspond with the yellow spots on top.

They were in a sphagnum/bark mix and I transferred them to full water culture when I saw this happening. They've been in Hydroton for about a 12 days and one pb is sending up a new growth.

I've not been able to find this type of leaf patterning in the two books I have, or the sticky on this site. At least not a match that I could make... Any ideas? I have it inside next to my bed right now, with western afternoon sun through the wood blinds.

[estación seca]

Oncidium hybrids are prone to spotting. I don't know enough to tell whether this represents a bacterial or fungal infection, or is dying tissue around an injury of some sort.

The brown center is the already-dead portion, while the yellow zones are the zone where cells are collapsing now. If a pathogen, it has already likely spread past the yellow zones.

The St Augstine Orchid Society has a good page on diseases.

I personally wouldn't repot an orchid I thought might be diseased into semi-hydroponic or water culture. A lot of diseases spread via water droplets. I might repot into new bark or LECA in a regular pot, but only if the old potting medium were so bad the plant needed the repotting to survive the pathogen attack.

[silken]

My Howeara Lava Burst has similar looking spots on last year's leaves. The new growth is clear of spots and it is in spike. I don't know what causes it but I don't get water on the leaves and as mentioned above I too find that some Oncidiums tend to do this. And then others don't. This was grown in the greenhouse all summer so it may be heat stress, but not likely a pest as there aren't the usual outdoor insects in the greenhouse and there is no evidence of a bug of any sort. I don't like spots, but I just accept them.

[Keiki Paste]

Thanks, estacion seca, for that link! It looks to me like I might have mites. I'm going to try the home made oil soap wash some time this week.

And I didn't intend to repot it. On watering day, I picked it up by the plant, and the pot fell right off. I didn't have any bark so I decided to just put it in water until I got some. After I cleaned the roots, I grabbed the first thing I saw, which was a little, shallow pinch bowl from the cupboard to set it in while it was still wet... and what a pretty display it made!! So I've kept it there, stabilized with the Hydroton. I'm going to see it I can keep it this way because I really like the look.



---------- Post added at 11:56 AM ---------- Previous post was at 11:53 AM ----------

These were outside on a table under an umbrella at all times. It's been pretty rainy and humid and everyone is doing very well outdoors, but I started to get the feeling that this Howarea was too warm. It seems to have perked up slightly since been inside, about 2 weeks.

I'm going to try a mite treatment and cross my fingers!