Is this Thrips?

[EmeraldMistress]

I posted these pictures to the orchid subreddit to ask what was going on with my new Oncidium. Someone suggested that the black dots are indicative of a thrips infestation. I’ve looked and looked all over the plant and can’t find any bugs. I tapped the leaves and flowers over a sheet of paper and didn’t see any fall off. I’ve blown into an open flower and didn’t see any moving around inside. But I’ve also lost several flowers in the week since I’ve brought it home; I assumed it was either from the change in environment causing early flower loss, or just that some of the flowers were near the end of their life span anyway. But now I wonder if the flower loss was due to the bugs. Either way, I want to be more confident that it is in fact thrips before I start treating it; no sense in spraying it with chemicals for no reason.

Someone else suggested unpotting it to check for root issues, and that’s definitely on my list of things to look at, but is also a bit more invasive. I was hoping to come here an hear about other ways I could check for thrips or perhaps another idea on what the issue was before I took the whole plant out of its pot. The third picture of the leaf with the spots on it wasn’t included in the Reddit post - I didn’t really notice it until I started looking really closely for the bugs, but I figured it might help to include it here for diagnostic purposes. Thank you!!

[claypot]

No. Either over fertilization or too dry atmosphere. Oncidiinae demand boyant atmosphere. The object to dry air.

[Roberta]

Agree with Claypot ... probably underwatering. Oncidiums (and relatives) need to stay a lot more damp than Phalaenopsis or Cattleyas. I'd suggest, giving the pot a really good bath under the faucet (so water runs through the pot) That will not only hydrate the medium, but also flush out any build-up of fertilizer sales, and pull fresh air into the root zone. Then, you can track the weight of the pot using a kitchen scale or postal scale, when the rate of weight loss starts to slow down (not much more water to lose), time to water again

[Dimples]

I wouldn’t jump straight to thrips either. Browning tips at the end of delicate leaves is very common in plants. Even with ideal culture it is likely to happen as leaves age. Inconsistent watering, increasing soluble salts in the media, lower humidity, root disfunction, among other factors can contribute to brown tips. There are some plants where it’s nearly impossible to avoid.

I don’t grow this type of orchid so can’t say if the stippling on the leaf is normal or not. If conditions allow, spraying the plant with plain water in the sink or shower can knock off pests and slow their population growth until you figure out if you need to treat. If it turns out you don’t have a pest problem, no biggie. Just make sure the plant dries off somewhat quickly after the shower.

[EmeraldMistress]

Originally Posted by Roberta

Oncidiums (and relatives) need to stay a lot more damp than Phalaenopsis or Cattleyas. I'd suggest, giving the pot a really good bath under the faucet (so water runs through the pot) That will not only hydrate the medium, but also flush out any build-up of fertilizer sales, and pull fresh air into the root zone.

I’ve been watering in this way pretty much every day, and I soaked it once last week with diluted fertilizer. The leaves are getting worse I’ve been thinking of making a humidity tray; do you think that would work? Should I just invest in an actual humidifier? Is there any chance this is residual sun damage from the shop I got it from? Either way once it’s done blooming and I repot it, I’m going to put some moss in with the bark to help keep it moist longer!

[Clawhammer]

Definitely not thrips.

[Dimples]

Humidity trays have been shown to be ineffective. If you find that you need to boost the humidity in the area/room/space a humidifier is a good choice.

You don't need one with lots of bells and whistles but the ability to set a target humidity level and have the device turn on/off automatically is really handy.

What is the humidity level currently? If your average humidity is at or over 40% that is typically sufficient for all but the pickiest of plants. In general, humidity is one of the less important aspects of growing plants. Address the other concerns first, then work on humidity if needed.

[estación seca]

Even if you can't see any I would treat for spider mites. Their damage can look just like this. They are very common on thin-leafed orchids when conditions are warm and arid, like most homes in winter. The easiest treatment is to take the plant to the shower and spray all surfaces with water. This dislodges adults and kills eggs. Do this every 3-5 days and see if it stops spreading. Once under control every 1-2 weeks should suffice.

[claypot]

Wow, no wonder you have problems watering every day. I would imagine the roots are so wet they cannot breathe then you soak thoroughly weekly with fertilizer - as I said first up - over fertilization. There is a difference between keeping moist and keeping wet. Plants need to dry out between waterings but not to total dryness. Watering weekly is more than adequate and remember the mantra about fertilizer........Orchids are very weak feeders so at most "feed weakly weekly". Remember that in the wild these plants are epyphytic living dangling supported on trees so get a chance to dry and breathe between rain - that is why we use open composts like bark so the roots can breathe.

[estación seca]

Oncidiums should not dry out completely. The original photos show a largish plant in pot small for that plant, in a bark mixture. In a winter-heated home in Tennessee I could imagine it possible an underpotted Oncidium in bark or LECA might need watering every day. Watering a plant potted like this under those low-humidity conditions once a week would not be enough.