White scarring on the underside of Phalaenopsis leaves

[Wade Coleman]

One of my Phalaenopsis has some white colored scarring on the underside of a few of its leaves. When you rub it, nothing flakes off. The plant seems pretty unaffected by them and is actively growing new roots and two new leaves, but I’m worried it may be a cause for concern in the future.

[rbarata]

If you notice, Phals' leaves are like as if they are impermeable. When water fall on them it forms drops and doesn't wet them.
They are covered by a serum layer that sometimes have these spots (maybe from water splashes).
Nothing to worry about.

[camille1585]

It's always hard to tell from photos, but it looks like thrips damage. Have a very close look at those areas and near it, if it's thrips you may be able to spot their larvae (light yellow to white-ish, and very small, around 2mm long.). Adults are harder to spot because they fly off easily when disturbed. Thrips like to hide, so are very often on the underside of leaves.

[dangerouseddy]

some kind of a spider mite I would think, seen lots of damage like that. having had the displeasure of hosting false spider mites on some of my phals.

[Wade Coleman]

So how would I go about getting rid of these thrips/ spider mites?

UPDATE: upon further inspection I did notice TINY reddish orange critters on/ around the scarring.

[Roberta]

Spider mites! Soapy water, perhaps with some neem oil will knock them down temporarily, but will need to be repeated every 5 days or so for several weeks (or a couple of months) to get successive generations since it is only effective on the ones it contacts. Pyrethrin-contining pesticides are effective (and relatively low toxicity). Insecticides are not effective since these are arachnids not insects. (Bayer's Advanced 3-in-1 does contain a miticide along with the imadacloprid insecticide, but a small part of the formulation) Anything you use must be repeated for several weeks. It is best if you rotate approaches to prevent development of resistance.

[bethmarie]

I concur. Classic signature of the evil spider mite. Spider mites populations are something you want to stay on top of, so keep a close eye on the rest of your plants. Personally, I'd do a proactive soapy spray and rinse of any nearby plants.

[Wade Coleman]

Which soaps are safe to use? I have African Black Soap which is a natural organic soap made with these ingredients: palm oil, cocoa pod, palm kernel oil, coconut oil, unrefined Shaea butter, plantain skin ash, water, vitamin E, and natural sodium. Would this be safe to use on my plants? Also, would I have to apply just once to my other plants or a few times for a certain number of weeks?

[Roberta]

Pretty fancy soap... won't hurt the plants, but I'd suggest that simpler is better... either Safer's Soap (from any garden center... hint, don't use hard tap water with it to dilute or the calcium makes a mess) or plain old dishwashing detergent (maybe 1/2 teaspoon to a quart of water) On the plants other than the affected ones, vigilance is most important - you can spray once to be prophylactic about it, but if any sign of the little nasties shows up, multiple sprayings. Soap clogs the breathing pores of the mites (and insects as well) and drowns them... but it's not going to get all, and it doesn't touch the eggs. And no residual effect. So if there is even one left after treatment, unless you come back and nail it, the cycle starts all over again.

[Wade Coleman]

Okay nice info! So how do I know if/ when the notes are gone? Since they’re so tiny, how do I know if I’ve gotten them all?