Please help me figure out what caused this leaf damage

[jocierk]

So I discovered this while I was watering today. I have seen a much less severe version of this on some of my leaves (the damage on top of the leaves, not the white stuff on the bottom) before but never anything this advanced. The whitish stuff on the undersides doesn't scrape off at all. There is also a rusty colored powder in some spots that you can't really see in the pics but you can see it in the discoloration of the water drop (circled). The tops of the top leaves still look totally normal so I think that is how I haven't seen this until now. I honestly don't have a clue what this is and I have done some research and I can't find anything. I did have some spider mites for a little bit due to low humidity (we just moved and I have been working out how to keep up the humidity in the new space) but there were never very many of them and I haven't seen any at all for at least a few weeks now. Is this mite damage? Any help at all is greatly appreciated and please ask if you have any questions that will help diagnose. Thanks!

[King_of_orchid_growing:)]

I'm not sure if I'm correct, but they kinda look like a very, very severe infestation of spider mites.

You might want to grab a jeweler's loupe and start looking for little red spider-like creatures. Or little brown spider-like creatures.

Do not confuse springtails for spider mites. Although, quite honestly, if you do have springtails in your potting media, you need to change it out because the wood chips are most likely going bad.

[Judi]

I agree with Philip, I was also thinking spider mite damage.

Spider mites can be hard to eradicate--it is easy to think they have all been wiped out only to find some were missed and are taking over your collection.

[estación seca]

Once you have them, you have to treat for spider mites even if you don't see them. I don't like using pesticides unless I need to. A good squirt of water from a spray bottle to the undersides of leaves will work as a mite preventative most of the time. It knocks them off the plant and they're unable to climb back up. But when I see them I use rubbing alcohol. Be sure and treat plants around the victim that don't look like they're affected - they are. Rubbing alcohol doesn't eradicate them completely so you have to treat every 2-5 days depending on temperature - higher temperatures, more frequently. After a couple of weeks they'll be gone for a while. But they always come back, so you have to watch carefully.

[gngrhill]

Originally Posted by estación seca

Once you have them, you have to treat for spider mites even if you don't see them. I don't like using pesticides unless I need to. A good squirt of water from a spray bottle to the undersides of leaves will work as a mite preventative most of the time. It knocks them off the plant and they're unable to climb back up. But when I see them I use rubbing alcohol. Be sure and treat plants around the victim that don't look like they're affected - they are. Rubbing alcohol doesn't eradicate them completely so you have to treat every 2-5 days depending on temperature - higher temperatures, more frequently. After a couple of weeks they'll be gone for a while. But they always come back, so you have to watch carefully.

That's a depressing prognosis

[estación seca]

Originally Posted by gngrhill

That's a depressing prognosis

Well, it's just like... we have to wash our hands over and over again, and we have to brush our teeth over and over again... it's just a fact of life. Spider mites are well-established in cultivation, so we have to deal with them.

[Plodde]

This is something i am dealing with at the moment as well.
I foolishly brought an outdoor plant into my small indoor greenhouse. The plant had spider mites ; (. I took the plant out once i realized what was going on and hoped for the best.

Yesterday i found one spider mite on my Dendrobium Kingianum and a couple webs. AHHHHHHHHH. I couldn't even sleep last night i was so devastated.

Today i took everything out of my indoor greenhouse and scrubbed the walls and floors, sprayed bleach on everything and then whipped that down. Then sprayed bayer rose pest kill and let that sit then whipped everything again.

I rinsed all of my plants off, whipped their leaves with alcohol and sprayed the bayer rose pest killer on all the tops and bottoms of the leaves. Once everything was hung back up safely in the greenhouse i sprayed everything with neem oil.

This is something I will be doing again on Tuesday and then again on Friday and then again on Sunday.

I am hoping this is not something i will have to deal with forever. So many people seem to say this is a problem that once u have u have forever and i really hope this isn't the case.

[estación seca]

Originally Posted by Plodde

I am hoping this is not something i will have to deal with forever.

In desert areas there are a lot of excellent host plants for mites. If you ever open your greenhouse - for example, to walk through the door or to get some ventilation - mites can enter.

An entomologist friend told me the mites aren't native here but are firmly established. Mites don't like high humidity and can be washed off with plain water. Most people who spray their plants with water regularly don't have that much trouble with them. Imidacloprid isn't that effective on mites and isn't effective at all applied into the potting mix. Mites stay on plants so washing the structure isn't necessary. They are only mobile for a short period of their life cycle, which is why spraying with water works so well - they fall off the plant and can't climb back up.

After a cold winter they are almost absent outside here. But eventually their numbers build up. Some of their favorite host plants are things in the tomato family. Some people refuse to grow such things in an attempt to minimize mite problems, but I like to grow tomatoes, peppers and eggplant. Plus our native Datura, a host, is really pretty, and I wouldn't want to remove it from my property.

[silken]

Imidacloprid isn't a miticide. You need to use a pesticide that says it is a miticide or effective against mites. I have read that using imidacloprid (which I do use for scale) can help mites thrive because it kills their natural predators.

[Plodde]

The Bayer product does say it works against spider mites.