Anyone confirm that this is spider mite damage? At first I thought it was sunburn, but now I'm not so sure. The area is sunken and is a very pale yellow. It appeared on two sections of this very nice, large TBM. Please help!!! Arggggg!!!

Thanks for the good photos. Good News I don't think it's mite damage.

Looks like sun burn. If it were mites I think you could probably see them on that last shot. I did notice on the weather report yesterday the UV index was extreme.

do you water during the day?

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Looks like sun burn.

That's a bit of relief! Well a big relief actually. Yeah I generally water in the day Kada mate, why?

The reason it looks wet is that I blasted it with water, hoping I might blast any mites away haha

yeah looks like sunburn to me... no need to worry. put it in the shade and of course don't wet the plant if you water in full sun in the middle of the day in hot weather. even better, water in late afternoon or early morning, or at night if you can see.
even if it was spider mite damage i wouldn't be overly concerned if it happened to my lone TBM coz these things seem to be pretty tough, lol she'll be right mate.. though i am rather biased seeing as i officially don't like these things ever since one their utterly lethal spines speared underneath my thumbnail pretty deep, drew blood and hurt like hell for weeks. hence the specimen in question has since been de-spined. if ya gonna get a monstrose get a FRED or LSM/totem pole (Lophocereus schottii monstrose), way cooler plants IMO.

it looks very much like what I have on a loph -

http://forum.auscactiforum.net/pests-diseases-id-control-prevention-f8/another-kind-of-rot-yay-t460.htm


I'm not sure what it is yet but isn't sunburn. (under fluros) I haven't seen any mites yet either.

I had some TBM that I bought with same kind of that pitting - I repotted them and gave TLC - the new growth looks healthy and the pitting didn't spread.

good luck