Cactus mites

[Herts Mike]

Cruel Tina.

It’s flowering ok.

[iann]

Mite damage starts as a characteristic mottled scarring, then merges together into a general light scarring. Heavy infestations can cause deeper scarring of the skin and eventually death of the plant.

Identification of the mite isn't so hard. Spider mites (Tetranychus) can be seen with the naked eye. They are a straw colour, not red. They are supposedly red during winter when they aren't feeding, but I've not seen it. They often have a dark spot on either side, just about visible with the naked eye on full-size adults. Young mites are essentially just small versions of the adults. Spider mites will rapid form dense colonies with webbing.

If you can't see any mites, then flat mites (Brevipalpus) are likely. You will need a lens, or possibly a macro camera, to spot them for sure. Large adults are just about visible to the naked eye when you know where to look, but not too good for identification. Under a lens, they are a dull orangey colour, slightly translucent-looking, not the bright red that appears in some photos. The front four legs tend to be visible facing forwards, the rear four legs facing backwards but harder to spot. They are very difficult to spot on densely-spined plants like some Mammillarias. Unless you're ridiculously vigilant then the first sign of them will be permanent damage that will continue to develop even if you instantly remove the mites. Flat mites cause damage out of all proportion to their size and numbers. Apparently their feeding methods kill more cells than spider mites.

I don't have any good photos, just a bit too small for my camera. I'm sure I've seen some here in the forum, perhaps someone could post? Orchid growers suffer from the same, or a very similar, mite, so you can find good info from them.

Resistance may be widespread, but they can certainly be controlled with miticides. Very few are legally available now, perhaps only the permethrins? Oil or soap sprays will also work obviously, but rely on contact and have no lasting effect. Eradication of spider mites is impossible because they will just reinfest from the background population. Eradication of flat mites should be possible because they aren't native, but you'd need to be very careful not to re-introduce them. And extra careful not to introduce them at all if you're lucky enough not to have any.

[rcapra]

The theme that Pattock has raised is of great importance. I would like to be able to read a report concerning the biological cycles of the main parasites. Brevipalpus is among these, in my experience, more than Tetranychus; my impression is that the lesions to the plants that form in the area not exposed to the sun are mainly related to Brevipalpus.
Ruggero

[Pattock]

Some species of Brevipalpus mites are known to transmit pathogenic viruses. They are also know to inject saliva into the plant which contains immune-response modulating proteins. In the case in this paper, they induce the salicylic acid mediated pathways to make colonisation of the plant easier.

https://www.frontiersin.org/articles/10 ... 01147/full

Lots of pages repeat the sentence: "Brevipalpus mites inject toxic saliva into fruits, leaves, stems, twigs, and bud tissues of numerous plants including citrus."

[rcapra]

this link may be relevant:
https://www.youtube.com/watch?v=wavSVEZ ... ningVideos

[habanerocat]

Some info here but may be a bit outdated now.

viewtopic.php?t=166990&hilit=red+spider+mite

[habanerocat]

Don't laugh. These actually work.
Not as strong as a X10 loop mind but handy enough....

external-content.duckduckgo.com.jpg (76.03 KiB) Viewed 830 times

[fatich]

What do you think about these red ones?
I havent seen any damage but i might use some killer.

[SimonT]

They are difficult to see of course but this does look like mites.
Although it seems like only a small number, there look like quite a few immature mites- the white dots that are not part of the pattern on the plant.

Out of interest, did you give this plant a cold rest over winter?

[Ali Baba]

What do you think about these red ones?
I havent seen any damage but i might use some killer.

It’s difficult to tell but they could well be Brevipalpus eggs