Orange Spots on Cactii

Hi,

Knocked off one of these sections so thought we could let it dry off and then plant up, but noticed it had some very small orange spots on it.
None noticed on the other nearby cactii.

With a glass could see loads more even smaller orange spots, so tried to see if we could move a larger one if it was a bug, but as you can see it pulled away from the plants flesh.

Is this normal for this plant or is it some form of Rust or as some sites suggest sunburn if any water spray had go on it ??

Assuming its worth planting up this time of year; should we water it in or let it root to seek out water, plus does it need bottom heat in our frost free (3-4C) greenhouse.
thanks.

 

My thought was rust, just something about the shape and colour, so I googled it and found this Rust fungus? - CactiGuide.com
Search https://www.google.com/search?client=firefox-b-d&q=cactus+rust
I don't remember seeing it on any of mine, but most come in over winter to 15°C and are kept very dry.

 

I think that may be one of the Opuntias that likes it slightly warmer, is it microdasys.

You can get something called orange rot, but not sure its that, caused by low temperature and humidity.

I certainly wouldn't be watering or trying to root cuttings at those temperatures.

 

Can put that plant and any cuttings into a dry heated propagator or indoors to see if it changes anything.

It does look quiet healthy otherwise, its only had a few nights of down to 3 or 4c before the heater kicks in (digitallly controlled)

 

I dont heat my cacti above a minimum of zero, I also dont water any after the end of September whatever the weather is like, mine are all bone dry now and some are a bit shrivelled but I wont be watering any until March at the earliest and only then if we get sunny days.
I'd just leave the cutting dry until the days get longer and warmer even if it shrivels it should be ok, within reason.
Maybe a sunny window sill indoors for that one and I'd still keep it on the dry side of damp.

 

Yes, they are all on the dry side, probably only lightly watered twice since October and then only during a sunny warm period.

The orange dots do seem separated unlike a Rust or Rot which you would assume more a spreading mass ; they do look like they are actively growing ..?

 

Well I wouldn'y like to guess really, Orange rot as I've heard is terminal usually, so I hope it isn't that, but I dont know what it could be.
Rust usually leaves an orange stain on your fingers.
Only other problem I'm finding is scab.