I have been using a Sansi 36w LED grow lights to extend day length for some seedlings growing on a windowsill over the winter. I have this setup so it should gives PPFD 200uM/s/m2 according to the information that comes with this light. This a fairly modest intensity of light on paper but seemed to ...

Is there a recommended PPFD range for growing cacti from seed?

Cold treatment seems to be a good option as long as the plants with survive this. This might even kill eggs as well. In the UK I've never seem a mealy bug on outside plants- purely an indoor problem. Using cold is safe, saves money and is eco friendly. Perfect, just I'm not sure of the dose of cold ...

So what's been the best control method ever for these pests?
Were mealybugs easier to control with the old, now banned, insecticides or is this just a bad year?

How many seed do you sow per packet? This was my first year growing cacti from seed (in many years). I was growing mainly various Rebutia and I had no idea how well they would germinate or grow on. So I bought larger packets and ended up with the seedlings I wanted but I think I could of got by with...

I think it gives exact instructions on the SB site about using SB Invigorator against scale. I don't really know how these different approaches would compare. I guess just try and see if it works for you. You can get sooty mould with lots of sap sucking insects and they excrete excess sugars that th...

I think you'll hear lots of different preferences as to which pesticides to use but I found the general RHS guide quite useful. https://www.rhs.org.uk/advice/profile?PID=224 Personally I use Bug Clear Ultra if required. If you do have scale then it can be quite persistent and you might have to do mo...

It still look like scale to me.
You can get sooty mould with scale as they can produce honeydew which then starts the mould.
Scale also can blacken if you kill it- so it shows up better once pesticides have done their job!

Looks like scale insect to me.

This site might help to clarify... https://www.zengardentr.com/urun/frithia-pulchra-tohumu They are selling this plant "Frithia pulchra rote bluete seed dark lilac colored flowers meseb plant" (my Google translated from Turkish). So it looks as if the name is called "rote bluete"...