Two choices, either it is a fungus or it is Root aphids. Look very closely at the white stuff on the roots, the aphids are almost the same colour and hard to see. If they are there then wash the roots bare and repot in fsh compost and water with Provado Vine Weevil Killer.
If no bugs then water with a systemic Fungicide.

primula often have a 'mealy' floury appearance on the stem and buds. is this what you mean. roots though could be root hairs. or aphids as owdboggy suggests. A photo would help.

The farina on Auriculas is usually confined to the flowers rather than on the roots though.

it is definitely on the roots and where the compost lays up against the stem, also could any suggest a systemic fungicide that would clear up the problem
if it is a fungus please?

Not sure what ones are available now. I use Copper sulphate which is good and reasonably organic, but not systemic. Have a look in the appropriate section of any good Garden Centre.