potatoes

Question

My potatoes have got a scab. These appear to been caused by minute white ‘worms.’

Answer 1

There is a disease called potato scab which is caused by bacteria, but insect or other invertebrate damage could cause the wounds that allow the bacteria in:

https://www.gardeningknowhow.com/edible/vegetables/potato/treating-scab-in-potatoes.htm
http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_Scab.htm

If those pictures don't match what your potatoes have, the "worms" you see might be nematodes, which can cause several diseases on potatoes. Some of the diseases cause a scabby appearance.

http://ipm.ucanr.edu/PMG/r607200111.html