Just wondered if anyone could help me out with identifying a problem with my
brussel sprouts.

The plants are still quite small (approx. 9" high) and they have been out
for a couple of weeks. They have been looking really healthy up until now.
Last night I noticed that some of the plants seem to have small holes in the
leaves. Also, on the underside of some of the leaves are white flaky bits
which fall off when you touch the leaf. They don't look too bad at the
moment but I want to nip any diseases / pests in the bud at the early stage.
Any ideas (organic if possible)?

Jeannie