How do I treat white mould in newly established vegetable garden?

[John 3:16]

I used old straw to mulch the veggie patch but didn't realise the white stuff growing in it was white mould until I google imaged it. I have already watered it in and the white stuff blew everywhere like powder so even if I remove the straw it's likely the white stuff has got into seedlings.
What spray do I use?

I live in QLD Australia.