blight notification

I was at the site yesterday and some-one casually mentioned there was blight in the potatoes.  Fortunately I only had earlies so no panic for me     this time,  BUT this is my first year growing and reading these posts it seems like a big deal  as this the plant equivalent  of a  communicable disease - how do other sites make people aware, is there any requirement to notify of blight, central national register etc?  could it be mistaken and how do you check / get it tested?

thanks DD, as ever