Disease on my potatoes?

Hey Gardener's Corner peeps!
I've recently started to grow some potatoes, after having pretty good success with Carrots earlier in the year (some small plots in the backyard. Nothing fancy).

Anyways, they've been going from strength to strength until recently when I noticed a few issues cropping (pardon the pun...) up. Most notably, the leaves on most are starting to curl up and discolour slightly, while a few have black marks attached to them. I thought this was dirt at first, but it doesn't really want to budge.

I can't see any bugs or anything. At least not from a quick look. I only picked up on this a few days ago - been busy lately - so I'm not sure how long ago this started. Any thoughts or ideas? So far things have been running pretty smoothly, so this is my first time dealing with a veggie disaster. Will try and grab a pic later if I can, but my phone isn't that great :P

Thanks!

 

Sounds like you've got the start of blight. See this info from RHS :
Potato and tomato blight/RHS Gardening

 

Thanks! That's super interesting. I've been doing a bunch of searching today and saw it mentioned a few times.
I couldn't get a pic today, but this is probably the closest I could find online (source):



According to that site, this is Rhizoctonia. Though I'm still a little torn, as the leaves look more like the page you linked. I might have to do a little more digging (again, apologies for the puns...). Thanks for your help though!