Potato Problem!

Hi All! Spotted some of our Maris Peer looking a bit poorly today, I don't think it's Blackleg  but it looks like something called Rosy Rustic moth which apparently occurs in new ground, it's not new ground (had onions in it last year) but it has been manured since then. Iv'e dug up the affected plants bagged and binned them. Any help would be appreciated, Ta, Ian.

Could be cutworms.  They chew stems at ground level.

Thanks aunt S, I just googled cutworm and I'm not ruling it out but I don't think so, they look quite noticeable and the damage is over quite a lot of stem and the stem seems hollow, I'll have another look tomorrow but keep  the suggestions coming, much appreciated. Ian

Thanks Yorkie, all the rest of our plants look fine, it was just three or four that looked sick, the seed looked OK, so I'm just going to keep an eye on the rest. I have another spud related topic to post tho. so I'll start a new thread. Cheers, Ian