What's wrong with my peas

[Sim2500]

http://imgur.com/a/yEhW80c

Started great, producing peas and then with the hot weather, leaves are wilting and new leaves are forming properly

This strain hurst green shaft so should be resistant to fusarium wilt

[ameno]

It's definitely pea wilt.
"Resistant" doesn't mean immune, and fusarium isn't the only thing which can cause foot rot (and subsequent wilt) in peas, anyway.
I get pea wilt really bad where I am. I have to grow short, early varieties, and even then I usually only get a single flush of pods from them, as half of the plants usually die before the second flush comes in.