What is WRONG with my Garden Wednesday

Help! There's something wrong with my garden. One of our 4 x 4 square foot above ground containers seems to have come down with something and it is even jumping the container and heading towards my spinach in the next box over! It appears to have started in the swiss chard with just a few leaves looking dried




and then spread from there.....



to my bean bush, and like I said, seems to have jumped the container to the first couple leaves of spinach nearby.

I'm not a gardener so I'm looking for answers from those of you that know more than I do. The problem started in the container that has sweet corn and I know that they are known for having diseases so I am wondering if that might be the problem. Also, in case it'll help diagnose the problem, it's been pretty wet here.

I'd love some advice. I'm going to go out there and take off all the affected leaves and hope that helps.

Help me....

SAVE THE CHARD! SAVE THE CHARD! SAVE THE CHARD!