Broad bean problem

Most of my beans are doing well, but a couple of days ago, one of them started looking a bit dodgy. The leaves just began to wilt, then the stem itself. Just one stem. All  the other stems from the same plant look well enough. There are beans just beggining to show on this stem, and flowers look ok. There are no obvious signs of anything amiss. No infestations. It's got enough water. I just dont want it to pass anything on to the other plants. Would it be best to oik it out?