I had 9 perfectly healthy brug seedlings that I planted in the ground about 10 days ago. Ever since then, they have been falling over due to part of the stem dying. I've saved all of them by cutting off the bottom and repotting it. The first one I found a few days ago, is already putting out new leaves, and I also cut off the tops and put them in water to root.

Here's a picture of the damage. I thought at first of cutworms, but it's too far above the soil level and whatever it is isn't cutting the stems, just sucking the juice out.