D.E.A.D Kesum!

I came back from Eid holiday only to find my kesum leaves brown and black. It seems to only affect young leaves. Sad day indeed. I pulled out one kesum to check the root, it is rooting all right but doesn't look happy. I replanted it in a pot.
My only pak choy on the other hand is growing but the leaves are yellowish. Still a long way to go for me and this project...