Colocasia blight probably

I’ve been so carefully growing three colocasias from bulbs in large pots. All three have sprouted well with the black magic already fairly tall with a large healthy leaf. The two green esculanta looked really promising with 4/5 sprouts coming up. I was planning on moving them from indoors to outside this week.  One has now been affected with something that I think might be blight. Rusty patch on the one leaf that came up and rust coloured areas sowing on all sprouts. I’ve moved them outside for ventilation and separated the pots. If this is the disease is there any way to save them now or write them off? Pic of the affected one - I removed the leaf