No, it is more likely sun burn. The same thing is happening to my plants, a couple of my tomatoes and peppers, they grow out of it.

Were they under weaker light before transplanting?

Describe the burn.

Fertilizer burn is going to usually just look like the tips of the leaves are dying (turning brown and crispy). Sunburn is going to look like the leaves are turning white but otherwise fine.

Yes they look like they are turning white. I brought them at a local nursery and didn't know i should harden them off first. It was pretty hot when I first put them out. It has cooled down now so hopefully they will recover? Should I remove burnt leaves? Thanks for your replies.

Do sunburnt plants usually come up burnt straight away or is it sometimes a delayed reaction?